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Title: Locomotive Engine Running and Management
Author: Sinclair, Angus
Language: English
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[Illustration]
LOCOMOTIVE ENGINE
RUNNING AND MANAGEMENT:
A Treatise on Locomotive Engines,
SHOWING THEIR PERFORMANCE IN RUNNING DIFFERENT
KINDS OF TRAINS WITH ECONOMY AND DISPATCH;
ALSO DIRECTIONS REGARDING THE CARE,
MANAGEMENT, AND REPAIRS OF
LOCOMOTIVES AND ALL
THEIR CONNECTIONS.
BY
ANGUS SINCLAIR,
MEMBER OF THE BROTHERHOOD OF LOCOMOTIVE ENGINEERS, MEMBER OF THE
AMERICAN SOCIETY OF MECHANICAL ENGINEERS, ASSOCIATE MEMBER
OF THE AMERICAN RAILWAY MASTER MECHANICS’ ASSOCIATION,
ASSOCIATE MEMBER OF THE UNITED
STATES NAVAL INSTITUTE, ETC.
_TENTH EDITION._
NEW YORK:
JOHN WILEY AND SONS.
1888.
COPYRIGHT, 1884,
BY JOHN WILEY & SONS.
ELECTROTYPED AND PRINTED
BY RAND, AVERY, AND COMPANY,
BOSTON, MASS.
PREFACE.
While following the occupation of a locomotive engineer, I often
observed peculiarities about the working of my engine, while running,
that I did not entirely understand. As I was perfectly aware, even
before making my first trip on a locomotive engine, that there is no
effect without a cause, I never felt satisfied to accept any thing
as incomprehensible without investigation, and fell into the habit
of noting down facts about the working of the engine, with the view
of studying out, at leisure, any thing which was not quite clear.
When, some years ago, I abandoned engine-running to take charge of
the round-house at the mechanical headquarters of the Burlington,
Cedar Rapids, and Northern Railway, in Iowa, the practice of keeping
notes was continued. The work connected with the ordinary repairing
of running-engines, the emergency repairing executed to get engines
ready hurriedly to meet the traffic demands on a road then chronically
short of power, and diagnosing the numerous diseases that locomotives
are heir to, provided ample material for voluminous notes. Those notes
formed the raw material from which this book was constructed.
The original intention was, to publish a book on Locomotive Engine
Running alone, and the first portion of the work was prepared with
that idea in view; but, before the articles were finished, I joined
the editorial staff of the _American Machinist_. The correspondence in
the office of that paper convinced me that an urgent demand existed,
among engineers, machinists, and others, for plainly given information
relating to numerous operations connected with the repairing and
maintenance of locomotives. To meet this demand, the chapters on
“Valve-Motion” and all the succeeding part of the book were written.
Most of that matter was originally written for the pages of the
_American Machinist_, but was afterwards re-arranged for the book.
In preparing a book for the use of engineers, firemen, machinists,
and others interested in locomotive matters, it has been my aim to
treat all subjects discussed in such a way that any reader would
easily understand every sentence written. No attempt is made to convey
instruction in any thing beyond elementary problems in mechanical
engineering, and all problems brought forward are treated in the
simplest manner possible.
The practice of applying to books for information concerning their
work, is rapidly spreading among the engineers and mechanics of this
school-spangled country; and this book is published in the hope that
its pages may furnish a share of the needed assistance. Those men, who,
Socrates-like, search for knowledge from the recorded experience of
others, are the men, who, in the near future, will take leading places
in our march of national progress. To such men, who are earnestly
toiling up the steep grade of Self-help, this book is respectfully
dedicated.
ANGUS SINCLAIR.
NEW YORK CITY,
Jan. 1, 1885.
PREFACE TO THE THIRD EDITION.
I desire to thank the railroad world and the technical press for
the kind reception they have extended to my book. The necessity for
publishing the third edition within three months after the first one
was issued, indicates that the book was wanted.
In the present edition I have corrected a few errors, and made some
necessary alterations, that will add to the value of the book.
ANGUS SINCLAIR,
NEW YORK, April 6, 1885.
CONTENTS.
CHAPTER I.
PAGE
ENGINEERS AND THEIR DUTIES 1
Attributes that make a Good Engineer.--How Engineering
Knowledge and Skill are Acquired.--Public Interest in
Locomotive Engineers.--Ignorance _versus_ Knowledge.--
Illiterate Engineers not wanted in America.--Growing
Importance of Engineers’ Duties.--Individuality of
American Engineers.--Necessity for Class Improvement.--
The Skill of Engineers influences Operating Expenses.--
Methods of Self-improvement.--Observing Shop Operations.--
Where Ignorance was Ruin.--Prejudice against studying
Books.--The Kind of Knowledge gained from Books.
CHAPTER II.
HOW LOCOMOTIVE ENGINEERS ARE MADE 11
Reliable Men needed to run Locomotives.--Early Methods
of making Locomotive Engineers.--Practice of raising
Engineers from Machinists and Technical-school Graduates
not found satisfactory.--Experience demonstrated that
Firemen made the Best Engineers.--Difficulties of running
Locomotives at Night, and during Bad Weather.--Kind of
Men to be chosen as Firemen.--Modern Methods of selecting
Firemen.--First Trips.--Popular Misconception of a
Fireman’s Duties.--Learning Firemen’s Duties.--A Good
Fireman makes a Good Engineer.--Learning an Engineer’s
Duties.--Conditions of Engine Running that vanquish the
Inexperienced Man.--Learning to keep the Locomotive
in Running-order.--Methods of Promotion on our Leading
Roads.--Nature of Examination to be passed.--Master
Mechanics on the Best Method of Educating Young Men for
Engineers.
CHAPTER III.
INSPECTION OF THE LOCOMOTIVE 30
Locomotive Inspectors.--Good Engineers Inspect their own
Engines.--What comes of neglecting Systematic Inspection
of Locomotives.--Confidence on the Road derived
from Inspection.--Inspection on the Pit.--Outside
Inspection.--Oil-cups.--Inspection of Running-gear.--
Attentions to the Boiler.--Miscellaneous Attentions.--
Reward of Thorough Inspection.
CHAPTER IV.
GETTING READY FOR THE ROAD 39
Raising Steam.--Precautions against Scorching Boilers.--
Starting the Fire.--Fireman’s First Duties.--Saving the
Grates.--Supplies.--Engineer’s First Duties.--Reaching
his Engine in Good Season.--Oiling the Machinery.--
Quantity of Oil that Different Bearings need.--Leaving the
Engine-house.
CHAPTER V.
RUNNING A FAST FREIGHT TRAIN 48
Running Freight Trains.--The Engine.--The Train.--The
Division.--Pulling out.--Hooking back the Links.--
Working the Steam Expansively.--Advantage of Cutting-off
Short.--Boiler Pressure Best for Economical Working.--
Running with Low Steam.--The Throttle-lever.--Management
of the Fire.--Conditions that demand Good Firing.--
Highest Type of Fireman.--Scientific Methods of Good
Firemen.--The Medium Fireman.--The Hopelessly Bad
Fireman.--Who is to Blame for Bad Firing?
CHAPTER VI.
GETTING UP THE HILL 61
Special Skill and Attention required to get a Train up a
Steep Grade.--Getting Ready for the Grade.--Working
up the Hill.--Wheel-slipping.--How to use Sand.--
Slippery Engines.--Feeding the Boiler.--Choice of Pump
and Injector.--Fall of Boiler-temperature not indicated
by the Steam-gauge.--Some Effects of Injudicious
Boiler-feeding.--Careful Feeding and Firing preserve
Boilers.--Operating the Dampers.--Loss of Heat through
Excess of Air.--Loss of Heat from Bad Dampers.
CHAPTER VII.
FINISHING THE TRIP 74
Running over Ordinary Track.--Stopping-places.--Knowledge
of Train-rights.--Precautions to be observed in
approaching and passing Stations.--The Best Rules must be
Supplemented by Good Judgment.--Operating Single Tracks
Safely.--Causes of Anxiety to Engineers.--Acquaintance
with the Road.--Final Duties of the Trip.
CHAPTER VIII.
RUNNING A FAST PASSENGER TRAIN 82
Average Speed.--Speed between Jersey City and
Philadelphia.--Requisites of a High-speed Locomotive.--
Making up the Fire.--Getting ready for the Trip.--The
Train to be pulled.--The Start.--Getting the Train over
the Road.--How the Engineer did his Work.--Qualifications
that make a Successful Engineer.--How the Firing was done.
CHAPTER IX.
HARD-STEAMING ENGINES 92
Importance of Locomotives Steaming Freely.--Essentials for
Good-steaming Engines.--Causes Detrimental to making
Steam.--Petticoat-pipe.--The Smoke-stack.--Obstructions
to Draught.--Choking the Netting with Oil.--Silicious
Deposit on Flue-sheet.--The Extended Smoke-box.--
Steam-pipes leaking.--Defects of Grates.--Lime, Scale,
and Mud.--Preventing Accumulation of Mud in Boilers.--
Temporary Cures for Leaky Flues.--Good Management Makes
Engines Steam.--Intermittent Boiler-feeding.--Too Much
Piston Clearance.--Badly Proportioned Smoke-stacks.--The
Exhaust Nozzles.
CHAPTER X.
SHORTNESS OF WATER.--PUMP DISORDERS 109
Trouble develops Natural Energy.--Shortness of Water a
Serious Predicament.--How to deal with Shortness of
Water.--Watching the Water-gauges.--What to do when
the Tender is found empty between Stations.--A Trying
Position.--Watching the Strainers.--Care of Pumps.--
How the Condition of Pumps can be tested.--Lift of
Pump-valves.--Keep Pipes tight, and Packing in Order.--
Sand in the Pump-chambers.--Delivery Orifice choked with
Lime Sediment.--Minor Pump Troubles.
CHAPTER XI.
INJECTORS 119
Invention of the Injector.--Trying to find out how the
Injector worked.--The Principle of the Injector’s
Action.--Different Forms of Injector.--A Heater-pipe
acting as an Injector.--Skill and Reflection Needed in
Repairing Injectors.--Care of Injectors.--The Most Common
Causes of Derangement.--How to Keep an Injector in Good
Order.--Curious Cases of Trouble with an Injector.--
Common Defects.--Care of Injectors in Winter.--Sellers
Injector.--The Nathan Manufacturing Company’s Monitor
Injector.--The Korting Injector.--The Hancock Inspirator.
CHAPTER XII.
BOILERS AND FIRE-BOXES 136
Care of Locomotive Boilers.--Factor of Safety.--Boiler
Explosions.--Preservation of Boilers.--Causing Injury
to Boilers.--Dangers of Mud and Scale.--Blowing off
Boilers.--Over-pressure.--Relieving Over-pressure.--
Bursted Flues.
CHAPTER XIII.
ACCIDENTS TO THE VALVE-MOTION 143
Running Worn-out Engines.--Care and Energy defy Defeat.--
Watching the Exhaust.--The Attentive Ear detects
Deterioration of Valves.--Locating the Four Exhaust
Sounds.--Identifying Defects by Sound of the Steam.--
Accidents Prevented by attending to the Note of Warning
from the Exhaust.--Neglecting a Warning.--How an
Eccentric-strap Punched a Hole in a Fire-box.--Interest
in the Valve-motion among Engineers.--Trouble with the
Valve-motion.--A Wrong Conclusion.--Locating Defects of
the Valve-motion.--Position of Eccentrics.--Method of
Setting Slipped Eccentrics.--Slipped Eccentric-rods.--
Detecting the Cause of a Lame Exhaust.--What to do when
Eccentrics, Straps, or Rods Break.--Different Ways of
securing the Cross-head.--Broken Tumbling-shaft.--
Broken Valve-stem, or Valve-yoke.--When a Rocker-shaft
or Lower Rocker-arm Breaks.--Miscellaneous Accidents to
Valve-motion.--Broken Steam-chest Cover.--Steam-pipe
Bursted.--Testing the Valves.
CHAPTER XIV.
ACCIDENTS TO CYLINDERS AND STEAM CONNECTIONS 162
Importance of the Piston in the Train of Mechanism.--Causes
that lead to Broken Cylinder-heads.--Broken Cylinder-heads
often Preventable.--When a Main Rod breaks.--Crank-pin
broken.--Throttle disconnected.--Oiling the Valves when
the Throttle is Disconnected.--What causes a Disconnected
Throttle.--Bursting a Dry Pipe.--Other Throttle
Accidents.--Pounding of the Working-parts.--Some Causes
of Pounding.--Locating a Mysterious Pound.
CHAPTER XV.
OFF THE TRACK.--ACCIDENTS TO RUNNING-GEAR 172
Getting Ditched.--Dealing with Sudden Emergencies.--
Stopping a Freight Train in Case of Danger.--Saving the
Heating Surfaces.--Getting the Engine on the Track.--
Understanding the Running-gear.--Broken Driving-spring.--
Equalizer Broken.--Accidents to Trucks.--Broken Frame.--
Broken Driving Axles, Wheels, and Tires.
CHAPTER XVI.
CONNECTING-RODS, SIDE RODS, AND WEDGES 182
Care of Locomotive Rods.--Functions of Connecting-rods.--
Effects of Bad Fitting.--Striking Points and Clearance.--
Watching Rods on the Road.--Side Rods.--Adjustment of
Side Rods.--Keying Side Rods.--Difficulty in locating
Defects.--Pounding in Driving-boxes and Wedges.--
Importance of having Wedges properly Fitted.--Influence of
Half-round Brasses.--Position of Boxes while setting up
Wedges.--Necessity for keeping Boxes and Wedges Clean.--
Temperature of the Box to be considered.--Small Disorders
that cause Rough Riding.
CHAPTER XVII.
THE VALVE-MOTION 199
The Locomotive Slide-valve.--Invention and Application
of the Slide-valve.--Description of the Slide-valve.--
Primitive Slide-valve.--Outside Lap.--Some Effects of
Lap.--Inside Lap.--The Extent of Lap usually adopted.--
First Application of Lap.--The Allen Valve.--Advantages
of the Allen Valve.--Case where the Allen Valve proved
its Value.--Inside Clearance.--Lead.--Operation of
the Steam in the Cylinders.--Back Pressure in the
Cylinders.--Effect of too Much Inside Lap.--Running into
a Hill.--Compression.--Definition of an Eccentric.--
Early Application of the Eccentric.--Relative Motion of
Piston and Crank, Slide-valve, and Eccentrics.--Attempts
to Abolish the Crank.--Valve Movement.--Effect of
Lap on the Eccentric’s Position.--Angular Advance of
Eccentrics.--Angularity of Connecting-rod.--Effect on
the Valve-motion of Connecting-rod Angularity.--Aids
to the Study of Valve-motion.--Events of the Piston
Stroke.--What Happens Inside the Cylinders when an Engine
is Reversed.--Events of the Stroke in Reversed Motion.--
Purpose of Relief-valve on Dry Pipe.--Using Reverse-motion
as a Brake.
CHAPTER XVIII.
THE SHIFTING-LINK 229
Early Reversing Motions.--Invention of the Link.--
Construction of the Shifting Link.--Action of the Link.--
Valve-motion of a Fast Passenger Locomotive.--Effect of
changing Valve-travel.--Weak Points of the Link-motion.--
Why Decreasing the Valve-travel Increases the Period of
Expansion.--Influence of Eccentric Throw on the Valve.--
Harmony of Working-parts.--Adjustment of Link.--Slip of
the Link.--Radius of Link.--Increase of Lead.
CHAPTER XIX.
SETTING THE VALVES 246
The Men who learn Valve-setting.--Best way to learn
Valve-setting.--Preliminary Operations.--Connecting
Eccentric-rods to Link.--Marking the Valve-stem.--Length
of the Valve-rod.--Accuracy Essential in Locating the Dead
Center Points.--Finding the Dead Centers.--Turning Wheels
and Moving Eccentrics.--Setting by the Lead Opening.--
Ascertaining the Point of Cut-off.--Adjustment of Cut-off.
CHAPTER XX.
LAYING OUT LINK-MOTION 257
Preliminary Explanations.--Definition of Terms used.--
Conditions.--Problems Involved in Laying Out
Link-motion.--To find the Position of Crank when the
Piston is at Full and Half Stroke.--To find the
Center Line of Motion and the Amount of Offset in the
Lower Rocker-arm.--To find the Relative Positions of
Crank-pin and Eccentrics when the Piston is at Full and
Half Stroke.--To determine the Correct Length of the
Eccentric-rods.--To find the Position of the Center
of Saddle-pin.--To Find the Position of the Center of
Lifting-shaft and the Length of its Arms.--Dimensions of
Locomotives.
CHAPTER XXI.
THE STEVENS VALVE-GEAR 287
Description of Motion.--Arrangement of the Motion.--Valve
Movement.--Valve-stems and Stuffing-boxes.--How Movement
of Valve is Governed.--How Exhaust Lead is Controlled.
CHAPTER XXII.
THE JOY VALVE-GEAR 292
Description of Motion.--How to Apply this Gear to American
Locomotives.--Construction Directions.--How Lap and Lead
are Regulated.--Advantages claimed for the Motion.--
Action of the Motion.--Rules for laying down the Center
Lines of the Motion.
CHAPTER XXIII.
THE STEAM ENGINE INDICATOR 303
Purpose of the Indicator.--Description of Instrument.--
Operation of the Indicator.--Lines of the Diagram.--
Data Necessary for Analyzing the Diagram.--Advantages of
Indicating Locomotives.
CHAPTER XXIV.
THE WESTINGHOUSE AIR-BRAKE 309
Invention of the Westinghouse Atmospheric Brake.--Distinct
Classes of Inventions.--Benefits conferred on Train
Men by Good Brakes.--First Trials of the Westinghouse
Atmospheric Brake.--First Roads that Adopted the
Westinghouse Brake.--Outlines of the Atmospheric Brake.--
How Eastern Railroads kept aloof from the Westinghouse
Brake.--Lesson of the Revere Railroad Accident.--Weak
Points of the Atmospheric Brake.--The Westinghouse
Automatic Air-brake.--Life-saving Value of the Automatic
Brake.--First Railroads that adopted the Westinghouse
Automatic Air-brake.--Essential Parts of the Westinghouse
Automatic Air-brake.--The Air-pump.--How the Air-pump
Works.--How the Air-end Operates.--Air-pump Disorders.--
Puny Difficulties Vanquish the Ignorant Engineer.--Causes
that make Brakes Inoperative often Easily Remedied.--Care
of the Air-pump.--Pump Packing.--How Steam Passages get
Choked.--Sagacity needed in Repairing Air-pumps.--Gradual
Degeneration of the Air-pump.--Causes that make a Pump
Pound.--The Triple Valve.--Action of the Triple Valve.--
To prevent creeping on of Brakes.--How to Apply and
Release the Brake.
CHAPTER XXV.
THE EAMES VACUUM BRAKE 341
Efficiency of the Brake on the Elevated Railroads.--
Operation of the Brake.--The Diaphragm.--The Ejector.--
Care of the Brake.
CHAPTER XXVI.
POWER OF LOCOMOTIVES AND TRAIN RESISTANCES 346
Calculating Power of Locomotives.--Proportion of Adhesion
to Traction.--Estimating Tractive Power.--Horse-power of
Locomotives.--Formulas of Train Resistances.--Experiments
of Train Resistances on the Erie Railway.--Conditions that
Increase Train Resistances.--Resistance of Curves.--Work
done by a Locomotive pulling a Train.--Record of Fast
Express Train made by Professor P. H. Dudley’s Dynagraph
Car.--Calculations of Weight of Trains that Locomotives
can Pull.
CHAPTER XXVII.
WATER FOR LOCOMOTIVE BOILERS 359
How Water gets mixed with Lime.--Expense entailed by
using Bad Water.--Efforts of Master Mechanics to secure
Good Water.--Loss of Faith in Purifying Methods.--
Scale-making Agencies.--To Ascertain the Quality of
Water.--Appliances needed in Testing Water.--Preparing
for the Experiments.--Lime held in Solution by Free
Carbonic Acid.--Test for Lime Salts.--Test for Sulphate
of Lime.--Test for Carbonate of Magnesia.--Test for Salts
of Iron.--Test for Chlorine.--Learning the Manipulation
of Tests.--Making Qualitative Tests.--The Soap-test for
Hardness.--Modification of the Clark Soap-test.--Applying
the Soap-test.--Difficulties of purifying Water for
Locomotives.--Mud.--Carbonate of Lime.
CHAPTER XXVIII.
EXAMINATION FOR LOCOMOTIVE ENGINEERS 376
Principal Duties of an Engineer.--Carrying Water
in Boiler.--Procedure when Short of Water.--
Boiler-foaming.--Disconnecting the Engine.--Slipping an
Eccentric.--Breaking a Valve-yoke.--Cylinder-packing
Blowing.--Broken Rocker-arm.--Broken Link-hanger.--
Broken Side Rods.--Throttle Disconnected.--Broken Tires.
LOCOMOTIVE ENGINE RUNNING.
CHAPTER I.
_ENGINEERS AND THEIR DUTIES._
ATTRIBUTES THAT MAKE A GOOD ENGINEER.
The locomotive engine which reaches nearest perfection, is one which
performs the greatest amount of work at the least cost for fuel,
lubricants, wear and tear of machinery, and of the track traversed:
the nearest approach to perfection in an engineer, is the man who can
work the engine so as to develop its best capabilities at the least
cost. Poets are said to be born, not made. The same may be said of
engineers. One man may have charge of an engine for only a few months,
and yet exhibit thorough knowledge of his business, displaying sagacity
resembling instinct concerning the treatment necessary to secure the
best performance from his engine: another man, who appears equally
intelligent in matters not pertaining to the locomotive, never develops
a thorough understanding of the machine.
HOW ENGINEERING KNOWLEDGE AND SKILL ARE ACQUIRED.
A man who possesses the natural gifts necessary for the making of a
good engineer, will advance more rapidly in acquiring mastery of the
business than does one whom Nature intended for a ditcher. But there
is no royal road to the knowledge requisite for making a first-class
engineer. The capability of handling an engine can be acquired by a few
months’ practice. Opening the throttle, and moving the reverse lever,
require but scanty skill; there is no great accomplishment in being
able to pack a gland, or tighten up a loose nut; but the magazine of
practical knowledge, which enables an engineer to meet every emergency
with calmness and promptitude, is obtained only by years of experience
on the footboard, and by assiduous observation while there.
PUBLIC INTEREST IN LOCOMOTIVE ENGINEERS.
Ever since the incipiency of the railroad system, a close interest has
been manifested by the general public in the character and capabilities
of locomotive engineers. This is natural, for no other class of men
hold the safe-keeping of so much life and property in their hands.
IGNORANCE VERSUS KNOWLEDGE.
Two leading pioneers of railway progress in Europe took diametrically
opposite views of the intellectual qualities best calculated to make
a good engineer. George Stephenson preferred intelligent men, well
educated and read up in mechanical and physical science; Brunel
recommended illiterate men for taking charge of engines, on the novel
hypothesis, that, having nothing else in their heads, there would be
abundant room for the acquirement of knowledge respecting their work.
In every test of skill, the intelligent men proved victors.
ILLITERATE ENGINEERS NOT WANTED IN AMERICA.
No demand for illiterate or ignorant engineers has ever arisen in
America. Many men who have spent an important portion of their lives on
the footboard, have risen to grace the highest ranks of the mechanical
and social world. The pioneer engines, which demonstrated the
successful working of locomotive power, were run by some of the most
accomplished mechanical engineers in the country. As an engine adapted
to the work it has to perform, the American locomotive is recognized to
have always kept ahead of its compeers in other parts of the world. No
inconsiderable part of this superiority is due to the fact, that nearly
all the master mechanics who control the designing of our locomotives
have had experience in running them, and thereby understand exactly the
qualities most needed for the work to be done.
GROWING IMPORTANCE OF ENGINEERS’ DUTIES.
The safe and punctual operation of our railroads has always depended
to a great extent upon the discriminating care of the engineer.
The present tendency of railroad operating is to increase his
responsibility. Every advance in brake improvement increases the duties
of the enginemen, and upon them will soon devolve the entire management
and control of trains while in motion.
INDIVIDUALITY OF AMERICAN ENGINEERS.
Writing on the fitness of various railroad employés for their duties,
that eminent authority, Ex-Railroad-Commissioner Charles F. Adams,
jun., says, “In discussing and comparing the appliances used in the
practical operating of railroads in different countries, there is one
element, however, which can never be left out of the account. The
intelligence, quickness of perception, and capacity for taking care
of themselves,--that combination of qualities, which, taken together,
constitute individuality, and adaptability to circumstances,--vary
greatly among the railroad employés of different countries. The
American locomotive engineer, as he is called, is especially gifted in
this way. He can be relied on to take care of himself and his train
under circumstances which in other countries would be thought to insure
disaster.”
NECESSITY FOR CLASS IMPROVEMENT.
While American locomotive engineers can confidently invite comparison
between their own mechanical and intellectual attainments and those of
their compeers in any nation under the sun, there still remains ample
room for improvement. If they are not advancing, they are retrograding.
The engineer who looks back to companions of a generation ago, and says
that we know as much as they did, but no more, implies the assertion
that his class is going backward. On very few roads, and in but rare
instances, can this grave charge be made, that the engineers are
falling behind in the intellectual race. On the contrary, there are
signs all around us of substantial work in the cause of intellectual
and moral advancement.
THE SKILL OF ENGINEERS INFLUENCES OPERATING EXPENSES.
No class of railroad-men affects the expenses of operating so directly
as engineers do. The daily wages paid to an engineer is a trifling sum
compared to the amount he can save or waste by good or bad management
of his engine. Fuel wasted, lubricants thrown away, supplies destroyed,
and machinery abused, leading to extravagant running repairs, make up
a long bill by the end of each month, where enginemen are incompetent.
Every man with any spark of manliness in his breast will strive to
become master of his work; and, stirred by this ambition, he will avoid
wasting the material of his employer just as zealously as if the stores
were his own property; and only such men deserve a position on the
footboard.
The day has passed away when an engineer was regarded as perfectly
competent so long as he could take his train over the road on time.
Nowadays a man must get the train along on schedule time to be
tolerated at all, and he is not considered a first-class engineer
unless he possesses the knowledge which enables him to take the
greatest amount of work out of the engine with the least possible
expense. To accomplish such results, a thorough acquaintance with all
details of the engine is essential, so that the entire machine may
be operated as a harmonious unit, without jar or pound: the various
methods of economizing heat must be intimately understood, and the laws
which govern combustion should be well known so far as they apply to
the management of the fire.
METHODS OF SELF-IMPROVEMENT.
To obtain this knowledge, which gives power, and directly increases
a man’s intrinsic value, young engineers and aspiring firemen must
devote a portion of their leisure time to the form of self-improvement
relating to the locomotive. Socrates, a sagacious old Greek
philosopher, believed that the easiest way to obtain knowledge was
by persistently asking questions. Young engineers can turn this
system to good account. Never feel ashamed to ask for information
where it is needed, and do not imagine that a man has reached the
limit of mechanical knowledge when he knows how to open and shut
the throttle-valve. The more a man progresses in studying out the
philosophy of the locomotive and its economical operation, the more he
gets convinced of his own limited knowledge. A young engineer who seeks
for knowledge by questioning his elders must not feel discouraged at
a rebuff. Men who refuse to answer civilly questions asked by juniors
searching for information, are generally in the dark themselves, and
attempt by rudeness to conceal their own ignorance.
OBSERVING SHOP OPERATIONS.
The system in vogue in most of our States, especially in the West, of
taking on men for firemen who have received no previous mechanical
training, leaves a wide field open for engineering instruction. Such
men can not spend too much time watching the operations going on in
repair-shops; every detail of round-house work should be closely
observed; the various parts of the great machine they are learning
to manage should be studied in detail. No operation of repairs is
too trifling to receive strict attention. Where the machinists are
examining piston-packing, facing valves, reducing rod-brasses, or
lining down wedges, the ambitious novice will, by close watching of
the work, obtain knowledge of the most useful kind. Looking on will
not teach him how to do the work, but interesting himself in the
procedure is a long step in the direction of learning. Repairing of
pumps and injectors is interesting work, full of instructive points
which may prove invaluable on the road. The rough work performed by
the men who change truck-wheels, put new brasses in oil-boxes, and
replace broken springs, is worthy of close attention; for it is just
such work that enginemen are most likely to be called upon to perform
on the road in cases of accident. To obtain a thorough insight into
the working of the locomotive, no detail of its construction is too
trifling for attention. The unison of the aggregate machine depends
upon the harmonious adjustment of the various parts; and, unless a man
understands the connection of the details, he is never likely to become
skillful in detecting derangements.
WHERE IGNORANCE WAS RUIN.
I knew a case where the neglect to learn how minor work about the
engine was done, proved fatal to the prospects of a young engineer.
A new engine-truck box had been adopted shortly before he went
running; and, although he had often seen the cellar taken down by the
round-house men when they were packing the trucks, he never paid close
attention to how it was done. As the new plan was a radical change from
the old practice, taking down the new cellar was a little puzzling
at first to a man who did not know how to do it. One day this young
engineer took out an engine with the new kind of truck, and a journal
got running hot. He crept under the truck among snow and slush, to
take the cellar down for packing; but he struggled half an hour over
it, and could not get the thing down. Then the conductor came along, to
see what was the matter; and, being posted on such work, he perceived
that the young engineer did not know how to take the cellar out of
the box. The conductor helped the engineer to do a job he should
have needed no assistance with. The story was presently carried to
headquarters with additions, and was the means of returning the young
engineer to the left-hand side.
PREJUDICE AGAINST STUDYING BOOKS.
There is a silly prejudice in some quarters against engineers
applying to books for information respecting their engines. Engineers
are numerous who boast noisily that all their knowledge is derived
from actual experience, and they despise theorists who study
books, drawings, or models in acquiring particulars concerning the
construction or operation of the locomotive parts. Such men have
nothing to boast of. They never learn much, because ignorant egotism
keeps them blind. They keep the ranks of the mere stopper and starter
well filled.
THE KIND OF KNOWLEDGE GAINED FROM BOOKS.
The books on mechanical practice which these ultra practical men
despise, contain in condensed form the experience and discoveries that
have been gleaned from the hardest workers and thinkers of past ages.
The product of long years of toilful experiment, where intense thought
has furrowed expansive brows, and weary watching has whitened raven
locks, is often recorded on a few pages. A mechanical fact which an
experimenter has spent years in discovering and elucidating, can be
learned and tested by a student in as many hours. The man who despises
book-knowledge relating to any calling or profession, rejects the
wisdom begotten of former recorded labor.
A careful perusal of _Forney’s Catechism of the Locomotive_ will teach
the young engineer valuable lessons about his engine which can be daily
substantiated by practice. In nearly every instance, reading such a
work acts as a stimulant to the perceptive faculties of an engineer.
An explanation of a point helps to throw new light on something that
was hazy, but now appears perfectly clear. An assertion made that
a man does not agree with provokes thought, and thought leads to
investigation. A writer may continually present matters at variance
with the views of a reader, and yet be the means of imparting valuable
knowledge. When an engineer wishes to gain a thorough knowledge of the
valve-motion,--and most of us pride ourselves on what we know about
this subject,--he may go in for a systematic study of Auchincloss on
_Link and Valve Motions_. Here he will obtain information that can
never be reached by mere practice with the actual motion; yet access
to, and observation of, the working-motion, will engrave the principles
upon his memory so that they can never be forgotten. _Porter on the
Indicator_ is a good source from whence accurate knowledge respecting
the expansive working of steam can be obtained. Many other springs
of knowledge flow clear and free. What is needed is the inclination
to receive and the determination to obtain. When a man is searching
honestly for information upon mechanical subjects, he will quickly find
means of gratifying his desire.
CHAPTER II.
_HOW LOCOMOTIVE ENGINEERS ARE MADE._
RELIABLE MEN NEEDED TO RUN LOCOMOTIVES.
Locomotive engine running is one of the most modern of trades,
consequently its acquirement has not been controlled by the exact
methods associated with ancient guild apprenticeships. Nevertheless,
graduates to this business do not take charge of the iron horse
without the full meed of experience and skill requisite for performing
their duties successfully. The man who runs a locomotive engine on
our crowded railroads has so much valuable property, directly and
indirectly, under his care, so much of life and limb depending upon his
skill and ability, that railroad companies are not likely to intrust
the position to those with a suspicion of incompetency resting upon
them.
EARLY METHODS OF MAKING LOCOMOTIVE ENGINEERS.
The prevailing methods of raising locomotive engineers have been
evolved from experience with the kind of men best adapted to fill the
position. In the early days of the railroad world, when such men as
George Stephenson, Horatio Allen, John B. Jervis, Ross Winans, and
other pioneer engineers, demonstrated the successful operation of
the locomotive, they usually turned over the care of their engines
to the men who had assisted in constructing the machines, or in
putting them together. This was the best that could be done at the
time; and the men selected generally proved competent for the trust
reposed in them; but it gave rise to a belief that no man could run a
locomotive successfully unless he were a machinist. The possession of
mechanical skill necessary for making repairs was considered the best
recommendation for an engineer. Under this system, all that a machinist
was required to do,--so that he could graduate as a full-fledged
engineer,--was to practice moving engines round in the yard for a few
days, when he was reported ready for the road. Akin to this sentiment
was that which recommended youths of natural mechanical ability for the
position of locomotive engineer without subjecting them to any previous
special training. Graduates from mechanical institutes were deemed
capable of running an engine as soon as they were perfectly certain
about how to start and stop the machine. The late Alexander L. Holley
used to relate an anecdote of this kind of an engineer. During a severe
winter storm, the train Holley was traveling on got firmly stalled in
a snow-bank. In its struggles with the frozen elements, the engine got
short of water; and Holley found the engineer trying to fill the boiler
by shoveling snow down the smoke-stack!
PRACTICE OF RAISING ENGINEERS FROM MACHINISTS AND TECHNICAL-SCHOOL
GRADUATES NOT FOUND SATISFACTORY.
But it came to pass that more light in the matter of engine-running
dawned upon the minds of railroad managers. They discovered that
expertness in effecting repairs on locomotives was not so essential
in an engineer as was the less pretentious ability of working the
engine so that the train would be pulled over the road safely and on
time: they perceived but scanty merit in inherited mechanical genius
which did not inspire a youth with sagacity enough to see that certain
destruction would befall the heating-surface when he attempted to run
without water in the boiler. Experience demonstrated, that, to manage
an engine on the road so that its best work should be developed at
the least cost, certain traits of skill and training were necessary,
which were altogether different from the culture that made a man smart
at constructing or repairing machinery. It was found that one man
might be a good machinist, and yet make no kind of a decent runner; a
second man would be equally expert in both capacities; while a third
man, who never could do a respectable job with tools, developed into
an excellent engineer. One of the best millwrights I ever knew, a man
who achieved considerable celebrity for skill in his craft, became a
fireman with the ambition of becoming a locomotive runner. He fired
acceptably for two years, then was promoted, but quickly found that
he could not run an engine, and acknowledged that to be the case by
returning to the left side. He was too nervous, and lacked confidence
in himself. Overweening egotism is not an attractive feature in a man’s
character; but, every thing else being equal, it is the self-confident
man that makes the successful engineer.
EXPERIENCE DEMONSTRATED THAT FIREMEN MADE THE BEST ENGINEERS.
The experiment of raising locomotive engineers from machinists and
mechanical empirics was the uncertain groping in the dark for the
right man to fill the right place. When the search for pretentious men
proved unsatisfactory, the right men were found at hand, accumulating
the necessary experience on the fireman’s side of the engine. Then
it became a recognized fact, that, to take hold and run an engine
to advantage, a man must learn the business by working as fireman.
There have been frequent cases of men becoming successful locomotive
engineers without any previous training as firemen, but they were the
exceptions that proved the rule.
DIFFICULTIES OF RUNNING LOCOMOTIVES AT NIGHT, AND DURING BAD WEATHER.
In the matter of speed alone, there is much to learn before a man
can safely run a locomotive. During daylight a novice will generally
be half out in estimating speed; and his judgment is merely wild
guess-work, regulated more by the condition of the track than by the
velocity his train is reaching. On a smooth piece of track, he thinks
he is making twenty-five miles an hour, when forty miles is about the
correct speed: then he strikes a rough portion of the road-bed, and
concludes he is tearing along at thirty miles an hour, when he is
scarcely reaching twenty miles; since the first lurchy spot made him
shut off twenty per cent of the steam. At night the case is much worse,
especially when the weather proves unfavorable. On a wild, stormy
night, the accumulated experience of years on the footboard, which
trains a man to judge of speed by sound of the revolving-wheels, and to
locate his position between stations from a tree, a shrub, a protruding
bank, or any other trifling object that would pass unnoticed by a less
cultivated eye, is all needed to aid an engineer in working along with
unvaried speed without jolt or tumult. On such a night, a man strange
to the business can not work a locomotive, and exercise proper control
over its movements. He may place the reverse lever-latch in a certain
notch, and keep the steam on; he can regulate the pump after a fashion,
and watch that the water shall not get too low in the boiler; he can
shut off in good season while approaching stations, and blunder into
each depot by repeatedly applying steam; but he exerts no control over
the train, knows nothing of what the engine is doing, and is constantly
liable to break the train in two. A diagram of his speed would
fluctuate as irregularly as the profile lines of a bluffy country. This
is where a machinist’s skill does not apply to locomotive-running until
it is supplemented by an intimate knowledge of speed, of facility at
handling a train, and keeping the couplings intact, and of insight into
the best methods of economizing steam.
These are essentials which every man should possess before he is put
in charge of a locomotive on the road. The great fund of practical
knowledge which stamps the first-class engineer, is amassed by general
labor during years of vigilant observation on the footboard, amidst
many changes of fair and foul weather.
As passing through the occupation of fireman was the only way men could
obtain practical knowledge of engine-running before taking charge,
railroad officials all over the world gradually fell into the way
of regarding that as the proper channel for men to traverse before
reaching the right-hand side of the locomotive.
KIND OF MEN TO BE CHOSEN AS FIREMEN.
As the pay for firemen rules moderately good, even when compared with
other skilled labor; and as the higher position of engineer looms
like a beacon not far ahead,--there is always a liberal choice of
good men to begin work as firemen. Most railroad companies recognize
the importance of exercising judgment and discretion in selecting the
men who are to run as their future engineers. Sobriety, industry, and
intelligence are essential attributes in a fireman who is going to
prove a success in his calling. Lack in any one of these qualities will
quickly prove fatal to a fireman’s prospects of advancement. Sobriety
is of the first importance, because a man who is not strictly temperate
should not be tolerated for a moment about a locomotive, since he is a
source of danger to himself and others; industry is needed to lighten
the burden of a fireman’s duties, for oftentimes they are arduous
beyond the conception of strangers; and wanting in the third quality,
intelligence, a man can never be a good fireman in the wide sense of
the word, since one deficient in mental tact never rises higher than a
human machine. An intelligent fireman may be ignorant of the scientific
nomenclature relating to combustion, but he will be perfectly familiar
with all the practical phenomena connected with the economical
generation of steam. Such a man does not imagine that he has reached
the limit of locomotive knowledge when he understands how to keep an
engine hot, and can shine up the jacket. Every trip reveals something
new about his art, every day opens his vision to strange facts about
the wonderful machine he is learning to manage. And so, week by
week, he goes on his way, attending cheerfully to his duties, and
accumulating the knowledge that will eventually make him a first-class
locomotive engineer.
MODERN METHODS OF SELECTING FIREMEN.
On the various roads throughout the North American continent, there is
great diversity of practice in the selection of men for the position of
fireman.
On numerous roads, especially in the Western States, men are taken from
all occupations; no preliminary training being deemed necessary before
putting a man on an engine as fireman. A list of applicants is kept by
the master mechanic, and likely men recommended for firemen. When a man
is wanted, the first one who can be found conveniently is sent out; and
the engineer must break him in as best he can. On other roads, again,
the men intended for firemen are taken to work about the round-house,
and are employed in helping with the cleaning, repairing, and preparing
of locomotives for the road. This plan is greatly in vogue in Europe,
and on certain of the older roads of America; and it has many features
to recommend it over the practice of placing men entirely devoid of
railroad experience upon engines. It is better for the men themselves,
since working about engines familiarizes each to some extent with the
work he is expected to do as an engineer’s helper, for that is really a
fireman’s position; it is better for the company, since the officers
get the opportunity of observing a man’s habits before he receives
training that entails some expense; it is better for the engineer,
since his assistant is not entirely strange to the work he is expected
to do.
FIRST TRIPS.
A youth entirely unacquainted with all the operations which a fireman
is called upon to perform, finds the first trip a terribly arduous
ordeal, even with some previous experience of railroad work. When
his first trip introduces him to the locomotive and to railroad life
at the same time, the day is certain to be a record of personal
tribulation. To ride for ten or twelve hours on an engine for the first
time, standing on one’s feet, and subject to the shaking motion, is
intensely tiresome, even if a man has no work to do. But when he has
to ride during that period, and in addition has to shovel six or eight
tons of coal, most of which has to be handled twice, the job proves
no sinecure. Then, the posture of his body while doing work is new;
he is expected and required to pitch coal upon certain exact spots,
through a small door, while the engine is swinging about so that he
can scarcely keep his feet; his hands get blistered with the shovel,
and his eyes grow dazzled from the resplendent light of the fire. Then
come the additional side duties of taking water, shaking the grates,
cleaning the ash-pan, or even the fire, where bad coal is used, filling
oil-cans, and trimming lamps, to say nothing of polishing and keeping
things clean and tidy. By the time all these duties are attended to,
the young fireman does not find a great deal of leisure to admire the
passing scenery.
POPULAR MISCONCEPTION OF A FIREMAN’S DUTIES.
A great many idle young fellows, ignorant of railroad affairs, imagine
that a fireman’s principal work consists in ringing the bell, and
showing himself off conspicuously in coming into stations. They look
upon the business as being of the heroic kind, and strive to get
taken on as firemen. If a youth of this kind happens to succeed, and
starts out on a run of one hundred and fifty miles with every car a
heavy engine will pull stuck on behind, his visions of having reached
something easy are quickly dispelled.
Like nearly every other occupation, that of fireman has its drawbacks
to counterbalance its advantages; and the drawbacks weigh heaviest
during the first ten days. The man who enters the business under the
delusion that he can lead a life of semi-idleness must change his
views, or he will prove a failure. The man who becomes a fireman with a
spirit ready and willing to overcome all difficulties, with a cheerful
determination to do his duty with all his might, is certain of success;
and to such a man the work becomes easy after a few weeks’ practice.
LEARNING FIREMEN’S DUTIES.
Practice, combined with intelligent observation, gradually makes a man
familiar with the best styles of firing, as adapted to all varieties
of engines; and he gets to understand intimately all the qualities of
coal to be met with, good, bad, and indifferent. As his experience
widens, his fire management is regulated to accord with the kind of
coal on hand, the steaming properties of the engine, the weight of the
train, the character of the road and of the weather. Firing, with
all the details connected with it, is the central figure of his work,
the object of pre-eminent concern; but a good man does not allow this
to prevent him from attending regularly and exactly to his remaining
routine duties.
A GOOD FIREMAN MAKES A GOOD ENGINEER.
There is a familiar adage among railroad men, that a good fireman is
certain to make a good engineer; and it rarely fails to come out true.
To hear some firemen of three months’ standing talk, a stranger might
conclude that they knew more about engine running than the oldest
engineer in the district. These are not the good firemen. Good firemen
learn their own business with the humility born of earnestness, and
they do not undertake to instruct others in matters beyond their own
knowledge. It is the man who goes into the heart of a subject, who
understands how much there is to learn, and is therefore modest in
parading his own acquirements, that succeeds.
LEARNING AN ENGINEER’S DUTIES.
When a fireman has mastered his duties sufficiently to keep them going
smoothly, he begins to find time for watching the operations of the
engineer. He notes how the boiler is fed; and, upon his knowledge
of the engineer’s practice in this respect, much of his firing is
regulated. The different methods of using the steam by engineers, so
that trains can be taken over the road with the least expenditure of
coal, are engraven upon the memory of the observant fireman. Many
of the acquirements which commend a good fireman for promotion
are learned by imperceptible degrees,--the knowledge of speed, for
instance, which enables a man to tell how fast a train is running on
all kinds of track, and under all conditions of weather. There would
be no use in one strange to train service going out for a few runs
to learn speed. He might learn nearly all other requisites of engine
running before he was able to judge within ten miles of how fast the
train was going under adverse circumstances. The same may be said
of the sound which indicates how an engine is working. It requires
an experienced ear to detect the false note which indicates that
something is wrong. Amidst the mingled sounds produced by an engine
and train hammering over a steel track, the novice hears nothing
but a medley of confused noises, strange and meaningless as are the
harmonies of an opera to an untutored savage. But the trained ear of
an engineer can distinguish a strange sound amidst all the tumult of
thundering exhaust, screaming steam, and clashing steel, as readily
as an accomplished musician can detect a false note in a many-voiced
chorus. Upon this ability to detect growing defects which pave the way
to disaster, depends much of an engineer’s chances of success in his
calling. This kind of skill is not obtained by a few weeks’ industry:
it is the gradual accumulation of months and years of patient labor.
CONDITIONS OF ENGINE RUNNING THAT VANQUISH THE INEXPERIENCED MAN.
I once knew a machine-shop foreman, a man of extensive experience in
building and repairing engines, who took a locomotive out on trial
trip. A side-rod pin began to run hot; and, although he was leaning
out of the cab-window, he did not observe any thing wrong till a drop
of babbitt struck him in the eye. An experienced engineer watching the
rods would have detected the condition of affairs before babbitt was
thrown.
A difficult thing for an inexperienced man to control in running a
locomotive at night, when the conditions of adhesion are bad, is the
slipping of the drivers. Slipping is a simple matter enough to those
who feel it in the vibrations of the engine; but the novice has not
this sensitiveness to slipping vibration developed, and he must depend
upon his eyesight or his hearing to detect it. On a dark, stormy night,
the eye is useless as a means of judging as to the regularity of the
revolving wheels: the howling wind or rain, rattling on the cab, drowns
the sound of the exhaust. Under circumstances of this kind, an engine
might jerk the pins out before the empirical engineer discovered the
wheels were slipping.
LEARNING TO KEEP THE LOCOMOTIVE IN RUNNING-ORDER.
As his acquaintance with the handling and ordinary working of the
locomotive extends, the aspiring fireman learns all about the packing
of glands, and how they should be kept so as to run to the best
advantage: he displays an active interest in every thing relating to
lubrication, from the packing of a box-cellar to the regulating of a
rod-cup. When the engineer is round keying up rods, or doing other
necessary work about his engine, the ambitious fireman should give a
helping hand, and thereby become familiar with the operations that
are likely to be of service when he is required to draw upon his own
resources for doing the same work.
Of late years the art of locomotive construction has been so highly
developed, the amount of strain and shocks to which each working part
is subjected has been so well calculated and provided against, that
breakages are really very rare on roads where the motive-power is kept
in first-class condition. Consequently, firemen gain comparatively
small insight, on the road, into the best and quickest methods of
disconnecting engines, or of fixing up mishaps promptly, so that a
train may not be delayed longer than is absolutely necessary. A fireman
must get this information beyond the daily routine of his experience.
He must search for the knowledge among those competent to give it.
Persistent inquiry among the men posted on these matters; observation
amidst machine-shop and round-house operations; and careful study of
locomotive construction, so that a clear insight into the physiology of
the machine may be obtained,--will prepare one to meet accidents, armed
with the knowledge which vanquishes all difficulties. Reflecting on
probable or possible mishaps, and calculating what is best to be done
under all contingencies that can be conceived, prepare a man to act
promptly when a breakdown occurs.
METHODS OF PROMOTION ON OUR LEADING ROADS.
In the method of promotion of firemen, considerable diversity of
practice is followed by the different railroads. On certain roads,
with well-established business, and little fluctuation of traffic,
firemen begin work on switch engines, and are promoted by seniority, or
by selection through the various grades of freight trains, thence to
passenger service, from whence they emerge as incipient engineers. A
more common practice, and one almost invariably followed in the West,
is for firemen to begin as extra men, in place of firemen who are sick
or lying off. From firing extra, they get advanced, if found competent
and deserving, to regular engines. Then, step by step, they go ahead
to the best paying runs, till their turn for being “set up” comes
round. Passenger engines are not fired by any but experienced men, but
the oldest firemen do not always claim passenger-runs. For learning
the business of engine-running, freight service is considered most
valuable; and many ambitious firemen prefer the hard work of a freight
engine on this account.
NATURE OF EXAMINATION TO BE PASSED.
When a fireman has obtained the experience that recommends him for
promotion, on nearly all well-regulated roads he is subjected to some
form of examination before being put in charge of an engine. In some
cases this examination is quite thorough. The tendency to require
firemen to pass such an ordeal is extending, and its beneficial effect
upon the men is unquestioned. The usual form of examination is, for
officers connected with the locomotive department to question the
candidate for promotion on matters relating to the management of the
locomotive, and how he would proceed in the event of certain mishaps
befalling the engine. Parties belonging to the traffic department
propound questions relating to road-rules, train-rights, understanding
of time-card, and so on.
MASTER MECHANICS ON THE BEST METHOD OF EDUCATING YOUNG MEN FOR
ENGINEERS.
The Master Mechanics’ Association appointed a committee to investigate
the “best manner of educating young men for locomotive engineers,” and
the following report was made:--
“Considering this subject to be of vital importance to the Association,
and to the public in general, and that proper care and attention have
not been given to it in the past, the committee have spared no pains to
get all the information they possibly could on this subject, knowing
and feeling that men selected to fill the responsible position of
locomotive engineers must possess faculties, that, as a general thing,
do not belong to all the human race; and, as locomotive engineers have
to be selected from the ranks of firemen, they feel that due care and
caution should be exercised in selecting young men for firemen. Now, to
arrive at a proper conclusion,--one that would be satisfactory to the
Association and to the railways of the country,--your committee sent
circulars to all the master mechanics in the United States, Canada, and
Mexico. We sent out five hundred and thirty-two circulars, to which we
received seventy-six replies; being an average of one answer to every
seven sent. Many of these replies contain very valuable information,
and were from many of the leading roads of this country, Canada, and
Mexico. Your committee beg leave to return thanks for the answers to
their circular.
“The opinions given us by the different master mechanics who replied,
were as follows: Five recommended that none but machinists should be
locomotive engineers; nineteen thought that nothing more was needed
than to have a young man fire from three to four years with good,
competent engineers, to make him a good runner; fifty-two thought that
one year in the shop and round-house, with two to three years’ firing,
was necessary to make a competent engineer; many recommended that
young men, while firing, read and study books that would give them a
general knowledge of the locomotive, such as _Forney’s Catechism of the
Locomotive_, and several other works of that kind. Many of the replies
admitted that machinists would make the best runners if they would
consent to fire one year after having learned their trade, as they
would then have the advantage of knowing all about the construction of
the locomotive. Of course, when speaking of that class of men, they
meant bright, intelligent young machinists, men with nerve and energy,
and quick to act in cases of emergency. Of course, there are some who
would never make engineers, no matter what opportunities were given
them. If young men of this kind would consent to run one year or more
as firemen, we could select our locomotive engineers from among that
class; but they will not do it, from the belief that they are just as
competent to run a locomotive as the best engineer on the road for
which they are working: and, if they are given an opportunity to run an
engine, they are certain to make a failure. This being the fact, we are
compelled to select our engineers from among the ranks of the firemen,
as the best and safest runners. Now, this being the class of men from
which we have to select our engineers, some uniform mode of instructing
them for the responsible position that many of them will have to fill
in the future, will have to be adopted by the different railroads in
America. Your committee would therefore recommend the following:--
“All master mechanics should have full control of the engineers and
firemen in the employ of their respective roads, with full power to
hire and discharge the same,--of course, recognizing the rights that
the general managers or superintendents have to order the discharge of
any engineer or fireman for neglect of duty.
“1st, The qualifications for the position of fireman on all the
railways in America should be as follows: The applicant should be
from eighteen to twenty-four years old, able-bodied, and in good
health, with a good common-school education, and a fair knowledge of
arithmetic, and of sober and steady habits. All applicants should be
required to make application in their own handwriting, signing it in
the presence of the master mechanic, or the person he may appoint to
hire that class of men. In selecting men for firemen, great care should
be exercised. The master mechanic should endeavor, so far as lies in
his power, to select energetic, smart, and active young men,--men of
nerve, and presence of mind, quick to act in cases of emergency which
may occur in the position they may be selected to fill in the future.
If we select men of that kind, there will be very little difficulty in
educating them up to the proper standard to fill the place of engineers.
“2d, There should be three grades of firemen, classed as junior,
intermediate, and senior firemen,--the young man just commencing, to
be classed as junior fireman, and so on up to senior fireman; the
senior fireman receiving the highest pay for his services, the others
in proportion. When a fireman has fired four years, and is worthy
of promotion, and fully competent to run a locomotive, there may be
no vacancies in the engineer force on the road by which he may be
employed. In that case we recommend that he receive a small amount more
per day than the senior fireman (say from fifteen to twenty cents per
day more), and be ranked as veteran fireman. On the road which one of
your committee represents in this convention, this custom has been in
vogue for a number of years, and has worked exceedingly well. All the
engineers on this road have been educated under this rule, and to-day
no engineers in the country rank higher than they do.
“Proper care should be taken, in selecting young men for firemen, as to
their ability to distinguish colors in a practicable, common-sense way.
We recommend that all railroads having a sufficient number of employés
to justify them in so doing, have a reading-room and library for their
firemen and engineers, in which the other employés could participate.
The library, to some extent, should consist of works on the locomotive
engine that a man with a fair education could understand. While we
do not think it essentially necessary, still we believe it would be
beneficial to some extent to let firemen work one year out of the four
in the shop and round-house, so that they might obtain a more perfect
knowledge of all the parts of the locomotive.
“Young men consisting of the class we have mentioned, are certain to
make good runners; and there will be no difficulty, at the proper time,
in selecting good junior engineers from among that class of men. All
opportunities possible should be given firemen to get such knowledge
of the theory and movements of the different parts of the locomotive
as would be beneficial to them when they enter on their career as
engineers. To accomplish this end, monthly lectures might be given
in the reading-room by men of good practical common sense, who fully
understand what they are talking about. If possible, these lectures
should be given by one of the engineers. The firemen would learn more
from him, as they would better understand what he was saying; he having
formerly been one of them.
“Your committee is convinced, that, if the mode recommended by them
is adopted generally throughout the country, a large majority, if not
all, of the firemen, would be educated to a point from which there
would be no difficulty in selecting men who will make good and reliable
engineers.
“3d, The fireman now being competent to run a locomotive, and being
placed in charge of one, has yet some few things to learn that he did
not have the opportunity of learning, from the fact that he was not
running the engine. While he may run carefully, and avoid accidents, he
has to learn to run his engine with economy in the consumption of fuel
and the cost of repairs. To learn this, and to give the young engineer
an opportunity to become a first-class man in his occupation, we
recommend there be three grades of engineers,--first, second, and third
grades,--and that the remuneration they receive be according to grade;
the fireman just promoted ranking in the third grade; after one year’s
service he enters the second grade; when two years have passed, he
enters the first grade, and becomes a first-class locomotive engineer.”
CHAPTER III.
_INSPECTION OF THE LOCOMOTIVE._
LOCOMOTIVE INSPECTORS.
On railroads where the system of “long runs” for locomotives
prevails, there is a locomotive inspector employed, whose duty it is
to thoroughly examine every available point about every engine that
arrives at his station, and find out what repairs are needed, and to
detect the incipient defects which lead to disaster on the road. Some
roads that do not practice long runs have an inspector who examines
every engine. This plan is very effectually used on the elevated
railroads of New York, and has much to do with the immunity from
accident of their engines. These inspectors are not employed to exempt
engineers from looking over their engines, but merely to supplement
their care. In some cases engineers are brought sharply to task if they
overlook any important defect which is discovered by the inspector.
GOOD ENGINEERS INSPECT THEIR OWN ENGINES.
The engineer who has a liking for his work, and takes pride in making
his engine perform its part, so as to show the highest possible record,
does not require the fear of an inspector behind him as an incentive to
properly examine his engine, and keep it in the best running-order.
He recognizes the fact, that upon systematic and regular inspection of
the engine while at rest, depends in a great measure his success as a
runner, and his exemption from trouble.
WHAT COMES OF NEGLECTING SYSTEMATIC INSPECTION OF LOCOMOTIVES.
The man who habitually neglects the business of inspecting his engine,
and leaves to luck his chances of getting over the road safely, soon
finds that the worst kind of luck is always overtaking him on the road.
A careful man may have a run of bad luck occasionally, but the careless
man meets with nothing else. Among a great many men who have failed
as runners, I can recall numerous cases where carelessness about the
engine was the only and direct cause which led them to failure. One of
the most successful engineers that ever pulled a throttle on the Erie
Railroad was asked by a young runner to what cause he attributed his
extraordinary good fortune. His reply was, “I never went out without
giving my engine a good inspection.” This man had been running nearly
half a century, and never needed to have his engine hauled to the
round-house.
CONFIDENCE ON THE ROAD DERIVED FROM INSPECTION.
When a locomotive is thundering over a road ahead of a heavy train in
which may be hundreds of human beings, the engineer ought to understand
that the safety of this freight of lives depends to a great extent upon
his care and foresight. As the train rushes through darkened cuttings,
spans giddy bridges, or rounds curves edged by deep chasms, no one
can understand better than the engineer the importance of having every
nut and bolt about the engine in good condition, and in its proper
place. The consciousness that every thing is right, the knowledge
that a thorough inspection at the beginning of the journey proved the
locomotive to be in perfect condition, give a wonderful degree of
comfort and confidence to the engineer as he urges his train along at
the best speed of the engine.
INSPECTION ON THE PIT.
Between the time of an engine’s return from one trip and its
preparation for another, a thorough examination of all the machinery
and running-gear should be made while the engine is standing over a
pit. Monkey-wrench in one hand, and a torch in the other if necessary,
the engineer ought to enter the pit at the head of the engine, and
make the inspection systematically. The engine-truck, with all its
connections, comes in for the first scrutiny. Now is the time to
guard against the loss of bolts or screws, which leads to the loss of
oil-box cellars on the road. This is also the proper time to examine
the condition of the oil-box packing. The engineers of my acquaintance
who are most successful in getting trains over the road on time, attend
to the packing of the truck-boxes themselves. Nothing is more annoying
on the road than hot boxes. They are a fruitful source of delay and
danger, and nothing is better calculated to prevent such troubles
than good packing and clear oil-holes. The shop-men who are kept for
attending to this work are sometimes careless. They can hardly be
expected to feel so strongly impressed with the importance of having
boxes well packed as the engineer, who will be blamed for any delay.
He should, therefore, know from personal inspection that the work is
properly done.
When the engineer is satisfied that the truck, pilot-braces,
center-castings, and all their connections, are in proper condition,
he passes on to the motion. His trained eye scans every bolt, nut,
and key in search of defects. The eccentrics are examined, to see
that set screws and keys are all tight. Men who have wrestled over
the setting of eccentrics on the road are not likely to forget this
part. Eccentric-straps are another point of solicitude. A broken
eccentric-strap is a very common cause of break-down, and these straps
very seldom break through weakness or defect of the casting. In nearly
all cases the break occurs through loss of bolts, or on account of
oil-passages getting stopped up. The links are carefully gone over,
then the wedges and pedestal braces come in for an examination which
brings the assurance that no bolts are missing, or wedge-bolts loose.
Passing along, the careful engineer finds many points that claim his
attention; and, when he gets through, he feels comfortably certain that
no trouble from that part of the engine will be experienced during the
coming trip. The runners who do not follow this practice are not aware
of how much there is to be seen under a locomotive when the examination
is undertaken in a comprehensive manner.
OUTSIDE INSPECTION.
In going round the outside of the engine, the most important points for
examination are the guides and the rods. Guide-bolts, rod-bolts, and
keys, with the set screws of the latter, are the minutiæ most likely
to give trouble if neglected. In going about the engine oiling, or for
any other purpose, it is a good thing to get in the habit of searching
for defects. When a man trains himself to do this, it is surprising
how natural it comes to make running inspections. As he oils the
eccentric-straps, he sees every bolt and nut within sight; as he drops
some oil on the rods, he identifies the condition of the keys, set
screws, or bolts; while oiling the driving-boxes, the springs can be
conveniently examined; and, when he reaches the engine-trucks with the
oil-can, he is sure to be casting his searching eyes over the portions
of the running-gear within sight.
OIL-CUPS.
The oil-cups should be carefully examined, to see that they are in good
feeding-order. A great many feeders have been invented, which guarantee
to supply oil automatically; but I have never yet seen the cup which
could long dispense with personal attention. And this does not apply
to locomotives alone, but to all kinds of machinery. The worst sort of
oil-cup will perform its functions fairly in the hands of a capable
man, and the most pretentious cup will soon cease to lubricate
regularly if the engineer neglects it. The oil-cups should be cleaned
out at regular intervals: for mud, cinders, and dust work in; and they
sometimes retain glutinous matter from the oil, which forms a sticky
mixture that prevents the oil from running. The eccentric-strap cups
and the tops of the driving-boxes should receive similar attention.
In looking round an engine, it is a good plan to watch the different
oil-cups to see that they are not working loose. Many cups that are
strewed over the country could be saved by a little more attention. A
cup flying off a rod when an engine is running fast becomes a dangerous
projectile. I have known several cases where cups went back through the
cab-window. I have also seen several cases where cups worked off the
guides or cross-head, and got between the guides, doing serious damage.
One instance was that of an engine out on the trial-trip. It smashed
the cross-head to pieces, and let the piston through the cylinder-head.
INSPECTION OF RUNNING-GEAR.
A sharp tap with a hammer on the tread of the cast-iron wheel will
produce a clear, ringing sound if the wheel is in good order. The
drivers can generally be effectively inspected by the eye. If oil be
observed working out between the wheel and axle, attention is demanded;
for the wheel may be getting loose. Moisture and dirt issuing from
between the tire and wheel indicate that the former is becoming loose,
and this is a common occurrence when the tires are worn thin. When a
wheel is running so that the flange is cutting itself on the rail,
something is wrong, which also demands immediate attention. Oblique
travel of wheels may be produced by various causes. If the axles of
the driving-wheels are not secured at right angles to the frames, and
parallel with each other, the wheels will run tangentially to the
track, according to the inclination of the axles. Violent strains or
concussions, such as result from engines jumping the track about
switches, sometimes spring the frames, and twist the axle-box jaws
away from their true position enough to cause cutting of flanges
without disabling the engine. Tires wearing unevenly in consequence
of one being harder than the other, produce a similar effect. Where
there are movable wedges forward and aft of the boxes, the wheels are
often thrown out of square by unskillful manipulation of these wedges.
Engineers running engines of this kind should leave the forward wedges
alone. Sometimes the center-pin of the engine-truck gets moved from
the true central position, leading the drivers towards the ditch.
Diagnosing the cause of wheel-cutting is no simple matter, and it is a
wise plan for engineers to allow the shop-men to devise a remedy.
ATTENTIONS TO THE BOILER.
On our well-regulated roads, engineers are not required to inspect
their boilers; as expert boiler-makers, who can readily detect a broken
stay-bolt, or broken brace, have to make periodical examinations.
But a prudent engineer will keep a sharp lookout for indications
that show weak points about any part of the boiler or fire-box. This
department can not receive too much vigilance. A seam or stay-bolt
leaking is a sign of distress, and should receive immediate attention.
Leaks under the jacket should never be neglected, although they are
hard to reach; for they may proceed from the beginning of a dangerous
rupture. A leak starting in the boiler-head should make the engineer
ascertain that none of the longitudinal braces have broken. I once
had some rivet-heads on my boiler-head start leaking, and presently
the water-glass broke. After shutting off the cocks, I found that the
boiler-head was bulged out. I reduced the pressure on the boiler as
quickly as possible. When the boiler was inspected, it was found that
two of the longitudinal braces were broken, and the head-sheet was bent
out two inches.
MISCELLANEOUS ATTENTIONS.
If an engineer is going to take out an engine the first time after it
has been in the shop for repairs, it is a good plan to examine the tank
to see if the workmen have left it free from bagging, greasy waste,
and other impediments, which are not conducive to the free action of
pumps or injectors. Keeping the tank clean at all times saves no end of
trouble through derangement to feeding-apparatus. The smoke-box door
should be opened regularly, and the petticoat-pipe and cone examined.
These things wear out by use, and it is better to have them renewed
or repaired before they break down on the road. A cone dropping down
through failure of the braces makes a troublesome accident on the
road. I have known of several cabs being badly damaged by fire through
the cone dropping down, and closing up the stack. Where engines have
extended smoke-boxes, the nettings and deflectors must be inspected at
frequent intervals.
REWARD OF THOROUGH INSPECTION.
To go over an engine in the manner indicated, requires perseverance
and industry. The work will, however, bring its full reward to every
man who practices the care and watchfulness entailed by regular and
systematic inspection. It is the sure road to success. He who regards
his work from a higher plane than that of mere labor well done, will
experience satisfaction from the knowledge, that, understanding
the nobility of his duties, he performed them with the vigor and
intelligence worthy of his responsible calling.
CHAPTER IV.
_GETTING READY FOR THE ROAD._
RAISING STEAM.
It used to be the universal custom, that, when an engine arrived from
a trip, the fire was drawn, and the engine put into the round-house
for ten or twelve hours before another run was undertaken. During this
period of inaction, the boiler partly cooled down. When the engine was
wanted again, a new fire was started in time to raise steam. The system
of long runs, introduced on many roads, has changed this; and engines
are now generally kept hot, unless they have to be cooled down for
washing out, or repairs. When an engine comes in off a trip, the fire
is cleaned from clinker and dead cinders, and the clean fire banked.
It is found that this plan keeps the temperature of the boiler more
uniform than is possible with the cooling-down practice, and that the
fire-box sheets are not so liable to crack, or the tubes to become
leaky.
Where it is still the habit to draw the fire at the end of each trip, a
supply of good wood is kept on hand for raising steam. To raise steam
from a cold boiler, some theorists recommend the starting of a fire
mild enough to raise the temperature about twenty degrees an hour. The
exigencies of railroad service prevent this slow method from being
practicable, and the ordinary practice is to raise steam as promptly as
possible when it is wanted.
PRECAUTIONS AGAINST SCORCHING BOILERS.
The first consideration before starting a fire in a locomotive, is
to ascertain that the boiler contains the proper quantity of water.
The men who attend to the starting of fires should be instructed not
to depend upon the water-glass for the level of the water, but to
see that it runs out of the gauge-cocks. I have known several cases
where boilers were burned through those firing up being deceived by
a false show of water in the glass, and starting the fire when the
boiler was empty. If the boiler has been filled with water through the
feed-pipes by the round-house hose, care should be taken to see that
the check-valves are not stuck up. Where there is sand in the water, it
frequently happens, that, in filling up with a hose, all the valves get
sanded, and do not close properly. When there is steam on the boiler,
this source of danger will generally be indicated at once by the steam
and water blowing back into the tank; but, where the boiler is cold,
the water flows back so silently and slowly, that the crown-sheet may
be dry before the peril is discovered.
STARTING THE FIRE.
The water being found or made right, the next consideration is the
grates. Before throwing in the wood, all loose clinkers left upon the
grates should be cleaned off: care should be taken, to see that the
grates are in good condition, and connected with the shaker levers.
This is also the time to see that no accumulation of cinders is left on
the brick arch, the water-table, or in the combustion chamber, should
the engine be provided with either of these appliances. In starting the
fire, it is considered the best plan to put enough wood in the fire-box
to raise sufficient steam to operate the blower before the fire needs
replenishing. To do the job in a clean, workman-like manner, the fire
should be started from below: otherwise every part of the cab will be
veneered with soot and dust, and the bright work tarnished.
FIREMAN’S FIRST DUTIES.
On most roads, the engineer and fireman are required to be at their
engine from fifteen minutes to half an hour before train-time. A good
fireman will reach the engine in time to perform his preliminary duties
deliberately and well. He will have the dust brushed off from the
cab-furnishing, and from the conspicuous parts of the engine, the deck
swept clean, the coal watered, and the oil-cans ready for the engineer.
His fire is attended to, and its make-up regulated,--the kind of coal
used, the train to be pulled, and the character of the road on the
start. With an easy or down grade, for a mile or two on the start, the
fire does not need to be so well made up as when the start is made on
a heavy pull. But every intelligent fireman gets to understand in a
few weeks just what kind of a fire is needed. It is the capability of
perceiving this and other matters promptly, that distinguishes a good
from an indifferent fireman. When a young fireman possesses these “true
workman” perceptions, and is of an industrious, aspiring disposition,
anxious to become master of his calling, he will prove a reliable help
to the engineer; and his careful attention to the work will insure
comfort and success on every trip. There must be a certain amount of
work done on the engine, to get a train along; and, if the fireman can
not do his part efficiently, it will fall upon the engineer, who must
get it done somehow.
SAVING THE GRATES.
An important duty, which is never neglected by first-class firemen,
before taking the engine away from the round-house, is that of looking
to the grates, and seeing that the ash-pan is clean. When grates get
burned, in nine cases out of ten it happens through neglecting the
ash-pan. Some varieties of bituminous coal have an inveterate tendency
to burn the grates. Such coal usually contains an excess of sulphur,
which has a strong affinity for iron, and at certain temperatures
unites with the surface of the grates, forming a sulphuret of iron.
Neglecting the ash-pan, and letting hot ashes accumulate, prepares the
way for bad coal to act on the grates. Keeping the ash-pan clear of hot
ashes is the best thing that can be done to save grates, since that
prevents the iron from becoming hot enough to combine with sulphur.
SUPPLIES.
Before starting out, the fireman ought to ascertain that all the
supplies necessary for the trip are in the boxes; that the requisite
flags, lanterns, and other signals are on hand, and that all the
lamps are trimmed. He should also know to a certainty that all his
fire-irons are on the tender, that the latter is full of water, and
that the sand-box is full of sand.
These look like numerous duties as preliminary to starting, but they
are all necessary; and the fireman who attends to them all with the
greatest regularity, will be valued accordingly. Nearly all firemen are
ambitious to become engineers. The best method they can pursue, to show
that they are deserving of promotion, is to perform their own duties
regularly and well. A first-class fireman will save his wages each trip
over the expenditure made by the mediocre fireman: a persistently bad
fireman should be sent to another calling without delay. Few railroad
companies can afford the extravagance of a set of bad firemen.
ENGINEER’S FIRST DUTIES.
Try the water. That is the most important call upon the engineer when
he first enters the cab. If the engine has a glass water-gauge, he
should ascertain by the gauge-cocks if the water-level shown in the
glass be correct. A water-glass is a great convenience on the road, but
it should only be relied on as an auxiliary to the gauge-cocks. Many
engineers have come to grief through reposing too implicit confidence
in the water-glass. Engineer Williams was considered one of the most
reliable men on the A. & B. road. With an express train he started out
on time one morning; and he had run only two miles when the boiler
went up in the air, with fatal results to both occupants of the cab.
An examination of the wreck showed unmistakable evidence of overheated
sheets. Circumstantial evidence indicated that the glass had deceived
the engineer by a false water-level. When he pulled out, the fire-box
sheets, which were of copper, became weakened by the heat, so that the
crown-sheet gave way; the re-action of the released steam tearing the
boiler to pieces. Numerous less serious accidents originating from the
same cause might be cited.
REACHING HIS ENGINE IN GOOD SEASON.
An engineer who has a proper interest in his work, and thoroughly
appreciates the importance of it, will reach his engine in time to
perform the duties of getting her ready for the road leisurely, without
rush or hurry. Although a good fireman may relieve the engineer of many
preliminary duties, the engineer himself should be certain that the
necessary supplies and tools are on the engine, and that water is in
the tank, and the sand-box filled.
OILING THE MACHINERY.
Oiling the machinery is such an important part of an engineer’s work,
and the success of a fast run is so dependent upon this being properly
done, that it should never be performed hurriedly. Although practice
with short stoppages at stations may have got an engineer into the
way of rushing round an engine, and oiling at express-speed, it is no
reason why the first oiling of the trip should not be carefully and
deliberately attended to when there is an opportunity. In addition to
filling oil-cups, lubricators, and oil-boxes, this is a good time to
complete the inspection, which assures the engineer that every thing
about the engine is in proper running-order. When any thing in the
way of repairs has been done to the engine since she came off the
last trip, special attention has generally to be given to the parts
worked at. New wheels require close care with the packing of the boxes;
rod-brasses reduced entail an additional supply of oil to the pins for
the first few miles; guides closed should insure a free supply of oil
till it is found that the cross-heads run cool.
QUANTITY OF OIL THAT DIFFERENT BEARINGS NEED.
While oiling, the engineer should bear in mind that it is of paramount
importance that the rubbing-surfaces receive lubrication sufficient to
keep them from heating; but, while making sure that no bearings shall
run dry, lavish pouring of oil should be avoided. There are still too
many cases to be noticed, of men pouring oil on the machinery without
seeming to comprehend the exact wants. We are constantly seeing cases
where oil-cups waste their measure of oil through neglect in adjusting
the feeders. A steady supply, equal to the requirements, is what a
well-regulated cup provides. With the ordinary quality of mineral oil,
six drops will lubricate the back end of a main rod for one mile when
the engine is pulling a load. This applies to eight-wheel engines on
passenger service. Heavier small-wheeled engines will require a quarter
more oil. Guides can be kept moist with five drops of oil to the
mile. A dry, sandy road will require a more liberal supply. With good
feeders, properly attended to, the supply can equal the demand with
close accuracy. An oil-cup which runs out the oil faster than it is
needed, wastes stores, besmears every thing with a coating of grease,
and is likely to leave the rubbing-surfaces to suffer by running dry
before it can be replenished. A cup in that condition also advertises
the engineer to be incompetent.
LEAVING THE ENGINE-HOUSE.
Before moving the engine out of the house, the cylinder-cocks should
be opened so that water, or the steam condensed in warming the pipes
and steam-chest, may escape. After ringing the bell, and giving
workmen employed about the engine time to get out of the way, the
throttle should be opened a little, and the engine moved out slowly
and carefully. If there is a sufficient pressure of steam in the
boiler, and the engine refuses to move, something is wrong. Never force
an engine. Any work which may have been performed upon it while in
the house will probably indicate the nature of the defect. The most
common cause of stalling engines in the house is a miscalculation of
the piston-travel, permitting it to push against the cylinder-head.
Sometimes, however, the setting of the valves is at fault. I knew a
case where the machinist connected the backing-up eccentric-strap with
the top of the link, and the mistake was not discovered till they
attempted to move the engine out of the house. Another blunder, the
result of gross carelessness, was where a cold chisel was left in the
steam-chest. But a more representative case was that which happened to
Engineer Amos, on the B. & C. road. His engine had the piston-packing
set up; and the following morning, when he tried to take it out of the
house, it would not pass a certain point. Thinking that the packing was
set up rather tight, he backed for a start, determined to make it go
over on the run. He succeeded, too, but a hammer which had been left in
the cylinder went out through the cover.
While running from the round-house to the train, is a good time to
carefully watch the working of the various parts of the engine. Should
any defects exist, they are better to be detected now than after the
engine is out with a train. The brakes can be tested conveniently
at this time, and the working of the water-pumps tried. All these
matters are regularly attended to by the successful engineer: they are
habitually neglected by the unlucky man, and misfortune never loses
sight of him.
CHAPTER V.
_RUNNING A FAST FREIGHT TRAIN._
RUNNING FREIGHT TRAINS.
By far the greater proportion of American locomotive engineers are
employed on freight service. On most roads, the freight engines
constitute from seventy-five to ninety per cent of the whole locomotive
equipment. On this kind of service, locomotive engineers learn their
business by years of hard practice in getting trains over the road
as nearly as possible on time. On the best of roads, there is much
hardship to be undergone, working ahead through every discouragement
of bad weather or hard-steaming engines. The man who brings the most
energy, good sense, and perseverance to his aid, will come out most
successfully above these difficulties.
Every department of locomotive engine running has difficulties peculiar
to itself. Every kind of train needs to be handled understandingly, to
show the best results; but, I think, getting a heavy fast freight train
on time, over a hilly road, having a single track, requires the highest
degree of locomotive engineering skill. Therefore, I have selected that
form of train as the first subject of description.
THE ENGINE.
The engine that takes the train over the road weighs 35 tons, and has
1,100 square feet of heating-surface for generating steam for cylinders
17 by 24 inches, which, through the pistons, transmit power to wheels
60 inches diameter. The engine is an ordinary eight-wheeled bituminous
coal-burning American type of locomotive, built by one of our best
makers, and well adapted for pulling any kind of train over a Western
railroad.
THE TRAIN.
This consists of 20 loaded cars, making an aggregate weight of 450 tons.
THE DIVISION.
The physical character of the country, which is rolling prairie,
makes the road undulatory,--up hill, then down grade, with occasional
stretches of level track. Some of the gradients rise to sixty feet
to the mile, extending over two miles without sagging a foot. Sound
steel rails, well tied, are supported by a graveled road-bed, making
an excellent track, and presenting a good opportunity for fast running
where high speed is needed. The train is run on card-time, stopping
about every twelve miles. Like all other Western roads, the stations
are unprotected by signals; and the safety of trains is secured mostly
by vigilance on the part of the engineer and other train-men.
PULLING OUT.
When the engineer gets the signal to go, he drops the reverse lever
into the full forward notch, gives the engine steam gently, with due
care to avoid breaking couplings, and pulls the sand-lever. A slight
sprinkling of sand only is dropped on the rails, which keeps the engine
from slipping while getting the train under way. A clear, level fire
is burning over the grates before the start is made, and this suffices
till the most crowded switches are passed: so, when the signal to start
is given, the fireman closes the fire-door, and opens the damper; these
duties not preventing him from keeping a lookout for signals.
HOOKING BACK THE LINKS.
As the engine gets the train into motion, the engineer gradually hooks
up the links. This is not done by a sudden jerk as soon as the engine
will move, with the steam cutting off short. He waits for that till the
train is well under the control of the engine, hooking up gradually.
Some men think that it is best to get the valves up to short travel as
soon as possible, without reflecting that it is better for the motion
to let the engine be going freely before hooking up short. I have
often seen men coming into terminal stations with a heavy fire and the
safety-valves blowing, and the engine toiling slowly along with the
links hooked up to eight inches cut. In cases of this kind, a runner
may better work the engine well down, so that the valve will travel
freely over the seat. By doing so when the engine is working slow
and heavy, there will be less wear to the valves, and less danger of
breaking a valve yoke. It is only in cases where there is an advantage
in saving steam, that benefit is derived from working the engine close
hooked back. There is a right time for all things, and working steam
expansively is no exception to the rule.
WORKING THE STEAM EXPANSIVELY.
At the right time, our engineer gets the reverse lever notched up;
for he knows, that to obtain the greatest amount of work out of the
engine, with the least possible expenditure of fuel, the links must be
hooked back as far as can be done consistently with making the required
speed. Some engines will not steam freely when run close back if they
are burning coal that needs a strong draught. This is the exception,
however, and most engines will steam best in this position; and many of
those that fail to steam well cutting off short are not properly fired,
or the draught appliances need adjusting. Most firemen who run with a
heavy fire fail worst with engines that steam indifferently when hooked
up. Engineers should give this their attention, and do every thing
possible to make the engine steam while working with the lever as near
the center notch as can be done while handling the train.
ADVANTAGE OF CUTTING OFF SHORT.
When the links are notched close towards the center, the travel of the
valves is so short that they close the steam-ports shortly after the
beginning of the stroke, at six, nine, or twelve inches of the piston’s
travel, as the case may be, permitting the steam to push the piston
along the remainder of the stroke by its expansive power. Steam at a
high pressure is as full of potential energy as a compressed spiral
spring, and is equally ready to stretch itself out when the closing
of the port imprisons it inside the cylinder; and, by this act of
expanding, it exerts immense useful energy, which would escape into
the smoke-stack unutilized if the cylinders were left in communication
with the boiler till the release took place. Suppose, for instance,
that a boiler pressure of ten tons is exerted upon the piston from the
beginning to the middle of the stroke, and is then cut off. During the
remainder of the stroke, the steam will continue to press upon the
piston with a regularly diminishing force, till, at the end of the
stroke, if release does not take place earlier, it will still have
a pressure of five tons. The work performed by the steam during the
latter part of the stroke is pure gain, due to its expansive principle.
If the steam is cut off earlier, at a third or fourth of the piston
travel, the gain will be correspondingly great. With the slide-valve
link-motion used on locomotives, the steam can not be held to the end
of the stroke; but the principle of expansion holds good during the
period the steam is held in the cylinders after the cut-off.
The observing engineer of any experience does not require to have
the advantages of working his engine expansively impressed upon his
attention. His fuel-record has done that more eloquently than pen can
write.
BOILER PRESSURE BEST FOR ECONOMICAL WORKING.
There is a close and constant relation between the boiler pressure
carried, and the useful work obtained from expansion of steam. The
higher the pressure, the greater elasticity the steam possesses. The
tendency of modern steam engineering is, to employ intensely high
boiler pressure, expanding the steam by means of excellent valve-gear
in steam-jacketed cylinders, so that it is reduced to low tension
before escaping into the atmosphere, or into the condenser, as the
case may be. Wonderfully economical results have been obtained in this
manner,--results which can never be approached in locomotive practice
while the ordinary slide-valve is used. But, while we can not hope to
rival the record of high-class automatic cut-off engines, their methods
can teach us useful lessons.
It is advisable to keep the steam constantly close to the blowing-off
point. During a day’s trip, considerably less water will be evaporated
when a tension of 140 pounds is carried, than will be required
with a pressure of 100 pounds or under. And, where less water is
evaporated, a smaller quantity of fuel will be consumed in doing
the work. Running with a low head of steam is a wasteful practice,
for several good reasons. The comparatively light pressure upon the
surface of the water allows the steam to pass over damp, or mixed
with a light watery spray, which diminishes its energy; since the
wet steam contains less expansive medium than dry steam. It requires
nearly the same expenditure of fuel to evaporate water at the pressure
of the atmosphere alone, that it does to make steam at the higher
working tensions: consequently, the work obtained by the expansion of
the high-pressed steam is clear gain over the results to be obtained
by working at a low pressure. This is a very important principle in
economical steam engineering. Engineers who are accustomed to making
long runs between water-tanks, when every gallon is needed to carry
them through, know that their sure method of getting over the dry
division successfully, is to carry steam close to the popping-point,
pull the throttle wide open, hug the links close to the center, and see
that no loss occurs through the safety-valves.
RUNNING WITH LOW STEAM.
There are engineers who habitually carry merely sufficient steam to get
them along on time, under the mistaken belief that they are working
economically. John Brown runs steadily, and takes as good care of his
engine as any man on the A. & B. road; but he dislikes to hear the
steam escaping from the safety-valves, and prevents it from doing so by
habitually using steam thirty pounds below the blowing-pressure. The
consequence is, that he always makes a bad record on the coal-list,
compared with the other passenger men.
THE THROTTLE-LEVER.
In the interest of economy, the throttle-lever should be kept wide
open when practicable, and the speed regulated by the reverse-lever.
Experiments with the indicator have demonstrated beyond a doubt,
that running with the throttle-valve partly closed, wire-draws the
steam before it reaches the cylinders, whereby the initial pressure
is materially reduced, and its power for expansive work seriously
diminished.
MANAGEMENT OF THE FIRE.
The engine has moved only a few rods from the depot when the steam
shows indications of blowing off; and then the fireman sets to
work,--not to pile a heap of coal indiscriminately into the fire-box.
That is the style of the dunce whose natural avocation is grubbing
stumps. Ours is a model train, and a model fireman furnishes the
power to keep it going. He throws in four or five shovelfuls at each
firing, scattering the coal along the sides of the fire-box, shooting
a shower close to the flue-sheet, and dropping the required quantity
under the door. With the quick intuition of a man thoroughly master of
his business, our model fireman perceives at a glance, on opening the
door, where the thinnest spots are; and they are promptly bedded over.
The glowing, incandescent mass of fire, which shines with a blinding
light that rivals the sun’s rays, dazzles the eyes of the novice,
who sees in the fire-box only a chaotic gleam; but the experienced
fireman looks into the resplendent glare, and reads its needs or its
perfections. The fire is maintained nearly level; but the coal is
supplied so that the sides and corners are well filled, for there the
liability to drawing air is most imminent. With this system closely
followed, there is no difficulty experienced in keeping up a steady
head of steam. But constant attention must be bestowed upon his work
by the fireman. From the time he reaches the engine, until the hostler
takes charge at the end of the journey, he attends to his work, and to
that alone; and by this means he has earned the reputation of being
one of the best firemen on the road. His rule is, to keep the fire up
equal to the work the engine has to do, never letting it run low before
being replenished, never throwing in more coal than the keeping up of
steam calls for. The coal is broken up moderately fine, a full supply
being prepared before the fire-door is opened; and every shovelful
is scattered in a thin shower over the fire,--never pitched down on
one spot. Some men never acquire the art of scattering the coal as it
leaves the shovel; and, as a result, they never succeed in making an
engine steam regularly. Their fire consists of a series of coal-heaps.
Under these heaps, clinkers are prematurely formed; and between them
spaces are created, through which cold air comes, and rushes straight
for the flues, without assimilating with the gases of combustion, as
every breath of air which enters the fire-box ought to do.
CONDITIONS THAT DEMAND GOOD FIRING.
Roads that are hilly require far more skillful management to get a
train along than is called for on level roads, and the greater part of
the extra dexterity is needed from the fireman. To get a heavy train up
a steep hill, it is generally run at a high speed before reaching the
grade, so that the momentum of the train can be utilized in climbing
the ascent. Running for a hill is a particularly trying time on the
fireman; for the engine is rushing at a high speed, and often working
heavily. This ordeal must be prepared for in advance, by having the
fire well made up, and kept at its heaviest by frequent firing. When
the engine gets right on to the grade, toiling up with decreasing
speed, every pound of steam is needed to save doubling, and steady
watchfulness is required to prevent a relapse of steam; but the danger
of the engine “turning” the fire is not nearly so great as it was when
running fast for the hill.
HIGHEST TYPE OF FIREMAN.
The highest type of fireman is one, who, with the smallest quantity
of fuel, can keep up a good head of steam without wasting any by the
safety-valves. He endeavors to strike this mean of success by keeping
an even fire; but it sometimes happens, that the closest care will not
prevent the steam from showing indications of blowing off. When this is
the case, he keeps it back by closing the dampers, or, if that is not
sufficient, opens the door a few inches. Immense harm is done to flues
and fire-boxes by injudicious firing.
SCIENTIFIC METHODS OF GOOD FIREMEN.
It is not necessary that a man should be deeply read in natural
philosophy, to understand intimately what are actually the scientific
laws of the business of firing. Mr. Lothian Bell, the eminent
metallurgist, somewhere expresses high admiration for the exact
scientific methods attained in their work by illiterate puddlers.
Although they knew nothing about chemical combinations or processes,
they manipulated the molten mass so that, with the least possible
labor, the iron was separated from its impurities. In a similar way,
firemen skillful in their calling have, by a process of induction,
learned the fundamental principles of heat-development. By experiments,
carefully made, they perceive how the greatest head of steam can
be kept up with the smallest cargo of coal; and they push their
perceptions into daily practice.
If an accomplished scientist were to ride on the engine, observing the
operations of a first-class fireman, he would find that nearly all the
carbon of the coal combined with its natural quantity of oxygen to
produce carbon dioxide, thereby giving forth its greatest heat-power;
and that the hydro-carbons, the volatile gases of the coal, performed
their share of calorific duty by burning with an intensely hot flame.
He would find that these hydro-carbon gases, although productive of
high-power duty when properly consumed, were ticklish to manage just
right, for they would pass through the flues without producing flame
if they were not fully supplied with air; and, if the supply of air
were too liberal, it would reduce the temperature of the fire-box below
the igniting-point for these gases, which is higher than red-hot iron,
and they would then escape in the form of worthless smoke. Our model
fireman manages to consume these gases as thoroughly as they can be
consumed in a locomotive fire-box.
THE MEDIUM FIREMAN.
John Barton is considered a first-class fireman by some men. He works
hard to keep up steam, and is never satisfied unless the safety valves
are screaming. He carries a heavy fire all the time; and, when the
pop-valves rise, he pulls the door open till they subside, gets in a
few shovelfuls more coal, closes the door till the steam blows off
again, and repeats the operation of throwing open the door. This man
has learned only the half of his business. He has got through his
head how to keep up steam, but he has not acquired the more delicate
operation of keeping it down wisely and well. Training with an
intelligent engineer anxious to make a good fuel-record, will, in a few
months, improve Barton wonderfully. Barton is the medium fireman.
THE HOPELESSLY BAD FIREMAN.
Behind him comes Tom Jackson, the man of indiscriminately heavy
firing. Tom’s sole aim is to get over the road with the least possible
expenditure of personal exertion. He tumbles in a fire as if he were
loading a wagon, the size of the door being his sole gauge for the
lumps. When the fire-box is filled to the neighborhood of the door,
he climbs up on the seat, and reclines there till the steam begins to
go back through drawing air: then he gets down again, and repeats the
filling-up process, intent only on getting upon the seat-box with as
little delay as possible. His firing is regulated by the appearance
of the smoke issuing from the stack. So long as it continues of
murky blackness, he reclines in happiness: when the first streaks of
transparency appear in the smoke, he becomes unhappy, but gets up, and
suppresses smoke-consumption by smothering the flames with green coal.
If by any chance the engine steams so freely that the safety-valves
blow, the door is jerked wide open, and kept there till she cools down.
So the round goes. A hot, scorching fire, which heats the sheets and
flues to their highest temperature, is continually being interrupted
by the sudden cooling from a heavy load of damp coal, or a chilling
current of cold air. No wonder, that, with such treatment, leaky flues,
weeping stay-bolts, and pouring mud-rings, make their own protests,
often reiterated on the pages of round-house work-books.
WHO IS TO BLAME FOR BAD FIRING?
The destruction inflicted upon the heating-surface of locomotives by
the changes of temperature due to bad firing, should be charged to the
engineer. The fireman commits the havoc, but the engineer is more to
blame for allowing it to be done. Engineers often permit firemen to do
their work badly rather than have words about it. But this is mistaken
policy. A little firmness in the start will convince the worst of
firemen that they must strive to fire properly, or quit; and a man who
is indisposed to do his work well, deserves his walking-papers without
delay. There is no kindness in retaining a hopelessly bad fireman on an
engine. As a fireman, he is a continual loss to his employers; he is no
credit to his fellow-workmen; and if, by the mistaken forbearance of
engineers, he ever reaches the right-hand side, he will be a reproach
to the engineering fraternity.
CHAPTER VI.
_GETTING UP THE HILL._
SPECIAL SKILL AND ATTENTION REQUIRED TO GET A TRAIN UP A STEEP GRADE.
In the last chapter, some details were given of the methods pursued in
starting out with a heavy fast freight train. Where a train of that
kind has to climb heavy grades, special skill and attention are needed
in making the ascent successfully.
GETTING READY FOR THE GRADE.
The track for the first two miles from the starting-point is nearly
level, permitting the engineer and fireman to get ready for a long pull
not far distant. At the second mile-post a light descending grade is
reached, which lasts one mile, and is succeeded by an ascending grade
two and a half miles long, rising fifty-five feet to the mile.
WORKING UP THE HILL.
At the top of the descending grade, the engineer shuts off the steam
while the fireman oils the valves: then he puts on a little steam,
using a light throttle while the train is increasing in speed, until
the base of the ascent is nearly reached, when he gets the throttle
full open, letting the engine do its best work in the first notch
off the center. By this time the train is swinging along thirty miles
an hour, and is well on to the hill before the engine begins to feel
its load. Decrease of speed is just becoming perceptible when the
valve-travel gets the benefit of another notch, and the engine pulls
at its load with renewed vigor. But soon the steepness of the ascent
asserts itself in the laboring exhausts; and the reverse-lever is
advanced another notch, to prevent the speed from getting below the
velocity at which the engine is capable of holding the train on this
grade. While the engineer is careful to maintain the speed within
the power of his locomotive, he is also watchful not to increase the
valve-travel faster than his fire can stand it; for, were he to jerk
the lever two or three notches ahead at the beginning of the pull,
the chances would be that he would “turn” its fire, or tear it up so
badly that the steam would go back on him before he got half a mile
farther on. Before the train is safe over the summit, it will probably
be necessary to have the engine working down to 18 inches: but the
advance to this long valve-travel is made by degrees; each increase
being dependent upon, and regulated by, the speed. The quadrant is
notched to give the cut-off at 6, 9, 12, 15, 18, and 21 inches.
Repeated experiments, carefully watched, have convinced the engineer
of this locomotive, that its maximum power is exerted in the 18-inch
notch; so he never puts the lever down in the “corner” on a hill. A
great many engines act differently, however, showing increased power
for every notch advanced. If the cars in the train should prove easy
running,--and there are great differences in cars in this respect,--it
may not be necessary to hook the engine below 15 inches, or even 12
will suffice for some trains; but this can only be determined by seeing
how it holds the speed in the various notches.
WHEEL-SLIPPING.
As the engine gets well on to the grade, and is exerting heavy
tractive power, the wheels are liable to commence slipping; and it
is very important that they should be prevented from doing so. An
ounce of prevention is known to be worth a pound of cure; and it pays
an engineer to assure himself that no drips from pump-glands, or
feed-pipes, or cylinder-cocks, or from any other fountain, are dropping
upon the rails ahead of the driving-wheels. There is no use telling an
engineer of the decreased adhesion which the drivers exert on half-wet
rails, from what they do on those that are clean and dry. Knowing the
difference in this respect, every engineer should endeavor to prevent
the wetting of the rails by leaks from his engine; for hundreds of
engines get “laid down” on hills from slipping induced by this very
cause.
HOW TO USE SAND.
The first consideration in this regard is to have clean, dry sand, and
easy-working box-valves. Then the engineer should know how far the
valves open by the distance he draws the lever. In starting from a
station, or working at a point where slipping is likely to commence,
the valves should be opened a little, and a slight sprinkling of sand
dropped on the rails. This often serves the purpose of preventing
slipping just as well as a heavy coating of sand. And it has none of
the objectionable features of thick sanding. Trains often get stalled
on grades by the sand-valves being allowed to run too freely. It is not
an uncommon occurrence for engineers to open the valves wide, and let
all the sand run upon the rails that the pipe will carry, so that a
solid crust covers each rail, and every wheel on the train gets clogged
with the powdered silica; and, after the train has passed over, a
coating is left for the next one that comes along.
The wheels scatter their burden of powdered sand into the axle-boxes,
and it grinds its way inside the rod-brasses, and part of it gets
wafted upon the guides; and in all these positions it is matter
decidedly in the wrong place. And this body of sand under the wheels
increases the resistance in the same way, as a wagon is harder to pull
among gravel than it is on a clean, hard road: the indiscreet engineer
complains about the train being stiff to haul; and the chances are,
that he goes twice up the hill before the whole train is got over.
Uncle Toby’s plan is, when pulling on a heavy grade, to open the valve
enough to let the drivers leave a slight white impression on the rails.
If they slip, he gives a few particles more sand, but decreases the
supply again so soon as the drivers will hold with the diminished
quantity. Uncle Toby seldom needs to double a hill.
SLIPPERY ENGINES.
These remarks apply to ordinary engines with ordinary rail-conditions.
Occasionally we find an engine inveterately given to slipping, and no
conditions seem able to keep it down. Such an engine is as ready to
whirl its wheels as an ugly mule is to kick up its heels, and upon as
little provocation. With a dirty, half-wet rail, an engine of this kind
loses half its power. The causes that make an engine bad for slipping
are various. Very hard steel tires, or excess of cylinder power, are
the most frequent causes of slipping; but badly worn tires sometimes
produce a similar effect; or the blame may rest in a short-wheel
base, deficient in weight, or in too flexible driving-springs. To get
a slippery engine over the road when the rails are moist and dirty,
requires the exercise of unmeasured patience by the engineer. Job was a
cantankerous old Arab beside the engineer who passes cheerfully through
this ordeal. The tendency of an engine to slip may be checked to some
extent by working with the lever well ahead towards full stroke, and
throttling the steam. This gives a more uniform piston-pressure than
is possible while working expansively. Of two evils, it is best to
choose the least. The smallest in this case is losing the benefits of
expansion, and getting over the road.
FEEDING THE BOILER.
Some engineers claim that the most economical results can be obtained
from an engine by running with the water as low as possible, consistent
with safety. They hold, that, so long as the water is sufficiently high
to cover the heating-surfaces, there is enough to make steam from;
and the ample steam-room remaining above the water, assures a more
perfect supply of dry steam for the cylinders than can be had from the
more contracted space left above a high-water line. Old engineers,
running locomotives furnished with entirely reliable feeding-apparatus,
may be able to carry a low-water level advantageously, especially
with light trains and level roads; but with ordinary men, average
pumps or injectors, and the common run of roads, a high-water level
is safest. With a high-water level the temperature of the boiler can
be kept nearly uniform; for the increased volume of water holds an
accumulated store of heat, which is not readily affected by the feed.
And the surplus store is convenient to draw upon in making the best of
a time-order, or in getting over a heavy grade. Then, if the pumps or
injectors fail, a full boiler of water often enables a man to examine
the delinquent feeding-apparatus, and set it going; whereas, with low
water, the only resource would be to dump the fire.
CHOICE OF PUMP AND INJECTOR.
The engine on this train has one pump and one injector. The pump is
preferred for ordinary feeding-purposes, and is kept graduated to
supply the needs of the boiler while the engine is working, without
the foot-cock being moved. On a heavy pull, the pump in this condition
would not keep up the water-level; so the injector is called upon to
make up the deficiency. When the engine gets upon the heavy part of the
grade, it makes steam very freely; and, when the indications of getting
hot appear, the injector is started. During the remainder of the
ascent, the water is supplied as liberally as it can be carried; and
the top of the grade finds the engine with a full boiler. This enables
the engineer to preserve a tolerably even boiler temperature; for in
running down the long descent which follows, where the engine runs
two miles without working steam, the pump can be shut off, and sudden
cooling of the boiler avoided. The preservation of flues and fire-box
sheets depends very much upon the manner of feeding the water. Some
men are intensely careless in this matter. In climbing a grade, they
let the water run down till there is scarcely enough left to cover the
crown-sheet when they reach the summit. Then they dash on the feed, and
plunge cold water into the hot boiler, which is then peculiarly liable
to be easily cooled down, owing to the limited quantity of hot water
it contains. The fact of having the steam shut off, greatly aggravates
the evil; for there is then no intensity of heat passing through the
flues to counteract the chilling effect of the feed-water. If it is
necessary to pump while running with the steam shut off, the blower
should be kept going; which will, in some measure, prevent the change
of temperature from being dangerously sudden. There will probably be
some loss from steam blowing off, but that is the smaller of two evils.
Engineers are not likely to feed the boiler too lavishly when working
hard, for the injection of cold water instantly shows its effect by
reducing the steam-pressure. But this is not the case when running with
the throttle closed. The circulation in the boiler is then so sluggish,
that the temperature of the water may be reduced many degrees, while
the steam continues to show its highest pressure.
Writers on physical science tell us that the temperature of water and
steam in a boiler is always the same, and varies according to pressure;
that, at the atmosphere’s pressure, water boils at 212 degrees,
and produces steam of the same temperature. At 10 pounds above the
atmospheric pressure, the water will not evaporate into steam until it
has reached a temperature of 240 degrees, and so on: as the pressure
increases, the temperature of water and steam rises. But under all
circumstances, while the water and steam remain in the same vessel,
their temperature is the same. This is an acknowledged law of physical
science; yet every locomotive engineer of reflection, who has run on a
hilly road, knows that circumstances daily happen where the law does
not hold good.
FALL OF BOILER-TEMPERATURE NOT INDICATED BY THE STEAM-GAUGE.
If an engine, of the class represented as pulling our train, passes
over the top of the grade with half an inch of water in the glass,
there will be about 700 gallons in the boiler. Now, suppose it runs
down the hill without using steam, and keeps pumping till the water
rises six inches in the glass, there will be about 200 gallons more
water in the boiler. It is no unusual thing to do this with a mild
fire, and yet have no diminished tension of steam shown by the
gauge, although 200 gallons of water of about 60 degrees have been
injected amongst 700 gallons at 361 degrees, the temperature due to a
steam-pressure of 140 pounds. This ought to reduce the mean temperature
below 300 degrees, yet the pointer of the steam-gauge keeps indicating
140. That the pressure of steam and the temperature of the water do not
accord, is shown directly the throttle is opened to perform work. The
brisk circulation due to the rush of steam through the dry pipe now
brings the temperature of water and steam to equilibrium, and backward
the index of the steam-gauge travels. The steam-pressure goes back
faster than is due to the supply drawn for the cylinders; because the
latent heat of the steam passes into the water, helping to bring the
whole contents of the boiler to an even temperature.
SOME EFFECTS OF INJUDICIOUS BOILER-FEEDING.
Meanwhile, with an engine operated in this fashion, the train will
probably stand for fifteen minutes, till sufficient steam is raised to
proceed with.
The fact that newly injected water does not immediately rise in
temperature to the heat indicated by the pressure-gauge, can also be
tested by filling up a boiler with an injector while the engine is at
rest on a side-track. Working an injector causes greater circulation
than feeding with a pump, and the water goes into the boiler at a
higher temperature. For this reason the injector is superior to the
pump as a feeding-medium. But, if the engineer pulls out directly after
filling up the boiler with an injector, the steam will go down a few
pounds, no matter how good a fire may be on the grates.
On level roads, the pump or injector should be set to supply the needs
of the boiler; and a skillful engineer can regulate this so well, that
the foot-cock has seldom to be moved. The best results in getting
trains over the road, and in preserving boilers, are obtained in this
way. The runner who adopts the intermittent system of feeding is always
in trouble, or, as the boys say, “he is always nowhere.”
CAREFUL FEEDING AND FIRING PRESERVE BOILERS.
A case where the conservative effect of careful firing and feeding was
strikingly illustrated, came under the author’s notice a year or two
ago. During the busiest part of the season, the fire-box of a freight
engine belonging to a Western road became so leaky that the engine was
really unfit for service. Engines, like individuals, soon lose their
reputation if they fail to perform their required duties for any length
of time. This engine, “29,” soon became the aversion of train-men. The
loquacious brakeman, who can instruct every railroad-man how to conduct
his business, but is lame respecting his own work, got presently to
making big stories out of the amazing quantity of water and coal that
“29” could get away with, and how many trains she would hold in the
course of a trip. The road was suffering from a plethora of freight,
and extreme scarcity of engines; and on this account the management was
reluctant to take this weakling into the shop. So the master mechanic
turned “29” over to Engineer Macleay, who was running on a branch
where delays were not likely to hold many trains. Mac deliberated
about taking his “time” in preference to the engine, which others had
rejected, but finally concluded to give the bad one a fair trial. The
first trip convinced the somewhat observant engineer that the tender
fire-box was peculiarly susceptible to the free use of the pump, and
to sudden changes of the fire’s intensity of heat. So he directed the
fireman to fire as evenly as possible, never to let the grates get bare
enough to let cold air pass through, to keep the door closed except
when firing, to avoid violent shaking of the grates, and never to
throw more than three or four shovelfuls of coal into the fire-box at
one time. His own method was, to feed with persistent regularity, to
go twice over heavy parts of the division in preference to distressing
the engine by letting the water get low, and then filling up rapidly.
This system soon began to tell on the improved condition of the
fire-box. The result was, that, within a month after taking the engine,
Mac was pulling full trains on time; and this he continued to do for
five months, till it was found convenient to take the engine in for
rebuilding.
OPERATING THE DAMPERS.
According to the mechanical dictionary, a damper is a device for
regulating the admission of air to a furnace, with which the fire can
be stimulated, or the draught cut off, when necessary. Some runners
regard locomotive dampers in a very different light. They seem to think
the openings to the ash-pan are merely holes made to let air in, and
ashes out; that doors are placed upon them, which troublesome rules
require to be closed at certain points of the road to prevent causing
fires. Those who have made their business a study, however, understand
that locomotive dampers are as useful, when properly managed, as are
the dampers of the base-burner which cheers their homes in winter
weather. To effect perfect combustion in the fire-box, a certain
quantity of oxygen, one of the constituents of common air, is required
to mix with the carbon and carbureted hydrogen of the coal. The
combination takes place in certain fixed quantities. If the quantity
of air admitted be deficient, a gas of inferior calorific power will
be generated. On the other hand, when the air-supply is in excess of
that needed for combustion, the surplus affects the steam-producing
capabilities of the fire injuriously; since it increases the speed
of the gases, lessening the time they are in contact with the
water-surface, and a violent rush of air reduces the temperature of
portions of the fire-box below the heat at which carbureted hydrogen
burns.
LOSS OF HEAT THROUGH EXCESS OF AIR.
In the fire-boxes of American engines, where double dampers are the
rule, far more loss of heat is occasioned by excess of air than there
is waste of fuel through the gases not receiving their natural supply
of oxygen. The blast from the nozzles creates an impetuous draught
through the grates; and when to this is added the rapid currents of air
impelled into the open ash-pan by the violent motion of the train, the
fire-box is found to be the center of a furious wind-storm. The excess
of this storm can be regulated by keeping the front damper closed, and
letting the engine draw its supply of air through the back damper. When
the fire begins to get dirty, and the air-passages between the grates
become partly choked, the forward damper can be opened with advantage.
So long as an engine steams freely with the front damper closed, it
is an indication that there is no necessity for keeping it open. With
vicious, heavy firing, all the air that can be injected into the
fire-box is needed to effect indifferently complete combustion; and the
man who follows this wasteful practice can not get too much air through
the fire. Consequently, it is only with moderately light firing that
regulation of draught can be practiced. Running with the front damper
open all the time is hard on the bottom part of the fire-box, and the
ever-varying attrition of cold wind is responsible for many a leaky
mud-ring.
LOSS OF HEAT FROM BAD DAMPERS.
In Britain, where far more attention has been devoted to economy of
fuel than has been bestowed upon the matter this side of the Atlantic,
locomotives are provided with ash-pans that are practically air-tight,
and the damper-doors are made to close the openings. In many instances,
the levers that operate the dampers have notched sectors, so that the
quantity of air admitted may equal the necessities of the fire. British
locomotives, as a rule, show a better record in the use of their fuel
than is found in American practice; and a high percentage of the saving
is due to the superior damper arrangements.
Imagine the trouble and expense there would be with a kitchen-stove
that had no appliance for closing the draught! Yet some of our
locomotive builders turn out their engines with practically no means of
regulating the flow of air beneath the fire.
CHAPTER VII.
_FINISHING THE TRIP._
RUNNING OVER ORDINARY TRACK.
The hill which our train encounters nearly at the beginning of the
journey is the _Pons Asinorum_ of the division. The style in which
it is ascended shows what kind of an engine pulls the train, and it
tests in a searching manner the ability of the engineer. Our engine
has got over the summit successfully; and the succeeding descent is
accomplished with comfort to the engine, and security to the train. And
so the rest of the trip goes on. The train speeds merrily along through
green, rolling prairies, away past leafy woodlands and flowery meadows:
it cuts a wide swath through long cornfields, startles into wakefulness
the denizens of sleek farmhouses, and raises a rill of excitement as it
bounds through quiet villages. But every change of scene, every varied
state of road-bed,--level track, ascending or descending grade,--is
prepared for in advance by our engine-men. Their engine is found in
proper time for each occasion, as it requires the exertion of great
power, or permits the conservation of the machine’s energy. Over long
stretches of undulatory track the train speeds; each man attending
to his work so closely that the index of the steam-gauge is almost
stationary, and the water does not vary an inch in the glass. This
is accomplished by regular firing and uniform boiler-feeding, two
operations which must go together to produce creditable results.
STOPPING-PLACES.
There are few stops to be made, and these are mostly at water-stations.
Here the fireman is ready to take in water with the least possible
delay; and, while he is doing so, the engineer hurries around the
engine, feeling every box and bearing, and dropping a fresh supply
of oil where necessary. And, while going thus around, he glances
searchingly over the engine, his eye seeking to detect absent nuts, or
missing bolts or pins: any thing wrong may now be observed and remedied.
At the coaling-stations the fireman finds time to rake out the ash-pan,
and the engineer bestows upon the engine and tender a leisurely
inspection besides oiling around.
KNOWLEDGE OF TRAIN-RIGHTS.
Next to studying the idiosyncrasies of his engine, our model engineer
prides himself on his intimate acquaintance with the details of the
time-table. The practice becoming so common on our best-regulated
railroads, of examining candidates for promotion to the position of
engineer on their knowledge of the time-table, has a very salutary
effect upon aspiring firemen, and induces them to acquire familiarity
with the rules governing train-service, which they never forget.
Our engineer is well posted on all the rules relating to the movement
of trains; his mind’s eye can glance over the division, and note
meeting or passing points; and the relative rights of each train stand
blazoned forth in bold relief before his mental vision. This knowledge
regulates his conduct while nearing stations; for, although every
stopping-point is approached cautiously, those places where trains may
be expected to be found, are run into with vigilant carefulness, the
train being under perfect control. Depending blindly upon conductors
and brakemen to keep safe control of the train at dangerous points is
opening the gate of trouble. An engineer is jointly responsible with
the conductor for the safety of his train, and he should make certain
that every precaution is taken to get over the road without accident.
PRECAUTIONS TO BE OBSERVED IN APPROACHING AND PASSING STATIONS.
Running past stations where trains are standing side-tracked, requires
to be done with special care, particularly in the case of passenger
trains; for, at such points, there is danger of persons getting injured
by stepping inadvertently past a car or a building, in front of a
moving train. This peril is guarded against by reducing the speed as
far as practicable, after whistling to warn all concerned, by ringing
the engine-bell, and keeping a sharp lookout from the cab.
THE BEST RULES MUST BE SUPPLEMENTED BY GOOD JUDGMENT.
Rules framed by the officers of our railways for the guidance of
employes are always safe to follow as far as they go, and neglect of
their behests will soon entail disaster. But circumstances sometimes
arise in train-service to which no rule applies, and the men in
charge must follow the dictates of their judgment. This happens often,
especially on new roads; and the men who prove themselves capable
of wrestling successfully with unusual occurrences, of overcoming
difficulties suddenly encountered, are nature’s own railroaders. It
is this practice of acting judiciously and promptly, without the aid
of codified directions, which gives to American railroad men their
striking individuality, known to the men of no other nation following
the same calling. European railway servants carry ponderous books of
“rules and regulations” in their pockets, and these rules are expected
to furnish guidance for every contingency; so, when an engine-driver
or guard gets into an unusual dilemma, he turns over the pages of his
rule-book for counsel and direction. The American engineer or conductor
under similar circumstances takes the safe side, and goes ahead.
OPERATING SINGLE TRACKS SAFELY.
For many years to come, the great majority of our railroads will be
single tracks, as they now are. The operating of single-track roads is
only done safely by the exercise of unsleeping vigilance on the part of
all concerned in the movement of trains. Delays sometimes occur through
mistaken excess of caution, as in the case of an engineer in Iowa,
who mistook the lantern of a benighted farmer for the headlight of an
approaching train, and backed to the nearest telegraph station; or
that of a conductor in Michigan, who side-tracked his train to let the
evening star pass. Such mistakes make pleasantry among train-men, but
all acknowledge that it is better to err on the safe side than to run
recklessly into danger.
On this subject the remarks of Kirkman are strongly applicable. Writing
on the “intelligent discrimination exercised by train men,” he says,
“It is observable in the practical application of the system under
which trains are operated, that the employes connected with the train
service do not always attach the significance to specific signals
or rules that would naturally be supposed. Especially is this so in
reference to use of signals. Their acquaintance with the every-day
working of trains teaches them that allowance must always be made
for the ignorance, stupidity, or thoughtlessness of employes; and
they strive constantly to protect themselves, and the passengers and
property intrusted to their care, from the fatal effects that would
oftentimes follow a blind obedience to the orders given them....
The engineer of an irregular train that is running under special
telegraphic instructions at the rate of sixty miles an hour, can
not depend implicitly upon the accuracy of the reports he receives
in reference to the location and intention of other trains.... His
orders are to proceed. He has been trained to obey. Outwardly he is
unconcerned, but inwardly he is filled with apprehension; and, as he
proceeds on his course, he scrutinizes the track with an intensity and
a sagacity that never wearies.”
CAUSES OF ANXIETY TO ENGINEERS.
“The anxiety upon the part of the engineer is not occasioned by fear
for his personal safety, though that doubtless has its influence; but
it is the knowledge born of observation and experience, that blind
adherence to orders, no matter what the circumstances, or from whom
emanating, may not only cost him his life, but may involve the lives
of many others,--the lives of people believing in him, and trusting in
him, and as unconscious of danger as they are helpless to avoid it.”
ACQUAINTANCE WITH THE ROAD.
Next in importance to knowing well how to manage the engine, and
intimate familiarity with the time-table and its rules, comes
acquaintance with the road. In the light of noonday, when all nature
seems at peace, when every object can be seen distinctly, the work of
running over a division is as easy as child’s play. But when thick
darkness covers the earth, when the fitful gleam of the headlight
shines on a mass of rain so dense that it seems like a water-wall
rising from the pilot, or when blinding clouds of snow obliterate every
bush and bank, it is important that the engineer should know every
object of the wayside. A person unaccustomed to the business, who rides
on a locomotive tearing through the darkness on a stormy night, sees
nothing around but a black chaos made fitfully awful by the glare from
the fire-box door. But even in the wildest tempest, when elemental
strife drowns the noise of the engine, the experienced engineer
attends to his duties calmly and collectedly. A cutting or embankment,
a culvert or crossing, a tree or bush, is sufficient to mark the
location; and every mile gives landmarks trifling to the uninitiated,
but to the trained eye significant as a lighted signal. One indicates
the place to shut off steam for a station, another tells that the
train is approaching a stiff-pull grade; and the engine-men act on the
knowledge imparted. And so the round of the work goes. Working and
watching keep the train speeding on its journey. Nothing is left to
chance or luck: every movement, every variation of speed, is the effect
of an unseen control. As a stately ship glides on its voyage obedient
as a thing of life to the turn of the steersman’s wheel; so the king of
inland transportation, the locomotive engine, the monarch of speed, the
ideal of power in motion, pursues its way, annihilating space, binding
nations into a harmonious unit, and all the time submissive to the
lightest touch of the engineer’s hand.
To get a freight train promptly over the road day after day, or night
after night, an engineer must know the road intimately, not only
marking the places where steam must be shut off for stations or grades,
but every sag and rise must be engraved on his memory. Then he will
be prepared to take advantage of slight descents to assist in getting
him over short pulls, where, otherwise, he would lose speed; and the
same knowledge will avail him to avoid breaking the train in two while
passing over the short depressions in the track’s alignment, called
sags in the West.
FINAL DUTIES OF THE TRIP.
With an engine properly fired, there is but little special preparation
needed for closing up the trip without waste of fuel. The fire is
regulated so that a head of steam will be retained sufficient to take
the engine into the round-house after the fire-box is cleaned out. In
drawing the fire, the blower should be used as sparingly as possible;
for its blast rushes a volume of cold air through the flues, which is
apt to start leaks. Many engineers find flues, or stay-bolts, which
were dry at the end of one trip, leaking when the engine is taken out
for the next run. In nine cases out of ten, the cause has been too much
blower. So soon as the ash-pan is cleaned out, the dampers should be
closed so that the fire-box and flues may cool down gradually.
CHAPTER VIII.
_RUNNING A FAST PASSENGER TRAIN._
Materials for the following notes were taken during a trip on the
Pennsylvania Railroad:--
AVERAGE SPEED.
The New York and Chicago limited express train, run on the Pennsylvania
system of railroads, passes over the distance of 912 miles between
the two cities in twenty-five hours and twenty-nine minutes, making
an average speed of 35.29 miles an hour. All the known resources of
mechanical science have been ransacked to produce appliances for
reducing delays, so that the highest possible percentage of the time
provided for the journey should be devoted to running. Water for
steam-making is collected, as the train runs along, from troughs
placed in the middle of the track; a system of absolute block signals,
controlled by vigilant train-dispatchers, provides a clear line; and
stops are made only for the purpose of changing the locomotives at
the end of divisions. The lines over which the train runs traverse a
multitude of cities and towns, most of them having the streets crossing
the track on the level; and a great many other railroads are crossed
at grade. Therefore, although the actual stops between Jersey City and
Chicago are only seven, a run exceeding ten miles without meeting with
the necessity of checking the speed is rare.
SPEED BETWEEN JERSEY CITY AND PHILADELPHIA.
The run of ninety miles from Jersey City to Philadelphia is made at an
average speed of 45 miles an hour, leaving an average of 34 miles an
hour for the remainder of the journey. To keep on time, some parts of
the first division must be traversed at a speed over 60 miles an hour,
while 50 miles an hour must be maintained over a considerable portion
of the other divisions.
REQUISITES OF A HIGH-SPEED LOCOMOTIVE.
The first essential for a high-speed locomotive is the means of
generating steam freely as fast as it is used up by the cylinders. The
next consideration is properly designed steam-distribution gear, and
well-proportioned machinery, so that the heat energy produced by the
boiler may be converted into useful work in propelling the engine with
the least possible loss of power. To handle the fast trains between
New York and Philadelphia, the mechanical talent of the Pennsylvania
Railroad, aided by fifty years’ inherited experience, has produced the
form of engine known as Class K. This is an anthracite-coal-burning
locomotive, with 1,205 square feet of heating-surface to supply steam
to cylinders 18 inches by 24 inches, which turn two pairs of coupled
drivers 78 inches in diameter. The traction force of the engine is thus
(18^2 × 24)/78 = 99.69 pounds for each pound of effective pressure per
square inch of the pistons. The valves are the plain slide, with 1¼
inch outside lap, no inside lap, 1/16 inch lead in full gear, and a
full travel of 5½ inches. The steam-ports are 16¾ inches long and 1½
inches wide; while the exhaust port is 3¼ inches wide, securing free
emission of steam.
MAKING UP THE FIRE.
Locomotives belonging to this company are not permitted to cool down,
unless the fire has to be drawn that work may be done. At the end of
a trip, the fire is cleaned and banked to wait for the next run. By
getting to the round-house two hours before train-time, we find our
engine receiving the first work of preparation for the trip. The fire
is spread over the grates, and a fresh supply of coal laid over the
whole fire. To make an engine steam freely with anthracite coal, it is
very important that the fire should be properly burned through before
starting out. About two hours’ time is needed for this, so that the
mass of coal will get properly ignited without the aid of the blower.
A fire that has to be forced along with the blower never proves
satisfactory.
GETTING READY FOR THE TRIP.
The engineer and fireman reach the round-house about half an hour
before train-time, and each proceeds to do his own line of work
preparing the engine for the run. The engineer attends to oiling
round,--an important matter where ninety miles have to be passed
without stopping. Each bearing and rubbing surface is provided with
an oil-cup, with feed carefully regulated to supply the required
lubrication. Mechanical ingenuity has arranged excellent methods for
securing regular lubrication, but the care and skill of the engineer
are needed to keep them working properly. As he moves round the engine,
his trained eye detects the smallest defect; and, as he examines
every cup and reservoir, the touch in time that prevents delay is
given wherever needed. At the same time the machinery gets a final
inspection, and the air-pump is started going. Meanwhile, the fireman
has been attending to his duties,--giving the fire its finishing
touches, filling oil-cans, and brushing the dust off the cab-fittings.
Now we back up to the train. The air-hose is coupled, two minutes’ fast
pumping of the air-pump charges the car reservoirs with their full
pressure of air, and we are ready for the start. While waiting for the
signal, I look into the fire-box, and see a furnace 10 feet long and
42 inches wide filled up with coal to a depth of 10 inches. It takes
about a ton and a half of coal to make this fire ready for the road.
The fire was level on the surface; but the greatest depth was in the
front, where the grates slope downward. The fire-box alone gives a
heating-surface of 120 square feet.
THE TRAIN TO BE PULLED.
The train consists of five Pullman sleeping-cars and one dining-car,
the six cars weighing 200 tons. The engine and tender, in working
order, weigh 74 tons, which gives a total weight of 274 tons to be
moved by the force exerted by the pistons.
THE START.
As the signal is given to start, the engineer drops the links full
forward by means of the steam reverse gear, pulls the throttle lever
open, and the engine responds by moving forward. A sprinkling of sand
is dropped upon the rails, the throttle-valve is opened a little wider,
and with resounding exhausts the engine is working into speed. From the
start, the necessity of pushing forward, and utilizing every second of
time, is recognized. The train has not moved more than its own length
when a speed of ten miles an hour is reached. The engineer now hooks
back the links to cut off at ten inches, pulls the throttle wide open,
and “lets her go.” While waiting at the station, steam was kept down to
130 pounds by the injector and heater. The injector was shut off just
before starting. When we got out about half a mile, the steam-gauge
began to point towards 140, the popping pressure; and the engineer
started the injector, and it was kept going continually during the
remainder of the trip. It is a No. 9 Sellers, and can supply the boiler
during the heaviest work without reaching the limit of its capacity.
There is a No. 8 injector on the fireman’s side, but it is never used
to run by. The injector and air-pump are two things about these engines
that seldom need to be touched on the road after they are set to work.
GETTING THE TRAIN OVER THE ROAD.
The first two miles out of Jersey City a grade of about 40 feet is
ascended, but the summit is reached in four minutes; then the links are
hooked up to the 8-inch cut-off, which is the ordinary running-point
with this train. Next mile is passed in 85 seconds, but is finished
by shutting off steam to let the engine roll over a bridge. Here the
valves are oiled, a duty which is repeated three times during the
trip. Although steam was shut off for only about 300 yards, the speed
was perceptibly reduced; and it took a minute and a half to make the
next mile. Three miles succeeding that were traversed in 3½ minutes,
one of them being run in 59 seconds; but again a demand for reduced
speed intervened in the shape of the street-crossings of Newark,--the
city being approached by a sharp curve. Here the speed was reduced to
12 miles an hour, and two miles were run at a rate under 30 miles an
hour. A spurt is again made; and the second mile, after getting clear
of the street-crossings, is passed in 63 seconds, the next mile in 61
seconds, when another reduction of speed for Elizabeth streets and a
railroad crossing takes place. After passing this town, a speed of one
mile in 57 seconds was attained, several miles having been traversed
in a minute each: then came the watering-point, where the speed was
reduced under 20 miles an hour. Thus it was through the whole trip,--a
struggle to get up speed: then comes the necessity for dissipating
part of the power gained in raising the load to the required velocity.
The engine maintained a speed of sixty miles an hour easily enough;
but it was a laborious proceeding, increasing the speed in a couple
of miles from a mile in two minutes to a mile in one minute. Several
heavy grades were ascended, one of them three miles long, which reduced
the speed in the second two miles to 30 miles an hour, although the
links were dropped to ten inches cut-off. The highest speed attained
during the run was a mile in 55 seconds. The greatest speed was
reached with the links hooked back to cut-off at 7 inches. It is well
understood by engineers running these trains, that high velocity
can only be attained with the lever well notched back. Sixty miles
an hour is nearly the maximum speed these engines will make cutting
off at 8 inches, and the train is so heavy that the amount of steam
represented by that cut-off is needed to maintain the speed on curves
or slightly ascending grades. The fastest running is done under the
favorable conditions of a straight, level track, or descending grade,
where the engine can handle the train at 6 or 7 inches cut-off. When
running over 60 miles an hour, if the lever be advanced a notch the
speed will decrease; for more steam gets into the cylinders than can be
exhausted at the high piston velocity, and back pressure ensues, which
acts as a brake upon the engine. Even with the big driving-wheels of
this locomotive, the piston-speed at 60 miles an hour is very high.
In traversing a mile in one minute, the wheels make 258½ revolutions,
giving a piston-speed of 1,034 feet.
HOW THE ENGINEER DID HIS WORK.
The engineer exhibited remarkable skill and intelligence in handling
the engine. The water was carried steady without any fluctuation,
which enabled the fireman to maintain the steam at an even pressure.
Where the speed had to be reduced, no more braking was done than was
absolutely necessary; and the brake was applied so gradually, that it
was hard to distinguish that the speed was not being reduced merely
through natural loss of inertia. Every time the steam was shut off,
the links were dropped, giving the valves full travel. Many engineers
do not recognize the urgent necessity for doing this. They will shut
off steam, and leave the engine running hooked up, a practice which
proves destructive to valves, their seats, pistons, and cylinders.
Take the case of this engine cutting off at six inches of the stroke.
As the piston moves from the point of cut-off to the point of release,
a partial vacuum is formed in the cylinder; and, as soon as the valve
opens the exhaust, the hot, cinder-laden gases from the smoke-box
rush in through the nozzles to fill the void in the cylinder. During
the return stroke, compression begins about eight inches before the
completion of the stroke; and, as the compression is too great for the
valve to hold down, it is jerked violently away from its seat, causing
the clattering so well known where engines are running hooked up after
the steam is shut off. I have known several cases of valves getting
“cocked” from this cause alone.
QUALIFICATIONS THAT MAKE A SUCCESSFUL ENGINEER.
The ability to manage his engine skillfully, so that its best
powers may be economically developed, is the first requisite of
a good engineer; but that qualification must be supplemented by
others scarcely less essential. Sagacity, sound judgment, judicious
self-reliance, are attributes which advance men in all callings; and
they are peculiarly valuable possessions for the man who presides over
the safety of a railway train. It would be hard to find a business
where capacity for suddenly adapting circumstances to ends is likely to
prove so useful as it is to an engineer. Some men get along smoothly
with engine and train so long as every thing goes on regularly,--trains
on time, and engines in perfect order. But let the least difficulty
arise, and they succumb like a house of cards. Imbecile, helpless
creatures, they are vanquished by the first cloud of trouble. Their
true vocation is away from railways. Self-confidence is not always
popular; but the engineer who is perfectly satisfied with his own
ability to grapple successfully with every emergency, to overcome every
difficulty, and avoid every danger, is the individual who gets trains
promptly over the road. He who possesses adaptability for railroading
acquires a mastery of the work quickly, but mere affinity for the
calling will not invest a man with the aggregation of facts respecting
the business which are requisite for meeting the emergencies of train
service. This must be acquired by industry and observation.
HOW THE FIRING WAS DONE.
The fireman’s part of the work of getting the train over the road was
no less skillfully done than that of the engineer. During the first
seven miles of the trip, he did nothing for the fire other than crack
up some coal-lumps. All the coal burned was broken down to pieces about
the size of two bricks. When he seemed to think the proper time had
come, he glanced at the fire, then threw in one shovelful of coal. To
pitch coal upon the right spot in a fire-box ten feet long, requires
considerable skill when the engine is swinging at a mile-a-minute
speed; but this youth seemed equal to the task. He did not pile in a
load of coal, and then climb up into the cab, to wait for it to burn,
as is the practice of the poor fireman. After he began to fire, he kept
at it. About every two minutes he got in a shovelful of coal. When the
engine was working hard getting into speed, he varied his intervals
of firing; but he worked on a system, which was to keep up the body
of fire, and maintain the temperature as nearly even as possible. He
followed scientific methods, whether he understood any thing about
science or not. He never hesitated about the spot where the coal was
going, but pitched it in, and closed the door quickly, waiting till the
turn for the next installment came round. By this means the steam never
felt the chilling effect that results from heavy-charge firing. The
steam-gauge index kept pointing at 135 as steadily as if it had been
fastened there. About eight miles from Philadelphia the fireman stopped
putting in coal, and in the remainder of the run he several times used
the hoe to level the fire.
When we stopped at the station, about four inches of glowing cinders
covered the grates.
CHAPTER IX.
_HARD-STEAMING ENGINES._
IMPORTANCE OF LOCOMOTIVES STEAMING FREELY.
As the purpose of a locomotive engine attached to a train is to take
that train along on time, and as engines are generally rated to pull
cars according to their size, it is of the utmost importance that
they should make steam freely enough to keep up an even pressure on
the boiler while the cylinders are drawing the supply necessary to
maintain speed. A locomotive that does not generate steam as fast as
the cylinders use it, is like a lame horse on the road, a torture to
itself, and to every one connected with it.
ESSENTIALS FOR GOOD-STEAMING ENGINES.
To steam freely, an engine must be built according to sound mechanical
principles. The locomotives constructed by our best manufacturers, the
engines which keep the trains on our first-class roads moving like
clock-work, are designed according to proportions which experience
has demonstrated to be productive of the most satisfactory results
for power and speed, combined with economy. There are certain
characteristics common to all good makers. The valve-motion is planned
to apply steam to the pistons at nearly boiler pressure, with the
means of cutting off early in the stroke, and retaining the steam long
enough in the cylinders to obtain tangible benefits from its expansive
principle. Liberal heating-surface is provided in the boiler, its
extent being regulated by the size of the cylinders to be supplied with
steam. With a good valve-motion, and plenty of heating-surface served
with the products of good coal, an engine must steam freely if it is
not prevented from doing so by malconstruction or adjustment of minor
parts, or by the wasting of heat in the boiler or in the cylinders.
An engine of that kind will steam if it is managed with any degree of
skill. But as the best lathe ever constructed will turn out poor work
under the hands of a blundering machinist, so the best of locomotives
will make a bad record when run without care or skill. Regular
feeding--the water supplied at a rate to equal the quantity evaporated,
which will maintain a nearly level gauge--is an essential point in
successful running. It is hardly second in importance to skillful
firing.
CAUSES DETRIMENTAL TO MAKING STEAM.
When an engine is steaming badly, almost the first action of an
experienced engineer is to examine the petticoat-pipe. The influence
which this pipe exercises on the steaming qualities of an engine has
already been adverted to, but its importance can not be too strongly
urged upon the attention of the young engineer. It is one of the most
successful devices invented for regulating the vacuum in the smoke-box,
so that the currents of hot gases shall flow evenly through all the
flues. Any thing which interferes to disturb the flow of these
currents, crowding them away from any section of the flue-surface,
will have a prejudicial effect upon the steam. The pipe may be set too
high to produce an even draught, or the fault may be in the opposite
direction. Its diameter may not be suitable for the conditions of
smoke box and stack, or its shape may be at fault. Not unfrequently
the pipe is fastened obliquely, so that the blast impinges on the side
of the stack, producing evil results; or the braces which keep it in
position occasionally break, and the draught is permitted to shoot in
every direction but the direct way to the atmosphere, and the effect is
immediately apparent on the steam-gauge.
PETTICOAT-PIPE.
The petticoat-pipe performs, in relation to draught, functions of
a similar nature to those performed by the tubes of an injector in
inducing the flow of water; and its efficiency is reduced by the same
disturbing agencies. The pipe must have a size in proportion to the
diameter of stack, and it must be set so that it shall deliver the
exhaust-steam to make a straight shoot through the stack. When these
conditions are properly arranged, the exhaust-steam goes through the
stack like a piston, leaving a vacuum behind. The petticoat-pipe is
a device confined mainly to American locomotives; and its purpose is
to regulate the draught in the smoke-box so that the currents of hot
gases are drawn uniformly through the flues, the top, bottom, and
sides getting about the same heating intensity as passes through the
middle rows. The opportunity for the exhibition of good firing depends
greatly upon the petticoat-pipe being constructed properly, and secured
at the right position. It is impracticable to lay down a positive
rule for dimensions and best position of these pipes, for engines
of the same proportions frequently require different petticoat-pipe
arrangements to make them steam freely. For our 17 × 24 engine, there
is a petticoat-pipe 11½ inches in diameter, with a flare, at bottom,
17 inches wide. The pipe reaches within 3 inches of the bottom of the
stack, and is set one inch above the nozzle. This gives good results
in our case. When engines with sufficient heating-surface do not steam
freely, the trouble nearly always lies in malproportioned or badly
set petticoat-pipes. Sometimes a very small change in the position of
this pipe will have a wonderful effect upon the steaming qualities of
the engine. If the pipe is set too high, most of the draught will pass
through the lower flues; and the upper rows will become filled with
soot, and many of them are likely to get choked with fine ashes, which
remains there for want of draught to force it out. Should it be too
low, the bottom rows of flues will suffer from the effect of defective
draught. When the petticoat-pipe is just right, the flues will look
uniformly clean inside, which can be ascertained by a close inspection
of the smoke-box. In addition to making the engine lose the benefit of
its full heating-surface, a badly arranged petticoat-pipe concentrates
the draught so much that it tears the fire to pieces at one particular
point; and the only resource for the man who wishes to keep up steam
is to fire heavily, thereby preventing cold air from being drawn
through the crevices. Many engines will not steam with a light fire,
and yet do well with a heavy body of coal on the grates. In nearly
every instance of this kind, the fault lies in the petticoat-pipe;
and, if this is properly adjusted, the engine will be found capable of
carrying a light fire, and will show far more economical results than
could be reached with heavy firing. Some engineers assume that the
petticoat-pipe must be right when an engine steams freely, even though
a heavy fire is necessary to produce this result. This is a mistake.
It may be badly set or badly proportioned, only a degree smaller
than it is where the engine will not steam to keep the train going.
By closely watching the action of the blast on the fire of an engine
that calls for heavy firing, the engineer learns where the fault lies.
When the engine is laboring on a hard pull, he should open the door;
and if he finds, that, in a particular section of the fire-box, the
smaller pieces of coal are dancing and glowing with an incandescence
more brilliant than the other parts, and if he finds that this is
repeatedly the case, he may conclude that the nozzles are too small,
or the petticoat-pipe is working the mischief with his coal-account.
Should the nozzles be the proper size, he had better lose no time in
beginning to experiment with this pipe. He can lower it a quarter of an
inch at a time, and mark the effects of the change on the fire. Should
that produce no improvement, he may try raising it; or, if there is a
movable sleeve on the top, that may be set in different positions. An
engineer can test a petticoat-pipe much better by manipulating it on
the road than in the round-house. If no change of position will improve
the working of the pipe, one of different dimensions should be tried.
Perseverance in this line will bring the right thing in the end. I
knew an engineer who tried five different petticoat-pipes before the
proper one was reached. Such a thing causes labor, and needs patience;
but it pays when the fuel-account for running ten thousand miles comes
in.
THE SMOKE-STACK.
The ordinary purpose of the smoke-stack is to convey the smoke and
exhausted gases to the atmosphere. If it is intended to perform its
functions in a straightforward manner, it is made about the same
diameter as the cylinders, and its highest altitude rises from 14
to 15 feet above the rail. The stack is a simple-enough article to
look at, yet a vast amount of inventive genius has been expended upon
attempts to expand its natural functions. Attempts have been made
to utilize it as an apparatus for consuming smoke, and hundreds of
patents hang upon it as a spark-arrester. Patentees, in pushing their
hobby, seem occasionally to forget that a locomotive requires some
draught, as a means of generating steam; and stacks are frequently so
hampered with patent spark-arresters that the means of making steam are
seriously curtailed. Were it not for the danger of raising fires by
spark-throwing, it would be more economical to use engines with clear
smoke-stacks; and the extended front end, with open stack, is a good
move in this direction.
OBSTRUCTIONS TO DRAUGHT.
Every obstruction to free draught entails the use of strong artificial
means to overcome it. The usual resort is contracted nozzles, which
induce a sharp blast, and use up more fuel than would be required
with an open passage to the atmosphere. Among the obstacles to free
steaming, that come under the category of obstructed draught, may
be placed a wide cone fastened low, and netting with fine meshes.
When the draught passage is interrupted to a pernicious extent by
spark-arresting appliances, their effects can be perceived on the fire
when steam is shut off; for the flame and smoke prefer the fire-box
door to the stack as a means of exit. Sometimes steam-making is
hindered by the netting getting gummed up with spent lubricants and
dirt from the cylinders. Cases occur where this gum has to be burned
off before free draught can be obtained. Waste soaked with coal-oil
will generally burn off the objectionable coating.
CHOKING THE NETTING WITH OIL.
Gumming of the netting is usually caused by carelessness in oiling
the valves. Some runners will shut off for a minute while the fireman
oils the valves, and the lubricant scarcely gets time to reach the
steam-chest when the throttle is opened wide again; and instead of
soaking over valves and cylinders, and into the remotest part of
piston-packing, the oil goes through the stack with the first puff of
steam. It is best, in oiling the valves, to leave the cup-plugs open
long enough for the oil to be sucked out of the pipes. Then, when steam
is applied, it should be done by slightly opening the throttle, so that
it will work the oil into the piston-packing; and, after a few turns
run this way, there will be no loose oil left to defile the netting.
SILICIOUS DEPOSIT ON FLUE-SHEET.
Certain kinds of coal deposit a hard, silicious substance upon the back
flue-sheet, which gradually accumulates till the draught is seriously
impeded. This, of course, prevents the full benefit of the hot gases
being obtained; and consequently the steam goes down. Flues stopped
up with cinders produce a similar effect. The flues getting choked up
with cinders is not always an indication that the petticoat-pipe is
performing its duty improperly. Stopping up of flues is often caused
by wild, unskillful firing. A shovelful of coal pitched high, deposits
part of its load direct in the flues; and some pieces that are a close
fit do not go through. They stick half way; and small cinders soon
follow, that quickly close up the entire passage.
THE EXTENDED SMOKE-BOX.
By this arrangement, the spark-arresting device is transferred from the
smoke-stack to the smoke-box, and the exhaust steam escapes direct to
the atmosphere, without meeting obstruction from a cone or netting. The
netting is generally an oblong screen, extending from above the upper
row of flues to the top of the extended smoke-box, some distance ahead
of the stack. This presents a wide area of netting for the fire-gases
to pass through. The draught through the flues is regulated by an
apron or diaphragm-plate, extending downwards at an acute angle from
the upper part of the flue-sheet. With the long exhaust-pipe used with
the extended smoke-box, the tendency of the exhaust is to draw the
fire-gases through the upper row of flues. The diaphragm-plate performs
the same duties here, of regulating the draught through the flues
equally, as the petticoat-pipe does with the diamond-stack. It is of
great consequence, for the successful working of the engine, that the
draught should be properly regulated: otherwise there will be trouble
for want of steam.
When an engine having an extended smoke-box does not steam properly,
experiments should be made with the diaphragm fastened at different
angles, till the point is reached where equal draught through the flues
is obtained. Closing the nozzles, as a means of improving the steaming
of such an engine, is certain to make matters worse.
STEAM-PIPES LEAKING.
The blowing of steam-pipe joints in the smoke-box is very disastrous
to the steaming qualities of a locomotive. This has a double action
against keeping up steam. All that escapes by leaking is so much
wasted, and its presence in the smoke-box interrupts the draught.
If the steam-pipe joints are leaking badly, they can be heard when
the fire-door is open and the engine working steam. Some experienced
engineers can detect the action of leaky steam-pipe joints on the fire;
but the safest way to locate this trouble is by opening the smoke-box
door, and giving the engine steam.
DEFECTS OF GRATES.
Grates that are fitted so close as to curtail the free admission of
air below the fire prevent an engine from steaming freely. The effect
of this will be most apparent when the fire begins to get dirty. This
is not a common fault. I once knew of an engine’s steaming being very
seriously impaired by two or three fingers in one section of grate
being broken off. The engine steamed well with a light fire, till, in
dumping the fire at the end of a journey, the men knocked some of the
fingers off. Next trip, it seemed a different engine. Nothing but heavy
firing would keep up an approach at working-pressure. I experimented
with the petticoat-pipe without satisfaction, assured myself that no
leaks existed among the pipes; the stack, with its connections, was
faultless; and the engineer was puzzled. The defect was discovered by
watching the effect of the blast upon the fire. Signs of air-drawing
were often to be seen at the point where the broken fingers were. This
was where the mischief lay. Too much cold air came through, unless the
opening were bedded over by heavy fire.
A drop-grate that did not close properly had a similar effect upon
another engine which came under the author’s notice; and a change,
which shut the opening, effected a perfect remedy.
LIME, SCALE, AND MUD.
In calcareous regions, where the water-supply for locomotives is drawn
from wells, the most common cause for bad-steaming engines is leaky
heating-surfaces, or water-surfaces incrusted with lime deposits.
When he sees water pouring from flues and stay-bolts, an engineer has
no difficulty in divining the reason why his engine steams poorly;
nor need he be far-seeing to perceive a remedy in the boiler-maker’s
calking-tools skillfully applied. The case of incrustation is,
however, more difficult to comprehend in all its bearings. When water
containing lime-salts touches the hot flues or fire-box, evaporation
takes place; and the solid substance previously in solution is left
behind, and adheres to the heating-surfaces, gradually forming a
refractory scale which is an indifferent conductor of heat. As this
scale becomes thick, it stands up, like a non-conducting barrier,
between the water and the hot sheets; and it takes a much greater
expenditure of heat to evaporate the water inside, just as a kettle
coated with scale is much harder to boil than a clean one. When a
boiler gets badly fouled with scale and mud, these impurities exercise
a pernicious effect upon the steaming qualities of a locomotive.
PREVENTING ACCUMULATION OF MUD IN BOILERS.
Mud-drums, with blow-off cocks attached, serve to check the growth
of this evil when the engineer is careful to make frequent use of
these appliances; and a strong pressure of washing-out water, poured
frequently through the boiler, has an excellent cleansing effect: but
some kinds of scale defy mud-drums and the best methods of washing
out, leaving the only resort to be the removal of flues for cleansing.
The filling up of a boiler with scale and mud, so as to prevent the
engine from steaming freely, is necessarily a gradual process; and
an observant engineer has time to note the change, and recommend the
proper remedy.
TEMPORARY CURES FOR LEAKY FLUES.
Leaky flues or stay-bolts may sometimes be dried up temporarily
by putting bran, or any other substance containing starch, in the
feed-water. Care must be taken not to use this remedy too liberally,
or it will cause foaming. It is, however, a sort of granger resort, and
is seldom tried except to help an engine to the nearest point where
calking can be done.
GOOD MANAGEMENT MAKES ENGINES STEAM.
No engine steams so freely but that it will get short under
mismanagement. The locomotive is designed to generate steam from water
kept at a nearly uniform temperature. If an engine is pulling a train
which requires the evaporation of 1,500 gallons of water each hour,
there will be 25 gallons pumped into the boiler every minute. When
this goes on regularly, all goes well; but if the runner shuts the
feed for five minutes, and then opens it to allow 50 gallons a minute
to pass through the pump, the best engine going will show signs of
distress. Where this fluctuating style of feeding is indulged in,--and
many careless runners are habitually guilty of such practices,--no
locomotive can retain the reputation of doing its work economically.
INTERMITTENT BOILER-FEEDING.
The case of Fred Bemis, who still murders locomotives on a road in
Indiana, is instructive in this respect. Fred was originally a butcher;
and, had he stuck to the cleaver, he might have passed through life
as a fairly intelligent man. But he was seized with the ambition to
go railroading, and struck a job as fireman. He never displayed any
aptitude for the business, and was a poor fireman all his time through
sheer indifference. But he had no specially bad habits; and, in the
course of years, he was “set up.” He had the aptitude for seeing a
thing done a thousand times without learning how to do it. All his
movements with an engine were spasmodic. Starting from a station with a
roaring fire and full boiler, the next stopping-point loomed ahead; and
to get there as soon as possible was his only thought. He would keep
the reverse-lever in the neighborhood of the “corner,” and pound the
engine along. The pump would be shut off to keep the steam from going
back too fast, till the water became low: then the feed would be opened
wide, and the steam drowned down. In vain a heavy fire would be torn to
pieces by vigorous shaking of the grates. The steam would not rally,
and he would crawl into the next station at a wagon pace. A laboring
blower and shaker-bar would resuscitate the energies of the engine in a
few minutes if the flues and fire-box were not leaking too badly, and
the injector would provide the water for starting on; but no experience
of delay and trouble seemed capable of teaching Bemis the lesson how to
work the engine properly. He soon became the terror of train men, and
the boiler-makers worked incessantly on his fire-box. But he is still
there, although he will not make an engineer if he runs for a century.
TOO MUCH PISTON CLEARANCE.
On one of our leading railroads a locomotive was rebuilt, and fitted
with the extension smoke-box, which was an experiment for that road,
and consequently was looked upon with some degree of distrust. When
the engine was put on the road, it was found that it did not steam
satisfactorily. Of course, it was at once concluded that the draught
arrangements were to blame; and experiments were made, with the view
of adjusting the flow of gases through the tubes to produce better
results. The traveling engineer of the road had charge of the job, and
he proceeded industriously to work at locating the trouble. He tried
every thing in the way of adjusting the smoke-box attachments that
could be thought of, but nothing that was done improved the steaming
qualities of the engine. He then proceeded to search for trouble in
some other direction. The result of his examination was the discovery
that the engine was working with three-fourth inch clearance at
each end of the cylinders. This, he naturally concluded, entailed a
serious waste of steam; so he had the clearance reduced to one-fourth
inch. When the engine got out after this change, it steamed very
satisfactorily; and the extension smoke-box is no longer in disrepute
on that road.
BADLY PROPORTIONED SMOKE-STACKS.
Mistakes are frequently made when the open stack is adopted, as is
practicable with the extended smoke-box, of making the stack too wide
for the exhaust. This leads to deficiency of draught for the steam
that is passing through the stack, because the steam does not fill the
stack like a piston creating a clean vacuum behind it. Where an engine
fails to steam freely after being equipped with an extended smoke-box,
attention should be directed to the proportion of stack diameter to the
size of cylinders.
THE EXHAUST NOZZLES.
Locomotives, with their limited heating-surface, require intense
artificial draught to produce steam rapidly. Many devices have been
tried to stimulate combustion, and generate the necessary heat; but
none have proved so effectual and reliable as contracted exhaust
orifices. As the intermittent rush of steam from the cylinders to
the open atmosphere escapes from the contracted openings of the
exhaust-pipe, it leaves a partial vacuum in the smoke-box, into which
the gases from the fire-box flow with amazing velocity. As the area of
the exhaust nozzles is increased, the pressure of steam passing through
becomes lessened, and the height of the vacuum in the smoke-box is
decreased. Consequently, with wide nozzles, the velocity of the gases
through the flues is slower than with narrow ones; for there is less
suction in the smoke-box to draw out the fire products: and, where the
gases pass slowly through the flues, there is more time given for the
water to abstract the heat. Any change or arrangement which will retain
the gases of combustion one-tenth of a second longer in contact with
the heat-extracting surfaces, will wonderfully increase the evaporative
service of a ton of coal. Experiments with the pyrometer, an instrument
for measuring high temperatures, have shown that the gases passing
through the smoke-box vary from 400 degrees up to 900 degrees
Fahrenheit; and they show that increase of smoke-box temperature keeps
pace with contracted nozzles. From this, engineers can understand
why lead gaskets do not keep blower-joints in a smoke-box tight, the
melting-point of lead being 627 degrees.
Inordinately contracted nozzles are objectionable in another way.
They cause back pressure in the cylinders, and thereby decrease the
effective duty of the steam. Double nozzles are preferable to single
ones; because with the latter the steam has a tendency to shoot over
into the other cylinder, and cause back pressure.
Engineers anxious to make a good record, try to run with nozzles as
wide as possible. Contracted nozzles destroy power by back pressure:
they tear the fire to pieces with the violent blast, and they hurry the
heat through the flues so fast that its temperature is but slightly
diminished when it passes into the atmosphere. The engineer, who, by
intelligent care, reduces his smoke-box temperature 100 degrees, is
worthy to rank as a master in his calling.
The other day an engineer came into the round-house, and said, “You had
better put 3½ inch nozzles in my engine: I think she will get along
with that increase of size.” He had been using 3¼ inch nozzles. The
change was accordingly made. When he returned from the next trip, he
expressed a doubt about the advantage of the change. But it happened
that his own fireman was off, and a strange man was sent out, who,
although a good fireman, failed to keep up steam satisfactorily. On
the following trip, however, the fireman who belonged to the engine,
returned, and found no difficulty in getting all the steam required.
But this fireman is one who would stand far up among a thousand
competitors. Considerable practice and intelligent thoughtfulness,
combined with unfailing industry, have developed in this man an
excellence in fire management seldom attained. He follows a unique
system, which seems his own. It is the method of firing light carried
to perfection. His coal is all broken down fine, and lies within easy
reach. His movements are cool and deliberate, no hurry, no fuss. When
he opens the door, his loaded shovel is ready to deposit its cargo
over the spot which a glance shows him to be the thinnest portion of
the fire. On the parts of the run where the most steam is needed, he
fires one shovelful at brief intervals, keeping it up right along. In
this way the steam never feels the cooling effect of fresh fire, for
the contents of the fire-box are kept nearly uniform. This plan is a
near approach to the automatic stoker which mechanical visionaries
predict will effect perfect firing in the vague future. To follow out
such a system requires perseverance and self-denial, but these are well
rewarded to the man whose work is his pride.
CHAPTER X.
_SHORTNESS OF WATER.--PUMP DISORDERS._
TROUBLE DEVELOPS NATURAL ENERGY.
Trouble and affliction are known to have a purifying and elevating
effect upon human character; difficulties encountered in the
execution of work, develop the skill of the true artisan; and trouble
on the road, or accidents to locomotives, furnish the engineer
with opportunities for developing natural energy, ingenuity, and
perseverance, if these attributes are in him, or they publish to his
employers his lack of these important qualities.
One of the most serious sources of trouble that an engineer can meet
with on the road, is shortness of water.
SHORTNESS OF WATER A SERIOUS PREDICAMENT.
Deficiency of steam with a locomotive that is expected to get a train
along on time, is a very trying condition for an engineer to endure.
But a more trying and more dangerous ordeal, is want of water. Where
steam is employed as a means of applying power, water must be kept
constantly over the heating-surfaces while the fire is incandescent, or
their destruction is inevitable. With a boiler which evaporates water
rapidly, and in such large quantities as that of the locomotive, the
most perfect feeding apparatus is necessary. Nearly all locomotives
are well supplied in this respect. Good pumps or efficient injectors
provide the engineer with excellent appliances for feeding the boiler
under ordinary circumstances. But conditions sometimes occur where the
best of pumps, or the most reliable of injectors, fail to force water
into the boiler.
HOW TO DEAL WITH SHORTNESS OF WATER.
When from any cause he finds the boiler getting short of water, the
engineer should resort to all known methods within his power to
overcome the difficulty, by removing the obstacle that is preventing
the feeding apparatus from operating. But, while doing so, the safety
of his fire-box and flues should not be overlooked for a moment. The
utmost care must be taken to quench the fire before the water gets
below the crown-sheet. This can be performed most effectually by
knocking the fire out; but sometimes the temporary increase of heat,
occasioned by the act of drawing the fire, is undesirable; and, in such
a case, the safest plan is to dampen the fire by throwing wet earth, or
fine coal saturated with water, upon it. Or a more urgent case still
may intervene, when drenching the fire with water is the only means
of saving the sheets from destruction. This should be a last resort,
however; for it is a very clumsy way of saving the fire-box, and is
liable to do no small amount of mischief. Cold water thrown upon hot
steel sheets, causes such sudden contraction, that cracks, or even
rupture, may ensue.
WATCHING THE WATER-GAUGES.
As “burning his engine” is the greatest disgrace that can
professionally befall an engineer, every man worthy of the name
guards against a possibility of being caught short of water unawares,
by frequent testing of the gauge-cocks. It is not enough to have
a good-working water-glass. If an engineer is ambitious to avoid
trouble, he runs by the gauge-cocks, using the glass as an auxiliary.
Careful experiments have demonstrated the fact, that the water-glass,
working properly, is a more certain indication of the water-level than
gauge-cocks; for, when the boiler is dirty, the water rises above its
natural level, and rushes at the open gauge-cock. This can be proved
when water is just below a gauge-cock level. If the cock is opened
slightly, steam alone passes out; but, when the full opening is made,
water comes. But water will not come through a gauge-cock, unless the
water-level is in its proximity; and an engineer can tell, when his
gauge shows a mixture of steam, that the water shown is not to be
relied upon. It is not “solid.” On the other hand, a water-glass out
of order sometimes shows a full head of water when the crown-sheet is
red-hot.
WHAT TO DO WHEN THE TENDER IS FOUND EMPTY BETWEEN STATIONS.
The most natural cause for pumps or injectors ceasing to work,
is absence of water from the tender. This condition comes round
on the road occasionally, where engineers neglect to fill up at
water-stations, or where there are long runs between points of
water-supply. When an engineer finds himself short of water, and the
means of replenishing his tank too distant to reach, even with the
empty engine, he should bank or smother the fire, and retain sufficient
water in the boiler to raise steam on when he has been assisted to the
nearest water-tank. This will save tedious delay, especially where an
engine has no pumps. Occasionally, from miscalculations or through
accidents, the fire has to be quenched, and insufficient water is left
in the boiler to start a fire on safely. In this event, buckets can be
resorted to, and the boiler filled at the safety-valves, should there
be no assistance, or means of pumping up. Every possible means should
be exhausted to get the engine in steam, before a runner requests to
have his engine towed in cold.
A TRYING POSITION.
I once knew a case where an engineer inadvertently passed a water-tank
without filling his tender. He had a heavy train, and was pushing along
with a heavy fire, on a severe, frosty night, when every creek and
slough by the wayside was lost in heavy ice. Presently his pump stopped
working, and he spent some time trying to start it before he discovered
that the tender was empty. By the time this fact became known, his
boiler-water was low, and a heavy fire kept the steam screaming at the
safety-valves. He had no dump-grate, and the fire was too heavy to
draw. It seemed a clear case of destroying the fire-box and flues. But
he was a man of many resources. First, he tried to get water through
the gauge-cock--he had only one gauge--to quench the fire, but found
the plan would not work. Then he filled up the fire-box nearly to the
crown-sheet with the smallest coal on the tender, and partly smothered
the fire. He then partly opened the smoke-box door, and started for
the water-station. After getting the engine going, he hooked the
reverse-lever in the center, and kept the throttle wide open, to make
the most of the steam-supply. He saved his engine.
WATCHING THE STRAINERS.
When the top of a tank is in bad order, and permits cinders and small
pieces of coal to fall through rivet-holes, or through seams, the
engineer may look out for grief with his pumps or injectors. On the
first signs of the water failing, he should examine the strainers;
and he will probably find that these copper perforations, which stand
like wardens guarding the safety of the pumps and injectors, have
accumulated a mass of cinders that obstructs the flow of the water.
CARE OF PUMPS.
Mechanical prognostications seem to indicate that pumps, as locomotive
attachments, have outgrown their usefulness, and that their days are
numbered. They have done good service while no better method of feeding
locomotive boilers was known; but, since the advent of injectors, pumps
have begun to disappear. They still hold their own, however, on a great
many roads; and a description of their management will be of general
interest.
HOW THE CONDITION OF PUMPS CAN BE TESTED.
If an engineer is in the habit of pumping regularly, and of watching
his engine closely, he can tell immediately from the steam when the
pump stops working. Then he will open the pet-cock; and its action
will indicate, to some extent, where the trouble lies. If the pet-cock
throws a feeble stream of water, the trouble probably is in the lower
valve. If that sticks up, or part of the bottom cage breaks, the
plunger will push the water back into the feed-pipe on the return
stroke, consequently there will be no pressure to throw a strong stream
through the pet-cock. When the upper or pressure-valve is damaged, or
is stuck up, the pet-cock will throw a full stream during the inward
stroke of the plunger; but, on the outward stroke, the plunger will
draw the water out of the branch-pipe, and air will be sucked in at
the open pet-cock. When the check-valve is damaged, or stuck up, steam
and water will blow back through the branch-pipe when the pet-cock
is left open. If the steam thus escaping from the check-valves heats
the pump and valves to a high temperature, it will be prevented from
working, from several causes. The heat generates a low form of steam,
which fills up the space behind the plunger; therefore, no vacuum is
formed to draw the water. Not infrequently the pump-valves expand so
much from the heat, that they stick fast away from their seats. If the
pump has stopped through the presence of impurities on either of the
valves or cages, the engineer knows that he may remove the obstruction
by steam-pressure; so, after letting the feed-pipe fill with water, he
opens the heater-cock, and closes the foot-cock, letting the steam and
water blow through the pump. If he considers the obstruction to be in
the strainer, and has not time to stop and take it down, he blows steam
from the heater through to the tender, which gives temporary relief.
If any of the pump-valves are stuck up, and can not be got back to
their seats by blowing water and steam through them, the engineer will
take a soft hammer, and tap the seats lightly, with good prospects of
remedying the defect. In case no improvement can be effected in that
way, and there is no other feeding-medium to rely upon, the engineer
can take down the top or bottom chamber in a few minutes to remove any
impurities that may be keeping the pump from working. He will then be
likely to find a piece of packing that has passed through the pump,
bushing, or some other foreign substance, jammed between the cage and
the valve, keeping the latter immovable. Or the trouble may be a broken
valve or cage, which will render the pump useless till repaired.
LIFT OF PUMP-VALVES.
When a pump-valve has much lift, it is very liable to pound itself or
the cage so heavily that breakage occurs. The proper lift required for
pump-valves depends to some extent upon the diameter of the valves
themselves, those of liberal thickness requiring less lift than a
valve of narrow compass. The engine pulling our train has pump-valves
two and one-half inches in diameter: the pump-plunger, being worked
from the cross-head, has a diameter of two inches. The bottom valve
has three-thirty-seconds of an inch of lift, the middle valve has
one-eighth of an inch of lift, and the check-valve rises one-fourth of
an inch. These dimensions produce very satisfactory results for all
speeds. The pump performs its work with remarkable smoothness, is free
from pounding or fluctuating, and gives no trouble about repairs.
Engines employed on fast passenger service have their valve-lifts
one-thirty-second of an inch less than this one, and slow freight
engines are regulated to rise one-sixteenth of an inch more than the
dimensions given.
KEEP PIPES TIGHT, AND PACKING IN ORDER.
In order to insure the regular and satisfactory working of a pump, care
should be taken to prevent leaks about the feed-pipes or heater-pipes:
the packing should be kept in good order, and the chamber-joints should
be perfectly air-tight. During the outward stroke of the plunger, a
vacuum should be produced inside the pump, into which the water rushes.
If this vacuum gets partly filled with air or vapor, the working of
the pump will be unsatisfactory. Nothing is so liable to produce this
undesirable condition as badly packed glands or leaky joints. A poor
pump can often be made to produce fair work, by attention and care
bestowed upon its attachment; and lack of care will soon render the
best-constructed pump unreliable.
SAND IN THE PUMP-CHAMBERS.
The pump has one arch-enemy, which comes off victor in every conflict.
That is sand. The railway idiom which uses the word “sand” to express
courage, originated in the knowledge of how certainly and quickly a
handful of sand would vanquish the best pump that mechanical skill
might produce. The grit works its way among the packing, and tears and
cuts the plunger out of shape: it insinuates itself up between the
cages and valves, and holds the latter so fast that hard hammering is
often needed to dissolve the compact. Proper washing out of the tank,
cleansing of feed-pipes, and the use of water free from sand, is the
only sure remedy for this evil. Where an engineer is situated so that
he must take water containing sand in suspension, partial relief will
be obtained by giving the valves free side-room in the cages; but an
injector will be found much superior to a pump as a means of putting
sand-contaminated water into a boiler.
DELIVERY ORIFICE CHOKED WITH LIME SEDIMENT.
When a pump begins to show distress from over-pressure,--which will
be indicated by the breaking out of joints, the rejection of stuffing
and box-packing, and the bursting of branch-pipe,--the orifice between
the check and the boiler should be examined; for that aperture often
becomes almost closed by the accumulation of lime-salts.
MINOR PUMP TROUBLES.
Where the feed-pipes and other connections are perfectly air-tight,
some pumps will pound badly when the water is shut off. This can
be prevented by making a minute hole in the feed-pipe; or a more
convenient place is the upper part of the heater-pipe, away above the
water-level.
Should the valves of a pump be leaky on their seats, the pump will
not work satisfactorily. Where the lower valve is not properly ground
on the seat, the plunger sucks air from the feed-pipe, or through the
joints or packing, and, at the return stroke, compresses part of the
air in the pump, and forces the remainder back into the feed-pipe
through the leaky valve. This process goes on after the feed is put
on; the accumulated air stands like a cushion between the plunger
and the water; and the pump will not go to work until the pet-cock
is opened, when the air rushes out, permitting the water to flow in.
Engineers having pumps that will not work till the pet-cock is opened,
should have the suction-valve ground in; and they will find a decided
improvement from the operation.
For slow train service, pumps perform the service of boiler-feeding
fairly well; but, for fast passenger trains, a pump should not be
tolerated. A pump can not be constructed for high-speed engines that
will throw water regularly at high velocity of stroke.
CHAPTER XI.
_INJECTORS._
Injectors have made remarkably rapid strides into public favor during
the last ten years. It is a safe prediction to say, that, before the
end of another decade, there will be no new pumps put upon locomotives.
So long as injectors were imperfectly understood, and were used with no
regularity, they retained the name of being unreliable; but, so soon as
they began to be made the sole feeding-medium for locomotive boilers,
they had to be worked regularly, and kept in order, which quickly made
their merits recognized.
INVENTION OF THE INJECTOR.
The feed injector was invented by Henri Giffard, an eminent French
scientist and æronaut. Its successful action was discovered during a
series of experiments made with the view of devising light machinery
that might be used to propel balloons. Although Giffard designed the
most perfect balloon that was ever constructed, the injector was not
used upon it; and the invention was laid aside, and almost forgotten.
During the course of a sea-voyage, Giffard happened to meet Stewart of
the engineering firm, Sharp, Stewart, & Co., of Manchester, England.
In the course of a conversation on the feeding of boilers, Giffard
remembered his injector, and mentioned its method of action. Stewart
was struck with the simplicity of the device, and undertook to bring
it out in England, which he shortly afterwards did, representing the
interests of the inventor so long as the original patents lasted. By
his advice, William Sellers & Co. of Philadelphia were given control of
the American patents.
Seldom has an invention caused so much astonishment and wild
speculation among mechanics, and even among scientists, as the
injector did for the first few years of its use. Scientists were not
long in discovering the philosophy of the injector’s action, but that
knowledge spread more slowly among mechanics. It was regarded as a case
of perpetual motion,--the means of doing work without power, or, as
Americans expressed it, by the same means a man could raise himself by
pulling on his boot-straps.
TRYING TO FIND OUT HOW THE INJECTOR WORKED.
Among the mechanics I associated with, the injector was spoken of as
a machine having a secret method of action. There was supposed to be
some part inside, where a vacuum was formed, which sent the water into
the boiler. We were all familiar with the vacuum of condensing engines,
and it was a convenient solution of the mystery. I remember committing
what we regarded as a heinous sin, in trying to find out the secret
of the injector. On a Sunday forenoon in a Scotch town, where it was
considered next to a crime to miss going to church, three of us stole
quietly into an engine-house, and took an injector apart, when we knew
the foreman, like a pious man, was listening to the sermon. All our
plans had been laid the previous day, and the necessary tools laid
conveniently at hand. The feeling of disappointment we experienced at
finding nothing to explain the working of the thing, is still vivid in
my memory.
THE PRINCIPLE OF THE INJECTOR’S ACTION.
The principle of the injector’s action is that of induced currents,
which is much more popularly understood to-day than it was twenty-five
years ago. A current of any kind has a tendency to induce a movement in
the same direction of any body it passes over or touches. Thus, we are
all familiar with the fact that a current of air called wind, passing
over the surface of a body of water, sets waves in motion, and dashes
the water high up on the shore above its original level. In the same
way, a jet of steam moving very rapidly, when injected into a body of
water under favorable conditions, imparts a portion of its motion, and
starts momentum sufficient to overcome the original pressure of the
steam. That is how the injector is made to force water into a boiler
against the same pressure the steam is starting from. The principle
is now utilized in the arts for many useful purposes. The ordinary
locomotive blast, blowers, steam siphons, steam-jets, jet exhausters,
and argand burners, are common instances of its application.
When the action of the injector is closely examined, its mystery as
a source of power disappears; for it is found that an amount of heat
equal to the mechanical equivalent of work done, is used up during the
operation of feeding. Thus, when a given quantity of heat units pass
from the throttle to work the injector, the whole of the heat does not
return to the boiler along with the feed-water, as was first supposed
to be the case; but a portion of heat representing the foot pounds of
work done is dissipated, besides other losses incident to leakage,
radiation, and convection.
DIFFERENT FORMS OF INJECTOR.
There are a great many different forms of injectors in use, but all of
them conform to certain elementary principles in their mode of action.
Steam passes from the boiler through the steam-pipe and receiving-tube
_A_ (Fig. 1) at a high velocity, and, combining with the water at the
point _B_, condenses, but imparts considerable momentum to the water,
which rushes along into the delivery pipe, raises the check-valve, and
passes into the boiler.
[Illustration: FIG. 1.]
The tubes of the injector are arranged so that a concentrated jet of
steam shall impinge upon the water to force it through passages that
are designed in the best form for maintaining the solidity of the
current. The speed imparted to the water represents the work performed
by the steam, and upon this velocity depends the successful action
of the injector. As the current of water for starting the injector
could not be induced against the constant pressure on the check-valve,
which equals the pressure at the throttle, an overflow is provided
where the water can flow unchecked till the necessary momentum is
obtained, when the overflow is closed. All deviations in construction
from the elementary injector shown in Fig. 1 are made for the purpose
of extending the action of the injector under varied conditions, for
making it work automatically under different pressures of steam, and
for improving its capacity to lift water above its natural level.
A HEATER-PIPE ACTING AS AN INJECTOR.
Before the invention of the injector, cases occasionally happened of
the heater-pipe acting as an injector. Where the end of the heater pipe
was carried through the feed-pipe, and pointed towards the check-valve,
starting the heater under favorable conditions would carry the water
into the boiler. A great many old engineers relate instances where this
has happened.
SKILL AND REFLECTION NEEDED IN REPAIRING INJECTORS.
Injectors can be kept in good order with less work than is needed
to keep a pump going, but the highest kind of mechanical skill is
required for the injector when repairs must be done. Almost any kind
of machinist can fit a new chamber or plunger into a pump. Many men
who will do this job satisfactorily will get badly left when they
try to put a defective injector in order. To do such work, thoughtful
reflection is called for, besides the hand that can do accurate
fitting. A workman who may be good on guides or cross-heads or links,
takes an injector apart that will not work, and can perceive nothing
wrong with it, because he has not got the philosophy of the thing
through his head; and he must have that before he can have insight into
the probable cause of derangement.
CARE OF INJECTORS.
When an engineer finds that an injector refuses to work, his first
resort should be the strainer. That gets choked with cinders or other
impurities so frequently, that no time should be lost in examining
it. One day, when I was running a round-house, an engineer came in
breathless, with the information that his engine was blocked in the
yard, and he must dump his fire, as he could not get his injector to
work. The thermometer stood at twenty degrees below zero, and an Iowa
blizzard was blowing; so the prospect of a dead engine in the yard
meant some distressingly cold labor. I asked, the first thing, if he
had tried the strainer; and his answer was, that the strainer was all
right, for the injector primed satisfactorily, but broke every time he
put on a head of steam. I went out to the engine, and had the engineer
try to work the injector. By watching the overflow stream, I easily
perceived that the injector was not getting enough water, although it
primed. An examination showed that the strainer was full of cinders,
and the injector went to work all right when the obstruction to the
water was removed.
THE MOST COMMON CAUSES OF DERANGEMENT.
Sand and cinders are the greatest cause of failures with injectors; as
they are, indeed, with all water-feeding apparatus. I knew a case where
water for a locomotive, running on a short branch, was taken out of
a sandy creek with a siphon. The tank had generally about six inches
of sand in the bottom. The engine had a pump and an injector; but all
the feeding had to be done by the latter, for the pump never worked a
gallon of water. The injector worked the water through when it seemed
a quarter sand. In a short time the sand destroyed the tubes of the
injector, for it acted on them the same way as a sand-blast does in
cutting files or glass.
A very common cause of failure of injectors, is leakage of steam
through throttle-valve or check-valve, keeping the injector so hot that
no vacuum can be formed to make it prime. A great many injector-checks
have been turned out too light for ordinary service, while others are
made in a shape that will always leave the valve away from the seat
when they stop working. Then the engineer has to run forward, and pound
the check with a hammer to keep the steam from blowing back; and that
soon ruins the casting. Check-valves set in a horizontal position are
worthless with water that contains grit.
HOW TO KEEP AN INJECTOR IN GOOD ORDER.
To preserve a good working injector, the engineer should see that all
the pipes and joints are kept perfectly tight. It is hard to keep
pipes and joints tight when they are subjected to the continual jars
a locomotive must stand; but injectors can not be depended on where
there is a possibility of air mixing with the water. Leaky joints
or pipes are particularly troublesome to lifting injectors; for air
passes in, and keeps the steam-jet from forming a vacuum. At first
the injector will merely be difficult to start; but, as the leaks
get worse, there will be no starting it at all. Then, the air mixing
with the water is detrimental to the working of all injectors, as its
tendency is to decrease the speed of the water. The compact molecules
of water form a cohesive body, which the steam can strike upon with
telling force to keep it in motion. When the water is mixed with
air, it lacks the element of compactness; and the steam-jet strikes
a semi-elastic body, which does not receive momentum readily. This
mixture of steam and air does not act solidly on the check-valve, but
makes the water pass in with a bubbling sound, as if the valve were
moving up and down; and the stream of water breaks very readily when it
is working in this way.
CURIOUS CASES OF TROUBLE WITH AN INJECTOR.
I ran a Sellers improved injector on a locomotive about a year, and it
was an excellent feeding apparatus; but I several times had curious
cases of trouble in getting it to work. Once it began drawing air;
and I could not find out where the air was coming from, for the pipes
seemed all tight. But the air was going through, for I could hear its
mutterings; and the water kept breaking, which was an annoyance on
the road. A heater-pipe was attached to the injector feed-pipe; and I
afterward found out that the air was getting in at the top joint of
this pipe, which did not show a leak, being above the water.
Another time I had almost a failure with this injector out in the snow.
I was out with a snow-plow, opening the road through enormously deep
snow-drifts. We had worked on one bank for several days; and we made
water by shoveling snow into the tank, which was melted by blowing
steam through the heaters and injector. Cinders were passed into the
tank very freely with the snow, and presently I began to have trouble
with my injector. I took it apart several times, and cleaned out
cinders, when it went to work all right again. But a time came when it
refused to work when there were no cinders inside, and it seemed that
no amount of coaxing would make it start. It would prime all right;
but, so soon as I gave it steam, the water would break. Driven to my
wits’ end, I made the fireman try to work the injector, while I went
down and watched its action. Everything seemed tight: I had examined
the strainer, and there appeared no reason why it should not operate as
well as it ever did. While watching it, I saw a drop of water oozing
out at the stem of the overflow-valve; but I reasoned, “That can not
affect the working of the injector, because it is ahead of where the
water starts.” But, seeing that the thing would persist in not working,
I put a bit of packing in the overflow-stem, thinking it will do no
harm any way; and then the injector went to work all right, and I had
no more trouble with it. So a defect that may seem trifling, sometimes
proves serious to an injector.
COMMON DEFECTS.
As maintaining unbroken speed on the water put in motion is the first
essential in keeping an injector in good working-order, any thing
that has a tendency to reduce that speed will jeopardize its action.
A variety of influences combine to reduce the original efficiency
of an injector. Those with fixed nozzles are constructed with the
orifices of a certain size, and in the proportion to each other which
experiment has demonstrated to be best for feeding with the varied
steam-pressures. When these orifices get worn out of the proper size,
the injector will work badly; and nothing will cure it but new tubes.
The tubes sometimes get loose inside the shell of the injector, and
drop down out of line. The water will then strike against the side of
the next tube, or on some point out of the true line, scattering it
into spray, which contains no energy to force itself into the boiler. A
machinist examining a defective injector, should always make sure that
the tubes are not loose. Injectors that suffer from this defect will
not work without a high pressure of steam. Injectors suffering from
incrusted water-passages will generally work best with the steam low.
Cases of the latter kind are common in calcareous districts. I have
known instances where injectors got so incrusted with lime that the
passages were almost closed.
Joints about injectors that are kept tight by packing must be closely
watched. Many an injector that failed to work satisfactorily has been
entirely cured by packing the ram-gland.
CARE OF INJECTORS IN WINTER.
During severe frosty weather, an injector can be kept in order much
easier than a pump; but it needs constant watching and intelligent
supervision.
To keep an injector clear of danger from frost, it should be fitted up
so that all the pipes can be thoroughly drained, by frost-cocks put in
for that purpose. Bends in the pipes, where water could stand, should
be avoided as far as possible; and, where they can not be avoided, the
lowest point should contain a frost-cock.
To run an injector successfully, thoughtful care is requisite on the
part of the engineer; and, where this is given, the injector will prove
itself a very economical boiler-feeder.
SELLERS INJECTOR.
When the Giffard injector was first introduced into this country,
by William Sellers & Co., Philadelphia, it was a very defective
boiler-feeder; but that firm effected great improvements, and led the
way for making the injector the popular boiler-feeder it is to-day.
They made the instrument self-adjusting, and improved its design,
so that it would automatically feed, however much the pressure of
the boiler varied. After numerous changes, the injector of 1876 was
produced, which is shown by a sectional view in Fig. 2. The Sellers
injector of to-day remains substantially the same as it was when
exhibited at the Centennial Exposition.
[Illustration: FIG. 2.]
Referring to Fig. 2, _A_ is the receiving-tube, which will be closed
to the admission of steam by the valve _X_. A hollow spindle passing
through the receiving-tube into the combining-tube, is secured to the
rod _B_; and the valve _X_ is fitted to this spindle in such a way,
that the latter can be moved a slight distance (until the stop shown in
the figure engages with valve _X_) without raising the valve _X_ from
its seat. A second valve, _W_, secured to the rod _B_, has its seat
in the upper side of the valve _X_, so that it can be opened (thus
admitting steam to the center of the spindle) without raising the valve
_X_ from its seat, if the rod _B_ is not drawn out any farther, after
the stop on the hollow spindle comes in contact with the valve _X_.
_D_ is the delivery-tube, _O_ an overflow opening into space _C_, _K_
the check-valve in delivery-pipe, and _P R_ the waste-valve. The upper
end of the combining-tube has a piston _N N_ attached to it, capable
of moving freely in a cylindrical portion of the shell _M M_; and the
lower end of the combining-tube slides in a cylindrical guide formed in
the upper end of the delivery-tube.
The rod _B_ is connected to a cross-head, which is fitted over the
guide-rod _J_; and a lever _H_ is secured to the cross-head. A rod _L_,
attached to a lever on the top end of the screw waste-valve, passes
through an eye that is secured to the lever _H_; and stops _T_, _Q_,
control the motion of this rod, so that the waste-valve is closed when
the lever _H_ has its extreme outward throw, and is opened when the
lever is thrown in so as to close the steam-valve _X_; while the lever
can be moved between the positions of the stops _P_, _Q_, without
affecting the waste-valve. A latch _V_ is thrown into action with teeth
cut in the upper side of the guide-rod _J_, when the lever _H_ is drawn
out to its full extent, and then moved back; and this click is raised
out of action as soon as it has been moved in far enough to pass the
last tooth on the rod _J_. An air-vessel is arranged in the body of
the instrument, as shown in the figure, for the purpose of securing
a continuous jet when the injector and its connections are exposed
to shocks, especially such as occur in the use of the instrument on
locomotives.
The manipulation required to start the injector is exceedingly
simple,--much more so in practice, indeed, than it can be rendered in
description. Moving the lever _H_ until contact takes place between
valve _X_ and stop on hollow spindle, which can be felt by the hand
upon the lever, steam is admitted to the center of the spindle, and,
expanding as it passes into the delivery-tube _D_ and waste-orifice
_P_, lifts the water through the supply-pipe into the combining-tube
around the hollow spindle, acting after the manner of an ejector or
steam-siphon. As soon as solid water issues through the waste-orifice
_P_, the handle _H_ may be drawn out to its full extent, opening the
steam-valve _X_, and closing the waste-valve, when the action of the
injector will be continuous as long as steam and water are supplied to
it.
THE NATHAN MANUFACTURING COMPANY’S MONITOR INJECTOR.
[Illustration: FIG. 3.]
One of the most successful and enduring injectors in use is the
Monitor, the distinguishing feature of which is, that the injector is
constructed with fixed nozzles, that insure great durability, combined
with certainty of action. The Monitor injector is shown in section in
Fig. 3. To start the injector, the middle cock is opened, which is
the lifting-jet. When water appears at the overflow, the steam-valve
is opened, and the lifting-jet closed. The work of the injector is
regulated by the lazy-cock, which is the bottom handle. A movable
valve, operated by an eccentric on the stem, is now employed as a
lazy-cock; a common cock having been found troublesome during frosty
weather. The combining-tube is attached to the line-check, and can be
taken out with the check, which provides an easy means of effecting
examination or repairs.
THE KORTING INJECTOR.
[Illustration: FIG. 4.]
An examination of Fig. 4 will show that this injector is a double-tube
instrument; the first tube being proportioned for raising and
delivering the water under pressure to the second one, which
completes the operation of forcing the water into the boiler. This
arrangement enables the injector to be worked through a wide range of
steam-pressures without any adjustment of parts. By making the first
tube proportionately small, a high power of suction is obtained,
which enables the injector to feed water of such high temperature
that it may be delivered into the boiler above the boiling-point. The
Korting injector is operated entirely by one handle, and requires no
instruction to teach its working. The feed is regulated by the patent
combined regulation-valve and dirt-stop, which regulates the supply of
water, and prevents the possibility of dirt reaching the injector.
THE HANCOCK INSPIRATOR.
[Illustration: FIG. 5.]
Fig. 5 gives a cross-section of the Hancock inspirator. It consists
essentially of a lifting-jet and lifting-nozzle, combined with a
forcing-jet and force-nozzle or injector; steam being admitted to both
of these nozzles whenever the inspirator is working, to deliver the
supply-water to the force-nozzle, and to force it through the nozzle
into the boiler. Although both the lifting and forcing nozzles are
fixed, their proportion, one to the other, is such that the inspirator
requires no adjustment for changes in steam-pressure or water-supply;
the waste-valve being kept closed while the instrument is in operation,
except at the time of starting. The duplex nozzle arrangement of the
Hancock inspirator enables that instrument to feed water of high
temperature. In this respect it will act as well as the ordinary pump,
besides having all the advantages of an injector. A form of inspirator
is made specially for locomotive service, which is operated by a single
handle.
CHAPTER XII.
_BOILERS AND FIRE-BOXES._
CARE OF LOCOMOTIVE BOILERS.
The present tendency of steam engineering, in the effort to increase
the work performed in return for every pound of fuel consumed, is to
employ steam of very high pressure. The greater the initial pressure
of the steam, the greater are the advantages to be derived from its
expansive principle. To resist successfully the enormous aggregate of
pressure to which locomotive boilers are subjected, a well-constructed
strong boiler is absolutely necessary; and the various railroad
companies throughout the country meet the required conditions in an
admirable manner, as is evidenced by the remarkable exemption of
such boilers from serious accidents. Although the locomotive is the
most intensely pressed boiler in common use, that supreme disaster,
an explosion, is of rare occurrence, considering the vast number of
boilers doing service all over the States. This result is due to
constant care in the construction, in the maintenance, and in the
management, of the locomotive boiler. Like the conservation of liberty,
eternal vigilance is the price of safety.
FACTOR OF SAFETY.
There is perfect safety in using a boiler so long as a good margin
of resisting power is maintained above the tendency within to tear
the sheets asunder. This margin is very low for locomotive boilers
generally, hence the greater necessity for care in maintenance and
management. Years ago the mechanical world established by practice
a rule making one-fifth of the ultimate strength of a boiler its
safe working-pressure. That is, a boiler carrying 140 pounds
working-pressure should be capable of withstanding a tension of 700
pounds to the square inch before rupture ensues. Locomotive practice
in this country does not provide much more than half of that margin
of safety. When deterioration or accident reduces this margin, danger
begins.
BOILER EXPLOSIONS.
Certain mechanical empirics and impractical quasi-scientists have at
various times attempted to surround the cause of boiler explosions with
a halo of mystery. But our most accomplished scientists who have made
the subject a special study, and our best mechanical experts who have
devoted years of patient experiment and research to the investigation
of boiler explosion, attribute the terrible phenomenon to intelligible
causes alone. The conclusions of the practical part of the mechanical
world are well summed in one sentence in one of the annual reports of
the Master Mechanics’ Association. It says, “Explosions originate from
over-pressure: it matters not whether the whole boiler, or a portion of
it, is too weak to resist the pressure.”
PRESERVATION OF BOILERS.
The preservation of a boiler depends very much upon the care and
attention bestowed upon it by the engineer, and no other person is so
much interested in its safety. To prevent undue strains from being put
upon the boiler, the engineer should see that the safety-valves and the
steam-gauge are kept in proper order. To secure this, the steam-gauge
should be tested at least once a month. The rule established on
well-conducted roads, prohibiting engineers from interfering with
safety-valves, is a very judicious one; and no persons are more
interested in its strict observance than the engineers themselves.
CAUSING INJURY TO BOILERS.
Some men are idiotic enough to habitually screw down safety-valves,
that the engine may be able to overcome heavy grades without doubling.
This is criminal recklessness, and all train men are interested in its
suppression. Low water has often been blamed falsely as the cause of
disaster to boilers; a theory having prevailed, that permitting the
water to become low led to the generation of an explosive gas which
no sheet could withstand. That theory was exploded long ago; but,
nevertheless, it is certain that low water paves the way for explosions
by deteriorating the fire-box sheets, and destroying stay-bolts. A
careful engineer watches to prevent his engine from getting “scorched”
even slightly; for the smallest scorching may yield a harvest of
trouble, even after many days. The danger of scorching is most imminent
when an engine is foaming badly from the effects of impurities in
the feed-water or in the boiler. At such a time the water rises so
lavishly with the steam, that the gauges are no indication of the true
water-level. The steam must be shut off to find the true level of the
water. Where this trouble is experienced, the engineer should err on
the safe side, even though untold patience is needed to work the engine
along with the boiler full of water.
DANGERS OF MUD AND SCALE.
Mud within the boiler, and scales adhering to the heating surface, are
dangerous enemies to the preservation of boilers; and engineers should
strive to prevent their evil effects by rooting them out so far as
practicable. Much can be banished by washing out frequently; and scales
can, to some extent, be prevented by selecting the softest water on the
road. If water in a tank is so hard that it makes soap curdle instead
of lather when a man attempts to wash with it, that tank should be
avoided as far as possible.
BLOWING OFF BOILERS.
The sudden cooling down of boilers, by blowing them off while hot, is a
most pernicious practice, which is responsible for many cracked sheets
and broken stay-bolts. It also tends to make a boiler scale the heating
surfaces rapidly. Every time a boiler is blown out hot, if the water
contains calcareous solution, a coat of mud is left on the heating
surfaces, which dries hard while the steel is hot. If a piece of scale
taken from a boiler periodically subjected to this blowing-out process
be closely examined, it will be found to consist of thin layers, every
one representing a period of blowing off, just as plainly as the
laminæ of our rocks indicate the method of their formation. When a
boiler must be cooled down quickly for washing out or other purposes,
the steam should be blown off, and the boiler gradually filled up
with water. Then open the blow-off cock, and keep water running in
about as fast as it runs out until the temperature gets even with the
atmosphere. The boiler may now be emptied without injury. Or another
good plan is to blow off about two gauges of water under a pressure of
forty or fifty pounds of steam, then cool down the boiler gradually, to
prepare for washing.
Although the dangers of blowing off hot boilers, and then rushing
in cold water to wash out, are well known and acknowledged, yet the
practice is still followed on many roads where more intelligent action
might be expected.
OVER-PRESSURE.
Should it happen from any cause that the safety-valves fail to relieve
the boiler, and the steam runs up beyond a safe tension, the situation
is critical; but the engineer should not resort to any method of giving
sudden relief. To jerk the safety-valve wide open at such a time is a
most dangerous proceeding. A disastrous explosion lately occurred to a
locomotive boiler from this cause. The safety-valves had been working
badly; and, while the engine was standing on a side track, they allowed
the steam to rise considerably above the working-pressure. When the
engineer perceived this, he threw open the safety-valve by means of a
relief lever, and the boiler instantly went into fragments. Cases have
occurred where the quick opening of a throttle-valve has produced a
similar result. The proximate cause of such an accident was the violent
motion of water and steam within the boiler, induced by the sudden
diminution of pressure at one point; but the real cause of the disaster
was a weak boiler,--a boiler with insufficient margin of resisting
power. The weakest part of a boiler is its strongest point. This may
seem paradoxical, but a moment’s reflection will show that the highest
strength of a boiler merely reaches to the point where it will give
out. Hence engineers should see that a boiler is properly examined for
unseen defects so soon as signs of distress appear. Leaky throat-sheets
or seams, stay-heads dripping, or incipient cracks, are indications of
weakness; and their call should be attended to without delay.
RELIEVING OVER-PRESSURE.
When an engineer finds the steam rising beyond a safe pressure, he
should reduce it by opening the heaters, starting the injector,
dampening the fire, or even by blowing the whistle. The whistle offers
a convenient means of getting rid of superfluous steam, and its noise
can be stopped by tying a rag between the bell and the valve opening.
BURSTED FLUES.
Should any boiler attachment, such as a check-valve or blow-off cock,
blow out or break off, no time should be lost in quenching the fire.
That is the first consideration. A bursted flue will generally save
an engineer the labor of extinguishing the fire. In this case an
engineer’s efforts should be directed to reducing the pressure of
steam as quickly as possible, so that he may be able to plug the flue
before the water gets out of the boiler. Flue-plugs and a rod for
holding them are very requisite articles; but, in driving flue-plugs,
care must be exercised not to hammer too hard, or a broken flue-sheet
may result. Plugs are often at hand without a rod to hold them. In such
an emergency, a hard wooden rail can be used; the plug being fastened
to the end by means of nails and wire, or even wet cord. Where no iron
plug is available, a wooden plug driven well in, away from the reach
of the fire, may prevent a bursted flue from leaking, and enable the
engine to go along; but wooden plugs are very unreliable for such
a purpose. They may hold if the rupture in the flue should be some
distance inside; but, should the cause of leaking be close to the
flue-sheet, a wooden plug will burn out in a few minutes.
CHAPTER XIII.
_ACCIDENTS TO THE VALVE-MOTION._
RUNNING WORN-OUT ENGINES.
Some of our most successful engineers, the men who pull our most
important trains daily on time, attribute their good fortune in
avoiding delays, to training they received in youth, while running
or firing worn-out engines that could only be kept going by constant
attention and labor. In such cases men must resort to innumerable
makeshifts to get over the road; they have frequently to dissect the
machinery to remedy defects; they learn in the impressive school of
experience how a broken-down engine can best be taken home, and how
breaking down can best be prevented. Firemen and young engineers,
generally feel aggrieved at being assigned to run on worn-out
engines,--the scrap heaps as they are called: but the man who has not
passed through this ordeal has missed a Golconda of experience; his
potentialities are petrified without reaching action.
CARE AND ENERGY DEFY DEFEAT.
Among a certain class of seafaring men, the captain of a ship who fails
from any cause to bring his vessel safely into port, is regarded as
disgraced; and, therefore, a true sailor will use superhuman efforts
to prevent his ship from becoming derelict, often preferring to follow
it to the bottom rather than abandon his trust. In many instances
the sentiments and traditions of seamen teach railroad men valuable
lessons. The sacrifice of life is not desired or expected of engineers
in their care of the vessel they command; but every engineer worthy of
the name will spare no personal exertion, will shrink from no hardship,
that will be necessary to prevent his charge from becoming derelict.
Once I heard a hoary engineer, who had become gray on the footboard,
make the proud boast, “My engine never was towed in.” His calm words
conveyed an eloquent sermon on care and perseverance. He had been in
many hard straits, he had been in collisions, he had been ditched with
engines, but had always managed to get them home without assistance.
WATCHING THE EXHAUST.
What the beating pulse is as an aid to the physician in diagnosing
diseases, the sound of the exhaust is to the engineer as a means of
enabling him to distinguish between perfective and defective working of
the locomotive. The ability to detect a slight derangement by the sound
of the exhaust, can only be acquired by practice in watching those
steam-notes day after day, as they play their tune of labor through the
smoke-stack. When the steam-ports are even, and the valves correctly
set, with tight piston-packing, and valves free from leaks, the notes
of the exhaust will sound forth in regular succession in sharp,
ringing, clear tones, every puff seeming to cut the steam clean off at
the top of the stack. There is a long array of defects represented in
the journey from this case of apparently perfect steam performance, to
that where the exhaust steam escapes as an unbroken roar mixed with
uncertain, wheezy coughs.
THE ATTENTIVE EAR DETECTS DETERIORATION OF VALVES.
The deterioration of piston-packing, and the rounding of valve-seats,
which produce an asthmatic exhaust, may be followed in their downward
course if the engineer gets into the habit of listening to the exhaust,
and marking its changes. It is very important that he should do so. The
man whose ear from long practice has become sensitive to a false tone
of the exhaust, needs not to make experiments, by applying steam to the
engine while it stands in various positions, in order to find out where
a blow comes from,--whether it is in the pistons or in the valves.
LOCATING THE FOUR EXHAUST SOUNDS.
Leaning out of the cab-window, he watches the crank as it revolves,
and compares the noise made by the blowing steam with the crank
position. When pulling on a heavy grade is an excellent time for
noting imperfections in the working of valves and pistons; for the
movements are comparatively slow, while the pressure of steam on the
working-parts is so heavy that any leak sounds prominently forth. The
observing engineer perceives that the four sounds of the exhaust, due
to each revolution of the drivers, occur a few inches before the crank
reaches, first, the forward center, second, the bottom quarter, third,
the back center, fourth, the top quarter. The first and third position
exhausts emit the steam from the forward and back strokes of the
right-hand piston: the second and fourth exhausts are due to discharges
of the steam that has been propelling the left-hand piston. With
these facts impressed upon his mind, he will understand, that if an
intermittent blow occurs during the periods when the crank is traveling
from the forward center to the bottom quarter, or from the back center
to the top quarter, the chances will be that the right-hand piston
needs to be examined. For the greatest pressure of steam follows the
piston just after the beginning of each stroke, and that is the time
a blow will assert itself. Should the blow occur while the right-hand
crank is moving from the bottom quarter to the back center, or from the
top quarter to the forward center, it will indicate that the left-hand
piston is at fault. For at these periods the left-hand cylinder is
receiving its greatest pressure of steam.
IDENTIFYING DEFECTS BY SOUND OF THE STEAM.
It is generally understood that an intermittent or recurring blow
belongs to the pistons, and that a constant blow comes from the valves.
But sometimes the valves blow intermittently, being tight at certain
points of the travel, and leaky at other points. To distinguish
between the character of these blows is sometimes a little difficult
except to the thoroughly practiced ear. The sound of the blow can
be heard best when the door is open, and the novice should not fail
to listen for it under that condition. The valve blow is a sort of
wheeze, with the suggestion of a whistle in it: the piston makes a
clean, honest blow, which would break into a distinct roar if enough
steam could get through. But a whistling sound in the exhaust is, by
no means, a certain indication of the valves blowing through; for
sometimes the nozzles get clogged up with a gummy substance from the
lubricating oils, and a distinct whistling exhaust results therefrom.
With a watchful ear, the progress of degeneration in the valves can be
noted day after day; for it is a decay which goes on by degrees,--the
inevitable slow destruction that friction inflicts upon rubbing
surfaces. Pistons are more erratic in their calls for attention. With
them it is quite common for a stalwart blow to start out without any
warning, the cause generally being broken packing-rings. The various
kinds of steam packing seem more liable to have broken rings than the
old-fashioned spring packing, but they generally run longer with less
attention.
ACCIDENTS PREVENTED BY ATTENDING TO THE NOTE OF WARNING FROM THE
EXHAUST.
The habit of closely watching the exhaust is likely to prove
serviceable in more ways than in keeping the engineer posted on the
condition of the steam-distribution gear. Its sound often acts as
a danger alarm, which should never go unheeded. Many an engine has
gone home on one side, and not a few have been towed in cold, through
accidents to the valve-gear, which could have been prevented had the
engineer attended to the warning voice of a false exhaust. The nuts
work off an eccentric-strap bolt; and it drops out, letting the strap
open far enough to cause an uneven valve-travel. If the engineer hears
this, and stops immediately to examine the machinery, he is likely to
detect the defect before the strap breaks. Again, one side of a valve
yoke may have snapped, leaving the other side to bear the load; or
bolts belonging to different parts of the links or eccentric-straps
may be working out,--so that the uniformity of the valve-travel is
affected; and the same result may be produced by the eccentrics getting
loose. Young engineers, to whom these pages are addressed, should make
up their minds that an engine never exhausts an irregular note without
something being the matter which does not admit of running to a station
before being examined. It may only be an eccentric slipped a little
way, a mishap that is not calculated to result disastrously; but, on
the other hand, it is probably something of a more dangerous character.
NEGLECTING A WARNING.
Engineer Joy of the D. & E. road went in with a broken eccentric-strap.
Questioning him about the accident brought out the fact, that, in
starting from a station, he heard the engine make two or three curious
exhausts; but he was running on a time-order, and did not wish to cause
delay by stopping to examine the engine. But he had not gone half a
mile when he found it necessary to stop and disconnect the engine, and
by doing so held an express train forty minutes.
HOW AN ECCENTRIC-STRAP PUNCHED A HOLE IN A FIRE-BOX.
A representative case of neglecting a plain warning happened on an
Illinois road some time ago. John Thomas was pulling a freight train
up a grade, when, to use his own words, “The engine began to exhaust
in the funniest way you ever heard. She would get on to three legs for
an engine length or so, then she would work as square and true as she
ever did, but only for a few turns, when she got to limping again.”
This runner knew that something was wrong, and he determined to examine
the engine at the next stopping-point. But delays in such a case are
full of peril. When he got over the grade, and shut off steam, there
was a tumultuous rattling of the reverse-lever, succeeded by a fearful
pounding about the machinery; a tearing up of road-bed sent a shower
of sand and gravel over the train; then a scream from escaping steam
and water drowned all other noises, and the engine was enveloped in a
cloud of blinding vapor. The forward bolt of one of the eccentric-strap
rods had worked out, and allowed the end of the rod to drop on the
track. Then it doubled up, and tore away the whole side of the motion;
and part of a broken eccentric-strap knocked a hole in the fire-box.
Here was the progress towards destruction. A small pin got lost, which
permitted the nut of an important bolt to unscrew itself; then this
bolt, with many a warning jar and jerk, escaped from its place in the
link; and the conditions for a first-class break-down had come round.
INTEREST IN THE VALVE-MOTION AMONG ENGINEERS.
Whenever locomotive engineers congregate in the round-house, in the
lodge or division room, a fruitful theme of conversation and discussion
is the valve-motion. Curious opinions are often heard expressed upon
this complex subject. There are comparatively few men who understand it
properly: but it has a fascination which attracts all alike, the wise
and the ignorant; and the man who is altogether uncertain about the
true meaning of lap and lead, expansion and compression, is generally
more loquacious on valve-motion than the engineer who has made the
subject an industrious study.
TROUBLE WITH THE VALVE-MOTION.
However well each may understand his business, in one respect all
engineers are in perfect harmony; that is, in hating to encounter
trouble with the valve-gear on the road. The valves being the lungs
of the machine, any injury or defect to their connections strikes at
a vital organ. With a good valve-motion, and valves properly set,
the steam is distributed so that nearly an equal amount is admitted
through each part in regular rotation; the release taking place in even
succession. This makes the exhaust notes uniform in pitch and period. A
sudden departure from this uniformity indicates that something is wrong
with the valve-motion. It should be the signal to stop, and institute
a searching examination. In doing so, avoid jumping at conclusions
regarding the cause of the irregularity, and coolly examine,
separately, each part whose motion influences the valve-travel.
A WRONG CONCLUSION.
Fred Bemis missed his luck by jumping too readily at conclusions.
Something happened to his engine; and he stopped by compulsion,
and found it would not move either way. He felt certain that both
eccentrics on one side had slipped; and, considering himself equal to
setting any number of eccentrics, he got down, and fixed them in what
he supposed was the proper position. But, on trying to move the engine,
he found it still refused to go. He kept working at those eccentrics
without result till his water got low, and he was compelled to dump
the fire; the consequence being, that the engine went cold, and was
towed home. When an examination was made, it was found that a broken
valve-yoke was the cause of trouble.
LOCATING DEFECTS OF THE VALVE-MOTION.
When any thing goes wrong with the valve-motion, the first point of
investigation is, to find out which side is at fault. This can be
ascertained by opening the cylinder-cocks, and giving the engine steam.
With the reverse-lever in forward motion, the forward cylinder-cocks
should show steam when the crank-pins are traveling below the axle, and
the back cocks should blow when the pins make their similar revolution
above the axle. Any departure from this method of steam distribution
will make one side work against the other. When the engineer has
satisfied himself on which side the defect lies, he will do well to
thoroughly examine the eccentrics with their straps and rods, the links
with their hangers and saddles, the rocker box and arms with all the
bolts and pins connecting these articles. What might be regarded as a
trifling defect, sometimes makes an engine lame. I have known a loose
valve-stem key put an engine badly out of square. Eccentric-rods,
slipping, often produce this effect. When the eccentrics are found in
the proper position, the rocker-box secure in the shaft, and all the
bolts, pins, and keys in good order, and in their proper positions, the
fault may be looked for in the steam-chest.
POSITION OF ECCENTRICS.
With engines where keys are not used to secure the eccentrics to
the shaft, their slipping on the road is a common occurrence.
Eccentric-strap oil-passages getting stopped up, or neglect in not
oiling these straps or the valves, puts an unnecessary tension on
the eccentrics, which often results in their slipping on the shaft.
Engineers ought to mark the proper position for eccentrics on the
shaft; so that, when slipping happens, it can be adjusted without the
delay that often occurs in calculating the right position. When the
crank-pin is on the forward center, the body of the go-ahead eccentric
is above the axle, and the body of the back-up eccentric is below
the axle, each of the eccentrics being advanced about 1/16 of the
revolution from the right angle position towards the crank-pin; or,
to state it more accurately, the center of the eccentric is advanced
a horizontal distance to equal the lap and lead of the valve. If the
valve had neither lap nor lead, the eccentrics would stand exactly at
right angles to the crank. As it is, both of them have a tendency to
hug the crank; the eccentric which regulates the distribution of steam
following the crank. Every engineer should familiarize himself with the
correct position of eccentrics, so that, when trouble happens with the
valve-gear on the road, he will experience no difficulty in grappling
with the mishap.
METHOD OF SETTING SLIPPED ECCENTRICS.
The slipping of one eccentric is a trifling matter, which can be
quickly remedied if the set screws are in a position where they can be
reached conveniently. If it is a go-ahead eccentric, set the engine
on the center of the disabled side,--no matter which center,--put the
reverse-lever in the back notch of the quadrant, and scratch a line
with a knife on the valve-stem close to the gland. Then put the lever
in the forward notch, and move the slipped eccentric till the line
appears in the point where it was made. Fasten the set screws, and
the engine will be found true enough to proceed with the train. Care
must be taken in moving the eccentric to see that the full part is not
placed in the same position as the other one, or they will both be set
for back motion. A back-up eccentric slipped, while the go-ahead one
remains intact, can be adjusted in a similar way; the scratch on the
valve-stem being made with the engine in full forward motion, and the
adjustment of the eccentric done in full back motion. The philosophy
of this method is, that the valve is in nearly the same position at
the beginning of the stroke for the forward or back motion; and the
position of the eccentric, which has not moved, is used to find the
proper place for the one which slipped. Should the unusual circumstance
of both eccentrics on one side slipping overtake an engineer, he will
have to pursue a different method of adjustment. The most systematic
plan is to place the engine on the forward center, and set the go-ahead
eccentric above the axle, and the back-up eccentric below the axle.
With the reverse-lever in the forward notch, advance the top eccentric
till the front cylinder-cock shows steam, which can be ascertained by
blocking the wheels, and slightly opening the throttle. That will put
the go-ahead eccentric near enough to the proper position for running.
For the back-up eccentric, pull the reverse-lever into back motion,
and turn the eccentric towards the crank-pin till steam appears at the
front cylinder-cock; and that part of the motion will be right. Or the
back-up eccentric can be set by the forward eccentric in the manner
described where one eccentric has slipped.
SLIPPED ECCENTRIC-RODS.
Where slotted rods are used, they frequently slip, making the engine
lame. The cause of trouble in such a case can be identified by moving
the engine slowly, with the cylinder-cocks open. The disturbance to
the regularity of the valve’s motion, caused by a slipped rod, will
admit steam prematurely on one end of the cylinder, while it delays the
admission on the other end. The valve is made to travel more on one
side of the exhaust center than on the other. Lengthening or shortening
the valve-stem has a similar effect, but this makes the engine lame
in both gears; while the slipping of an eccentric-rod only makes the
engine lame in the motion that the rod belongs to. This is subject to a
slight modification, however; for the back-motion eccentric being badly
out of square, will affect the correctness of the forward motion, when
the engine is working close hooked up. But in full motion it will not
be perceptible.
DETECTING THE CAUSE OF A LAME EXHAUST.
If in moving the engine ahead slowly, with the cylinder-cocks open, it
is found that steam is admitted to the cylinder before the piston has
nearly reached the center or dead point, or that the back cylinder-cock
does not show steam till after the piston has passed the back center,
the eccentric-rod is too long. The rod being too short produces
precisely an opposite effect. The steam arrives late on the back
stroke, and ahead of time on the forward stroke. This is different
from the action of the steam where an eccentric has slipped. In that
case, there will be pre-admission of steam before the beginning of both
strokes, or post-admission, that is, late arrival of steam, for both
strokes. Take a go-ahead eccentric for example. If it slips backward
on the shaft, its effect will be to delay the admission of steam
till after the beginning of each stroke; and, if it slips forward,
the result will be to accelerate the lead of the valve opening the
steam-port before the piston has reached the commencement of each
stroke.
WHAT TO DO WHEN ECCENTRICS, STRAPS, OR RODS BREAK.
When either of these accidents happens, the safest plan is to take
down both straps and rods on the defective side. Some engineers leave
the back-up eccentric strap and rod on, when the forward strap or rod
has broken; but it is a little risky under certain conditions. After
getting the eccentric straps and rods down, drop the link-hanger
away from the tumbling-shaft, disconnect the valve-stem, and tie the
valve-rod to the hand-rail. Then set the valve in the middle of the
seat, so that it will cover both the steam-ports, and hold it in
that position by pinching the stem with the gland, which is done by
screwing up the gland obliquely. Take down the main rod, and block
the cross-head securely at the back end of the guides. Good hardwood
blocking prepared beforehand should be used for this purpose, and it
ought to be fastened with a rope or marline. A neater plan for holding
the cross-head in place is described by Frank C. Smith, in the _Torch_.
He says, “Have the blacksmith make a hook out of a piece of inch and a
half round iron; also a piece about fifteen inches long by one and a
half thick, and four inches wide, with a hole through the center for
the shank of the hook to pass through. This shank is threaded for a
nut. Now, when it is necessary to block a piston, get it to the back
end, pass the hook around the wrist of the cross-head, and the other
end through the straight piece which bears against the yoke supporting
the back end of the guides; run up a nut on the shank of the hook,
hard against the cross-piece, and the piston is secured.” The piston
being properly fastened, it is a wise supplement to the work to tie the
cylinder-cocks open, or to take them out altogether. The engine is now
ready to proceed on one side.
Young engineers can not be too strongly impressed with the necessity
for having the cross-head properly secured before trying to move
the engine. I have repeatedly known of serious damage being caused
by placing too much confidence in weak blocking. Taking out the
cylinder-cocks is a wise security against accidents of this kind; for,
should a little steam be passing through the valve, it has a port of
escape without putting heavy pressure on the piston.
DIFFERENT WAYS OF SECURING THE CROSS-HEAD.
In regard to the method of securing the piston when one side of an
engine is taken down, there is considerable diversity of opinion among
engineers. Some men maintain that the proper and quick plan is, merely
to move the piston to one end of the cylinder, pushing the valve in
the same direction, so that the steam-port will be open at the end
away from the piston. This will keep the cylinder full of steam, and
hold the piston from moving. But, if by any accident the valve should
be moved to the opposite end of the seat, steam would get to the wrong
end of the cylinder, and the piston would certainly smash out the head.
Another risky plan, practiced by men economical of work, is to place
the valve on the center of the seat, and let the piston go without
fastening. These slipshod methods do not pay.
BROKEN TUMBLING-SHAFT.
This accident is very serious; but it need not disable the engine,
although it will lessen the engineer’s power to manage it freely. To
get the engine going, calculate the position the links must stand in
to pull the train, and cut pieces of wood to fit between the block and
the top and bottom of the links, so that the latter may be kept in the
required position. For forward motion, there will be short pieces in
the top, and long pieces in the bottom. When back motion is needed,
reverse the pieces of wood. A common plan is to use one piece of wood,
working the engine in full gear.
The same treatment will keep an engine going when the tumbling-shaft
arms, the reach-rod, the link-hanger, or the saddle-pin breaks. The
failure of a link-hanger or saddle-pin will only necessitate the
blocking of one side.
BROKEN VALVE-STEM, OR VALVE-YOKE.
For a valve-stem broken, the eccentric-strap or link need not be
interfered with. If the break is outside the steam-chest, take down
the valve-stem rod, and set the valve on the middle of the seat; take
down the main rod, and secure the piston as previously directed. With
a valve-stem broken inside the chest, or a valve-yoke broken, a little
additional work is necessary. The steam-chest cover must now come up,
and the valve be secured in its proper place by pieces of wood, or any
other material that will keep it from moving; and the stuffing-box must
be closed, to prevent escape of steam through the space vacated by the
valve-stem.
WHEN A ROCKER-SHAFT OR LOWER ROCKER-ARM BREAKS.
A broken rocker-shaft, or the fracture of the lower arm, entails the
taking down of both eccentrics and the link, besides the main rod,
and the securing of the valves and piston. The breaking of an upper
rocker-arm is equivalent to a broken valve-stem, and requires the same
treatment.
MISCELLANEOUS ACCIDENTS TO VALVE-MOTION.
Accidents to the valve-seat, such as the breaking of a bridge, can be
fixed for running the engine home on one side, by covering the ports,
and stripping that side of the engine, just as had to be done for
a broken valve-yoke. If a serious break in a bridge occurs, it is
indicated by a tremendous blow through the exhaust port, out by the
stack. A mishap of much less consequence than a broken bridge is a
“cocked” valve, and the small mishap is very liable to be mistaken for
the greater one. Where the yoke is tight fitted, or out of true with
the line of the stem, some engines have a trick of raising the valve
away from the seat, and holding it there. This generally happens going
into a station; and, when steam is applied in starting out, an empty
roar sounds through the stack. Moving the valve with the reverse-lever
by quick jerks will generally reseat a cocked valve, but sometimes it
gets stuck so fast that it has to be hammered out of the yoke.
When a locomotive shows the symptoms which indicate a broken valve, a
broken bridge, or a cocked valve, the engineer should exhaust every
means of testing the matter from the outside before he begins an
interior inspection by raising the steam-chest cover. If jerking the
valve with the reverse-lever, or moving the engine a little, will not
stop the blow, he should disconnect the valve-stem, and shake the valve
by that means.
When a valve breaks, disabling its side of the engine so badly that it
can not be used, the valve should be taken out, and a piece of strong
pine-plank secured over the ports.
BROKEN STEAM-CHEST COVER.
A very serious and troublesome accident, which may come under the head
of steam-distribution gear, is the breaking of a steam-chest, or of
a steam-chest cover. It takes skillful management to get an engine
along when this has happened. The most effectual way to restrain
loss of steam when a chest or cover has broken, is to slack up the
steam-pipe, and slip a piece of iron plate, lined with sheet-rubber,
leather, canvas, or any other substance that will help to make a
steam-tight joint, into the lower joint of the steam-pipe. If this
is properly done, it ends the trouble, when the joints are tightened
up. But the difficulties in the way of loosening steam-pipe joints in
a hot smoke-box are often insurmountable, especially when the nuts
and bolts are solid from corrosion, which is generally the case where
they have not been touched for months. In such a case it is better to
resort to the more clumsy contrivance of fitting pieces of wood into
the openings to the steam-passage, and bracing them in place by means
of the steam-chest bolts. A man of any ingenuity can generally, by this
means, save himself the humiliation of being towed home, and yet avoid
spending much time over the operation. When the engineer has succeeded
in securing means for preventing the escape of steam, the main rod must
be taken down, and the valve-stem rod disconnected from the rocker-arm.
In this instance the piston needs no further attention, after the main
rod has been disconnected; for there will be no ingress of steam to the
cylinder to endanger its safety.
STEAM-PIPE BURSTED.
The breaking of a steam-pipe in the smoke-box is even a more harassing
mishap than a bursted steam-chest or cover. The only remedy for this
is the fastening of an iron plate to the top joint of the steam-pipe,
thereby closing up the opening. A heavy plug of hard wood may be driven
into the opening, and braced there for a short run; but such a stopper
is hard to keep in place, owing to the shrinkage caused by the intense
heat of the smoke-box.
TESTING THE VALVES.
An experienced engineer will most easily determine the existence of
leaks between the valves and their seats when the engine is working,
and the indications of that weakness have already been noticed. But it
sometimes happens that a man wishes to test the condition of the valves
when the engine is at rest. This can be most readily accomplished
by placing the engine so that the rocker-arm stands in the vertical
position. Open the smoke-box door so that the exhaust nozzles can be
seen. Now block the wheels, and give the engine steam. If the valve
blows, the steam will be seen issuing from the nozzle on the side under
examination. As the tendency of a slide-valve is to wear the seat
concave, it sometimes happens that a valve is tight on the center,
yet leaky in other positions. Moving the valve with the reverse-lever
as far as can be done without opening the steam-port, will sometimes
demonstrate this. The cranks should be placed on the eighths positions
when the valves are being tested.
CHAPTER XIV.
_ACCIDENTS TO CYLINDERS AND STEAM CONNECTIONS._
IMPORTANCE OF THE PISTON IN THE TRAIN OF MECHANISM.
The piston is an autocratic member of the machine. For thousands of
miles it toils to push the engine ahead, every thing going smoothly so
long as it is confined to its recurring journey; but let any attachment
break, or a key fly out that will increase the piston’s travel, and
away the piston goes, right through a cylinder-head.
CAUSES THAT LEAD TO BROKEN CYLINDER-HEADS.
The causes which most commonly lead the piston to smash out
cylinder-heads, are broken cross-heads, broken piston-rods, and broken
main-rods. A main crank-pin or wrist-pin breaking, is almost certain to
leave one end of the cylinder a wreck. These may be termed the major
causes for breaking out cylinder-heads; but there are numerous minor
causes, which are scarcely less destructive. A piston-rod key begins to
work loose. It is hammered down occasionally, which does not improve
its fit; and some day it jumps out altogether, letting the piston go
on a voyage of discovery. A machinist of the careless sort has been
examining a piston’s packing, and, in screwing up the follower-bolts,
one of them gets a twist too much. Drilling out a follower-bolt is a
troublesome operation, so Mr. Careless lets it go. On the road this
head drops out, and a broken cylinder-head is the consequence. One of
the worst causes of breakage to a cylinder that I have ever seen, was
caused by the packing-ring of the piston catching in the steam-passage.
Part of the ring broke off, and wedged itself between the advancing
piston and the cylinder. The wedge split the cylinder open, and the
remainder of the piston acted like a pulverizer upon the fragment of
the cylinder.
BROKEN CYLINDER-HEADS OFTEN PREVENTABLE.
The causes which eventually lead to broken cylinder-heads often
originate from preventable strains. Thus, cross-heads are frequently
fractured by main-rod connections pounding; and weaknesses, that
ultimately bring crank-pins to disaster, originate in a similar way.
A loose piston-key is liable to crack the piston-rod, if it does not
give trouble by jumping out. Loose guides have a tendency to spring
piston-rods, and throw unnecessary strain upon them. Pistons lined out
of true, are dangerous for the same reason. A pump-plunger working out
of line, or badly secured in the lug, throws a distressing load upon
the cross-head. And so the list of potential accidents grows. Like
the steady water-drop that wears into the adamantine rock, trifling
defects, assisted by time’s action, prove stronger than the most
massive machine.
When any thing happens to permit the piston to break out a
cylinder-head, the engine can be put in running trim by taking off
the valve-rod and main-rod, and setting the valve on the center of
the valve-seat. Blocking the cross-head is unnecessary, if the break
will allow the escaping steam to pass through; for then no further
tension can be put upon the piston to cause further damage. If, by an
extraordinary freak of good luck, a piston-rod breaks without causing
other damage, the cylinder-head must be taken off, and the piston
removed. Then cover the ports, and take down the main-rod on that side.
Or, if the cross-head is all right, the main-rod may be left untouched.
When the cross-head breaks, it generally entails taking out the piston,
centering the valve, and taking down the main-rod on that side.
WHEN A MAIN-ROD BREAKS.
With a broken main-rod which does not knock out the cylinder-head, the
main-rod and valve-rod should be taken down, the valve secured on the
center of the seat, and the cross-head blocked with the piston at the
back end of the cylinder.
CRANK-PIN BROKEN.
For a broken main crank-pin, the above method of stripping the engine
will do with the addition of taking down both side-rods. An accident
which disables one side-rod, requires that the other one shall be taken
down also, or there will be trouble when the engine is attempted to
be run with one side-rod. The rod might go all right so long as no
slipping happened. But, if the engine began to slip while passing over
the center, the side-rod would have no leverage on the back crank to
slip its wheel; and a broken rod or crank-pin would almost certainly
ensue.
A broken side-rod, that is not accompanied by other damage, requires
both side-rods to be taken down. All the inconvenience arising from
this is, that the engine is more liable to slip. But, with dry rails,
an engine can get along very well without its side-rods.
THROTTLE DISCONNECTED.
Any accident to the throttle-valve or its attachments, which deprives
the engineer of power to shut off steam, is very dangerous, and calls
for prompt action. Lose no time in reducing the head of steam to fifty
or sixty pounds, or to the pressure where the engine can easily be
managed with the reverse-lever.
With the aid of a power-brake, an engineer can get along fairly with a
light train, after an accident has happened which prevents the closing
of the steam from the cylinders; but constant vigilance and thoughtful
labor are needed.
OILING THE VALVES WHEN THE THROTTLE IS DISCONNECTED.
The greatest difficulty will be experienced in oiling the valves,
unless the steam-chests are provided with the automatic feeders, which
work with steam on.
If he is running on an undulatory road, an engineer can oil the valves
from the cab, by letting the steam down at the top of a hill, and
running down at a high speed. It can also generally be done on a level
track, by letting the fire burn low, getting up the best speed the
engine will attain, then putting the feed full on. As the steam drops
suddenly, put the reverse-lever in full motion; and the chances are,
that the valves can be oiled.
WHAT CAUSES A DISCONNECTED THROTTLE.
The most common causes of trouble with the throttle are the breaking or
working out of one of the bolts that operate the valve within the dome,
the breaking of a valve-rod, or working off of nuts that should secure
the connection. Where the throttle fails with the valve closed, and
the engineer finds it necessary to take the dome-cover off to prevent
his engine from being hauled in, he will generally find the trouble
to lie with the connections mentioned, or with the bolts belonging to
the bell-crank, that is located near the bottom of the stand-pipe.
Sometimes the nuts on the top of the throttle-valve stem work off: but,
in such a case, there is no difficulty in opening the valve; it is
when the engineer wants to close it, that the discomfiture comes in.
Some steam-pipes are provided with a release-valve near the throttle,
to relieve the pipe from intense back-pressure when the engine is
reversed. The sudden reversing of an engine sometimes jerks this
valve out of its seat, leaving an open passage between the boiler and
steam-chest. This acts like a mild case of unshipped throttle, and must
be controlled in a similar way.
BURSTING A DRY PIPE.
The bursting of a dry pipe is similar in effect to the action of a
throttle becoming disconnected while open; and it may even prove harder
to control, according to the size of the opening. Engineer Halliday
had a trying time with a case of this kind. While swinging along the
E., F., & G. road, with a heavy train of freight, a herd of horses ran
in from an open crossing-gate, and started up the track just in front
of the engine. As there was a bridge a short distance ahead, Halliday
reversed the engine in his anxiety to prevent an accident. The train
stopped for an instant, when the engine began to push it back. Halliday
tried to throw the lever to the center, but never before had he felt
such a pressure acting upon it. Again and again he tried to throw
the lever over; but every time it proved too formidable a struggle,
and the catch found its way into the full-back notch. Meanwhile, the
train was gaining speed in the wrong direction, and a passenger train
was not many miles behind. Beginning to realize the true state of
affairs, Halliday called for brakes, opened the fire-box door, closed
the dampers, and started the injector. Then he directed the fireman to
throw some bucketfuls of water upon the fire, while he tied down the
whistle-lever, letting the steam blow. The promptest means for reducing
the pressure of steam were now in operation, and his next move was to
try the reverse-lever again. Both men grasped the lever, and, by a
combined effort, forced it past the center; and Samson’s hair was cut.
It was afterwards found that a long rent had opened in the dry pipe,
letting the full boiler pressure upon the valves, which moved hard
through being dry; the hot gases pumped through them in reverse motion
having licked off every trace of lubricating unguent.
OTHER THROTTLE ACCIDENTS.
Cases of serious trouble resulting from accidents to throttle
connections would be easy to multiply. Two incidents with similar
originating conditions, but with very different results, will suffice.
Engineer Phelps was pulling a full train of coal over rails that were
neither wet nor dry, and had just enough frost upon them to be wicked.
He was having a bad time slipping, but was working patiently along,
when the throttle became disconnected with the valve open. The engine
at once started on a whirl of slipping that threatened disaster, but it
was immediately controlled by the engineer pulling the reverse-lever
to the center notch. Engineer Cook of the F., G., & H. road, was not
so fortunate when the stem of his throttle-valve broke on a slippery
day. As the wheels began spinning round, Cook lost his head, and kept
working at the throttle-lever to try to stop. Seeing this was of no
avail, he grasped the sand-lever, and tugged vigorously at the valves.
A season of tumult succeeded; and, when the engine stopped presently,
it was found to be a deplorable wreck. It was hard to tell, from the
look of the ruin, what part of the locomotive broke first; but the
crank-pins on one side were cleaned off, and the piston was out through
the cylinder-head. The side-rod on the other side broke close to the
strap, and was twisted up like a spiral spring.
POUNDING OF THE WORKING-PARTS.
It is good for an ambitious young engineer, who desires to thoroughly
master his calling, to walk occasionally into the room where a
well-managed automatic cut-off engine is at work, and watch its smooth,
noise-less movements. There he may find an ideal of how an engine
should run. The nature of the work performed by a locomotive engine
prevents it from being operated noiselessly, and the smoothness of
its action must always compare unfavorably with a well-constructed
stationary engine; but the connections which transmit the power of
a locomotive should be free from knock or jar, if they are properly
proportioned, and skillfully put together.
SOME CAUSES OF POUNDING.
To an engineer with a well-regulated mind, a pound about the engine is
a source of continual irritation. If a pound arises from a cause which
can be remedied by an engineer, the careful man will soon perform the
necessary work to end the noise. Sometimes the origin of a pound is
hard to discover: very often it is beyond the power of the engineer to
stop it. Some makes of locomotives always pound when working in full
gear. With such an engine, a nervous engineer will fuss, pushing up
wedges until they stick fast, and cause no end of grief to get them
down again. He will key up the main-rod connections till they run hot,
and he will prophesy that the engine is going to pieces. But the engine
hangs together all the same, and is only suffering from want of lead,
or want of compression. Where an engine is deficient in the cushioning
to the piston, due to compression or lead, the momentum of the piston
and connecting-rod is suddenly checked at the end of each stroke. The
concussion to these working-parts is so great that pounding will be
produced. As the engine gets hooked towards the center, this pounding
will cease, because the lead opening increases as the motion is notched
back. The most common causes for pounding with locomotives are worn
main-rod connections, and driving-boxes too loose in the jaws, or the
brasses loose in the driving-boxes. If side-rods are out of tram, or
have the brasses badly worn, they sometimes pound when passing the
centers. A cross-head will pound when the guides are worn very open.
This last defect is liable to cause a bent piston-rod. A piston makes
a tremendous pound when a badly connected rod allows it to touch a
cylinder-head, and a very ominous pound is produced when the spider
gets loose on the piston-rod, and a piston-rod loose in the cross-head
will make itself heard all over the engine.
LOCATING A MYSTERIOUS POUND.
Several years ago a very troublesome and mysterious pound caused the
writer a great deal of annoyance. He was running an old engine, with
cylinders that had been bored out until no counter-bore was left.
The piston had worn a seat leaving a small ridge at the end of its
back travel. The main-rod was taken down one day; and, in putting it
up again, the travel of the piston was slightly altered. The engine
started out with a pound, and kept it up. If any of my readers have
been working an engine that seemed to hang together merely by luck,
away on construction work on the wild prairies, with no machine-shops
in the rear to appeal to for aid or counsel, with all his own repairing
to do without tools or skilled assistance, they will understand the
difficulty experienced in locating that pound at the back end of the
cylinder.
A cylinder loose on the frame, or a broken frame, will jar the whole
machine; and both of these defects are serious, and demand increased
care in taking the engine along with the train. Loose driving-box
brasses produce a pound which is sometimes difficult to locate. In
searching for the cause of a pound, it is a good plan to place the
engine with one of the cranks on the quarter, block the wheels, and
have the fireman open the throttle a little, and reverse the engine
with the steam on. By closely watching in turn each connection, as the
steam through the piston gives a pull or a thrust to the cross-head,
the defect which causes the pound may be located. Never run with a
serious pound inside of a cylinder. It is an almost certain indication
that a smash is imminent.
CHAPTER XV.
_OFF THE TRACK.--ACCIDENTS TO RUNNING-GEAR._
GETTING DITCHED.
There is something pathetic in the spectacle of a noble locomotive,
whose speed capabilities are so wonderful, lying with its wheels in the
air, or sunk to the hubs in mud or gravel. Kindred sights are, a ship
thrown high and dry upon the beach, away from the element that gives it
power and beauty; or a monster whale, the leviathan of the deep, lying
stranded and helpless upon the shore.
Few engineers have run many years without getting their engine off the
track in some way,--over the ends of switches, by jumping bad track,
or getting into the ditch through some serious accident, collision or
otherwise. Most of them have felt that shock of the engine thumping
over the ties, and momentarily wondered in what position it was going
to stop; doing all in their power, meanwhile, to stop, and prevent
damage.
DEALING WITH SUDDEN EMERGENCIES.
Of course, an engineer’s first duty is to conduct his engine in a way
that will avoid accident so far as human foresight can aid in doing
so; but, when an accident is inevitable, his next duty is to use every
exertion towards reducing its severity. The most common form of serious
accident occurring on our railroads is a collision. Rear-end collisions
occur most frequently, although head-to-head collisions annually claim
many victims. When an accident of this kind is impending, the engineer
generally has but a few seconds of warning; but these brief seconds
well utilized often save many lives, and impress the principal actor
with the stamp of true heroism. Rounding a curve at a high speed, an
engineer perceives another train approaching. Quick as thought he
shuts off steam, applies the brake, reverses the engine, and opens
the sand-valves and the throttle. This will take about ten seconds’
time; and, if the engine is running thirty miles an hour, the train
will pass over forty-four feet each second. Assuming that no reduction
of speed has taken place till all the appliances for stopping are
in operation, four hundred and forty feet will be passed over as
a preliminary to stopping. With the automatic Westinghouse brake,
application and retarding power are almost simultaneous. Until he
has applied all means of reducing speed, an engineer rarely or never
consults his own safety, however certain death may be staring him in
the face. But after the brakes are known to be doing their work, aided
by sanded rails, and steam working against the piston, personal safety
is considered. A glance at the position of the two trains tells if they
are coming violently together; and the engineer jumps off, or remains
on the engine, as he deems best. This applies to trains equipped with
continuous brakes.
STOPPING A FREIGHT TRAIN IN CASE OF DANGER.
With freight trains where the means of stopping are not immediately
under the hand of the engineer, he must call for brakes on the first
indication of danger, and do all that a reversed engine can achieve to
aid in stopping the train. Where a driver brake is used, the engineer
will have to watch the reversed engine; because the wheels will soon
begin sliding, even on thick sand, and their retarding power will be
seriously diminished. To prevent this, the engineer should let off
the driver brake, and open the cylinder-cocks, till the wheels begin
to revolve, when the brake may be applied again. Working and watching
in this way greatly assist in stopping a train, and preventing the
flattening of wheels.
SAVING THE HEATING SURFACES.
Should the engine get into the ditch, the engineer’s first duty is
to save the engine from getting burned, unless saving of life, or
protecting the train, demands his attention. If the engine is in a
position where the flues or fire-box crown will be left without water,
the fire should be quenched as quickly as possible. Sand or gravel
thrown over the fire, and then saturated with water, is a good and
prompt way of extinguishing the fire.
GETTING THE ENGINE ON THE TRACK.
It can be understood in a few minutes after derailment whether or not
the engine can be put back on the track without assistance. Sometimes
a pull from another engine is all that is required: again, nothing
can be done without the aid of heavy tools to raise it up. In this
case, no time should be lost in sending for the wrecking outfit. It
often happens that an engine gets off the track while switching among
sidings, and sinks down in the road-bed so as to be helpless. In an
event of this kind, jacking up a few inches will often enable the
engine to work back to the rails. Before beginning to hoist with the
screw-jacks, some labor can generally be saved by putting pieces of
iron between the bottom of the driving-boxes and the pedestal-braces.
As the wheels begin to rise out of the gravel, pieces of plank or
wooden wedges should be driven under them to hold good every inch
raised. Where the attempt is made to work an engine on the rails by
means of wrecking-frogs, wooden filling should be laid down crosswise
to prevent the wheels from sinking between the ties, should they slip
off the frogs. Where jacking up has to be resorted to, there is often
difficulty experienced in getting up the engine-truck; as raising the
frame usually leaves the truck behind in the mire. The best plan is, to
jack up the front of the engine to the desired level, then with a rail
well manned pry up the truck, and hold it in position by driving shims
under the wheels. An engine will generally go on the rails easiest the
way it comes off.
When a derailed engine is being pulled on the track by another engine,
the work should be done carefully, and with proper deliberation. When
every thing is made ready for a pull, some men act as if the best plan
was to start both engines off with full throttle; and this often leaves
the situation worse than it was at first. When truck-wheels stand at
an angle to the track, it is often necessary to jerk them in line by
attaching a chain or rope to one side. A wrecking-frog should be laid
in front of the wheel outside the rail, and blocking before the inside
wheel, sufficient to raise the tread of the wheel above the level of
the rail. Then move ahead slowly, and the chances are that the wheels
will go on the rails. Sometimes the easiest way is to open the track at
a joint, move it aside to the line of the wheels, and spike it there,
then draw or run the engine on.
Having an engine off the track, is a position where good judgment is
more potent than a volume of written directions.
UNDERSTANDING THE RUNNING-GEAR.
The driving-wheels, axles, boxes, frames, with the trucks and all their
attachments, are somewhat dirty articles to handle. The examination
of how they are put together, and how they are hanging together,
is pursued under soiling circumstances. Perhaps this is the reason
these things are studied less than they ought to be. To creep under a
greasy locomotive to examine wheels, axles, and truck-boxes, is not a
dignified proceeding by any means; but it is a very useful one. The
running-gear is the fundamental part of the machine, and its whole
make-up should be thoroughly understood. The builds of trucks are so
multifarious that no specified directions can be given respecting
accidents happening to them. There is, therefore, the greater need
for an engineer’s familiarizing himself with the make-up of his
running-gear, so that, when an accident happens, he will know exactly
what to do. Disraeli said: “There is nothing so likely to happen as
the unexpected.” This applies very aptly to railroad engineering.
Industrious accumulation of knowledge respecting every part of the
machine is the proper way to defy the unexpected.
BROKEN DRIVING-SPRING.
The running-gear of some engines is so arranged, that, in case a
driving-spring breaks on the road, it can readily be replaced if a
spare spring is carried. With the average run of engines, however, and
the accumulating complication of brake-gear attached to the frames,
the replacing of a driving-spring is a tedious operation, that would
involve too much delay with an engine attached to a train. Consequently
engineers seldom attempt to change a broken spring. They merely remove
the attachments likely to shake out of place, and block the engine up
so as to get home safely. When a forward driving-spring breaks, it is
generally best to take the spring out with its saddle and hangers. Then
run the back drivers up on wedges to take the weight off the forward
drivers, and put a piece of hard wood or a rubber spring between the
top of the box and the frame. Now run the forward drivers on the
wedges, which will take the weight off the back drivers, and with a
pinch-bar pry up the end of the equalizer till that lever stands level,
and block it in that position by jamming a piece of wood between it
and the frame. For a back driving-spring, this order of procedure
should be reversed. A back driving-spring is often hard to get out of
its position; and it sometimes can be left in place, as it is not very
liable to cause mischief.
Where a spring drops its load through a hanger breaking, the mishap can
occasionally be remedied by chaining the spring to the frame. Should
this prove impracticable, the same process must be followed as that
which was made necessary by a broken spring.
EQUALIZER BROKEN.
For a broken equalizer, all the pieces likely to shake off, or to be
caught by the revolving wheels, must come out; and both driving-boxes
on that side must be blocked on top with wood or rubber. Where good
screw-jacks are carried, it will often prove time-saving to raise the
engine by jacking up at the back end of the frame instead of running it
up on wedges. Where the wedge plan is likely to prove easiest, it must
be adopted only on a straight track; and then too much care can not be
used to prevent the wheels from leaving the rails.
ACCIDENTS TO TRUCKS.
The breaking of an engine-truck spring which transmits the weight
to the boxes by means of an equalizer, requires that the equalizer
should be taken out, and the frame blocked above the boxes. This
blocking above the boxes is necessary to prevent the two unyielding
iron surfaces, which would otherwise come together, from hammering
each other to pieces. Wood or rubber has more elasticity, and acts as
a spring. Whatever may be the form of truck used, if the breaking of
a spring allows the rigid frame to drop upon the top of one or more
boxes, it must be raised, and a yielding substance inserted, if the
engine is to be run even at a moderate speed, and the engineer wishes
to avoid further breakage. Sometimes truck-springs, especially with
tanks, are so arranged that the removal of one will take away the
support of the frame at that point. In such a case, a cross-tie or
other suitable piece of wood must be fitted into the place to support
the weight which the spring held up.
BROKEN FRAME.
A broken truck-frame can generally be held together by means of a
chain, and a piece of broken rail or wooden beam to act as a “splice.”
Should a truck-wheel or axle break, it can be chained up to enable
the engine to reach the nearest side track where new wheels may be
procured, or the broken parts fastened so that the engine may proceed
carefully home. The back wheel of an engine-truck can be chained
up securely to a rail or cross-tie placed across the top of the
engine-frame. If an accident happens to the front wheels, and it proves
impracticable to get a sound pair, the truck should be turned round
when a side track is reached. An accident to the wheels or axle of a
tender-truck can be managed in the same way as an engine-truck, but the
cross-beam to support the chained weight must be placed across the top
of the tender. A bent axle or broken wheel that prevents a truck from
following the rail, can be run to the nearest side track by fastening
the wheels so that they will slide on the rails.
BROKEN DRIVING AXLES, WHEELS, AND TIRES.
Accidents of this nature often disable the engine entirely; but
sometimes the breakage occurs in such a way that the engine can run
itself home, or into a side track, by good and careful management.
Driving-axles generally break in the box, or between the box and the
wheel. When this happens to a main driving-axle, or when any thing
happens to the forward driving-wheel or tire of such a serious nature
that the engine can not be moved until the wheel is raised away from
the rail, the engineer’s first duty is to take down the main rod on
that side, and secure the piston, then to take down both of the side
rods. Cases could be cited where engineers have brought in engines with
broken axles without disconnecting any thing, but these men did not
take the safe side by a long way.
The rods being disconnected, run the disabled wheel up on a wedge or
block of wood, and secure it in the raised position by driving blocking
between the axle-box and the pedestal-brace. To get the box high enough
in the jaws, it is sometimes necessary to remove the spring and saddle
from the top of the box. A wheel may break and not fall to pieces, but
still be dangerous to use, except for moving along slowly. A tire may
break, and yet remain on the wheel, only requiring the most careful
handling. On the other hand, the breaking of a wheel or tire may render
the wheel useless, when it must be raised from the rail the same way as
was recommended for a broken axle, and the same precautions in regard
to stripping that side of the engine must all be taken. In the event of
an accident happening which disables both forward drivers, they must
both be raised from the rails, and the engine pulled in, the truck and
hind drivers supporting the weight. Both side rods must come down.
The breaking of back driving-axles, or accidents to wheels or tires,
is very difficult to manage; because the weight must be supported in
some way. The first act when such a mishap occurs, is to take down
both side rods. If the engine can be moved to the nearest side track
without further change, take it there; now jack up the back part of the
engine, and fasten two pieces of rail by chaining or otherwise to the
frames of the engine, their ends resting on the tank-deck, so that,
when the jacks are lowered, the tank will help to support the hind part
of the engine.
I have seen a case where one piece of rail was pushed into the draw-bar
casting, and it held the engine up through a journey of seventy miles.
If one of the back driving-wheels can be used, it lessens the weight
that has to be borne by any lever contrivance. When one wheel is
disabled, it must be blocked up in the jaws; and, should both wheels
be rendered useless, they must both be held up, so that as much as
possible of the weight may be thrown upon the forward drivers.
CHAPTER XVI.
_CONNECTING-RODS, SIDE RODS, AND WEDGES._
CARE OF LOCOMOTIVE RODS.
When it is found that an engineer runs his engine for months on arduous
train service, and has no trouble with his rods, he may safely be
credited with knowing his business, and attending to it skillfully.
In regard to the keeping of the machinery in working-order, the
engineer’s duties are mostly of a supervisory nature. When piston-rings
get blowing, when guides need closing, or when a pump gets working
badly, he reports the matter; and the work is done so that the defect
is remedied. With the rods it is different. Although he does not file
the brasses himself, he exerts great influence, for good or evil, in
the way he manipulates the keys, and by the care he takes of the rods.
Injudicious keying of rods is responsible for more accidents than the
mistakes in any other one direction, with, perhaps, the exception of
the current mistake of the hind brakeman, who supposes there is no use
in going back to flag when his train has stopped between stations.
FUNCTIONS OF CONNECTING-RODS.
The functions of rods being to transmit the motion of the pistons to
the running-gear, they have very heavy duty to perform. The conflicting
strains and shocks to which a locomotive is subjected while running
over a rough track at high speed, are, in many instances, sustained
by the rods: hence it is of special importance that this portion of
the motion should be kept in good order. Main rods convey the power
developed in the cylinders to the crank-pins by a succession of pulls
and thrusts equal in vigor to the aggregate of steam-pressure exerted
on the piston. To endure this alternating tension and compression
without injury to the working-parts, it is of the utmost importance
that the connections should be close fitted, yet free enough to prevent
unnecessary friction. In fitting up main-rod brasses, it does not
matter in what position the crank stands, so long as it is convenient
for doing the work. But, if the engine has been in service since the
pins were turned, they should be calipered through their horizontal
diameter when the crank is on the center; since it is well known that
the pins have a tendency to wear flat on the sides at right angles to
the crank’s length. The back ends of the main-rod brasses should be
fitted brass to brass; for that form of doing the work makes the most
secure job, and gives the connection all the advantages of a solid box,
preventing the straps and brasses from being knocked out of shape by
hammering each other,--a result that surely follows the open brasses
method of fitting back ends of main-rods. Leaving the forward end
brasses a little open is not injurious to that connection, because the
line of strain is not so varied as that of the back end.
EFFECTS OF BAD FITTING.
When the work of fitting a set of back-end brasses is completed, they
should be put in the strap, and tried on the pin. If, after being
keyed close together, they revolve on the pin without pinching, the
fit is not too tight. It is of the greatest consequence, in fitting
rod-brasses, to ascertain, beyond doubt, that the brasses have been
bored out true, and that they fit in the strap so that the line
of strain shall be in line with the cross-head and crank-pins. It
occasionally happens, through bad workmanship, that when the back end
of a rod is keyed up, and the front end not connected, the rod does not
point straight to the cross-head pin, but in a line some distance to
the right or left. The distance may be very small, yet sufficient to
cause no small amount of trouble. By some pinching and jamming, a rod
in this condition can be connected up; but it is almost sure to run
hot. And a rod in this condition will never run satisfactorily till it
is taken down and fitted by a competent machinist. The back end may be
all right, and the forward end suffering from oblique fitting. This is
even more common than the first case, and the effect is the same. A
rod in this condition, besides displaying a tendency to run hot, will
keep jerking the cross-head from side to side on the guides, and will
probably make the cross-head chafe the guides at certain points. Rods
never run cool, and free from jar, unless they are fitted to transmit
the power in a direct line between the pins.
STRIKING POINTS AND CLEARANCE.
Before putting up main rods, the striking points of the pistons should
be located and marked on the guides. Then, when the rods are put up,
the clearance should be divided equally between the two ends. The
identification of these points is of greater interest to the engineer
who is running the engine than to any other person; for upon their
correctness the success of his running may, to some extent, depend. An
engine may go out with the clearance badly divided, and run all right
for a few days, and the driving of a key may then cause the piston to
strike the head. A forcible instance of this kind once came under my
observation. A careless machinist, in working on main-rod brasses,
had mixed the liners, and shortened the rod, till the piston began to
touch the back head. When the engine was working light, there was just
a slight jar; but, when the load was heavy, the jar became a distinct
pound. The engineer could not locate the knock, and was disposed to
think it was in the driving-box. One day that he slipped the engine
badly, steam began to issue from the back cylinder-head, which was
cracked by a blow from the piston. The cause of the pound was then
discovered.
WATCHING RODS ON THE ROAD.
When an engineer starts out with an engine after the rod-brasses have
been filed, he should make them a special object of attention. If he
can not shake the connection laterally with his hands when there is
room for movement within the collars, he should slack up the key till
he can do so; for some one has made a mistake in fitting. So long as
the rod passes the center without jar when the engine is working hard
in full gear, the brasses are tight enough. After running a few miles
with newly fitted brasses, the rod will generally need keying up; for
liners that were comparatively loose when put up, get driven compactly
together, leaving lost motion. Although a connection may be put
together brass to brass, there is still some work left for the engineer
to do in the way of keying. To do keying correctly needs considerable
sagacity, especially in the case of side rods. In the case of back
ends of main rods, the key should be got down as soon as possible,
to hold the brasses immovably in the strap; but, after this point is
reached, there should be no more hammering on the key. Some men persist
in pounding down keys that are already snug, and the effect of their
blows is to spring the brass out of shape. A key acts as a wedge, which
it is; and, when the taper is slight, the blow imparted by a hammer
roughly used, exerts an immense force in driving it down. Something
must yield; and the brass gets sprung towards the pin, presenting a
ridge for a rubbing surface, which heats, and causes delay. After the
key is once driven tight home, its work is finished. If the pin then
indicates lost motion, the rod should be taken down, and the brasses
reduced. In the case of main rods, this should be done at the first
signs of pounding; for lost motion entails heavy shocks upon the
moving parts. The front end of main rods requires to be very carefully
watched, and the connection kept free from jar. Where this part is
kept regularly oiled, and free from lost motion, it gives scarcely
any trouble; but let the wrist-pin of the common cross-head once get
cut through neglect, and it is a difficult matter getting it in good
running-order again. The style of cross-head where the pin is part of
the casting, although greatly used, is a most awkward article to fit
up and keep in shape. The form of cross-head which works between two
guide-bars, and has its axis in line with the piston-rod, is becoming
deservedly popular.
SIDE RODS.
Many attempts have been made to dispense with side rods, and they
certainly are a troublesome part of the machinery to keep right; but
no better means of connecting driving-wheels has yet been devised. The
first method of coupling driving-wheels together, so that more than
one pair might be available for adhesion, was by means of cogs and
gearing. This was improved on by an endless chain working over pocketed
pulleys; but even this was an extremely crude device,--working with
tumultuous jerks, and a noise like a stamping-mill. One of the first
real improvements, which George Stephenson effected on the locomotive,
was the inventing of side rods. An essential element in locomotive
construction needed to make side rods run with safety, is, that all
the wheels connected shall be of the same circumference. There is a
practice on some roads of putting new tires on wheels just as they
come from the rolling-mill, without putting them in the lathe. Such
tires are seldom accurate in size; and they cause no end of trouble,
especially to side rods. This is one of the economical practices that
does not pay.
ADJUSTMENT OF SIDE RODS.
To connect driving-wheels so that they will run together in perfect
harmony, after ascertaining that they are the same size, the next
point is to secure the crank-pins at an equal distance from the
centers of the wheels. When this is done, and the wheels are trammed
parallel to the line of motion, the rods will move on a plane with the
centers of the crank-pins exactly the same distance apart as are the
centers of the driving-axles. The rods can be adjusted to the greatest
advantage with the steam raised, so that the heat of the boiler will
make the frames about the same length as when the engine is at work.
The expansion due to the heat of the boiler is short when measured by
a foot-rule, but it affects the smooth action of the side rods to a
remarkable extent.
Before tramming for the side rods, it is necessary to have the
driving-box wedges set up just tight enough to let the driving-boxes
move vertically in the jaws without sticking. The distance between the
centers of the driving-axles and the centers of the crank-pins having
now been found equal, the rods are fitted up; each connection being
secured a close fit to the pin, with the brasses held brass to brass.
With the brasses bored out exactly to the size of the crank-pins, and
the rods accurately fitted, a connection could be made which would bind
the two sets of drivers to move as an unbroken unit, were it not for
the disturbing element which appears in the shape of rough track. With
uneven track and worn wheel-tires, a tremendous tension is put on the
rods where the connections are closely fitted. Provision is made for
this source of danger by leaving the brasses of the back pins loosely
fitted. A yielding space is left between the brass and the pin, not
between the brass and the key or strap. The latter connections must be
perfectly snug, or the strap will soon be pounded out of shape.
In the case of ten-wheel and consolidation engines, the brasses of all
wheels behind the leading pair should be bored out one-sixty-fourth
larger than the pins, which will generally be sufficient. In case a pin
is sprung,--which is no rare circumstance,--room enough must be left in
the brass to let the pin pass over its tightest point without pinching.
The center is the proper position to put up side rods on. Some men
like to fit side rods with the cranks on the eighths position; holding
that there the greatest strain comes on, and, consequently, that there
fitting up should be done. That is a mistaken idea; for rods may be put
together on the eighths, and yet bind the pins badly in passing the
centers. On the other hand, if they pass the centers easily, they will
go round the remainder of the circle without danger.
KEYING SIDE RODS.
When it is necessary for an engineer to key up side rods, he should
select a place where the track is straight, and as even as possible.
Then he should put the cranks on the center, and take care that he
can move the connections laterally after the job is done. If he now
moves the engine so that the cranks are on the other center, and finds
that the rod connections can still be moved, that side is all right.
If the other side be treated in a similar manner, his rods are not
likely to give trouble. With a worn-out engine and rough road-bed,
it is a difficult matter to preserve the true mean between loose and
tight side-rod connections. But, in a case of doubt, the loose side
is the safe side. Yet most engineers are inclined to err on the side
of danger, for they will generally tighten up the rods to prevent
them from rattling. On a Western road, where solid-ended brasses were
adopted, it was often amusing to hear the engineers protesting against
the noise the side rods made when the brasses began to get worn. They
would rattle from one end of the division to the other; but they would
not break pins, or fracture themselves, and tear the cab to pieces,
or ditch a train, as happens so often from other rods being keyed to
prevent noise. Sprung crank-pins and broken side rods are very often
the result of injudicious keying.
DIFFICULTY IN LOCATING DEFECTS.
A locomotive has so many parts that bear a close relation to each
other, and that are so sympathetic when one of the parts becomes
disordered, that it is sometimes a difficult matter to immediately
locate a complaint. One of the signs of a defect, in many of the parts,
or one of the consequences of it, is a “pound,”--a complaint that we
hear of in a locomotive about as frequently, and with the same feeling,
as we do of malaria in the individual.
POUNDING IN DRIVING-BOXES AND WEDGES.
But we will deal now with the pounds in a locomotive, and will take
the location in which we find the most and serious ones,--namely, in
the driving-boxes and wedges,--and see why they pound, and what will
prevent them from doing so. The cause we will find, if in the wedges,
is due to a rocking of the box in them, or from causes arising from
imperfect fitting when they were put up, or lined up when the engine
was in the shop. This fitting of wedges on a locomotive that has done
service is a matter of importance in the immediate present and future
working of the parts themselves, and of other parts of the locomotive
as well. On stripping a locomotive that has done much service, it will
be found that the working of the wedges on the face of the pedestal
has worn it hollow, or pounded furrows on it, or has done both. This
occurs so frequently on the “live” wedge side, that it may be taken
as the rule, rather than the exception, to find the pedestal in this
condition. While it does not happen so frequently on the “dead” wedge
side as on the other, it will be found there also if the wedge has not
been held by a fastening to the pedestal, or securely fitted between
the top of the frame and the pedestal binder-brace. These defects will
be found on the back of the wedge also, and are produced by the same
cause and same motion as those on the pedestal face. These defects are
the most frequent cause of the driving-box pounding, or of the wedges
rocking; since thereby the wedges get thrown out of parallel to each
other, when it becomes necessary to adjust them during the service of
the locomotive.
In refitting wedges, these defects should be removed, the pedestal face
carefully straightened its entire length, and the wedge-back fitted to
it. It is not only necessary that the pedestal face should be smooth,
but that it should be straight its entire length. If not, when it
becomes necessary to adjust the wedge, if the pedestal is high on the
top end, the wedge is thrown out at the top, binding the box at that
point, and allowing it to swing at the bottom.
IMPORTANCE OF HAVING WEDGES PROPERLY FITTED.
With the pedestal face in a proper condition to avoid displacement of
the wedge, when moved to different positions on it, we should consider
what will be the method of lining the wedges, and what duty they have
to perform. This duty is merely to take up the lost motion between
the pedestal and boxes; and that, from their shape, they readily do
from time to time. While this duty is simple, the wedges ought to do
it without affecting any of the other parts of the locomotive,--a
condition of perfection that can be reached only by having all the
wedges perfectly parallel with the pedestals and with each other. If
the first condition is not complied with, the result, as stated, will
be the box swinging in the wedges. If the latter, then with the varying
position of the boxes in the pedestal due to the engine settling on the
springs, or to the change of position from the motion of the springs
when the locomotive is running, we will have a varying distance between
the centers of the wheels and length for the side rods.
Many of the complaints we hear of rods not working properly, are owing
to this defect in wedges not being parallel, by which the distances are
varied, and a strain thrown upon the rods that not only affects them,
but causes them in turn to bind the boxes against the wedges by trying
to compress or extend to a length varying as often as the motion of the
springs. While the motion of the springs is not much in proportion to
the length of the wedges, and the varying distance between centers of
wheels is in ratio to that proportion, if the wedges are not parallel,
we must remember how often the motion is occurring, and that, no matter
how slight the strain upon the rods may be, we are putting it on a
part of the locomotive that requires the minutest adjustment to enable
it to do its work properly and safely.
INFLUENCE OF HALF-ROUND BRASSES.
Driving-boxes fitted with a half-round brass have a tendency to close
at the bottom. This tendency is continuous, and becomes most marked as
the brass wears down, relieving the box of the strain put upon it by
the tight-fitting brass. With a properly fitted brass, and a collar
put up in good shape, the box can not close much: still, there will
be enough looseness to cause a slight pounding. During the first few
days’ service of a locomotive after new driving-brasses of this shape
are put in, the compression on the brass, resulting from the weight
of the engine, tends to close the bottom of the box, and permits the
box to rock. This evil may be, to some extent, prevented by fitting
the wedges slightly closer at the bottom. This closing of the box at
the bottom is not only an evil and annoyance in itself by causing
pounding, but is a further source of trouble by hastening the forming
of a shoulder on the top of the wedge. The tendency at all times is for
the axle-box to wear a shoulder at the top and bottom of its travel,
even when the box retains its proper shape; but, when it is distorted
by closing at the bottom, the rubbing surfaces are put out of the true
plane, and wear takes place much more rapidly. While the springs retain
their position, and impart to the axle-box a fixed range of motion, no
serious effect is felt from the worn wedges. But when the locomotive is
passing over rough frogs or bad rail-joints, where the motion of the
spring is increased, the frame pounds down upon the box, which for a
moment becomes fastened in the narrow space between the shoulders of
the wedges; and an effort is needed for the box to relieve itself, and
allow the spring to resume its motion. This causes the engine to ride
hard in some instances, where the condition of the track makes the box
catch frequently. Sometimes the box will be unable to relieve itself
without assistance, and much loss of time and annoyance result when the
wedge has to be pulled down to relieve the box.
The forming of the shoulder on top and bottom of the wedge may be
anticipated and prevented by planing the part where the ridges form,
leaving a face just the length of the box plus the space covered by the
motion of the springs. Not only does this aid in preventing the box
from forming a shoulder, but it also reduces the first cost of fitting
the wedges by reducing the surface to be squared and finished true.
POSITION OF BOXES WHILE SETTING UP WEDGES.
With the wedges in a proper condition when the locomotive enters
service, we yet must care for them and adjust them from time to time,
when it is necessary to take up the lost motion between the pedestals
and boxes. When doing this work, it is important that the position and
condition of the driving-box should be considered. The position of the
box should be such that the wedge may be set up to the proper degree
of tightness with certainty and without much labor. It is important
that a wheel position be found where the box would not be moved by the
wedge when the latter is being adjusted. This position will be found
where the box is up against the dead wedge, since the lost motion
will then be between the box and the wedge to be moved. To get all the
driving-boxes in that position at one time is a difficult matter, if it
is to be done by pinching the wheels. The position of the rods decides
the direction of their action on the wheel by the thrust or pull upon
the crank-pin. If the rod is above the wheel center, pinching behind
the back wheel will force both the wheels and boxes on that side up
against the dead wedge; but, should the rod be below the wheel center,
similar work with the pinch-bar will draw the forward box away from the
dead wedge, the side rod doing this by pulling on the crank-pin,--this
is always supposing the dead wedge to be in the front pedestals. The
best position, therefore, to get an engine into for setting up all the
wedges, is, with the side rods on the upper eighths; for then pinching
behind the back wheels will push all the boxes up to the dead wedges.
The work can then be done without putting unnecessary strain upon
the wedge-bolts, which are often found with the corners of the heads
rounded off, and the thread injured to such an extent that it will
not screw through the binder-brace,--a condition of matters nearly
always caused by trying to force up wedges without putting the engine
in the proper position. If the wedge-bolt, from faulty construction,
or through injury, is unable to move up the wedge, driving is resorted
to, by which means it is battered on the end; and the jarring of
each blow causes the ashes and dirt on top to fall behind the wedge,
throwing it out of parallel, and introducing material that will cause
the wedge to cut. The ashes and dirt that accumulate so readily on the
top of wedges and boxes cause no end of trouble, although the fact is
not generally recognized; and it will generally be fruitful labor to
have these parts well cleaned off before beginning to set up wedges.
Many complaints that are made, of wedges not being properly adjusted,
proceed from the disturbance that follows grit introduced between the
wedge and box.
NECESSITY FOR KEEPING BOXES AND WEDGES CLEAN.
The growing practice of close and stated inspection of locomotives to
detect defects, before waiting for them to develop into breakages that
cause trouble and delay to trains, will give especially good results if
applied to boxes and wedges. If the wedges are taken down and examined
at regular intervals, the ridges that appear so readily on the face,
when oil-grooves are cut on the sides of the driving-box, can be
smoothed off before they cause distortion of the surface. This is also
a good time for a thorough cleaning of the pedestals and box, and the
oil-holes can be examined and opened out properly. Work of this kind
often prevents boxes getting hot on the road, with all the entailed
delay and expense, which frequently include changing engines if the
train must be pushed on. One turn of a hot box will often wear a brass
more than the daily running for two years.
TEMPERATURE OF THE BOX TO BE CONSIDERED.
One condition of the box to be considered, when adjusting wedges,
is its temperature at the time the work is done, and what that will
be when the engine is in service. Adjusting wedges is often done as
a preliminary step to lining and adjusting side rods; and this is
done, on many roads, on the shop-day when the locomotive is in for
washing out and periodical repairs. At that time, the engine being
cold, the boxes will be at their lowest temperature, and, consequently,
at their smallest dimensions. Allowance should then be made with the
wedges for some expansion of the boxes. Another condition that should
be considered, is how the box has been running. A box that has been
running hot or warm, generally compels the wedge to be lowered to allow
for extra expansion. When this box has been repacked, or otherwise
cared for, the wedge is again set up. While doing this, it should
be remembered that a box that has been running hot is liable to be
distorted, and its journal bearing injured, so that it is likely to run
warm for some time, till the brass comes to a smooth bearing. If the
wedge will not permit the box to expand, it binds the journal, and is
likely to run still hotter, and is liable to stick in the jaws.
SMALL DISORDERS THAT CAUSE ROUGH RIDING.
Many complaints are made about pounds in driving-boxes and wedges, when
the trouble really exists elsewhere. Boxes with driving-spring saddles
whose foot is but the width of the top or spring-band, will oft-times,
if the band is not rounded where it rides on the saddle, or is not
fitted with a pin or other center bearing, tip on the box with each
motion of the spring. Or, if the saddle is moved from its worn seat
on the top of the box, it will rock and pound. Again, obstructions in
the bearing of the spring equalizer that will prevent the full motion
of the springs, and bring them to a sudden stop, will produce a motion
resembling that caused by a stuck box. Attention to details that are
sometimes considered the crude parts of a locomotive, will often prove
highly beneficial to the working of the locomotive; and especially is
this the case with the parts that transmit the motion of the springs.
CHAPTER XVII.
_THE VALVE-MOTION._
THE LOCOMOTIVE SLIDE-VALVE.
The nature of the service required of locomotive engines, especially
those employed on fast-train service, makes it necessary that the
steam-distribution gear shall be free from complication; and, for
convenience in working the engine, it is essential that means should
be provided for reversing the motion promptly, without endangering the
working-parts. The valve-gear should also be capable of regulating
the admission and exhaust of steam, so that the engine shall be
able to maintain a high rate of speed, or to exert a great tractive
force. These features are admirably combined in the valve-gear of the
ordinary locomotive. Designers of this form of engine have given great
consideration to the merit of simplicity. Numerous attempts have been
made to displace the common D slide-valve, but every move in that
direction has ended in failure.
INVENTION AND APPLICATION OF THE SLIDE-VALVE.
The slide-valve, in a crude form, was invented by Matthew Murray
of Leeds, England, towards the end of last century; and it was
subsequently improved by Watt to the D form. It received but little
application in England till the locomotive era. Oliver Evans of
Philadelphia appears to have perceived the advantages possessed by
the slide-valve, for he used it on engines he designed years before
locomotives came into service. The D slide-valve was better adapted for
high-speed engines than any thing tried during our early engineering
days, but it was on locomotives where it first properly demonstrated
its real value. The period of necessity brought the slide-valve into
prominence; and the galaxy of mechanical genius that heralded the
locomotive into successful operation recognized its most valuable
features, and it soon obtained exclusive possession of that form of
engine. Through good and evil report, and against many attempts to
displace it, the slide-valve has retained a monopoly of high-speed
reversible engines.
DESCRIPTION OF THE SLIDE-VALVE.
The slide-valve in common use is practically an oblong cast-iron box,
which rests and moves on the valve-seat. In the valve-seat, separated
by partitions called bridges, are three ports, those at the ends
being the openings of the passages for conveying steam to and from
the cylinders, while the middle port is in communication with the
blast-pipe, which conveys the exhausted steam to the atmosphere. On
the under side of the valve is a semicircular cavity, which spans the
exhaust-port and the bridges when the valve stands in its central
position. When the steam within the cylinder has performed its duty
of pushing the piston towards the end of the stroke, the valve cavity
moves over the steam-port, and allows the steam to pass into the
exhaust-port, thence into the exhaust-pipe. The cavity under the valve
thus acts as a door for the escape of the exhaust steam. This is a very
convenient and simple method of educting the steam; and the process
helps to balance the valve, since the rush of escaping steam striking
the under part of the valve tends to counteract the pressure that the
steam in the steam-chest continually exerts on the top of the valve.
PRIMITIVE SLIDE-VALVE.
[Illustration: FIG. 6.]
In its primitive form, the slide-valve was made merely long enough
to cover the steam-ports when placed in the central position, as
shown in Fig. 6. With a valve of this form, the slightest movement
had the effect of opening one end so that steam would be admitted
to the cylinder, while the other end opened the exhaust. By such an
arrangement, steam was necessarily admitted to the cylinder during the
whole length of the stroke; since closing at one end meant opening at
the other. There were several serious objections to this system. It was
very difficult to give the engine cushion enough to help the cranks
over the centers without pounding, and a small degree of lost motion
was sufficient to make the steam obstruct the piston during a portion
of the stroke. But the most serious drawback to the short valve was,
that it permitted no advantage to be taken of the expansive power of
steam. For several years after the advent of the locomotive, the boiler
pressure used seldom exceeded fifty pounds to the square inch. With
this tension of steam, there was little work to be got from expansion
with the conditions under which locomotives were worked; but, so soon
as higher pressures began to be introduced, the loss of heat entailed
by permitting the full-pressure steam to follow the piston to the end
of the stroke became too great to continue without an attempted remedy.
A very simple change served to remedy this defect, and to render the
slide-valve worthy of a prominent place among mechanical appliances for
saving power.
OUTSIDE LAP.
The change referred to, which so greatly enhanced the efficiency of
the slide-valve, consisted in lengthening the valve-face, so that,
when the valve stood in the center of the seat, the edges of the valve
extended a certain distance over the induction ports, as in Fig. 7.
This extension of the valve is called outside lap, or simply lap. The
effect of lap is to close the steam-port before the piston reaches the
end of the stroke, and the point at which the steam-port is closed is
known as the point of cut-off. When the steam is cut off, and confined
within the cylinder, it pushes the piston along by its expansive
energy, doing work with heat that would be lost were the cylinder left
in communication with the steam-chest till the end of the stroke.
[Illustration: FIG. 7.]
When a slide-valve is actuated by an eccentric connected directly
with the rocker-arm or valve-stem, the point of cut-off caused by the
extent of lap, remains the same till a change is made on the valve,
or on the throw of the eccentric, unless an independent cut-off valve
be employed. Locomotives having the old hook motion worked under this
disadvantage; because the hook could not vary the travel of the valve,
which is the method usually resorted to for producing a variable
cut-off. The link and other simple expansion gears perform their office
of varying the cut-off in this way.
SOME EFFECTS OF LAP.
In addition to cutting off admission of steam before the end of the
stroke, lap requires the valve to be set in such a way that it has also
the effect of leading to the exhaust-port being opened before the end
of the stroke. The point where the exhaust is opened is usually known
as the point of release. The change which causes release to happen
before the piston completes its stroke, leads to the closure of the
exhaust-port before the end of the return stroke is reached, which
imprisons the steam remaining in the cylinder, causing compression.
Where a valve has no inside lap, release and compression happen
simultaneously; that is, the port at one end of the cylinder is opened
to release the steam, and that at the other end is closed, letting the
piston compress any steam remaining in the cylinder into the space left
as piston clearance.
INSIDE LAP.
In some cases the inside edges of the valve cavity do not reach the
edges of the steam-ports when the valve is on the middle of the seat,
but lap over on the bridge a certain distance, as shown by the dotted
lines in Fig. 7. This is called inside lap, and its effect upon the
distribution of steam is to delay the release. By this means it
prolongs the period of expansion, and hastens compression on the return
stroke. Inside lap is an advantage only with slow-working engines. When
high speed is attempted with engines having much inside lap, the steam
does not have enough time to escape from the cylinders, and the back
pressure and compression become so great as to be very detrimental to
the working of the engine. As locomotive engineers have it, the engine
is “logy.”
THE EXTENT OF LAP USUALLY ADOPTED.
In locomotive practice, the extent of lap varies according to the
character of service the engine is intended to perform. With American
standard gauge engines, the lap varies from ½ inch to 1¼ inch. For
high-speed engines, the extent of lap ranges from ⅞ to 1¼. Freight
engines commonly get ⅝ to ¾ outside lap, and from 1/16 to ¼ inside lap.
With a given travel, the greater the lap the longer will the period for
expansion be.
FIRST APPLICATION OF LAP.
Lap was applied to the slide-valve in this country before its advantage
as an element of economy was understood in Europe. As early as 1829,
James of New York used lap on the valves of an engine used to run a
steam-carriage; and in 1832 Mr. Charles W. Copeland put a lap-valve on
a steamboat engine, and his father understood that its advantage was in
providing for expansion of the steam. Within a decade after our first
steam-operated railroad was opened, the lap-valve became a recognized
feature of the American locomotive; but the cause of the saving of
fuel, effected by its use, was not well comprehended. Many enlightened
engineers attributed the saving to the early opening of the exhaust,
brought about where outside lap was used, which they theorized reduced
back pressure on the piston; and in that way they accounted for the
enhanced economy resulting from the application of lap. It was not till
Colburn applied the indicator to the locomotive, that the true cause of
economy was demonstrated to be in the additional work taken from the
steam by using it expansively.
THE ALLEN VALVE.
[Illustration: FIG. 8.]
An improvement on the plain _D_ slide-valve has been effected in a
simple and ingenious manner in the Allen valve, which is receiving
considerable favor for high-speed locomotives. This valve is shown in
Fig. 8. The valve has a supplementary steam-passage, _A_, _A_, cast
above the exhaust cavity. The valve and seat are so arranged, that, so
soon as the outside edge of the valve begins to uncover the steam-port
at _B_, the supplementary passage begins receiving steam at _C_; and
this gives a double opening for the admission of steam to the port when
the travel is short. As the travel of the valve is always short when an
engine is running at high speed, the advantage of this double opening
is very great; for it has the effect of admitting the steam promptly
at the beginning of the stroke, and maintaining a full pressure on the
piston till the point of cut-off.
ADVANTAGES OF THE ALLEN VALVE.
With an ordinary valve cutting off at six inches, and having five
inches eccentric throw, the port opening seldom exceeds ⅜ inch. It
is a hard matter getting the full pressure of steam through such a
small opening in the instant given for admission. If an Allen valve
is used with that motion, the opening will be double, making ¾ inch,
which makes an important difference. The practical effect of a change
of this kind is that an engine will take a train along, cutting off
at six inches with the Allen valve, when, with the ordinary valve,
the links would have to be dropped to eight or nine inches. The valve
can be designed to work on any valve-seat, but the dimensions given
in Fig. 8 are those that have been found most satisfactory with our
large passenger engines. In designing an Allen valve for an old seat,
it is sometimes advisable to widen the steam-ports a quarter of an
inch or more, by chamfering off the outside edges that amount. Care
must be taken to prevent the valve from traveling so far as to put the
supplementary port over the exhaust-port, for that would allow live
steam to pass through. The proper dimensions can best be schemed out on
paper before making the required change on the seat.
In very carefully conducted experiments made on the Boston and Albany
Railroad, to compare the performance of the Allen valve with an engine
equipped with a common valve, it was found that the Allen valve
effected a fuel saving of seven per cent.
CASE WHERE THE ALLEN VALVE PROVED ITS VALUE.
On one of the leading railroads in this country, an engineer was
running a locomotive on a fast train where it was a hard matter making
the card-time. A few minutes could be saved by passing a water-station;
but this was done at serious risk, for the tender would nearly always
be empty by the time the next water-station was reached. The master
mechanic of the road determined to equip this engine with the Allen
valve: and, after the change was made, there was no risk in passing
the water-station; for there always was a good margin of water in the
tank when the next watering-place was reached. The engine seemed to
steam better, because the work was done with less steam; and there
was a decided saving of fuel. The change made the engine smarter, and
there seems to be no limit to the speed it can make. This valve can
be applied to any locomotive with trifling expense. When an engine is
designed specially for the Allen valve, the steam ports and bridges are
usually made a little wider than for the ordinary valve. The only real
difficulty in adopting the valve is getting the casting properly made,
so that the supplementary port will not be too rough for the passage of
steam, and the thin shell will be strong enough to stand the pressure.
INSIDE CLEARANCE.
For high-speed locomotives, where there is great necessity for getting
rid of the exhaust steam quickly, the valves are sometimes cut away
at the edges of the cavity, so that, when the valve is placed in the
middle of the seat, it does not entirely cover the inside of either of
the steam-ports. This is called inside clearance. In many instances
inside clearance has been adopted in an effort to rectify mistakes made
in designing the valve-motion, principally to overcome defects caused
by deficiency of valve-travel. The fastest locomotives throughout the
country do not require inside clearance, because their valve-motion
is so designed that it is not necessary. Inside clearance induces
premature release, and diminishes the period of expansion. Consequently
inside clearance wastes steam, and ought to be avoided.
LEAD.
There are certain advantages gained in the working of a locomotive,
by having the valves set so that the steam-port will be open a small
distance for admission of steam, when the piston is at the beginning of
the stroke. This opening is called lead. On the steam side of the valve
the opening is called steam-lead: on the exhaust side it is called
exhaust-lead. Lead is generally produced by advancing the eccentric on
the shaft, its effect being to accelerate every event of the valve’s
movement; viz., admission, cut-off, release, and compression. In
the most perfectly constructed engines, there soon comes to be lost
motion in the rod connections and in the boxes. The effect of this
lost motion is to delay the movement of the valves; and, unless they
are set with a lead opening, the stroke of the piston would in some
instances be commenced before steam got into the cylinder. It is also
found in practice, that this lost motion would cause a pounding at
each change in the direction of the piston’s travel, unless there is
the necessary cushion to bring the cranks smoothly over the centers.
Without cushion, the change of direction of the piston’s travel is
effected by a series of jerks that are hard on the working-parts. So
long as the lead opening at the beginning of the stroke is not advanced
enough to produce injurious counter pressure upon the piston, it
improves the working of the engine by causing a prompt opening for
steam admission at the beginning of the stroke. This is the time that
a full steam-pressure is wanted in the cylinder, if economical working
be a consideration. A judiciously arranged lead opening is therefore an
advantage; since it increases the port opening at the proper time for
admitting steam, tending to give nearly boiler pressure in the cylinder
at the beginning of the stroke. With the shifting link-motion, the
amount of lead opening increases as the links are hooked back towards
the center notch; the magnitude of the increase, in most cases, being
in direct proportion to the shortness of the eccentric-rods. A common
lead opening in full gear with the shifting link is 1/16 inch, which
often increases to ⅜ inch in the center notch. The tendency of wear
and lost motion is to neutralize the lead, so that, when a locomotive
motion gets worn, increasing the lead will generally improve the
working of the engine.
OPERATION OF THE STEAM IN THE CYLINDERS.
As the work performed by a steam-engine is in direct proportion to
the pressure exerted by the steam on the side of the piston which is
pulling or pushing on the crank-pin, it is important that the steam
should press only on one side of the piston at once. Hence, good
engines have the valves operated so that, by the time a stroke is
completed, the steam, which was pushing the piston, shall escape, and
not obstruct the piston during the return stroke, and so neutralize the
steam pressing upon the other side. When an engine is working properly,
the steam is admitted alternately to each side of the piston; and its
work is done against a pressure on the other side not much higher than
that of the atmosphere.
BACK PRESSURE IN THE CYLINDERS.
When, from any cause, the steam is not permitted to escape promptly and
freely from the cylinder at the end of the piston stroke, a pressure
higher than that of the atmosphere remains in the cylinder, obstructing
the piston during the return stroke, and causing what is known as back
pressure. There is seldom trouble for want of sufficient opening to
admit steam to the cylinders, for the pressure is so great that the
steam rushes in through a very limited space; but, when the steam has
expanded two or three times, its pressure is comparatively weak, and
needs a wide opening to get out in the short time allowed. This is one
reason why the exhaust-port is made larger than the admission-ports.
Nearly all engines with short ports suffer more or less from back
pressure, but the most fruitful cause of loss of power through this
source is the use of extremely contracted exhaust nozzles. Were it
not for the necessity of making a strong artificial draught in the
smoke-stack, so that an intense heat shall be created in the fire-box,
quite a saving of power, now lost by back pressure, would be effected
by having the exhaust opening as large as the exhaust-pipe. This not
being practicable with locomotives, engineers should endeavor to have
their nozzles as large as possible consistent with steam-making.
Engines with very limited eccentric throw will often cause back
pressure when hooked up, through the valve not opening the port wide
enough for free exhaust.
Locomotives suffering from excessive back pressure are nearly always
logy. The engine can not be urged into more than moderate speed under
any circumstances; and all work is done at the expense of lavish
waste of fuel, for a serious percentage of the steam-pressure on the
right side of the piston is lost by pressure on the wrong side. It is
like the useless labor a man has to do turning a grindstone with one
crank, while a boy is holding back on the other side. The weight of
obstruction done by the boy must be subtracted from the power exerted
by the man to find the net useful energy exerted in turning the
grindstone. In the same way, every pound of back pressure on a piston
takes away a pound of useful work done by the steam on the other side.
EFFECT OF TOO MUCH INSIDE LAP.
Engines that have much inside lap to the valves are likely to suffer
from back pressure when high speed is attempted. The inside lap delays
the release of the steam; and, where the piston’s velocity is high
the steam does not escape from the cylinder in time to prevent back
pressure.
RUNNING INTO A HILL.
Most of engineers are familiar with the tendency of some engines to
“run into a hill.” That is, so soon as a hill is struck, they suddenly
slow down till a certain speed is reached, when they will keep going.
This is generally produced by back pressure, its obstructing effect
being reduced when the engine is moving slow.
COMPRESSION.
The necessity which requires lap to be put on a slide-valve to produce
an early cut-off, in its turn causes compression, by the valve passing
over the steam-port, and closing it entirely for a limited period
towards the end of the return stroke. As the cylinder contains some
steam which did not pass out while the exhaust-port was open, this
is now squeezed into a diminishing space by the advancing piston. In
cases where too much steam was left in the cylinders through contracted
nozzles or other causes, or where, through mistaken designing of the
valve-motion, the port is closed during a protracted period, the
steam in the cylinder gets compressed above boiler tension, and loss
of useful effect is the result. Under proper limits, the closing of
the port before the end of the stroke, and the consequent compression
of the steam remaining in the cylinder, have a useful effect on the
working of the engine by providing an elastic cushion, which absorbs
the momentum of the piston and its connections, leading the crank
smoothly over the center. Where it can be so arranged, the amount of
compression desirable for any engine is the degree that, along with
the lead, will raise the pressure of the cylinder up to that of the
boiler at the beginning of the stroke. When this can be regulated, the
compression performs desirable service by cushioning the working-parts,
thereby preventing pounding, and by filling up the clearance space and
steam passages, by that means saving live steam. Compression probably
does some economical service by reheating the cylinder, which has
a tendency to get cooled down during the period of release, and by
re-evaporating the water, which forms by condensation of steam in the
cool cylinder.
Engines that are running fast require more cushioning than those that
run slow, or at moderate speeds. The link-motion, by its peculiarity
of hastening compression when the links are hooked up, tends to make
compression a useful service in fast running.
DEFINITION OF AN ECCENTRIC.
The reciprocating motion which causes the valves to open and close
the steam-ports at the proper periods, is, with most locomotives,
imparted from eccentrics fastened upon the driving-axle. An eccentric
is a circular plate, or disk, which is secured to the axle in such a
position that it will turn round on an axis which is not in the center
of the disk. The distance from the center of the disk to the point
round which it revolves is called its eccentricity, and is half the
throw of the eccentric. Thus, if the throw of an eccentric requires
to be 5 inches, the distance between the center of the driving-axle
and the center of the eccentric will be 2½ inches. The movement of an
eccentric is the same as that of a crank of the same stroke, and the
eccentric is preferred merely because it is more convenient for the
purposes to which it is applied than a crank would be.
EARLY APPLICATION OF THE ECCENTRIC.
On the early forms of locomotives, a single eccentric was used to
operate the valve for forward and back motion. The eccentric was
made with a half circular slot, on which it could be turned to the
position needed for forward or back motion. It was held in the required
position by a stop-stud fastened on the axle. Several forms of movable
eccentrics were invented, and received considerable application during
the first decade of railroad operating; but the best of them provided
an extremely defective reversing motion. The first engineer to apply
two fixed eccentrics as a reversible gear was William T. James of New
York, who made a steam carriage in 1829, and worked the engine with
four eccentrics,--two for each side. The eccentrics were connected
with a link, but the merits of that form of connection were not then
recognized here; for it was not applied to locomotives till it became
popular in England, and was re-introduced to this country by Rogers.
The advantage of the double fixed eccentrics seemed, however, to be
recognized from the time James used them; for the plan was adopted by
our first locomotive builders. The first locomotive built by Long, who
started in 1833 what was afterwards known as the Norris Locomotive
Works, Philadelphia, had four fixed eccentrics.
RELATIVE MOTION OF PISTON AND CRANK, SLIDE-VALVE, AND ECCENTRICS.
[Illustration: FIG. 9.]
When a locomotive is running, the wheels turn with something near a
uniform speed; but any part which receives a reciprocating motion
from a crank or eccentric travels at an irregular velocity. Fig. 9
shows the relative motion of the crank-pin and piston during a half
revolution. The points in the path of the crank-pin marked _A_, 1, 2,
_B_, 3, 4, _C_, are at equal distances apart. The vertical lines run
from them to the points _a_, _b_, _c_, _d_, _e_, represent the position
of the piston in relation to the position of the crank-pin. That is,
while the crank-pin traverses the half-circle, _A B C_, to make a half
revolution, the piston, guided by the cross-head, travels a distance
within the cylinder equal to the straight line _A C_. The crank-pin
travels at nearly uniform speed during the whole of its revolution, but
the piston travels with an irregular motion. Thus, while the crank-pin
travels from _A_ to 1, the piston travels a distance equal to the space
between _A_ and _a_. By the space between the lines, it will be seen
that the piston travels slowly at the beginning of the stroke, gets
faster as it moves along, reaches its highest velocity about half
stroke, then slows down towards the end till it stops, and is ready for
the return stroke.
ATTEMPTS TO ABOLISH THE CRANK.
Certain mechanics and inventors have been terribly harassed over this
irregular motion of the piston, and numerous devices have been produced
for the purpose of securing a uniform motion to the power transmitted.
These inventions have usually taken the shape of rotary engines.
Probably the fault these people find with the reciprocating engine is
one of its greatest merits, for the piston stopping at the end of each
stroke permits an element of time for the steam to get in and out of
the cylinder.
VALVE MOVEMENT.
The valve travels in a manner similar to the piston; although its
stroke is much shorter, and its slow movement is towards the limit
of travel. The small circle in the figure shows the orbit of the
eccentric’s center, and the valve-travel is equal to the rectilinear
line across the circle. If the valve opened the steam-ports at the
outside of its travel, the slow movement at that point would be an
objection, since the operation of opening would be slow: but the valve
opens the ports towards the middle of its travel, when its velocity is
greatest; and, the nearer to the mid travel the act of opening is done,
the more promptly it will be performed. This has a good deal to do with
making an engine “smart” in getting away from a station.
EFFECT OF LAP ON THE ECCENTRIC’S POSITION.
[Illustration: FIG. 10.]
With the short valve without lap used on the earliest forms of
locomotives, the eccentric was set at right angles to the crank or
“square” on the dotted line _e_, Fig. 10. The least movement of the
eccentric from its middle position had the effect of opening the
steam-ports. One advantage about an eccentric set in this position,
was that it opened and closed the ports when moving the valve at its
greatest velocity. Lengthening the valve-face by providing lap entails
a change in the location of the eccentric; for, were it left in the
right-angle position, the steam-port would remain covered till the
eccentric had moved the valve a distance equal to the extent of the lap
on one end, and the piston would begin its stroke without steam.
ANGULAR ADVANCE OF ECCENTRICS.
The change made on the eccentric location is to advance it from _e_
to _F_, being a horizontal distance equal to the extent of lap and
lead, and known as the angular advance of the eccentric. The centers
_F_ and _B_ represent the full part, or “belly,” of the forward and
back eccentrics in the position they should occupy, where a rocker is
employed, when the piston is at the beginning of the backward stroke.
It will be perceived that the eccentrics both incline towards the
crank-pin, and the eccentric which is controlling the valve follows the
crank-pin. Thus, when the engine is running forward, _F_ follows the
crank: when she is backing, _B_ follows.
It is a good plan for an engineer to make himself familiar with the
proper position of the eccentrics in relation to the crank, for the
knowledge is likely to save time and trouble when any thing goes
wrong with the valve-motion. With this knowledge properly digested, a
minute’s inspection is always sufficient to decide whether or not any
thing is wrong with the eccentrics.
ANGULARITY OF CONNECTING ROD.
In following out the relative motion of the piston and crank, we
discover a disturbing factor in what is called the angularity of the
connecting rod, which has a curiously distorting effect on the harmony
of the motion. When the piston stands exactly in the mid-travel point,
the true length of the main rod will be measured from the center of the
wrist-pin to the center of the driving-axle. If a tram of this length
be extended between these points, this will be found correct, as every
machinist accustomed to working on rods knows. Now, if the back end
of the tram should be raised or lowered towards the points where the
center of the crank-pin must be when the crank stands on the top or
bottom quarter, it will be found that the tram point will not reach the
crank-pin center, but will fall short a distance in proportion to the
length of the main rod. The dotted lines _a′_ and _b′_ in Fig. 11 show
how far a rod 7½ times the length of the crank falls short. A shorter
rod will magnify this obliquity, while a longer rod will reduce it.
[Illustration: FIG. 11.]
EFFECT ON THE VALVE-MOTION OF CONNECTING-ROD ANGULARITY.
As the opening and closing of the steam-ports by the valves are
regulated by the eccentrics, which are subject to the same motion as
the crank, following it at an unvarying distance, it is evident that
their tendency will be to admit and cut off steam at a certain position
of the crank’s movement. If the motion is planned to cut off at half
stroke, it will be apparent, that, in the backward stroke, the piston
will be past its mid travel before the crank-pin reaches the quarter,
so that end of the cylinder will receive steam during more than half
the stroke. On the forward stroke of the piston, however, the crank-pin
will reach the quarter before the piston has attained half travel;
the consequence being, that in this case steam is cut off too early.
The disturbing effect of the angularity of the connecting rod on the
steam distribution thus tends to make the cut-off later in the backward
stroke than in the forward stroke, resulting in giving the forward end
of the cylinder more steam than what is admitted in the back end. The
link-motion provides a convenient means of correcting the inequality
of valve opening due to the connecting-rod angularity, the details of
which will be explained farther on.
AIDS TO THE STUDY OF VALVE-MOTION.
An engineer or machinist who wishes to study out this peculiarity of
connecting-rod angularity, will find that the use of a tram or long
dividers will help him to comprehend it better than any letter-type
description. All through the study of the valve-motion, there are
numerous difficult problems encountered. The use of a good model will
be found an invaluable aid to the study of the valve-motion, and every
division of engineers or firemen should make a combined effort to
furnish their meeting-room with a model of a locomotive valve-motion.
In no way can the spare time of the men connected with locomotive
running be better employed than in the wide range for study presented
by a well-devised model. Great aid can be obtained in the study of
the valve-motion from good books devoted to the subject, and they
will impart more information than can be obtained by mere contact
with the locomotive. The valve and its movements are surrounded with
so many complicated influences, that an intelligent man may work for
years about a locomotive doing valve setting occasionally, and other
gang boss work, yet, unless he studies the valve-motion by the aid of
the drawing-board, or by models, which admit of changing sizes and
dimensions, he may know less about the cause of certain movements than
the bright lad who has been a couple of years in the drawing-office.
The man who thinks he can study the valve-motion, and understand
its philosophy, by merely running the engine, deceives himself. The
engineer who never looks at a book or a paper in search of information
about his engine, knows very little about any thing not visible to the
eye. Yet many men of this stamp, by looking wise, and by exercising
a judicious use of silence, pass among their fellows as remarkably
profound. But let a fireman, in quest of locomotive knowledge, put a
question to such a man, and he is immediately silenced with a “You
ought to know better” answer.
Where the use of a model can not be obtained, any one beginning
the study of the valve-motion can assist himself by making a cross
section of the valve and its seat, similar to those published, on a
strip of thin wood or thick paper. By slipping the valve on the seat,
its position at different parts of the stroke can be comprehended
more clearly than by a mere description. With a pair of dividers to
represent the motion of the eccentric, and strips of wood to act as
eccentric, and valve rod and rocker, and some tacks to fasten them
together, a helpful model can be improvised on a table or board. By the
time a student gets a rig of this kind going, he will see his way to
contrive other methods of self-help.
EVENTS OF THE PISTON STROKE.
By the aid of Fig. 10, we will trace the relative movements of the
crank and eccentric connections. For the sake of simplicity, the
eccentric is represented as connecting directly with the rocker-arm.
The crank-pin being at the point _A_, or the forward center, the piston
must be in the front of the cylinder, or at the beginning of the
backward stroke. Owing to the angular advance already referred to, the
eccentric center is at _F_; and, being a certain distance ahead of the
middle position, it has pushed the lower arm of the rocker from _a_ to
_b_, drawing back the top arm, which, in its turn, has moved the valve
so that it is just beginning to admit steam at the forward port, _i_.
As the crank-pin goes round, the eccentric follows it, opening the
steam-port wider till the eccentric reaches the point of its travel
nearest _A_, the limit of the throw. When the eccentric is at this
point of its throw, the valve must be at the outside of its travel;
and therefore the steam-port is wide open. By this time the crank-pin
is getting close up towards the quarter. After passing this point,
the forward eccentric begins to draw the bottom rocker-pin towards
the axle, and to push the valve ahead, this being the point where the
valve changes its direction of motion, just as the piston returns
when the crank-pin passes the center. When _F_ reaches the point _B_,
the valve is in the same position it occupied at the beginning of the
stroke; but, as it is traveling in the opposite direction, a very small
movement more closes the port, cutting off steam. When this happens,
the crank-pin has reached the point _x_. When _F_ gets to _g_, it is
on the central point of its throw; so the valve must then be on the
middle point of its travel, with the exhaust cavity just covering the
outside edges of the bridges, the forward edge being ready to put
the steam-port, _i_, in communication with the exhaust cavity. This
releases the steam from the forward end of the cylinder; and at the
same moment the inside edge of the valve covers the back port, _k_,
causing the piston-head to compress any steam left in the back part
of the cylinder. When the piston reaches the beginning of the forward
stroke, the eccentric _F_ has got to the point _f_, and the valve is
beginning to admit steam for the return stroke, the events of which are
similar to those described.
In actual practice, the steam distribution is a little different from
the manner that has been followed; for the link-motion provides the
means of equalizing the cut-off, making it uniform for both strokes.
This changes the events of the stroke a little; but the student who
engraves in his mind the movements as they are represented in the
diagram, will not be far astray.
WHAT HAPPENS INSIDE THE CYLINDERS WHEN AN ENGINE IS REVERSED.
Many men who have a fair understanding of the action of steam in
an engine’s cylinders during ordinary working, have no idea of the
operations performed in the cylinders when a locomotive is running
in reverse motion. All men who have had any thing to do with train
service, know, that, when an engine is reversed, the action works to
stop the train, even if the locomotive should have no steam on the
boiler; but just in what way this result comes round they can not
clearly perceive. In hopes of throwing light upon this subject for
those who have not studied it out, we will follow the events of a
stroke in reversed motion, as we did in the ordinary working.
EVENTS OF THE STROKE IN REVERSED MOTION.
Supposing an engine to be running ahead, and the necessity arises
for stopping suddenly, and the reverse-lever is pulled into the back
notch. When the crank-pin is on the forward center, and therefore
the piston at the forward end of the cylinder, about to begin its
backward stroke, the valve has the forward port open a distance equal
to the amount of lead, as in Fig. 10. But, as the back-up eccentric
has control of the valve, the latter is being pushed forward; and it
closes the forward port just as the piston begins to move back. This
shuts off all communication with the forward end of the cylinder; and
the receding piston creates a vacuum behind it, just as a pump-plunger
does under similar circumstances. At this time the back end of the
cylinder is open to the exhaust, and the piston pushes out the air
freely to the atmosphere. By the time the piston travels about two
inches, the valve gets to its middle position; and, immediately after
passing that point, it opens the forward end of the cylinder to the
exhaust, and closes the back port. When this event happens, the vacuum
in the forward end of the cylinder gets filled with hot gases, that
rush in from the smoke-box; and the receding piston keeps drawing air
into the cylinder in this way during the remainder of the stroke, and
air from that quarter seldom gets in without bringing a sprinkling of
cinders. The back steam-port is closed only during about two inches of
the stroke, while the lap of the valve is traveling over it. About the
time the piston reaches four inches of its travel, the back steam-port
is open to the steam-chest, and the piston forces the air through the
steam-pipes into the boiler during the remainder of the stroke. The
forward stroke is merely a repetition of the backward stroke described.
When it is necessary to reverse a locomotive, it is a better plan to
hook the lever clear back than to have it a notch or two past the
center, as some men persist in doing, under the mistaken belief that
they are in some way saving their engine from harsh usage. When the
link is reversed full, the cylinders are merely turned into air-pumps.
When the links are put near the center, the travel of the valve is
reduced; and the periods when the piston is creating a vacuum in
one end of the cylinder, and compressing the air in the other, are
prolonged. The result is, that, when the exhaust is opened in the
first case, the gases rush in violently from the smoke-box, carrying
a heavy load of cinders: in the other case, the piston compresses the
air in the cylinder so high that it jerks the valve away from its seat
in trying to find outlet. This causes the clattering noise in the
steam-chest, so well known in cases where engines are run without steam
while the reverse-lever is near the center.
A locomotive with the piston-packing in bad order will not hold well
running in reverse-motion. Some kinds of piston-packing do not seem
to act properly when the engine is reversed, especially at low speed.
Where a valve has much inside lap, there will be a vacuum in one end of
the cylinder, and compressed air in the other end. With piston packing
that requires pressure to expand it, the void at one end of the
cylinder may neutralize the pressure at the other by drawing the air
through the piston. This would be most liable to happen where the lever
was kept near the center.
PURPOSE OF RELIEF-VALVE ON DRY PIPE.
Should the throttle-valve close so tight that the compressed air from
the cylinders can not pass into the boiler, there is danger of bursting
the steam-chest or some part of the steam-pipes. The compressed air
will lift most of the throttle-valves far enough to prevent any great
danger from this source. In some engines a relief-valve is secured
in the dry pipe, which provides a passage for this compressed air.
When the cylinder-cocks of an engine are opened when the motion is
reversed, they form an outlet to the compressed air, and also admit
air to the sucking end without letting the piston draw air so freely
through the nozzles. Many cylinder-cocks are now made so that they
will open automatically to permit the piston to draw air through them.
The reversed engine will stop nearly as well with the cylinder-cocks
opened as when they are closed, and it is much more easily handled with
the cocks opened. Where the cocks are kept closed, the rush of hot
air from the smoke-box laps every trace of oil from the valve-seat,
and a heavy pressure--frequently above that of the boiler--is present
in the steam-chest. When the engine stops under these circumstances,
its tendency is to fly back; and an engineer has some difficulty in
controlling it with the reverse-lever till a few turns empty the chest
and pipes.
USING REVERSE-MOTION AS A BRAKE.
Numerous attempts have been made to utilize the reversed engine as a
brake for stopping the train, and even by this means to save some of
the power lost in stopping. Chatelier, a French engineer, experimented
for many years on this mechanical problem. He injected a jet of
water into the exhaust-pipe, which supplied low-tension steam to the
cylinder, instead of hot gas or air coming through the smoke-box. This
was pumped back into the boiler on the return stroke. Thus the act of
stopping a train was used to compress a quantity of steam, converting
the work of stopping into heat, which was forced into the boiler and
retained to aid in getting the train into speed again. Modifications of
this idea produce the car-starters that pass so frequently through our
Patent Office.
As a means of conserving mechanical energy, the Chatelier brake was not
a success; but, in the absence of better power brakes, it met with some
applications in Europe. Some of our mountain railroads use it, under
the name of the water-brake, as an auxiliary to the automatic brake.
CHAPTER XVIII.
_THE SHIFTING LINK._
EARLY REVERSING MOTIONS.
In the engineering practice of the world, before the locomotive
and marine engines came into use, there was no need for devices to
make engines rotate in more than one direction. When the need for a
reversible engine first arose, it was met by very crude appliances.
Locomotives were kept at work, earning money for their owners, which
were reversed by the man in charge stopping the engine, and by means
of a wrench changing the position of the eccentric by hand. A decided
improvement on the wrench was the movable eccentric, which was held in
forward or back gear by stops; the operation of reversing being done by
a treadle or other attachment located near the engineer’s position. A
serious objection to this form of reversing gear was, that the abrasion
of work enlarged the slot ends, and wore out the stops, leading to
inaccuracy and frequent breakage. A somewhat better form of reversing
motion was a fixed eccentric, with the means at the end of the
eccentric-rod for engaging with the top or bottom of a rocker-shaft,
which operated the valve-stem. This was the form of reversing motion
used on the early Baldwin engines. Numerous other appliances, more
or less defective, were experimented with before the double fixed
eccentrics were introduced. Till the link was applied to valve-motion,
the double eccentrics--an American invention--were the most important
improvement that had been made on the locomotive valve-motion since
the incipiency of the engine. The V hook, in connection with the
double eccentrics, made a fair reversing motion in comparison to any
thing that had preceded it. The objection to the hook was, that, when
the necessity arose for reversing the engine while in motion, much
difficulty was experienced in getting the hook to catch the pin. As
a simple, prompt, and certain reversing motion, the link was readily
acknowledged to be far superior to any thing that had previously been
tried.
INVENTION OF THE LINK.
There is no doubt but the link was first applied to a steam engine
by William T. James of New York, a most ingenious mechanic, who also
invented the double eccentrics. James experimented a great deal
about the period from 1830 to 1840, with steam carriages for common
roads; and it was in this connection that he invented the link. His
work having proved a commercial failure, the improvements on the
valve-motion were not recognized at the time; although the probability
is, that Long, who started the Norris Locomotive Works of Philadelphia,
and brought out the double eccentrics upon the locomotives built there,
was indebted to James for the idea of a separate eccentric for each
direction of engine movement.
The credit of inventing the ordinary shifting link is due to William
Howe of Newcastle, England. This inventor was a pattern-maker in the
works of Robert Stephenson & Co., and he invented the link in 1842
in practically its present form. The idea of Howe was to get out an
improved reversing motion; and he made a pencil-sketch of the link, to
explain his views to his employers. The superintendent of the works was
favorably disposed to the invention, and ordered Howe to make a pattern
of the motion, which was done; and this was submitted to Stephenson,
who approved of the link, and directed that one should be tried on a
locomotive. Although Stephenson gave Howe the means of applying his
invention, he does not seem to have perceived its actual value, for the
link was not patented; and Stephenson never failed to patent any device
which he thought worth protecting.
The link-motion was applied to a locomotive constructed for the Midland
Railway Company, and proved a success from the day it was put on.
Seeing how satisfactorily the invention worked, Robert Stephenson paid
Howe twenty guineas (one hundred and five dollars) for the device, and
adopted the link as the valve-gear for his locomotives. This is how the
shifting link comes to be called the “Stephenson link,” and the credit
for this invention was not extravagantly paid for.
The capability which the link possesses of varying the steam admission
and release, did not appear to be understood by the inventor; nor was
the mechanical world aware, for some time after the link was brought
into use, that it could be employed to adjust the inequality of steam
distribution, due to the angularity of the connecting rod.
CONSTRUCTION OF THE SHIFTING LINK.
[Illustration: FIG. 12.]
As usually constructed for American locomotives, the link is a slotted
block curved to the arc of a circle, with a radius about equal to the
distance between the center of the driving-axle and the center of the
rocker-pin. The general plan of the link-motion is shown in Fig. 12.
Fitted to slide in the link-slot is the block which encircles the
rocker-pin. The eccentric-rods are pinned to the back of the link;
the forward eccentric-rod connecting with the top, and the back-up
eccentric-rod with the bottom, of the link. Bolted to the side and near
the middle of the link is the saddle, which holds the stud to which the
hanger is attached; this, in its turn, connecting with the lifting arm,
which is operated by the reversing rod that enables the engineer to
place the link in any desired position.
ACTION OF THE LINK.
Regarded in its simplest form, the action of the link in full gear
is the same upon the valve movement as a single eccentric. When the
motion is working, as in the figure, with the eccentric-rod pin in
line with the rocker-pin, it will be perceived that the movement can
not differ much from what it would be were the eccentric-rod attached
to the rocker. Here the forward eccentric appears as controlling the
movement of the valve. Putting the link in back motion brings the end
of the backing eccentric-rod opposite the rocker-pin, the effect being
that the back-up eccentric then operates the valve. When the link-block
is shifted toward the center of the link, the horizontal travel of
the rocker-pin is decreased; consequently, the travel of the valve is
reduced; for, with ordinary engines, the travel of the valve in full
gear equals the throw of the eccentrics, the top and bottom rocker-arm
being of the same length. The motion transmitted from the eccentrics,
and their means of connection with the link, make the latter swing as
if it were pivoted on a center which had a horizontal movement equal to
the lap and lead of the valve. The extremities of the link, or rather
the points opposite the eccentric-rods, swing a distance equal to the
full throw of the eccentric. The variation of valve-travel that can be
effected by the link, is from that of the eccentric throw in full gear
down to a distance in mid gear which agrees with the extent of lap and
lead. The method of obtaining these various degrees of travel is by
moving the link so that the block which encircles the rocker-pin shall
approach the middle of the link.
When an engine is run with the lever in the center notch, the supply
of steam is admitted by the lead-opening alone. In full gear the
eccentric, whose rod-end is in line with the rocker-pin, exerts almost
exclusive control over the valve movement; but, as the link-block gets
hooked towards the center, it comes to some extent under the influence
of both eccentrics.
A thoughtful examination of Fig. 12 will throw light on the reason
why the proper position of a slipped eccentric can be determined by
the other eccentric when the engine is on the center. In the cut, the
crank-pin is represented on the forward center; and in that position
the eccentric centers are both an equal distance in advance of the
main shaft center. It will be evident now that the valve must occupy
practically the same position for forward or back gear, as each of the
eccentric-rods reaches the same distance forward. Putting the motion in
back gear would bring the backup eccentric-rod pin to the position now
occupied by the pin belonging to the forward eccentric-rod.
VALVE-MOTION OF A FAST PASSENGER LOCOMOTIVE.
Reducing the travel of the valve by drawing the reverse-lever towards
the center of the quadrant, and consequently the link-block towards the
middle of the link-slot, not only hastens the steam cut-off, but it
accelerates in a like degree every other event of steam distribution
throughout the stroke. To explain this point, let us take the motion
of a well-designed engine in actual service, which has done good
economical work on fast train running. The valve-travel is five inches,
lap one inch, no inside lap, lead in full gear 1/16 inch, point of
suspension 9/16 inch back of center of link.
EFFECT OF CHANGING VALVE-TRAVEL.
When this engine is working in full gear, the steam will be freely
admitted behind the piston till about eighteen inches of the stroke,
when cut-off takes place; and the release or exhaust opening will
begin at about twenty-two inches of the stroke, giving four inches for
expansion of steam. Now, if the links of this engine are hooked up so
that the cut-off takes place at six inches of the stroke, the steam
will be released at sixteen inches of the stroke; and at that point
compression will begin at the other end of the cylinder.
WEAK POINTS OF THE LINK-MOTION.
This attribute which the link-motion possesses, of accelerating the
release and compression along with the cut-off, is very detrimental
to the economical operating of locomotives that run slow. High-speed
engines need the pre-release to give time for the escape of the steam
before the beginning of the return stroke; and the compression is
economically utilized in receiving the heavy blow from the fast-moving,
reciprocating parts, whose direction of motion has to be suddenly
changed at the end of each stroke, and in helping to raise the pressure
promptly in the cylinder at the beginning of the stroke. A locomotive,
on the other hand, that does most of its work with a low-piston speed,
would not suffer from back pressure if the steam were permitted to
follow the piston close to the end of the stroke; and a very short
period of compression would suffice. If the engine, whose motion we
have been considering, instead of releasing at sixteen inches, could
allow the steam to follow the piston to twenty-two inches of the
stroke, after cutting off at six inches, a very substantial gain of
power would ensue. And this would be well supplemented by avoiding
loss of power, did compression not begin till within two inches of the
return stroke.
WHY DECREASING THE VALVE-TRAVEL INCREASES THE PERIOD OF EXPANSION.
Increase of expansion follows reduced valve-travel, from a similar
cause to that which produces expansion when lap is added to the edge of
a slide-valve. When the valve is made with the face merely long enough
to cover the steam-ports, there can be no expansion of the steam; for,
so soon as the valve ceases to admit steam, it opens the steam-port to
the exhaust. When lap is added, however, the steam is inclosed in the
cylinder, without egress for the time that it takes the lap to travel
over the steam-port. An arrangement of motion which will make the valve
travel quickly over the port, has a tendency to shorten the period
for expansion; while making the valve travel slowly over the port,
has the opposite effect, and protracts expansion. A valve with, say,
five inches travel, has a comparatively long journey to make during
the stroke of the piston; and the lap-edges will pass quickly over
the steam-ports,--much more quickly than they will when the travel is
reduced to three inches. In a case of this kind, there is more than the
mere reduction of travel to be considered. Suppose the valve has one
inch lap at each end. When it stands on the middle of the seat, it has
a reciprocating motion of two and one-half inches at each side of that
point to make. At the beginning of the stroke, it has been drawn aside
one inch (we will ignore the lead), but still has one and one-half
inch to travel before it begins to return. On the other hand, when the
travel is reduced to three inches, the valve has only one and one-half
inch to travel away from the center; and, one inch being moved to draw
the lap over the port, there only remains one-half inch for the valve
to move before it must begin returning. This entails an early cut-off;
for the valve must pass over the ports with its slow motion, and be
ready to open the port on the other end, before the return stroke. Thus
a travel of five inches draws the outside edge of the valve one and
one-half inch away from the outside of the steam-ports, three inches
travel only draws it one-half inch away, and a greater reduction of
travel decreases the opening in like proportion.
INFLUENCE OF ECCENTRIC THROW ON THE VALVE.
As reducing the travel of the valve diminishes the port opening, a
point is reached in cutting off early in the stroke where the port
opening is hardly any more than the port opening due to the lead. This
is what makes long steam-ports essential for a successful high-speed
locomotive. The best-designed engines give an exceedingly limited port
opening at short cut-offs, and badly planned motion sometimes seriously
detracts from the efficiency of the engine, by curtailing the opening
at the point where a very brief time is given for the admission of
steam. The magnitude of the eccentric throw exerts a direct influence
on the port opening when cutting off early. A long throw tends to
increase the opening, while a short throw reduces it. The long-throw
eccentric will draw the valve farther away from the edge of the
steam-port, when admitting steam for the same point of cut-off, than
a short-throw eccentric will move its valve. For an ordinary 17 × 24
inch locomotive, the throw of eccentric should not be less than five
inches, unless the engine is intended entirely for slow running. There
are many engines running with eccentric throw less than five inches,
but they are invariably slow unless the valve-lap is very short. With
an ordinary lap, an engine having an eccentric throw of 4½ inches needs
so much angular advance to overcome the lap, and provide lead, that the
rectilineal motion of the eccentric is very meager at the beginning of
the stroke. That is, the center of the eccentric is traveling downward
in its circular path, which gives little motion to the valve, just
as the crank gives decreased motion to the cross-head when near the
centers.
HARMONY OF WORKING-PARTS.
Hitherto we have regarded the link as merely performing the functions
of transmitting the motion of the eccentrics to the valves, with
the additional capability of reducing the travel at the will of the
engineer. Otherwise, the motion of the link is intensely complex; and
its movements are susceptible to a multitude of influences, which
improve or disturb its action on the valve. A good valve-motion is
planned according to certain dimensions of all the working-parts;
and any change in their arrangement will almost invariably entail
irregularities upon the link’s movement, which will radically affect
the distribution of steam. A link-motion schemed for an eccentric
throw of 4½ inches will not work properly if the throw be increased
to five inches: a link with a radius of 57 inches can not be changed
with impunity for one of 60 inches. Any change in the position of
the tumbling-shaft or rocker-arms distorts the whole motion, and any
alteration in the length of the rods or hangers has a similar effect.
That the link may perform its functions properly, all its connections
must remain in harmony.
ADJUSTMENT OF LINK.
A very important feature of the link is its property of adjustability,
which serves to neutralize the distorting effect of the connecting
rod’s angularity. As has already been explained, the angularity of
the main rod tends to delay the cut-off during the backward stroke,
while it is accelerated in the forward stroke. With the ordinary
length of connections, this irregularity would seriously affect the
working of the engine. But it is almost entirely overcome by the
link, which can be suspended in a way that will produce equality for
the period of admission and point of cut-off for both strokes in one
gear. Perfect equalization of admission and cut-off for both gears
has been found impossible with the link-motion; and designers are
generally satisfied to adjust the forward motion, and permit the back
motion to remain untrue. The point about the link which exercises the
most potent influence on adjusting the cut-off, is the position of the
saddle, or of its stud for connecting the hanger. This stud is called
the point of suspension. Raising the saddle away from the center of
the link will effect adjustment of steam admission; but in locomotive
practice the saddle is nearly always located in the middle of the link,
there being practical objections against raising it. Equalization of
steam distribution is produced by placing the hanger-stud or point of
suspension some distance back of the center line of the link-slot, the
distance varying from ⅛ inch to ⅞ inch.
Moving the hanger-stud affects the link’s movement in a way that is
equivalent to temporarily lengthening the eccentric-rod during a
portion of the piston-stroke. The length of the tumbling-shaft arms,
the length of hanger, the location of the rockers and tumbling-shaft,
the radius of link, and length of rods, all exercise influence on the
accurate adjustment of the valve-motion.
SLIP OF THE LINK.
In equalizing the valve-motion, and overcoming the discrepancy of steam
admission, due to the angularity of the connecting rod by moving the
link-hanger stud away from the center of the slot, a new distortion is
introduced. The link-block being securely fastened to the bottom of
the rocker-pin, moves in the fixed arc traversed by that pin, which is
nearly horizontal. The action of the eccentric-rods on the link, on the
other hand, forces the latter to move with a sort of vertical motion
at certain parts of the stroke, making it slip on the block. Moving
the hanger-stud back tends to increase this slip, which will become
excessive enough to seriously impair the efficiency of the motion if
not kept within bounds by the designer. Where the slip is very great,
the motion will not be serviceable, a consideration which can never be
overlooked; for the block will wear rapidly, producing lost motion, a
very undesirable defect about any part of a link-gear. With the long
rods which prevail in locomotive practice, designers have no difficulty
in keeping the slip within practical bounds; but with marine engines it
is sometimes necessary to sacrifice equality of steam admission to the
reduction of the slip. The greatest amount of slip is in full gear, and
it diminishes as the link-block is moved towards the center.
Placing the eccentric-rod pins back of the link-arc, as is almost
universally done in this country, has a tendency to make the link
slip on the block; and care has to be taken not to locate these pins
farther back than is actually necessary for other requirements of the
link-motion’s adjustment. Auchincloss, who is a recognized authority
for designing of link-motion, gives four varieties of alterations
capable of reducing the slip when it is found too great for a
practicable motion. His resorts are, either to increase the angular
advance, reduce the travel, increase the length of link, or shorten the
eccentric-rods. One, or a combination, of these methods may be adopted,
as the designer finds most convenient.
RADIUS OF LINK.
Among the constructing engineers who plan link-motion, there is
considerable diversity of opinion about what radius of link helps to
produce the best valve-motion. The distance between the center of
axle and center of lower rocker-pin may be accepted as approximately
correct, although some designers slightly increase beyond these points.
On the other hand, the locomotives sent out from a leading building
establishment have the radius of link drawn ¾ inch per foot short of
the distance between the axle and rocker; and the claim has been made,
that the arrangement produces an excellent motion.
A committee of the American Master Mechanics’ Association have placed
themselves on record on this subject by asserting that the distance
between the centers of axle and rocker-pin is the proper radius for
the link. That same committee recommended that the link-motion should
be planned to give as long a link-radius as possible, subject to the
first-mentioned conditions.
It must be noted that the middle of the link-slot is the radius arc. I
knew of a case where the links for an altered locomotive were finished
out of the true radius through the edge of the slot being taken as the
radius-curve.
INCREASE OF LEAD.
Most of the men who are at all familiar with the valve-motion are aware
of the fact, that, with the shifting link, the lead increases as the
link is notched towards the center. Where the valve has 1/16 inch lead
in full gear, it is no unusual thing to find it increase to ⅜ inch lead
opening at mid gear. The phenomenon is better known than its cause is
understood.
[Illustration: FIG. 13.]
The relative positions of link and eccentric centers of an engine,
when the crank is on the forward center, are shown in Fig. 13; the
link being represented with the block in the center, which represents
mid gear. It will be observed that the centers of the eccentrics _f_
and _b_, from which the rods receive direct influence, are both some
distance ahead of the center of the axle, the one above, the other
below. The eccentric-straps to which the rods are connected sweep round
the eccentric circles, and are controlled thereby. When the link is
moved up or down, each eccentric-rod pin, where it attaches to the
link, describes the arc of a circle with a radius drawn from its own
eccentric. If both rods were worked with a radius from the axle-center,
the link could be raised and lowered when the engine stands on the dead
center, without moving the rocker-pin at all; but, under the existing
arrangement, the link is influenced directly by one or other of the
eccentrics, whatever position in the link the block may stand. When the
engine is standing on the forward center, with the link in mid gear, as
shown in Fig. 13, it will be readily perceived that the block stands
at its farthest point away from the axle; for the rods are so placed
to reach their greatest horizontal distance ahead, and consequently
in this position the lead opening is greatest. If the link be now
lowered, the backing eccentric-rod will immediately begin to pull the
link back: and, as the pin of the forward eccentric-rod approaches the
central line of motion, it will also keep drawing the link back; so
that, by the time the link is in full gear, the lead opening will be
considerably reduced.
[Illustration: FIG. 14.]
When the engine stands on the back dead center, as shown in Fig. 14,
the eccentric centers will be on the other side of the axle, and the
eccentric-rods will be crossed. While in mid gear, the link-block is
drawn closer to the axle than it would be in any other position of the
link; and consequently the lead opening is greatest. If the link be
now lowered, the forward eccentric-rod will approach its horizontal
position, and consequently reaches farther on the central line of
motion, so it will push the link-block away from the axle, thereby
decreasing the lead. Pulling the link into back gear has a similar
effect.
The tendency of a link-motion to increase the lead towards the center
is made greater by shortening the eccentric-rods. Increasing the throw
of eccentric inclines to accelerate the lead towards the center, since
it throws the eccentric centers farther apart. For slow running,
hard-pulling locomotives, where increase of lead is a disadvantage,
the tendency to increase the lead is sometimes restrained in forward
gear by reducing the angular advance of the backing eccentric. This
expedient is, however, not necessary where proper care and intelligence
have been bestowed in the original design of the motion.
In studying this part of the valve-motion, a young machinist or
engineer will obtain valuable assistance by cutting a link template out
of a piece of pasteboard, and using strips of wood as eccentric-rods.
With these he can test on a drawing-board or table the various
positions of the link, and note, in a way that is easily understood,
the effect of changing the link into different positions.
CHAPTER XIX.
_SETTING THE VALVES._
THE MEN WHO LEARN VALVE-SETTING.
Most of intelligent machinists engaged on engine-work, make it an
object of ambition to learn to set valves; and the operation is
mastered as soon as the opportunity offers. It has been a practice in
numerous shops for those who have the work of valve-setting to do, to
invest the operation with fictitious mystery, to patiently disseminate
the belief that valve-setting is an exceedingly difficult matter. Cases
sometimes arise where the squaring of an engine’s valves is really an
arduous task, requiring intimate familiarity with delicate methods of
adjustment; but valve-setting, as it is usually practiced in building
establishments, in repairing-shops, and in round-houses, is merely a
matter of plain measurement.
A man may be a first-class engineer without knowing how to set valves,
and familiar acquaintance with the operation will not increase his
ability in managing his engine when merely getting a train over the
road on time is the consideration; but the method of valve-setting
is so closely associated with an intelligent appreciation of the
valve-motion’s philosophy, that most of engineers who take an extended
interest in their business, wish to acquire the knowledge of how the
valves are set.
BEST WAY TO LEARN VALVE-SETTING.
The best way to learn valve-setting is by taking part in the work.
Whatever can be said in books on a subject of this kind, provides but
an indifferent substitute for going through the actual operations.
But a man’s ambition to learn may exceed his opportunities; so, for
those who can not get a gang boss to direct them into the art of
valve-setting, this description will be made as plain as possible.
When an engine’s valve-motion is designed, the sizes of the
different parts are arranged; and, if this business is done by a
competent engineer, there will only be trifling changes necessary in
valve-setting.
PRELIMINARY OPERATIONS.
Let us suppose the engine to be an ordinary eight-wheel locomotive,
with cylinders 17 × 24 inches. Let us assume that the top and bottom
rocker-arms are straight, of equal length, and that the eccentric-rods
are connected to the link so as to be opposite the block in full gear.
This will make the extreme travel of valve equal the eccentric’s throw.
We will now look round to see that every thing connected with the
motion is ready for valve-setting.
First, it is necessary to see that the wedges are properly set up to
hold the driving-boxes in about the same position they will occupy when
the engine is at work.
CONNECTING ECCENTRIC-RODS TO LINK.
[Illustration: FIG. 15.]
[Illustration: FIG. 16.]
In looking over the motion, it is well to note that the eccentric-rods
are properly connected,--the forward eccentric-rod with the top, the
backward eccentric-rod with the bottom, of the link. When the crank-pin
is on the forward center, the eccentrics will occupy the position they
appear in, in Fig. 15, where the rods are open, and nearly horizontal.
The full parts of both eccentrics are advanced towards the crank-pin,
so that the centers of the eccentrics are advanced from a perpendicular
line drawn through center of axle, a horizontal distance equal to the
lap and lead. When the crank-pin is on the back center, the eccentric
centers will be behind the axle, and the rods will be crossed as they
are seen in Fig. 16. The reason why the rods must be crossed when the
crank is in this position, is, that the forward eccentric center is
below the axle, and the backward eccentric center is above. As the
forward eccentric-rod maintains its connection with the top of the
link, and the backward eccentric-rod is at the opposite end, crossing
of the rods is inevitable. This fact is worth imprinting on the memory,
for I have known of several cases where men got the rods up wrong by
putting them open when the engine stood with the crank on the back
center.
MARKING THE VALVE-STEM.
[Illustration: FIG. 17.]
In ordinary practice, valves are set with the steam-chest cover down,
and the position of the valve on the seat is identified by marks on the
valve-stem. Before the cover is put down, the valve is placed as in
Fig. 17, just beginning to open the forward steam-port; a thin piece of
tin being generally used to gauge the opening. When the valve stands
in this position, a tram is extended from a center punch-mark _c_,
on the stuffing-box, straight along the valve-stem as far as it will
reach; and the point, here located at _a_, is marked. The valve is then
moved forward till it begins to uncover the back port, when another
measurement is made with the tram, which locates the point _b_ on the
valve-stem. Whatever position the valve may stand on, it may now be
identified by the tram. When the tram cuts the space half way between
_a_ and _b_, the valve stands in the middle of the seat.
Some machinists do not believe in tramming from the stuffing-box, as
the point is liable to be moved in tightening down the steam-chest
cover. These generally measure from a point on the cylinder casting,
but that practice has its drawbacks.
LENGTH OF THE VALVE-ROD.
To prove the correct length of the valve-rod, the rocker-arm is set at
right angles to the valve-seat, which is its middle position. The valve
must now stand on the middle of the seat, which will be indicated by
the tram point reaching the dividing point between _a_ and _b_. Should
the valve not be right when the rocker is in its middle position, the
rod must be altered to put it right.
ACCURACY ESSENTIAL IN LOCATING THE DEAD CENTER POINTS.
Before proceeding to set the valves, a machinist can not be too careful
in locating the exact dead centers. Some men conclude, because there
is little motion to the cross-head close to the end of the stroke,
that a slight movement of the wheel to one side or the other is of
little consequence, and makes no perceptible difference in the relative
positions of piston and valve. This is a serious mistake; for, although
the piston is moving slowly, the eccentric is proceeding at its
ordinary speed, and the valve is moving fast. The loose, quick methods
of finding dead centers followed occasionally are not conducive to
exactness, and nothing but accuracy is permissible in valve-setting.
FINDING THE DEAD CENTERS.
The best way of finding the true center is by moving the cross-head
a measured distance round its extreme travel, recording the extent
of movement on the driving-wheel tire, whose motion is uniform; then
bisecting the distance between the marks on the tire, when the dividing
line will indicate the true center.
[Illustration: FIG. 18.]
Thus: Turn the wheels forward till the cross-head reaches within
one-half inch of its extreme travel, as shown in Fig. 18. From a point
_a_ on the guide-block, extend a tram on the cross-head, and mark
the extreme point reached _b_. Put a center punch-mark _c_ on the
wheel-cover, or other convenient fixed point, and from it extend a tram
on the edge of the tire, and scratch an arc _d_. Now, with tram in
hand, watch the cross-head, and have the wheels moved forward slowly.
When the cross-head passes the center, and moves back till the tram
extending from _a_ will reach the point _b_, stop the motion. Again
tram from the wheel-cover point, and describe a second arc on the tire,
which will be at _e_, now moved to the position which _d_ occupied when
the previous measurement was taken. With a pair of dividers bisect the
distance between _d_ and _e_. Mark the dividing point _C_ with a center
punch, and put a chalk ring round it. When the wheel stands so that the
tram will extend from _c_ to _C_, the engine will be on the forward
dead center.
All the other centers must be found by a similar process.
TURNING WHEELS AND MOVING ECCENTRICS.
When a measurement is going to be made for fore gear, the wheels must
be turned forward; and, when it is for the back gear, they must be
turned backward. Enough movement of the wheel must be given to take
up the lost motion every time the direction of movement is changed.
In moving an eccentric, it should also be turned far enough in the
opposite direction to take up the lost motion.
SETTING BY THE LEAD OPENING.
Put the reverse-lever in the full forward notch, and place the engine
on the forward center. If the lead opening in full gear is to be 1/16
inch, advance the forward eccentric till the point _a_ (Fig. 17) on
the valve-stem is that distance away from the tram point. Throw the
reverse-lever into the full backward notch, turn the wheels forward
enough to take up the lost motion, then turn them back to the forward
center. Move the backward eccentric (if it needs moving) till the tram,
extended on the valve-stem, strikes the same point that it reached for
the forward motion. It will be noted here, that the valve occupies the
same position for fore and back gear when the engine is on the center.
Put the reverse-lever in the forward notch again, and turn the wheels
ahead till the back center point is reached. Now tram the valve-stem
again, and, if the lead opening be the same for both gears as it was
on the forward center, that part of the setting is right. It is a good
plan to go over the points a second time to prove their correctness.
But it is not likely that the lead opening at the back end will be
right on the first trial. Instead of having the correct lead, the valve
will probably lap over the port, being what workmen call “blind,” or
it will have too much lead. Let us assume that our valve is 1/16 inch
blind. This indicates that the eccentric-rod is too long. We shorten
the rod till the valve is at the opening point, and, on turning the
engine to the forward center again, we will find that the valve there
has lost its lead. But our change has adjusted the valve movement, so
that on each center the valve is just beginning to open the steam-port.
Advancing the eccentric to give one end 1/16 inch lead will now have
the same effect upon the other end; and, assuming that the back motion
has been subjected to similar treatment with a like result, the lead
opening on that side is right. This process must now be repeated with
the other side of the engine.
ASCERTAINING THE POINT OF CUT-OFF.
The lead openings being properly arranged, we will proceed to examine
how the valves cut off the steam; for it is important that about the
same supply of steam should be furnished to each cylinder and to each
end of the cylinders. The angularity of the connecting rod tends to
give a greater supply of steam to the forward than to the back end of
the cylinder; but this inequality is, as has already been explained,
usually rectified by locating the hanger-stud a certain distance back
of the link arc.
To prove the cut-off, we will try the full gear first. Put the
reverse-lever in the full forward notch, starting from the forward
center, and turn the wheels ahead. The motion of our engine has been
designed so that the cut-off in full gear shall happen at 18 inches
of the stroke. With tram in hand, watch the movement of the valve as
indicated by the stem marks. As the piston moves away from the forward
end of the cylinder, the valve will keep opening till nearly half
stroke is reached, when it will begin to return, slowly at first, but
with increasing velocity as the point of cut-off is reached. When
the point _a_, Fig. 17, gets so that it will be reached by the tram
extended from _c_, the motion must be stopped; as that indicates the
point of cut-off. Now measure on the guide how far the cross-head has
traveled from the beginning of the stroke, and mark it down with chalk.
Then turn the wheels in the same direction past the back center, and
obtain the cut-off for the forward stroke in the same manner. The
cut-off for the other cylinder will be found in precisely the method
described.
In addition to trying the cut-off in full gear, it is usually tested at
half stroke and at 6 inches, or with the reverse-lever in the notches
nearest to these points. Some men begin at the first notch, and follow
the point of cut-off in every notch till the center is reached, and do
the same for back gear.
ADJUSTMENT OF CUT-OFF.
From various causes, it often happens that the cut-off is unequal in
the two strokes, or one cylinder may be getting more steam than the
other. Suppose, that, on one side of the engine, the valve is cutting
off at 18½ inches in forward gear, while at the other side it is
cutting off at 17½ inches of the stroke. The most ready way to adjust
that inequality is by shortening one link-hanger and lengthening the
other till a mean is struck. Where the discrepancy is smaller, it is
adjusted by lengthening the hanger at the short side.
A harder inequality to adjust is where the valve cuts off earlier for
one end of the cylinder than for the other. In new work this is readily
overcome by the saddle-stud, but such a change is seldom admissible
in old work. When the points of cut-off have been noted down, it will
frequently happen, that, instead of both ends cutting off at 18 inches,
one end will show the cut at 17 inches, while the other goes to 19
inches. This indicates something wrong, and demands a search for the
origin of the unequal motion. First ascertain if the rocker-arm is
not sprung. If that is all right, examine the link, which is probably
sprung out of its true radius. To straighten the rocker-arm is an easy
matter, but not so with case-hardened links; although some men are very
successful in springing them back. Where it is impracticable to remedy
an unequal cut-off by correcting the origin of the defect, several
plans may be resorted to for obtaining the required adjustment. One of
the most common resorts is to equalize the forward motion by throwing
out the back motion. Putting the rocker-arm away from its vertical
position when the valve is in the middle of the seat, by shortening or
lengthening the valve-rod, provides a means of adjustment. Sometimes
the equality of lead opening is sacrificed to obtain equality of
cut-off. The changes necessary to obtain adjustment of a distorted
motion can only be successfully arranged by one who has experience in
valve-setting or in valve-motion designing.
In many shops the cut-off is adjusted for the point where the engine
does most of the work,--say at 6 inches. Other master mechanics direct
the equalization to be made for half stroke, while some take the mean
between the half stroke and the ordinary working notch.
The final adjustments in valve-setting ought to be made when the engine
is hot.
CHAPTER XX.
By J. G. A. Meyer.
_LAYING OUT LINK-MOTION._
Fig. 19 is an outline of a link-motion such as is generally applied to
the American locomotive. It can be adjusted to control the movement of
the slide-valve in such a manner that equal portions of steam will be
admitted alternately at each end of the cylinder.
[Illustration: FIG. 19.]
In the following article we propose to explain how this can be
accomplished.
Although we would not advise any person to be satisfied with
approximate rules or constructions, yet cases do occur where the
approximate constructions, being so very near correct, on account of
their simplicity, are of greater practical value than the application
of the rigid and more difficult theoretical rules.
By these remarks, we do not wish the reader to understand that the
following constructions are all done according to the rules of
thumb--not by any means; for all, with the exception of a few points,
are theoretically correct. At the end of this article, we will point
out those points which are, and which are not, approximately found; so
that the reader may feel satisfied that our construction may always be
relied upon as being correct for all practical purposes.
In what follows, the cylinder will always be regarded as lying on the
right-hand side of the axle, the link being between cylinder and axle,
and the axle located in the center of pedestal.
To avoid any misunderstanding, we will explain the meaning of some of
the terms used.
The length of crank is the distance from center of axle to center of
crank-pin.
For convenience, we shall call the total distance from center of
eccentric-strap to the center of eccentric-pin in the link the length
of the eccentric-rod.
The throw of eccentric is double the distance from center of axle to
center of eccentric-wheel.
The length of the connecting rod is the distance from the center of
crank-pin hole to center of cross-head pin-hole.
The length of link-hanger is the distance from center to center of
holes.
CONDITIONS.
Since this article treats only on the adjustment of the link-motion,
the following items are supposed to be known and established: The lap
of valve, which in this case will be three-fourths of an inch; the
throw of eccentrics, 5 inches; the stroke of the piston, 24 inches; the
position of the rocker, as per Fig. 19; the length of the rocker-arms,
which are in this case of equal length; length of link-hanger and all
dimensions of link, complete, as shown in Fig. 19; and also the length
of the connecting rod.
The adjustment of the link-motion may at first sight appear to be a
difficult problem, as we must have a knowledge of the relative motions
of the piston and slide-valve; but by reducing this problem to several
elementary problems, so that the laws governing the relative motions
may be discovered and clearly defined, a clear conception of our
subject can be gained, and the solution of our original problem can be
accomplished with comparative ease.
In order to find what kind of elementary problems are applicable, let
us suppose that we are looking at a locomotive with a link-motion, as
shown in Fig. 19, applied and correctly adjusted. Now let us examine
it, commencing with the valve. We find that the valve receives its
motion from the upper rocker-arm, and this receives its motion from
the lower rocker-arm. According to our conditions, previously stated,
both of the rocker-arms are of the same length; and, therefore, the
arc described by the upper rocker-arm will be the same length as the
arc described by the lower one. We also notice that the link which
moves the lower rocker-arm is held in position by the lifting-shaft
arm. The question, then, will naturally arise, Must this lifting-shaft
arm have some particular length, and the center of lifting-shaft have
some particular position? We answer, “Yes;” and this is one of our
elementary problems to solve. Again, we notice that the saddle-pin
is not in the center of the link; and we ask again, “Why?” To answer
this will be another elementary problem. The next we notice are our
eccentric-rods. These we find, on examination, to have some particular
length; and to find this length is another elementary problem. Next
we examine our eccentrics: these, we find, are fastened to the axle;
and, since the crank is also fastened to the same axle, it follows that
there are some relative positions between them; to find these positions
is another elementary problem. Now let us look once more at the rocker,
and we find that the two rocker-arms are not in the same straight line:
hence, to find the amount of offset is another elementary problem. And,
lastly, we must be able to find the position of crank-pin to correspond
with the position of piston when at full stroke at either end of the
cylinder, and also when at half stroke moving in either direction.
Here, then, we have all the elementary problems that are necessary to
be understood for the solution of our original problem.
We will now explain all these problems, in an order the reverse to that
in which we stated them; hence we have the following order:--
1st, To find position of crank at full and half stroke.
2d, To find center line of motion, and amount of offset in rocker-arms.
3d, To find relative positions of crank-pin and eccentrics when at full
and half stroke.
4th, To determine the correct length of eccentric-rods.
5th, To find position of saddle-pin.
6th, To find the position of the center of lifting-shaft and length of
arms.
[Illustration: FIG. 20.]
PROBLEM 1, FIGS. 20 and 21.--_To find the position of crank when the
piston is at full and half stroke._--Let the center of wheel and the
axis of the cylinder be in the same straight line as _AD_, Fig. 20.
With any point _C_ as a center, and a radius equal to the length of the
crank, describe a circle _F_, ½_F_, _B_, ½_B_; and let us call this the
crank-pin circle. The straight line _AD_ intersects the circumference
of the circle in the points _F_ and _B_. The point _F_ will be the
center of crank-pin when piston is at full stroke at the forward end
of the cylinder, and point _B_ will be the center of crank-pin when
the piston is at full stroke at the rear end of the cylinder. With
the point _F_ as a center, and with a radius equal to the length of
the connecting rod, describe an arc intersecting the line _AD_ in the
point _F′_; with the point _B_ as a center, and with the same radius,
describe an arc intersecting the straight line _AD_ in the point _B′_;
and with the point _C_ as a center, and with the same radius, describe
an arc intersecting the straight line _AD_ in the point _C′_. Point
_F′_ will be the center of cross-head pin when the center of crank-pin
is at _F_, and _B′_ the center of cross-head pin when the crank-pin is
at _B_, and the point _C′_ will be the position of center of cross-head
pin when piston is at half stroke. With point _C′_ as a center, and
a radius equal to the length of the connecting rod, describe an arc
passing through the point _C_, and intersecting the crank-pin circle
in the points ½_F_ and ½_B_: these points will be the position of
crank-pin when the piston is at half stroke, or when the center of
cross-head pin is at _C′_.
[Illustration: FIG. 21.]
It often happens that the axis of the cylinder is above the center of
axle. When such is the case, we must follow the construction as shown
in Fig. 21. Let two inches be the distance that the center of axis of
cylinder is above the center of axle.
Draw a straight line _AD_ through the center of axle _C_; two inches
above this draw a straight line _GH_ parallel to _AD_; this line will
then pass through the axis of cylinder. With the center of axle _C_ on
the straight line _AD_ as a center, and a radius equal to the length
of the crank, describe a circle _F_, ½ _F_, _B_, ½ _B_: this circle
will be the crank-pin circle. With the point _C_ as a center, and a
radius equal to the length of the connecting rod plus the length of
the crank, describe an arc intersecting the straight line _GH_ in the
point _F′_: this point will be the position of the cross-head pin when
the piston is at full stroke forward. Through the points _F′_ and _C_
draw a straight line, intersecting the crank-pin circle in the point
_F_: this point will be the position of the center of the crank-pin
when the piston is at full stroke forward. Again, with the point _C_ as
a center, and a radius equal to the length of the connecting rod minus
the length of the crank, describe an arc intersecting the straight line
_GH_ in the point _B′_: this point will be the position of the center
of the cross-head pin when the piston is at full stroke in the rear
end of the cylinder. Through the points _B_ and _C_ draw a straight
line, intersecting the crank-pin circle in the point _B_: this point
will be the position of the center of crank-pin when the piston is at
full stroke in the rear end of the cylinder. Find a point _C′_ exactly
central between the points _B′_ and _F′_ on the line _GH_: in other
words, bisect the distance _B′ F′_ by the point _C′_. With the point
_C′_ as a center, and a radius equal to the length of the connecting
rod, describe an arc intersecting the crank-pin circle in the points
½_B_ and ½_F_: these two points will be the center of crank-pin when
the piston stands at half stroke. In the link-motion, as shown in
Fig. 19, the axis of the cylinder is supposed to be 2 inches higher
than the center of axle. For this reason the construction shown in
Fig. 21 will hereafter be used.
PROBLEM 2, FIG. 22.--_To find the center line of motion and the amount
of offset in the lower rocker-arm._--Let _C_ be the center of axle:
through _C_ draw the straight lines _AD_ and _KL_ perpendicular to
_AD_. The center of rocker we find in Fig. 19 to be 37½ inches in front
of the center of axle, and 7½ inches above. We therefore continue our
construction in Fig. 22 by drawing a straight line _MN_ 37½ inches
in front of, and parallel to, the straight line _KL_, and another
straight line _OP_ parallel to _AD_, and 7½ inches above it. These
two lines intersect in the point _Q_, and this point is the center of
rocker. With _Q_ as a center, and a radius equal to the length of the
lower rocker-arm, describe the arc _RS_: through the point _C_ draw
a straight line _CT_ tangent to the arc _RS_, then _CT_ will be the
center line of motion.
[Illustration: FIG. 22.]
To find the amount of offset in the lower rocker-arm, let us place the
center line of the upper rocker-arm perpendicular to a line drawn
parallel to the valve surface: but in our case this valve surface is
parallel to the line _AD_; hence our line drawn parallel to the valve
surface will also be parallel to the line _AD_, and the center line of
upper rocker-arm will be perpendicular to _AD_, and coincide with the
line _MN_. Through the point _Q_ draw a straight line perpendicular to
the line _CT_, and intersecting the arc _RS_ in the point _U_: then the
distance from the point _U_ to the line _MN_ will be the amount of the
offset in the lower rocker-arm.
[Illustration: FIG. 23.]
PROBLEM 3, FIG. 23.--_To find the relative positions of crank-pin and
eccentrics when the piston is at full and half stroke._--Let _C_ be
the center of axle. Through _C_ draw the horizontal line _AD_, and
find the positions of center of crank-pin at full and half stroke;
namely, the points _F_, ½_F_, ½_B_, _B_, as explained in Problem 1, and
shown in Fig. 21. Next draw the center line of motion as explained in
Problem 2 and Fig. 22. With the point _C_ as a center, and a radius
equal to ½ the throw of the eccentric (2½ inches), draw a circle; and
let us call this circle the “eccentric-circle.” On the line of motion
_CT_, lay off a point towards the rocker 13/16 of an inch from _C_
(this being the sum of the lap and lead,--¾ of an inch for the lap,
and 1/16 of an inch for the lead): through this point draw a straight
line perpendicular to the line of motion _CT_, and intersecting the
eccentric-circle in the points _x_ and _y_. The point _x_ will be the
center of the forward eccentric; and the point _y_ will be the center
of backward eccentric when the center of crank-pin is at _F_, full
stroke forward. Through the points _F_ and _C_ draw a straight line,
intersecting the eccentric-circle in the point _F″_. The line _FC_
will represent the center line of crank; and the distance between the
points _F″_ and _x_, measured on the eccentric-circle, is the amount
that the center of forward eccentric is set back of the center line of
crank; and the distance between the points _F″_ and _y_ is the amount
that the backward eccentric is set ahead of the center line of crank.
Since both the crank and eccentrics are fastened to the same axle,
it follows, that, whatever position the center line of crank may be
in, the distances between center line of crank and eccentrics--that
is, the distances between _F″_ and _x_, also _F″_ and _y_, measured
on the eccentric-circle--remain constant. Therefore, to find the
position of eccentrics when the crank stands at ½_F_ (half stroke),
draw the straight line ½_FC_ representing the center line of crank, and
intersecting the eccentric-circle in the point ½_F″_. From the point
½_F″_, lay off on the eccentric-circle a point with a distance equal
to _F″x_, back of the center line of crank, and indicate this point
by ½_x_; also from ½_F″_ measured on the same circle, lay off a point
in the front of the center line of crank, and with a distance equal
to _F″y_, and mark this point ½_y_; then the point ½_x_ will be the
position of forward eccentric, and the point ½_y_ will be the position
of backward eccentric when the crank-pin is at ½_F_. In precisely the
same manner we find the position of eccentrics when the center of
crank-pin is at _B_ (full stroke back). Through the points _C_ and _B_
draw a straight line, intersecting the eccentric-circle in the point
_B″_. From the point _B″_, and with a distance equal to _F″x_, lay off
a point on the eccentric-circle back of crank; this point will be the
position of forward eccentric when crank is at full stroke back; and,
in order to distinguish this from the other position of eccentric,
call this point _a_: also from _B″_, lay off in front of the crank the
position of backward eccentric at a distance equal to _F″y_, and call
this point _b_. In the same manner find points ½_a_ and ½_b_ when the
crank-pin is at ½_B_. We have now found the position of eccentrics when
the crank-pin stands in the following positions:--
Full stroke forward _F_, the forward eccentric will be at _x_.
Half stroke forward ½_F_, the forward eccentric will be at ½_x_.
Full stroke back end _B_, the forward eccentric will be at _a_.
Half stroke back end ½_B_, the forward eccentric will be at ½_a_.
Full Stroke forward _F_, the backward eccentric will be at _y_.
Half stroke forward ½_F_, the backward eccentric will be at ½_y_.
Full stroke back end _B_, the backward eccentric will be at _b_.
Half stroke back end ½_B_, the backward eccentric will be at ½_b_.
[Illustration: FIG. 24.]
PROBLEM 4, FIG. 24.--_To determine the correct length of the
eccentric-rods._--Let _c_ be the center of axle. Through this point
draw the horizontal line _AD_, also a line _KL_ perpendicular to _AD_.
The only purpose for which these two lines are drawn in this problem,
as well as the others, is to have some lines from which we can locate
other lines or points. Locate the center of rocker, and center lines of
rocker-arms, as explained in Problem 2, and shown in Fig. 22; the lower
arm standing perpendicular to the center line of motion, and the upper
arm vertical. When the arms stand in this position, the rocker-pins
will move through an equal distance on each side of these center lines
during the time that the valve is making its full travel.
Next find centers of eccentrics _x_ and _y_ when the crank is at full
stroke forward; also _a_ and _b_ when the crank is at full stroke
back, as explained in Problem 3, and shown in Fig. 23. Before we
proceed, let us give names to some of the lines, as shown in Fig. 6_a_
(p. 268). The arc _cᵥ{1}cᵥ{2}_ drawn through the center of opening
of the link, we will call the link-arc; and the arc _dᵥ{1}dᵥ{2}_
drawn through the center of eccentric-rod pin-holes, we will call
the eccentric-rod pin-arc. Both of these arcs are drawn from the
same center; that is, the center from which the link is drawn. Let
us now cut a paper template, as shown in Fig. 6_b_ (link structure).
This template is cut so that, if it is laid on the link, Fig. 6_a_,
the arc of the template _cᵥ{3}cᵥ{4}_ will coincide with the link-arc
_cᵥ{1}cᵥ{2}_, and _dᵥ{3}dᵥ{4}_ with the eccentric-pin arc _dᵥ{1}dᵥ{2}_,
the end of template _dᵥ{3}cᵥ{3}_ with the line _dᵥ{1}cᵥ{1}_, and
the end _dᵥ{4}cᵥ{4}_ with _dᵥ{2}cᵥ{2}_. On this template join the
points _cᵥ{3}cᵥ{4}_ by a straight line, and bisect this line by the
perpendicular line _ee_: on this line the center of the saddle-pin will
be located. On one side of this line draw the line _ffᵥ{1}_ parallel
to _ee_, and on the other side draw _fᵥ{2}fᵥ{3}_ also parallel to
_ee_; the distance from the point _f_ to the point _fᵥ{2}_ being equal
to the distance between the centers of eccentric-rod pins, and _fe_
equal to _efᵥ{2}_. The points _f_ and _fᵥ{2}_ on the arc _dᵥ{3}dᵥ{4}_
indicate the position on the template of the centers of eccentric-rod
pins. On the center line of motion _cT_, lay off from _v_ a point _v^1_
towards the axle, with a distance equal to _cᵥ{1}dᵥ{1}_, Fig. 6_a_;
then with the point _x_ as a center, and _cv^1_ as a radius, describe
the arc _xᵥ{1}xᵥ{2}_; in this arc the upper eccentric-rod will be
located as long as the center of forward eccentric remains at _x_.
With the point _y_ as a center, and _cvᵥ{1}_ as a radius, describe
the arc _yᵥ{1}yᵥ{2}_: in this arc the center of lower eccentric-rod
will be located as long as the backward eccentric remains at _y_. With
the point _a_ as a center, and _cvᵥ{1}_ as a radius, describe an arc
_aᵥ{1}aᵥ{2}_: in this arc the upper eccentric-rod pin will be located
while the forward eccentric is at _a_. With the point _b_ as a center,
and _cvᵥ{1}_ as a radius, describe the arc _bᵥ{1}bᵥ{2}_; and in this
arc the center of lower eccentric-rod pin will be located when the
backward eccentric is at _b_. Now adjust the template on the drawing so
that the point _f_ will be in the arc _xᵥ{1}xᵥ{2}_: point _fᵥ{2}_ in
the arc _yᵥ{1}yᵥ{2}_ and the line _ee_ coincide with the center line
of motion _cT_. Along the arc _cᵥ{3}cᵥ{4}_ of the template draw an arc
on the paper. Next move the template so that the point _f_ will be in
the arc _aᵥ{1}aᵥ{2}_, the point _fᵥ{2}_ in the arc _bᵥ{1}bᵥ{2}_, and
the line _ee_ coincide with the center line of motion _cT_, and along
the arc _cᵥ{3}cᵥ{4}_ of the template draw the second arc on the paper.
Now, if the distance measured on the arc _RS_ from the point _v_ (the
center of the lower rocker-arm pin) to the first arc drawn, is equal to
the distance measured on the arc _RS_ from _v_ to the second arc, the
radius _cvᵥ{1}_ will be the correct length of the eccentric-rods. But,
if the distance from _v_ to the first arc is less than the distance
from _v_ to the second arc, the length _cvᵥ{1}_ of the eccentric-rod
will be too short. In this case we must increase the length _cvᵥ{1}_
by adding an amount equal to one-half the difference of the distances
from _v_ to the first arc, and from _v_ to the second arc previously
drawn; and this last length so found will be the correct length of
eccentric-rods.
It will be proper to remark here, that the radius _cvᵥ{1}_ was assumed
to be the correct length of eccentric-rods; but since the rods cross
each other when the eccentrics are at _a_ and _b_, and do not cross
each other when at _x_ and _y_, the radius _cvᵥ{1}_ will always be
a trifle short. It is therefore necessary to make the correction as
explained.
In every case, the length of eccentric-rods must be so adjusted,
that, when the line _ee_ coincides with the center line of motion
_cT_, the arc _vvᵥ{2}_ (which is the amount that the rocker-pin is
drawn towards the axle from the line _Qv_ when the eccentrics are at
_a_ and _b_) must be equal to the arc _vvᵥ{3}_ (which is the amount
that the rocker-pin is moved towards the cylinders from the line _Qv_
when the eccentrics are at _x_ and _y_); the straight line _Qv_ being
perpendicular to the center line of motion _cT_.
PROBLEM 5, FIG. 25.--_To find the position of the center of
saddle-pin._--For this problem we again call to our aid the paper
template shown in Fig. 6_b_. We have already seen in Problem 4 that the
center of saddle-pin will be located on the line _ee_ drawn on this
template: it now only remains to determine the distance of this point
from the link-arc _cᵥ{3}cᵥ{4}_.
Since the inequality between the crank-angle _W_ and _Wᵥ{1}_, Fig. 23,
becomes the greatest when the crank stands at half stroke, it is of the
utmost importance to find such a position for the center of saddle-pin
that equal portions of steam will be admitted alternately when the
crank stands at half stroke. Or, in other words, the admittance of
steam must cease at the moment that the piston has completed one-half
stroke.
[Illustration: FIG. 25.]
Let us commence this problem as we began the others; namely, Through
the center of axle _C_, Fig. 25, draw the horizontal line _AD_, also
the vertical line _LK_. Find the position of crank at half stroke, as
shown in Fig. 21. Next find the position of center line of motion _CT_,
and position of rocker, as shown in Fig. 22. Find the relative position
of eccentrics and crank when at half stroke, as shown in Fig. 23.
Now, with a radius equal to the correct length of eccentric-rods,
previously determined (shown in Fig. 24), describe from the point ½_x_
as a center, the arc ½_xᵥ{1}_ ½_xᵥ{2}_; also with the point ½_y_ as a
center, and with the same radius, the arc ½_yᵥ{1}_ ½_yᵥ{2}_. Again,
from the point ½_a_ as a center, describe the arc ½_aᵥ{1}_ ½_aᵥ{2}_;
also with the point ½_b_ as a center, describe the arc ½_bᵥ{1}_
½_bᵥ{2}_, using the length of eccentric-rods as a radius for all the
arcs.
When the center of the forward eccentric is at ½_x_, the forward
eccentric-rod pin will be located in the arc ½_xᵥ{1}_ ½_xᵥ{2}_.
When the center of the forward eccentric is at ½_a_, the forward
eccentric-rod pin will be located in the arc ½_aᵥ{1}_ ½_aᵥ{2}_. When
the backward eccentric is at ½_y_, its eccentric-rod pin will be
located in the arc ½_yᵥ{1}_ ½_yᵥ{2}_. When the center of the backward
eccentric is at ½_b_, the eccentric-rod pin will be located in the arc
½_bᵥ{1}_ ½_bᵥ{2}_.
The next step is to find the relative position of the lower rocker-arm
pin when steam is cut off at half stroke.
[Illustration: FIG. 25_b_.]
In Fig. 8 (p. 274) we have placed the slide-valve centrally over the
ports, that is, it laps over each steam-port an equal amount, namely, ¾
of an inch, which is equal to the lap. In this position of the valve,
the center line of the upper rocker-arm will stand perpendicular to
the line drawn parallel to the valve-face, and the center line of the
lower rocker-arm will stand perpendicular to the center line of motion
_CT_: hence the center line of upper rocker-arm _MQ_ in Fig. 8 will
coincide with the line _MQ_ in Fig. 25, and the center of lower arm
_QU_ in Fig. 8 will coincide with the line _QU_ in Fig. 25.
Now let us follow the relative movement of the valve and piston. We
find, that, when the piston commences its backward motion, the valve
moves in the same direction, as shown by the arrow-points in Fig. 8_a_;
and, during the time that the piston is completing the half stroke,
the valve has finished its full travel backward, and commenced moving
forward, as indicated by the arrow-points, Fig. 8_b_; and, at the time
that the piston stands exactly at half stroke, the forward edge of the
valve is just closing the forward steam-port, and consequently cutting
off steam at half stroke when the piston is moving backward. From this
we see, that, when the piston has completed the half stroke when moving
backward, the center of the valve will be a little in the rear of the
center of exhaust-port; the distance between the center of valve and
the center of exhaust-port being ¾ of an inch, the amount of the lap:
the upper rocker-pin will stand ¾ of an inch behind the line _MQ_, and
the lower rocker-arm pin will be ¾ of an inch in front of the line
_QU_, as shown in Fig. 8_b_. We therefore draw in Fig. 25 a straight
line parallel to _QU_, and ¾ of an inch in front of it: this line will
intersect the arc _RS_ in the point ½_Fᵥ{3}_; and this point is the
position of the center of lower rocker-arm pin when the crank stands
at ½_F_, and steam cut off at half stroke. Let the piston complete
its backward stroke, and then commence moving forward towards half
stroke, as shown by the arrow-point, Fig. 8_c_. During this time the
valve has completed its full travel forward, and commenced traveling
backward, as indicated by the arrow-point, Fig. 8_c_; and, when the
piston stands exactly at half stroke, the rear edge of the valve is
just closing the rear steam-port, and consequently cutting off steam
at half stroke when the piston is moving forward. In this position the
center line of the valve will be ¾ of an inch in front of the center
of exhaust, the center of the upper rocker-arm pin will be ¾ of an
inch in front of the line _MQ_, and lower rocker-pin ¾ of an inch in
the rear of the line _QU_, as shown in Fig. 8_c_. We therefore draw in
Fig. 25 a line parallel to _QU_, and ¾ of an inch behind it; this line
will intersect the arc _RS_ in the point ½_Bᵥ{3}_; and this point will
be the position of the center of lower rocker-arm pin when the crank
stands at ½_B_, and steam cut off at half stroke. Now, remember, that
when the crank stands at ½_F_, Fig. 25, the forward eccentric will be
½_x_, and the backward eccentric at ½_y_; and, if the link is raised
or lowered while the eccentrics remain at ½_x_ and ½_y_, the forward
eccentric-rod pin will move in the arc ½_xᵥ{1}_ ½_xᵥ{2}_, and the
backward eccentric-rod pin will move in the arc ½_yᵥ{1}_ ½_yᵥ{2}_.
Let us now find the position of link when steam is cut off at half
stroke at either end of the cylinder.
The points ½_Fᵥ{3}_ and ½_Bᵥ{3}_ in Fig. 25 being located, place the
paper template on the drawing so that the point _f_ will lie in the
arc _xᵥ{1}xᵥ{2}_, and the point _fᵥ{2}_ in the arc _yᵥ{1}yᵥ{2}_, and
the link-arc _cᵥ{3}cᵥ{4}_ just touching the point ½_Fᵥ{3}_. While
the template is in this position, draw on the paper along the edge
_cᵥ{3}cᵥ{4}_ a portion of the link-arc, and mark the position that the
line _ee_ occupied, so that, when the template is removed, the line
_eᵥ{1}eᵥ{1}_ can be drawn on the paper to represent the line _ee_ of
the template. Next place the template so that the point _f_ will lie
in the arc ½_aᵥ{1}_ ½_aᵥ{2}_ the point _fᵥ{2}_ in the arc ½_bᵥ{1}_
½_bᵥ{2}_ and the link-arc _cᵥ{3}cᵥ{4}_ just touching the point ½_Bᵥ{3}_
and, while in this position, draw part of the link-arc _cᵥ{3}cᵥ{4}_ on
the paper, mark the position that the line _ee_ occupied, and, after
the template is removed, draw the line _eᵥ{2}eᵥ{2}_ on the paper to
represent the line _ee_ of the template. Now find by trial a point
_xᵥ{1}_ on the line _cᵥ{1}cᵥ{1}_, and another point _xᵥ{2}_ on the
line _eᵥ{2}eᵥ{2}_, so that the distances of these points from their
link-arcs are equal, and that a straight line drawn through them will
be parallel to the center line of motion.
The distance from _xᵥ{1}_ to the link-arc--or, which is the same
thing, the distance from the point _xᵥ{2}_ to the link-arc--will be
the correct distance between the center of saddle-pin and the link-arc
_cᵥ{1}cᵥ{2}_, Fig. 6_a_. Or, in other words, the position of the point
_xᵥ{1}_ or _xᵥ{2}_, Fig. 25, will indicate the proper position of the
point of suspension on the link. For future reference, let us mark this
point of suspension on the template, and indicate it by _X_, Fig. 6_b_.
[Illustration: FIG. 26.]
PROBLEM 6, FIG. 26.--_To find the position of the center of
lifting-shaft and the length of its arms._--In the last problem we
found the point of suspension of the link, so that it will cause the
valve to cut off equal portions of steam when the piston stands at half
stroke. It now remains for us to find the position of the lifting-shaft
and the length of the lifting-shaft arms, so that the greatest equal
amounts of steam will be admitted alternately at each end of the
cylinder. Here a little difficulty arises which needs explanation, so
that our construction may not seem inconsistent to the reader. It
would be an easy matter to place our lifting-shaft to accomplish the
object just stated; but, if we do this, the lead will not be equal
at each end of cylinder when the piston is at full stroke. Again, if
we locate our lifting-shaft in such a manner that equal lead will
be obtained, then the maximum cut-off will not be equal; but the
difference will be comparatively so small that it will not injure the
working of the engine. This small difference of the maximum cut-off is
therefore considered among practical men of little or no importance,
but it is always considered good practice to have an equal lead at full
stroke. Let us therefore adjust the lifting-shaft to obtain an equal
lead, and allow us to consider the maximum cut-off to be equal when the
lead is equal at full stroke.
For this problem we have to combine all the foregoing problems. Through
the center _C_ of axle draw the horizontal line _AD_, and the line
_KL_ perpendicular to it. Find the positions of crank at full and half
stroke, as per Problem 1. Locate the rocker, draw the center line of
motion _CT_, and amount of offset in lower rocker-arm, according to
Problem 2. Next, locate the relative positions of eccentrics when
the crank stands at full and half stroke, as explained in Problem 3.
Then with a radius equal to the correct length of eccentric-rods, as
explained in Problem 4, draw
From the point _x_ as a center, the arc _xᵥ{1}_ _xᵥ{2}_
” ” _y_ ” ” ” _yᵥ{1}_ _yᵥ{2}_
” ” ½_x_ ” ” ” ½_xᵥ{1}_ ½_xᵥ{2}_
” ” ½_y_ ” ” ” ½_yᵥ{1}_ ½_yᵥ{2}_
” ” _a_ ” ” ” _aᵥ{1}_ _aᵥ{2}_
From the point _b_ as a center, the arc _bᵥ{1}_ _bᵥ{2}_
” ” ½_a_ ” ” ” ½_aᵥ{1}_ ½_aᵥ{2}_
” ” ½_b_ ” ” ” ½_bᵥ{1}_ ½_bᵥ{2}_
From the point _b_ as a center, the arc _bᵥ{1}_ _bᵥ{2}_
” ” ½_a_ ” ” ” ½_aᵥ{1}_ ½_aᵥ{2}_
” ” ½_b_ ” ” ” ½_bᵥ{1}_ ½_bᵥ{2}_
Locate the points ½_Bᵥ{3}_ and ½_Fᵥ{3}_, indicating the position of
the center of lower rocker-pin when steam is cut off at half stroke;
find the points _xᵥ{1}xᵥ{2}_ indicating the positions of the point of
suspension when the link is lifted into the position to cut off at half
stroke, as explained in Problem 5, and shown in Fig. 25.
Now, in order to find the position of lifting-shaft and length of arms,
we must find four more additional points,--first, the position of the
point of suspension of the link when the piston is at full stroke
forward end of cylinder, and the crank-pin at _F_, the valve having
1/16 of an inch lead, and the engine moving forward, as indicated by
the arrow-point 1; also the position of the point of suspension of
the link when the piston is at full stroke at the opposite end of the
cylinder, valve 1/16 inch lead, and engine going in the same direction.
To find these two points, we must know the corresponding position of
the center of lower rocker-pin. In Fig. 8_a_ we see, that when the
piston is at full stroke forward, and valve with 1/16 inch lead, the
center of valve is 13/16 of an inch in the rear of the center line of
exhaust, and consequently the lower rocker-pin will be 13/16 of an inch
in front of the line _QU_. In the same manner we can show that the
center of lower rocker-pin will be 13/16 of an inch in the rear of the
line _QU_ when the piston is at the opposite end of the cylinder.
Let us now locate the positions of the lower rocker-pin in Fig. 26,
by drawing a line parallel to and in front of _QU_, with 13/16 of an
inch between them: this line will intersect the arc _RS_ in the point
_Fᵥ{3}_, and this point will be the center of lower rocker-pin when the
piston is at full stroke forward. Draw another line 13/16 of an inch in
the rear of _QU_ and parallel to it: this line will intersect arc _RS_
in the point _Bᵥ{3}_, and this point will be the center of rocker-pin
when the piston is at full stroke in the rear end of the cylinder.
Now place the paper template with the line _ee_ below the center line
of motion _CT_, the point _fᵥ{1}_ on the arc _xᵥ{1}xᵥ{2}_, the point
_fᵥ{2}_ on the arc _yᵥ{1}yᵥ{2}_, and the link-arc _cᵥ{3}cᵥ{4}_ just
touching the point _Fᵥ{3}_, and, while in this position, mark the point
_X_ of the template on the paper, which can be done with the aid of
a needle, and indicate the point on the paper by _xᵥ{3}_. This point
will be the position of the center of saddle-pin when the piston is at
full stroke in the forward end of the cylinder, the valve having 1/16
inch lead. Again, slide the template along until the point _fᵥ{1}_ is
on the arc _aᵥ{1}aᵥ{2}_, the point _fᵥ{2}_ on the arc _bᵥ{1}bᵥ{2}_,
and the link-arc _cᵥ{3}cᵥ{4}_ in contact with the point _Bᵥ{3}_; mark
the point _X_ of the template on the paper, and indicate this point by
_xᵥ{4}_. This point will be the position of the center of saddle-pin
when the piston is at full stroke in the rear end of the cylinder, the
valve having 1/16 inch lead. Secondly, to find the position of the
point of suspension of the link when the piston is at full stroke in
the forward end of the cylinder, valve having 1/16 of an inch lead, and
the engine moving backward, as indicated by the arrow-point 2; also the
position of the point of suspension of the link when the piston is at
full stroke at the opposite end of the cylinder, valve 1/16 of an inch
lead, engine going in the same direction. For this purpose, slide the
template along until the line _ee_ is above the line _CT_, and _fᵥ{1}_
in the arc _aᵥ{1}aᵥ{2}_, the point _fᵥ{2}_ in the arc _bᵥ{1}bᵥ{2}_, and
the link-arc _cᵥ{3}cᵥ{4}_ in contact with the point _Bᵥ{3}_; mark the
point _X_ on the paper, and indicate this point by _xᵥ{5}_. This point
will be the position of the center of saddle-pin when the piston is at
full stroke in the rear end of the cylinder, valve having 1/16 of an
inch lead. Again, slide the template along until the point _fᵥ{1}_,
will be in the arc _xᵥ{1}xᵥ{2}_, point _fᵥ{2}_ in the arc _yᵥ{1}yᵥ{2}_,
and the link-arc _cᵥ{3}cᵥ{4}_ in contact with the point _Fᵥ{3}_; mark
the point _X_ on the paper, and indicate this point by _xᵥ{6}_. This
point will be the position of the center of saddle-pin (or the point of
suspension) when the piston is at full stroke in the forward end of the
cylinder, valve 1/16 of an inch lead, engine moving backward. Now, once
more, with the point _xᵥ{3}_ as a center, and with the length of the
link-hanger as a radius, describe an arc; and with the point _xᵥ{4}_
as a center, and the same radius, describe another arc. These two arcs
will intersect each other in the point _g_. Again, with the length of
the link-hanger as a radius, and the points _xᵥ{1}xᵥ{2}_ as centers,
describe two arcs intersecting each other in the point _gᵥ{1}_, with
the points _xᵥ{5}xᵥ{6}_ as centers; and, with the same radius, describe
another two arcs intersecting each other in the point _gᵥ{2}_. Lastly,
through the points _g_, _gᵥ{1}gᵥ{2}_, draw an arc. The center _h_,
from which the arc has been described, will be the center of the
lifting-shaft, and the radius _hg_ or _hgᵥ{2}_ will be the length of
the lifting-shaft arms; that is, the length of the two arms to which
the link-hangers are attached: the length of the other lifting-shaft
arm, to which the reach-rod is attached, is made to suit the other
details of the engine.
When the admittance of steam ceases at the same time that the piston
has reached the half stroke, the practical man would say “that the
valve is cutting off equal at half stroke.” When the greatest equal
volume of steam is admitted alternately in each end of the cylinder,
the valve is said to be cutting off equal when the link is in full gear.
It is always conceded among engineers, that when the link-motion is
adjusted to cut off equal at half stroke, and also to cut off equal
when the link is in full gear, equal volumes of steam will be admitted
alternately when the link hangs at any intermediate point.
If, now, we examine Problem 5, we find, that, to obtain an equal
cut-off at half stroke, it is necessary to find the proper position of
saddle-pin.
Again, if we examine Problem 6, we find, that, in order to obtain an
equal cut-off when the link is in full gear, also an equal cut-off for
any point between full gear and half stroke, we have to determine the
proper position of the center of lifting-shaft and the correct length
of its arms.
Lastly, if we examine the first four problems, we find them simply to
be preparatory problems.
According to promise, we will draw attention to those points which have
been, and others which have not been, approximately found. Problems 1,
2, and 3 are theoretically correct. In Problems 4, 5, and 6, the use
of the template will not be admitted for theoretical reasoning; but,
if the construction is made with absolute accuracy, the result will be
theoretically correct.
* * * * *
The following are a few dimensions of locomotives made by well-known
makers:--
DIMENSIONS OF LOCOMOTIVES
============================+=================================
| BALDWIN.
+-----------+-------+-------------
| Standard | Mogul |Consolidation
| Passenger |Engine.| Engine.
| Engine. | |
----------------------------+-----------+-------+-------------
| | |
| Inches. |Inches.| Inches.
Dimensions of cylinders | 17 × 24 |18 × 24| 20 × 24
Length of steam-ports | 16 | 16 | 16
Width of steam-ports | 1¼ | 1¼ | 1¼
Width of exhaust-port | 2½ | 2½ | 2½
Throw of eccentrics | 5 | 5 | 5
Travel of valve | 5⅜ | 5⅜ | 5⅜
Outside lap of valve | ¾ to ⅞ | ¾ | ¾
Inside lap of valve |1/32 to ⅛ | 1/32 | 1/32
Distance between center of | | |
axle and center of rocker | 56 | 46 | 81
Length of upper rocker-arm, | 10½ | 10½ | 10½
Length of lower rocker-arm, | 9½ | 9½ | 9½
Length of link | 55 | 46 | 81
Length of link-hanger | 13½ | 15 | 15
Length of tumbling-shaft | | |
arm | 17 | 16 | 16
Length of connecting rod | 75 | 80 | 114½
Distance between centers of | | |
eccentric-rod pins | 11-9/16| 10½ | 10¾
Suspension of link back of | | |
link-center | ⅜ | 11/16 | 1
Lead of valve in full gear | 1/16 | 1/16 | 1/16
Lead of valve in center | ¼ | 1¼ | ¼
============================+===========+=======+=============
DIMENSIONS OF LOCOMOTIVES--_Continued_.
============================+=================================
| BROOKS.
+-----------+-------+-------------
| Standard | Mogul |Consolidation
| Passenger |Engine.| Engine.
| Engine. | |
----------------------------+-----------+-------+-------------
| | |
| Inches. |Inches.| Inches
Dimensions of cylinders | 18 × 24 |18 × 24| 20 × 24
Length of steam-ports | 16 | 15 | 16
Width of steam-ports | 1⅛ | 1⅛ | 1¼
Width of exhaust-port | 2½ | 2½ | 2½
Throw of eccentrics | 5 | 4½ | 5
Travel of valve | 5 | 5 | 5½
Outside lap of valve | ¾ | ⅜ | 13/16
Inside lap of valve | 1/64 | 1/64| 1/64
Distance between center of | | |
axle and center of rocker | 65 | 50 | 40
Length of upper rocker-arm, | 10½ | 9¾ | 10½
Length of lower rocker-arm, | 10½ | 8¾ | 9½
Length of link | 65 | 50 | 40
Length of link-hanger | 13 | 13½ | 15¼
Length of tumbling-shaft | | |
arm | 17⅜ | 18 | 16
Length of connecting rod | 96 | 84 | 77
Distance between centers of | | |
eccentric-rod pins | 11 |11-3/16| 11
Suspension of link back of | | |
link-center | ⅜ | ⅜ | ⅜
Lead of valve in full gear | 1/10 | 1/10| 1/10
Lead of valve in center | ⅜ | ⅜ | ⅜
============================+===========+=======+=============
DIMENSIONS OF LOCOMOTIVES--_Continued_.
============================+===========+=======+=============
| GRANT.
+-----------+-------+-------------
| Standard | Mogul |Consolidation
| Passenger |Engine.| Engine.
| Engine. | |
----------------------------+-----------+-------+-------------
| Inches. |Inches.| Inches.
Dimensions of cylinders | 17 × 24 |18 × 24| 20 × 24
Length of steam-ports | 16 | 16 | 16
Width of steam-ports | 1¼ | 1¼ | 1¼
Width of exhaust-port | 2½ | 2½ | 2½
Throw of eccentrics | 5 | 5 | 5½
Travel of valve | 5 | 5¼ | 5
Outside lap of valve | ¾ | ⅞ | ⅞
Inside lap of valve | None. | 1/16| 1/16
Distance between center of | | |
axle and center of rocker | 68-11/16| 40 | 80
Length of upper rocker-arm, | 10¼ | 9⅞ | 9⅞
Length of lower rocker-arm, | 10¼ | 8½ | 10½
Radius of link | 63 | 39⅜ | 80
Length of link-hanger | 12¾ | 14 | 12¾
Length of tumbling-shaft | | |
arm | 17 | 16 | 14
Length of connecting rod | 85 | 69½ | 112
Distance between centers | | |
of eccentric-rod pins | 12 | 12 | 12
Suspension of link back of | | |
link-center | ⅜ | ⅜ | 1-3/16
Lead of valve in full gear | 1/32 | 1/32| 1/32
Lead of valve in center | 5/16 | ⅜ | ¼
============================+===========+=======+=============
DIMENSIONS OF LOCOMOTIVES--_Continued_.
============================+===========+=======+=============
| PITTSBURG.
+-----------+-------+-------------
| Standard | Mogul |Consolidation
| Passenger |Engine.| Engine.
| Engine. | |
----------------------------+-----------+-------+-------------
| Inches. |Inches.| Inches.
Dimensions of cylinders | 17 × 24 |18 × 24| 20 × 24
Length of steam-ports | 15 | 16 | 18
Width of steam-ports | 1¼ | 1¼ | 1¼
Width of exhaust-port | 2½ | 2½ | 2½
Throw of eccentrics | 5 | 5 | 5
Travel of valve | 5 | 5½ | 5-7/16
Outside lap of valve | ⅞ | ¾ | ¾
Inside lap of valve | ⅛ | 1/32| 1/32
Distance between center of | | |
axle and center of rocker | 56 | 48 | 28
Length of upper rocker-arm, | 11 | 11¾ | 11¾
Length of lower rocker-arm, | 11 | 10¾ | 10¾
Radius of link | 56 | 48 | 80
Length of link-hanger | 14½ | 18¾ | 18½
Length of tumbling-shaft | | |
arm | 18 | 15 | 15
Length of connecting rod | 88 | 85 | 114½
Distance between centers | | |
of eccentric-rod pins | 12 | 12 | 12
Suspension of link back of | | |
link-center | ⅜ | ⅜ | 9/16
Lead of valve in full gear | 1/10 | 1/10| 1/10
Lead of valve in center | 5/16 | 11/32| ¼
============================+===========+=======+=============
DIMENSIONS OF LOCOMOTIVES--_Continued_.
============================+===========+=======+=============
| SCHENECTADY.
+-----------+-------+-------------
| Standard | Mogul |Consolidation
| Passenger |Engine.| Engine.
| Engine. | |
----------------------------+-----------+-------+-------------
| Inches. |Inches.| Inches.
Dimensions of cylinders | 17 × 24 |19 × 24| 20 × 24
Length of steam-ports | 16 | 16 | 16
Width of steam-ports | 1¼ | 1¼ | 1¼
Width of exhaust-port | 2½ | 2¾ | 2¾
Throw of eccentrics | 5¼ | 5¼ | 5¼
Travel of valve | 5½ | 5½ | 5½
Outside lap of valve | ⅞ | ¾ | ¾
Inside lap of valve | 1/32 | 1/32| 1/32
Distance between center of | | |
axle and center of rocker | 63 | 54 | 45
Length of upper rocker-arm, | 11 | 10¾ | 11
Length of lower rocker-arm, | 10 | 9¾ | 10
Radius of link | 63 | 54 | 45
Length of link-hanger | 13 | 16½ | 16½
Length of tumbling-shaft | | |
arm | 16 | 16 | 16
Length of connecting rod | 92½ | 90½ | 79½
Distance between centers | | |
of eccentric-rod pins | 12 | 12 | 12
Suspension of link back of | | |
link-center | ⅞ | ⅞ | ⅜
Lead of valve in full gear | 1/16 | 1/16| 1/16
Lead of valve in center | 5/16 | 5/16| 5/16
============================+===========+=======+=============
DIMENSIONS OF LOCOMOTIVES--_concluded_.
============================+===========+=======
| MASON.
+-----------+-------
| Standard | Mogul
| Passenger |Engine.
| Engine. |
----------------------------+-----------+-------
| Inches. |Inches.
Dimensions of cylinders | 18 × 24 |19 × 24
Length of steam-ports | 17 | 18
Width of steam-ports | 1¼ | 1¼
Width of exhaust-port | 2½ | 2½
Throw of eccentrics | 5 | 5
Travel of valve | 5 | 5
Outside lap of valve | ¾ | ¾
Inside lap of valve | 1/64 | 1/32
Distance between center of | |
axle and center of rocker | 38 | 49½
Length of upper rocker-arm, | 9 | 9
Length of lower rocker-arm, | 9 | 9
Radius of link | 58 | 49½
Length of link-hanger | 10 | 10
Length of tumbling-shaft | |
arm | 20 | 20
Length of connecting rod | 91-3/16 | 84
Distance between centers | |
of eccentric-rod pins | 12 | 12
Suspension of link back of | above
link-center | 3⅜ | 3⅜
Lead of valve in full gear | 1/16 | 1/16
Lead of valve in center | 5/16 | 5/16
============================+===========+=======
CHAPTER XXI.
_THE STEVENS VALVE-GEAR._
DESCRIPTION OF MOTION
This motion has been designed by A. J. Stevens, General Master
Mechanic, Central Pacific Railroad, to overcome the well-known
objections to the link-motion,--viz., letting the steam escape early in
the stroke when the engine is running hooked up; also, the closing of
the exhaust-port early, leading to excessive compression. The motion is
developed from the Walschaert motion, well known in Europe, and applied
to some extent to narrow-gauge engines in this country.
ARRANGEMENT OF THE MOTION
[Illustration: FIG. 27.]
In the Stevens motion two valves are employed, one at each end of the
cylinder, as can be seen in Fig. 27. The valves have supplementary
passages for steam and exhaust, being an improvement on the Allen
valve. Valves without the supplementary exhaust-port have been designed
by Mr. Stevens for his engines, and they are shown in two positions
in the supplementary figures 2 and 3 [p. 288]. These valves closely
resemble the Allen valve; but, in operating, steam is admitted to, and
exhausted from, the cylinder through the same passage. This arrangement
provides double area of admission and double area for exhaust
steam,--an important consideration, especially with high piston speed.
VALVE MOVEMENT
The valves are actuated by two motions,--one taken from a single
eccentric, the other derived from a connection with the cross-head. The
single eccentric is used to give both forward and backward motion, and
is set in the proper angle to the crank to produce motion in either
direction. For reversing the motion of the valve, a curved rocker-arm
_R_ (Fig. 27) is used, on which moves a sliding-block _r_. Attached to
the sliding-block is the link _H_, which connects with the lap-and-lead
lever _D_. The lower end of this lever is attached by the link _d_ to
the cross-head, from which the lever receives an oscillating motion.
This lever is suspended by a hanger from any convenient part of the
engine. Projecting from one side of the lap-and-lead lever are two
pins, to which are connected the valve-stem rods _m_ and _n_. These
pins are set upon the lever at points between 90 and 180 degrees apart,
so as to give a differential movement to the valve, which can not be
obtained when the pins are set opposite on the lever.
VALVE-STEMS AND STUFFING-BOXES.
Each valve has its own rod, and separate connection with the lever.
In most instances the stem of the back valve is made hollow, and the
stem of the forward valve is passed through it, so as to avoid the use
of more than one stuffing-box upon the steam-chest; but in several
instances they have been fitted up with two stuffing-boxes, the
separate valve-stems working side by side.
HOW MOVEMENT OF VALVE IS GOVERNED.
The valve being coupled up by independent rods to the lap-and-lead
lever, they will move together, and in the same general direction, from
the action of the eccentric. But besides this movement, common to both,
each valve is controlled and acted on by the angular position of the
two pins, which results from the rotary or oscillating movement of the
lap-and-lead lever upon its center; and each valve, instead of having
a uniform rate of travel, has a variable movement. The degree of this
variable movement is governed, both by the distance of the pins from
the center upon which the lever works and the length of the lever, and
can be increased or diminished by changing the position of one or the
length of the other in construction. The horizontal movement of the
valve received from the lap-and-lead lever while the same is at mid
travel, is very slight, while the piston or the cross-head is traveling
very rapidly. By this slow movement of the valve, steam is retained
in the cylinder until the piston has nearly completed its stroke;
and, on the other hand, the exhaust is kept open. As the cross-head
approaches either end of the stroke, the action of the valves is very
much accelerated, receiving, as they do, their motion from the combined
action of the lap-and-lead lever and the eccentric.
HOW EXHAUST LEAD IS CONTROLLED.
The exhaust lead is controlled by the pin in the lap-and-lead lever,
which is on the center, or horizontal, when the cross-head is at either
end of the cylinder. The steam lead is controlled by the pin that is
vertical, or above the center of the lap-and-lead lever, when the
cross-head is at either end of the stroke. Both steam and exhaust
lead are uniform at all points of cut-off. By this arrangement of the
valve-gear and valves, steam can be cut off at any point of the stroke
(by moving the sliding-block toward the center of the rocker-arm), and
is retained, if desired, to the last inch of the stroke. In receiving,
the steam is evenly distributed at all points of the cut-off.
There are about as many pieces to this gearing as to the ordinary
link-gear; but it is considerably cheaper in construction, and much
more durable; while it does away with two eccentrics, and their straps
and connections.
CHAPTER XXII.
_THE JOY VALVE-GEAR._
DESCRIPTION OF MOTION.
In this form of valve-gear, eccentrics and their equivalents are
entirely dispensed with. The motion for the valve is taken direct from
the connecting rod; and by utilizing independently the backward and
forward action of the rod, due to the reciprocation of the piston,
and combining this with the vibrating action of the rod up and down,
a movement results which is employed to actuate the valves of engines
using any combination of lap and lead desired, and giving an almost
mathematically correct cut-off for both sides of the piston for forward
and backward motion, and for all points of expansion intermediately.
The general outline of the motion can be understood by an examination
of Fig. 28, which gives three views of the gear. The sub-figures 1,
2, and 3 show the motion in elevation, plan, and transverse section
respectively.
[Illustration: FIG. 28.]
HOW TO APPLY THIS GEAR TO AMERICAN LOCOMOTIVES.
To apply this gear, the valve and steam-chest are placed, as is usually
the case in American locomotives, over the cylinders; the valve-stem
center being, however, in the same vertical plane as the cylinder
center line, immediately over it. All the valve-motion is thus
arranged on this plane,--perfectly central,--and there are no crooked
or side strains. To a point _A_ on diagram, about two-fifths along
the connecting rod from the piston end, a small hook-link is pinned.
From the lower end of this at _D_ is jointed a lever _E_, which, of
course, moves with the connecting rod both backward and forward, and up
and down; the point _D_, in fact, moving in a very irregular ellipse,
hereafter explained. The fulcrum _F_ of the lever _E_ is carried in
a block which slides in a slot-link _JK_, and from the upper end of
this lever _E_ the valve-stem rod _G_ is carried to the valve. This
slot-link _JK_ is centered so as to be able to be inclined from the
vertical either way. When standing in the vertical position, the engine
is in mid-gear, and the valve will only be opened for lead; but this
will be exact for each end, and exact also on either side of the center
line of the connecting rod. When the slot-link is inclined forward to
the front of the engine, the engine is in full gear forward; and, when
inclined backwards, it is in full gear for going back. Placed in any
intermediate position, the cut-off is regulated for any required degree
of expansion; the front and back of the piston receiving equal cut-off,
or equal amounts of steam.
CONSTRUCTION DIRECTIONS.
In laying out this valve-motion, it is necessary to make the center
or fulcrum _F_ of the lever _E_ coincide, when the crank is at either
extreme stroke, with the center on which the slot-link _JK_ vibrates:
then these two centers coinciding when the engine stands at lead (that
is, at either end of the stroke), the slot-link _JK_, which is, in
fact, the reversing agent, may be put forward or backward through all
degrees, without moving the valve, which thus has constant lead at all
grades of expansion.
If, however, it is desired to give increasing or decreasing lead in
the grades of expansion, this may be given by varying the coincidence
of these two centers accordingly, or by under-correcting or
over-correcting the action of the lever _E_, by varying the position of
_D_ on the link _B_.
HOW LAP AND LEAD ARE REGULATED.
The lap and lead together are dependent on the distance between the
center _F_ of lever _E_, and the center from which the motion is taken
for the valve.
ADVANTAGES CLAIMED FOR THE MOTION.
The first advantage claimed for Joy’s valve-gear over the link-motion
is, that it is considerably less costly, and that the working-parts are
lighter. The saving is not only in weight, however, but also in the
greater simplicity of parts, allowing increased facility for tooling
and fitting.
It may be needless to point out how readily this valve-motion is
adaptable to the requirements of the typical American locomotive,
considerably simplifying the present form of valve-motion, by
dispensing with the eccentrics and other working-parts, and bringing
the gear with all its strains into a direct line, and also leaving
the whole of the under part of the engine clear, and permitting a
considerable extension of the fire-box,--a most valuable feature.
All the parts are such that they can be readily made by machinery,
dispensing with hand labor except in putting them together.
ACTION OF THE MOTION.
The action transmitted to the valve is altogether different from that
transmitted by the link-gear, as by this gear it results from the two
distinct motions of the connecting rod imparted to the lever _E_; and
these two motions work variously, with and against each other, thus
giving to the valve a resultant motion somewhat partaking of the nature
of that produced by cams, it really being an accelerated and retarded
motion; these accelerations and retardations being so arranged as to
come at the right time on the revolution to give the desired result.
Thus, as the crank is passing over the center, the lever _E_ is not
affecting the valve at all as a lever, but the motion imparted to
the valve is due to the center of _E_ slipping down the curve of the
slot-link _J_; and this gives a smart opening of the lead with a
continued smart opening of the port. When the valve is fully open, as
the crank travels on, the lever _E_ has commenced acting on the valve;
but its center is still sliding down the slot-link _JK_; and the two
movements are opposite and destroying, or partially destroying, each
other, producing a retardation of the valve-motion almost amounting to
an arrest; and thus is given a nearly straight line on a valve-path
diagram where the port is kept fully open, the crank still traveling
on, and approaching the time for the cut-off to be effected. The
lever _E_ is in the best position to act as a lever at the same time
that its center is completing its movement in the slot _JK_, and is
commencing to return, being practically still: thus the lever action
of _E_, having full effect, rapidly closes the port. And so on for the
revolution, the time of release also getting its benefit.
RULES FOR LAYING DOWN THE CENTER LINES OF THE MOTION.
[Illustration: FIG. 29.]
Lay down the center line _aa_ (Fig. 29) of the cylinder, and that of
the valve-stem _bb_, at the relative distances required for the engine
to which the application is to be made; the valve-stem center line
being, however, in the plane of the vibration of the connecting rod.
Draw the path of the crank-pin, and the center lines of the connecting
rod _cc_^1_c_^1 for both upper and lower positions when the piston is
at half stroke. Take a point _d_ on the center line of the connecting
rod, where its vibration between _d_^1 and _d_^2 is equal to about
double the length of the full stroke of the valve (it is better to
allow rather more than less). It may, however, be chosen very much to
suit the other arrangements of the engine, such as the position of the
guides, brackets, etc., getting, however, if possible, a vibration
of the connecting rod fully equal to double the stroke of the valve,
to avoid too great an angle of the slide-link when put over for full
forward or backward gear.
Having chosen the point _d_, draw a vertical line _zz_ through it and
at right angles to _aa_, and mark off the two points _e_, _e_, on
each side, these being the extreme positions of the point _d_ on the
connecting rod for front and back stroke; from these points draw lines
to a point _f_ on the vertical, so far down that the angle between them
shall not be more than 90°,--less is better, if there is room to allow
of it (these will represent the center lines of the first link pinned
to the connecting rod). The point _f_, which will rise and fall with
the vibration of the connecting rod, is to be controlled as nearly as
may be on the vertical line by a link pinned forward near the cylinder
at _f_^1, or, if more convenient, it can be pinned backward.
Next, on the valve-stem center line _bb_, mark off on each side of
the vertical _zz_ the amount required for lap and lead together, at
_g-g_^1 and _g-g_^2; _g-g_^1 being lap and lead for the front end of
the cylinder, and _g-g_^2 being lap and lead for the back end of the
cylinder. Then, assuming the piston to be at the front of the cylinder,
and the centers of the connecting rod to be at _hh_^1 (_h_ being the
crank-pin), the point _d_, which we have chosen to take motion from,
will be at _e_^1, and the link pinned to the connecting rod, for
transmitting motion to the valve, will be at _e_^1 _f_. From a point
on this link, which has at first to be assumed, say at _j_ (which will
be about the half vibration of the connecting rod; that is, _d_^1 to
_d_), draw the center line of the lever actuating the valve, that is
joining _j_ and _g_; the point where this line crosses the vertical
_zz_, will be the center or fulcrum of the lever, and will also be the
center of oscillation of the curved links in which the blocks carrying
the center of the lever slide; this center is marked _m_. The function
of the link _e_^1 _f_, and the attachment of the valve-lever to it at
_j_, is to eliminate the error in vibration of the lever, center _m_,
which would otherwise arise from the arc passed through by the lower
end of that lever. Although the position of the point _j_ may be found
by calculation, it is much more quickly found by a tentative process;
and, to test it the assumed point _j_ be the correct one, we mark
off on each side of _m_, vertically, the correct vibration required,
_n_^1 _n_^2, which will be the same as the vibration of the connecting
rod on the vertical line _zz_. Then apply the distance _e_^1--_j_ to
_d_^1--_j_^1 and _d_^2 _j_^2. Then, if the length _jm_ be applied to
_j_^1 _n_^1 (measuring from _j_^1), and to _j_^2 _n_^2 (measuring from
_j_^2), and the point _m_ fall below _n_^1 _n_^2 in each case, it will
be necessary to take a point on _e_^1 _f_ higher than _j_; or if, on
the other hand, _m_ falls above _n_^1 _n_^2, then a point must be taken
on _e_^1 _f_ lower than _j_. This point will generally be found on a
second trial.
The point _m_, as said, now represents the center of oscillation for
the links and the center or fulcrum of the lever. And these must
coincide, when the piston is at each end of the stroke, the lead being
then fixed; and the links can be pulled over from forward to backward,
or any point of expansion, without altering the lead. This may be taken
as a test of the gear being set out correctly.
The point _g_ will be the point of attachment for the valve-stem link,
which may be made any convenient length; but, from that length as a
radius, the curve of the links must be drawn from a center _m_^1 on the
parallel line _m_-_m_^1; the angle at which this curve is set from the
vertical (which is mid-gear), will give forward or backward gear,--the
angle leaning forward _s_^1, or to the front of the engine, being
forward gear, and the reverse _s_^2 being backward gear. The amount of
the angle, marked on the curve of extreme vibration at _s_-_s_^1 or
_s_-_s_^2, will be equal to one-quarter more than the full opening of
the port at that angle (that is, if 1″ opening of port is required,
then the amount of angle _s_ to _s_^1 must be 1¼″), and the point of
cut-off will be about 75 per cent. Laid out in this form, the leads and
cut-offs for both ends of the cylinder, and for backward and forward
going, will be practically perfect and equal, and the opening of ports
also as near as possible equal. If a longer cut-off than 75 per cent
is required, it is only necessary to increase the angle of the curve
_oo_ beyond _s^1_ for forward gear, or beyond _s^2_ for backward gear.
It will be noticed, that, in this gear, the lap and lead are entirely
dependent on the action of the lever _j_, _m_, _g_, as a lever, and may
be varied according to the length of _mg_. And the opening of the port
(beyond the amount given as lead) is dependent on the amount of angle
imparted to the curved link _oo_, and will be, as above said, about
four-fifths of the amount of that angle from the vertical measured on
the line of extreme vibration.
Deviations from the above positions and proportions may be made without
materially altering the correctness of the results.
Thus, if it is found necessary to raise or lower the center _m_, to
clear wheels, frames, or other gear, this may be done till the angle of
_mm^1_ is out of the parallel of the cylinder center line up or down by
one in thirteen (1 in 13); it is not well to go beyond this; but the
lines _mm^1_ and _bb_ will be parallel, and the position of the curve
_oo_ for mid-gear will be at right angles to _mm^1_.
Again, the point _e^1_ may be taken either above or below the center
line of the connecting rod, if it be wished to avoid piercing the rod;
the pin at _e^1_ being carried in a small bush or block attached above
or below the connecting rod.
Again, for locomotives, if the wheels are so small that the link _e^1f_
would come too low, it may be cut short at the point _j_, and this
point connected by a link _ll_ to a small return-crank _p_, on the
crank-pin; the movement of the counter-crank being equal to that from
to _j^4_.
The diagram is drawn for an engine where the center of the crank-axle
is on the center line of the cylinder; but if this be below, as is
usual in American locomotives, then the base line on which to construct
the diagram of the valve-gear itself will be the average center line
assumed by the connecting rod for such lowering of the crank-axle
center, drawn from _c_, the middle position, to a point, say _r_,
representing the lowered center of the axle. The vertical _zz_ will be
at right angles to this new base line _cr_, all the other processes
following.
While the proportions shown on the diagram give the best average
results, these proportions may be varied within very wide limits,
according to the requirements of the design of the engine. Thus,
when the distance between the center of the cylinder and center of
valve-stem is small, as with a small cylinder and a long stroke, the
link _e^1f_ may be considerably lengthened: the point _j_ will thus
be dropped, and convenient angles for all the links, etc., will be
maintained, the room for the various movements being got below the
center line of the cylinder when it can not be had above; the reverse
proportioning of the parts being made when the conditions are reversed,
as with a large diameter of cylinder and a short stroke.
This system of laying out the motion, applies, with a few
modifications, to the Strong motion, and to all others where the
ellipse formed by the horizontal and vertical motion of the main rod is
used to actuate the valves.
CHAPTER XXIII.
_THE STEAM ENGINE INDICATOR._
PURPOSE OF THE INDICATOR.
In the course of these pages, reference has several times been made
to the indicator. This instrument is of great service to the steam
engineer in helping him to determine with accuracy questions of steam
distribution, that, without its aid, would remain in the realms of
speculation. Its diagram presents a reliable record of what is going on
inside the cylinders of a steam engine; and master mechanics who desire
to run their engines economically, can not afford to dispense with the
accurate information imparted by the indicator respecting individual
locomotives.
DESCRIPTION OF INSTRUMENT.
The indicator consists essentially of a small steam cylinder, whose
under side is connected by pipes to the main cylinder of the engine
under inspection. Inside the indicator cylinder is a nicely fitting
piston, whose upward movement is resisted by a spring of known
strength. The piston-rod passes up through the top of the indicator
cylinder; and its extremity is connected with mechanism for operating a
pencil, and marking on a card a diagram whose lines coincide with the
movement of the indicator piston.
OPERATION OF THE INDICATOR.
[Illustration: FIG. 30.]
[Illustration: FIG. 31.]
Fig. 30 is a perspective view of the Tabor indicator, an instrument
well adapted for application to high-speed engines, such as the
locomotive. In Fig. 31 the indicator is shown in section. The
construction of the instrument can be well understood from a careful
examination of these figures. In the sectional figure, the piston is
seen with its rod encircled by the spring passing up through the top
of the cylinder, and connecting with the lever which operates the
marking-pencil. By ingeniously designed mechanism, the lever is made
to move the pencil in a perfectly straight vertical line. The card to
be marked is fastened in the paper drum attached to the indicator.
This drum receives a circular motion from a cord which is operated by
the cross-head, and this connection is so arranged that the drum will
begin to move round just as the main piston begins its stroke. The
circular motion of the drum is continued till the piston reaches the
end of its stroke, when the drum reverses its movement, and returns
to the exact point from whence it started. Now the indicator cylinder
being in communication with the main cylinder, when the latter begins
to take steam, the pressure will be applied to the indicator piston,
which is pushed upward, at the same time transmitting its movement to
the pencil. The indicator piston will rise and fall in accordance with
the steam-pressure in the cylinder; and, the circular movement of the
drum coinciding with the cross-head movement, the pencil will describe
a diagram which represents the pressure inside the main cylinder at the
various points of the stroke.
LINES OF THE DIAGRAM.
[Illustration: FIG. 32.]
Fig. 32 represents an indicator diagram, such as might be taken from
a locomotive with well-constructed valve-motion cutting off steam at
about one-third of the stroke. In the figure, the line _IJ_ represents
the line that would be drawn by the pencil when no steam is admitted
to the indicator piston; so it is called the atmospheric line. This is
the neutral line of the diagram representing the position of the pencil
when both sides of the indicator piston are exposed to the atmosphere:
hence it is the base line from which pressures either above or below
are measured. The line _AB_ is the admission line, so called because
its beginning _A_ represents the point where the valve begins admitting
steam to the cylinder: _BC_ is the steam-line, usually considered as
beginning at the point of positive change in direction of the admission
line. Admission of steam does not cease till the point _D_ is reached,
but wire-drawing begins at _C_. The curve _DE_ is the expansion line,
and is traced while the valve is closed, and previous to the opening
of the exhaust; the pressure falling by expansion. At _E_, release
begins, and the exhaust line extends to _F_; from _F_ to _G_ is the
line of counter-pressure, drawn during the return stroke of the piston
and while the exhaust is open; and _G_ to _A_ is the compression line,
drawn during the return stroke after the exhaust-valve has closed.
DATA NECESSARY FOR ANALYZING THE DIAGRAM.
In proceeding to ascertain from the diagram calculations of the work
done by the engine, it will be remembered that vertical measurements
represent pressures in the cylinder, and horizontal measurements
positions of the piston. To understand the language of the diagram
properly, it is necessary that several things having reference to
permanent or accidental conditions be known. Those absolutely necessary
are, the scale of the indicator spring, the diameter of the engine
cylinder and stroke of the piston, the strokes made per minute, and
the boiler pressure. It is also desirable to know the dimensions of
steam-pipes, steam-ports, and exhaust nozzles.
ADVANTAGES OF INDICATING LOCOMOTIVES.
The purposes for which the indicator can be advantageously applied
to locomotives, are to show the condition of the valves and pistons,
and to prove whether or not the steam is used properly within the
cylinders. By its use the amount of power developed by the cylinders
can be computed.
Were the indicator used daily on locomotives, much waste of coal now
going on through steam being lost by leaky valves and pistons would be
avoided. The graphic tale of the diagram would force out of practice
the ordinary habit of running engines with the steam throttled, and
indubitable proofs of ruinous back pressure would make contracted
nozzles intolerable.
There is not room in a work of this kind to give the necessary
information for those who wish to learn the operating of the indicator
and the analysis of the diagram. Engineers who are ambitious to enter
upon this line of study, should secure one of the standard books
treating the subject.
CHAPTER XXIV.
_THE WESTINGHOUSE AIR-BRAKE._
INVENTION OF THE WESTINGHOUSE ATMOSPHERIC BRAKE.
In this exacting age, the traveling public are much more disposed
to find fault with systems that do not provide against fatalities
resulting from human fallibility, than to commend the perfection of
appliances which annually save more lives than would be lost in a
sanguinary war. The Westinghouse brake has performed this life-saving
service, yet its great conserving merit has been but feebly appreciated
outside of railroad circles. During the decade between 1860 and
1870, America became a reproach among nations for the frequency and
disastrous nature of its railroad accidents. To-day fewer railroad
travelers in America lose their lives by accidents beyond their own
control, than the travelers in any country under the sun. The credit
of this immunity from fatal accidents is almost entirely due to the
successful operation of the Westinghouse and other brakes that followed
the line suggested by this invention.
DISTINCT CLASSES OF INVENTIONS.
Inventions may be divided into two distinct classes. Far the more
numerous class are those which effect improvements on recognized
appliances. The other is the rare and more valuable class, to which
belongs the original inventor who devises an entirely new method for
performing a desired operation. Among this class of inventions may
be noted Watt’s separate condenser, which first rendered the steam
engine a commercial success; the multitubular boiler of Nathan Read,
which made a high-speed locomotive practicable; and the air-brake of
Westinghouse, which made fast traveling safe, by putting the train
speed under the control of the engineer.
BENEFITS CONFERRED ON TRAIN MEN BY GOOD BRAKES.
To the traveling public the air-brake has proved a source of
satisfaction by assuring exemption from accidents, but its greatest
blessing has been conferred upon train men. Being the greatest
sufferers from railway accidents, their risks of life and limb are
greatly reduced; and the agonizing helplessness that used to be so
often experienced with trains that could not be stopped in time to
avoid a disaster, is almost unknown on our well-managed roads. Mind has
become victor in its conflict with matter. When necessary, an engineer
can run a train at a high velocity over crowded lines without having to
shut off steam within a mile of each point where there may be another
train obstructing the track, or keep up his speed at the risk of his
life. People unacquainted with the inside operating of railroads have
no idea of the difficulties train men had to contend with in getting
fast trains over the road, before continuous brakes were supplied.
The train had to be run on schedule time, and all points where trains
might be expected had to be approached with care. This meant reduced
speed; and speed could not be reduced in short distances, so the risk
had to be taken of violating one rule to comply with another.
FIRST TRIALS OF THE WESTINGHOUSE ATMOSPHERIC BRAKE.
The Westinghouse atmospheric brake was patented April 13, 1869; and
the first public trial took place on the Panhandle road about the same
time. The trial was so satisfactory, that the Pennsylvania Railroad
Company, which have been always noted for their liberal patronage of
every meritorious device likely to promote the efficiency and safety
of railroad operating, had a train equipped with the brake. This was
the Walls accommodation train, a kind of service where frequent stops
were required, and was therefore well calculated to demonstrate the
true character of any brake. A number of public trials were made with
the brake thus fitted, among which was one by the Master Mechanics’
Association in the middle of September, 1869, on the Horseshoe Bend
on the Pennsylvania Railroad. Here a train of six cars, running down
a grade of 96 feet to the mile, at the rate of 30 miles an hour, was
stopped in a distance of 420 feet. Such a feat was unprecedented at
that time, and attracted wide-spread attention.
In the following month, official trials of the train were made by the
officers of the Pennsylvania Railroad near Philadelphia. The train was
then taken to Chicago, where numerous tests were made in the presence
of leading Western railroad officers. So convincing were these trials
of the decided efficiency of the brake, that, immediately afterwards,
the Michigan Central Railroad and the Chicago and North-Western
Railway each ordered a train to be fitted with the brake.
FIRST ROADS THAT ADOPTED THE WESTINGHOUSE BRAKE.
The first five sets of the Westinghouse brake fittings made were got
out in the shops belonging to the Pennsylvania Railroad Company at
Altoona, Penn. The first railroads to adopt the brake as a regular part
of their equipment, were the Pennsylvania, the Pittsburg, Cincinnati,
and St. Louis, the Union Pacific, the Chicago and North-Western, and
the Michigan Central Railroads.
Since the Westinghouse atmospheric brake was first tried, many changes
in details have been made, and numerous improvements have been
effected; but the essential points remain the same. And the best forms
of brakes subsequently got out by other inventors are founded on the
Westinghouse idea, just as much as the numerous types of locomotives
follow the design of Stephenson’s Rocket.
OUTLINES OF THE ATMOSPHERIC BRAKE.
Although the automatic air-brake is now becoming almost universal
in American railroad practice, most train men are familiar with the
working of the atmospheric brake under the name of “straight air.”
When first invented, the Westinghouse brake consisted of an apparatus
located on the locomotive for compressing air, which was stored in an
iron drum fastened somewhere about the engine. Underneath each car,
and connected with the ordinary brake attachments, was a cylinder
containing a piston, which operated the brake. The brake-cylinders
were kept in communication with the air-drum on the locomotive by iron
pipes. Connection between the cars where “stretching” and “compression”
made the train vary in length, was made by means of rubber flexible
hose. When the engineer wished to apply the brakes, he admitted the
compressed air into the supply pipes, through a three-way cock at his
hand. This air entered the cylinders under the cars, moving back the
pistons which pulled the levers operating the brakes. To release the
brakes, the air was permitted to escape out of the pipes into the
atmosphere.
Thus, what is really a complicated operation was performed in a simple
manner, and by means of machinery not liable to get out of order
readily. The instant application of every brake on a long train was
put in the hand of the engineer. On the first indication of danger,
his hand became powerful beyond the magical forces conceived by the
imagination of poets.
HOW EASTERN RAILROADS KEPT ALOOF FROM THE WESTINGHOUSE BRAKE.
The growth of the Westinghouse brake into public favor furnishes a
curious commentary on the different degrees of enterprise to be found
among railroad companies in the various sections of this country. It
was natural to suppose that railroads in the thickly settled States,
where trains had become too numerous for being safely operated with
crude brakes, and no signals, would have been the first to adopt an
improved appliance which gave promise of increased safety. Yet the
railroads in the Eastern States, with a few creditable exceptions,
were among the last to patronize the Westinghouse brake; and they
adopted it only when the influence of public opinion could no longer be
ignored. Western railroads that ran through sparsely settled prairies,
where trains were rare, and stopping room generally ample, were among
the first to encourage the inventor of the brake with their support.
LESSON OF THE REVERE RAILROAD ACCIDENT.
During the first two years after it was invented, the Westinghouse
brake made slow progress into practical application, except in the
West. In the ancient State of Massachusetts, it was hardly known till
the Revere accident happened near Boston. This was the case of a
crowded road being operated without signals or brakes, except those
of the most primitive description. A fast express train ran into the
rear end of an accommodation train, killing twenty-nine persons, and
severely injuring fifty-seven others. The engineer of the express
train, while running at a speed of twenty-five miles an hour, saw the
tail lights of the accommodation train when he was eight hundred feet
away. He whistled for brakes, and reversed his engine; but the train
could not be stopped.
The railroad superintendents throughout the conservative State of
Massachusetts then received enlightenment respecting the existence
of an efficient continuous brake in a vigorous fashion. The Revere
accident conveyed its lessons in a terrible way, but they were
effectual in convincing railroad managers that they could not afford to
dispense with a brake that proved itself to be reliable.
WEAK POINTS OF THE ATMOSPHERIC BRAKE.
Although the atmospheric brake could, with light trains, make stops
within the shortest distance it was desirable to stop trains with
safety to the passengers and rolling stock, it possessed certain weak
points which demanded remedy. In case of a train breaking in two,--an
accident which frequently happens, especially on rough track,--there
was danger of the engineer applying the brake without knowing that an
interval existed between the cars, and allowing the rear end of the
train to crash into the forward part. The signal given by the bell-rope
breaking, had a tendency to lead to an accident of this character.
Another objection to straight air was, that should derailment take
place, or any accident happen that would rupture the pipes or their
connections, the brake was rendered useless. These weak features did
not interfere with the working of ordinary traffic; and as providing
special appliances to meet cases of accident which are rare, does
not generally receive much consideration, the brake might have been
regarded as perfect enough for all practical purposes had it not failed
to meet satisfactorily a condition of ordinary train service. As the
length of trains was increased, it was found that the atmospheric brake
was slow in action. When a long array of pipes and many cylinders
had to be charged with air from the drum on the locomotive after the
necessity for applying the brake became apparent, and before it would
act, some seconds were required for the operation. Every additional car
put upon the train increased the length of pipes and the cylinders to
be filled, and so lengthened the time that elapsed between the instant
danger was perceived and the time at which the brake began to perform
its retarding work. The increase of time might be only a few seconds,
but they would probably be priceless moments when an accident was
impending.
THE WESTINGHOUSE AUTOMATIC AIR-BRAKE.
To overcome this line of weakness, the Westinghouse automatic air-brake
was invented. Where good station signals are in use, it has long been
accepted as an axiom among railway authorities, that a signal must be
constructed so that it will indicate danger when any accident happens
to its mechanism. This principle was brought into practical application
in the Westinghouse automatic air-brake. When any thing goes wrong with
the brake apparatus, its tendency is to apply the brake automatically.
A break in a pipe makes the brake fly on. Each car carries a supply
of compressed air sufficient to apply its own brakes several times.
By the new arrangement, the brakes on all the cars are applied almost
simultaneously, and instantly after the engineer turns the handle of
his stopping-valve. The brakes are applied by decreasing the pressure
in the pipes; so the breaking in two of the train, or the fracture of
an air-pipe or coupling, sets the brakes on all the cars on the train,
whatever side of the break the cars may be on. That in itself is an
invaluable feature in a continuous brake, and prevents cars from acting
as battering-rams upon each other in cases of derailment.
LIFE-SAVING VALUE OF THE AUTOMATIC BRAKE.
Every few days, notices get into the public prints relating how
frightful accidents were prevented by the prompt action of the
automatic air-brake. And hundreds of narrow escapes, where this brake
proves the preventive of destruction to life and property, receive no
record, and are known only to the employes connected with the operating
of trains. To the men familiar with train service, to those who are
intimately acquainted with the life-saving effected by the automatic
air-brake, it seems surprising that railroads could have been operated
without this or a similar appliance. They certainly were not operated
safely without it.
FIRST RAILROADS THAT ADOPTED THE WESTINGHOUSE AUTOMATIC AIR-BRAKE.
Patents for the Westinghouse automatic air-brake were granted in March,
1872. During the succeeding winter, trials of the brake were made by
the Pennsylvania Railroad; and it was shortly afterwards adopted by the
Philadelphia and Reading Railroad Company as their standard brake for
passenger trains. The example of that company was soon followed by the
St. Louis, Kansas City and Northern, the Chicago and Alton, the Toledo,
Wabash and Western, and the St. Louis, Iron Mountain and Southern
Railroads, all of which companies equipped their passenger rolling
stock with the automatic air-brake within a few months.
ESSENTIAL PARTS OF THE WESTINGHOUSE AUTOMATIC AIR-BRAKE.
The prominent features of the Westinghouse automatic air-brake consist
of the following leading parts: An air-pump, placed on the locomotive,
is operated by a steam cylinder, which forces air into an iron drum or
reservoir placed under the deck, or in any other convenient part about
the engine. The air is compressed to the density considered necessary
for the kind of train the locomotive usually pulls.
In the cab, located conveniently to the hand of the engineer, is the
engineer’s brake-valve, commonly called the “three-way cock,” which
regulates the flow of air from the main reservoir into the main
brake-pipes for supplying the auxiliary reservoirs with air. This
valve applies the train-brakes by letting the air escape from the main
brake-pipes, and releases them by again admitting the pressure of air
into the pipes.
From the main reservoir, the main brake-pipe connects with the
engineer’s valve, and thence along the train, supplying all the brakes
with the air required.
Under the floor of each car is fastened an auxiliary reservoir, which
holds a supply of air necessary for operating the brakes on that car.
So each car carries its own supply of air.
Connected with each car-truck is a brake-cylinder, in which is operated
a piston that applies the brake. The brake-levers connect with the
piston-rod in such a manner, that, when the piston is forced out by the
air-pressure, the brake is applied.
Attached to the auxiliary reservoir is the triple valve, whose action
connects the air-cylinder with the auxiliary reservoir.
THE AIR-PUMP.
When the air-brake was first invented, the distribution of steam
within the cylinder was effected differently from what it is in modern
pump-cylinders. The steam-valve consisted of a double piston, the
heads having ports on their edges which admitted and released the
steam. This valve did not move up and down, but received an oscillatory
motion from a small auxiliary engine placed on the top of the steam
cylinder-head. The movements of the auxiliary engine were regulated by
a reversing-rod (popularly known as a kicker-rod), working inside the
main piston-rod. This arrangement of steam distribution was somewhat
complicated, and liable to get out of order; and it was superseded by
the differential steam-valve movement now in use.
HOW THE AIR-PUMP WORKS.
[Illustration: FIG. 33_a_.]
In Fig. 33_a_, steam enters from the boiler at the nipple 35, and
fills the steam-space between the heads of the main piston-valve 15,
16, maintaining a constant pressure of steam there while the pump
is at work. The upper head of the main valve being of greater area
than the lower one, the tendency of the pressure is to raise the
valve. A downward movement of the valve is provided for by a separate
single-headed piston-valve 20, working in a cylinder above the main
valve. The reversing-rod 12 operates a slide-valve 13, which regulates
the admission and release of steam for the third piston.
In the cylinder shown in the engraving, the main valve is down, so that
steam is passing into the lower end of the main cylinder. Two small
ports can be seen close to the piston-head 16, one above the other. The
upper port is open, and is the admission port; the lower port, which
is closed by the small piston, is for exhausting the steam. The main
piston 7 is on its upward stroke, and the upper exhaust port seen
above the piston-valve 15 is open, while the steam port immediately
below it is closed by the valve-piston in the same way that the exhaust
port is closed at the other end. When the main piston 7 shall reach
near the top of its upward stroke, the plate 10 will strike on the
projection on the reversing-rod, pushing up the slide-valve 13. The
upper edge of this slide-valve will cut the steam off the passage
_a_, and open the passage _b_ to the exhaust. This takes the steam
away from the piston 20, and allows piston 15 to move upward, closing
the exhaust-port, and opening the upper steam-port. The same movement
makes the piston 16 close its steam-port, and open the exhaust. Piston
7 now begins to travel downward; and, when it reaches nearly to the
bottom of the cylinder, the plate 10 catches the knob on the end of the
reversing-rod, and pulls down the slide-valve 13 to the position it
holds in the engraving. Steam then rushes through the passage _a_, and
makes the piston 20 push down the main valve. That completes the circle
of the operations in the steam cylinder.
HOW THE AIR-END OPERATES.
[Illustration: FIG. 33_b_.]
The operation of the air part of the pump is very simple. While the
main piston (Fig. 33_b_), which is on the same rod as the piston of
the steam cylinder, is moving upward, it is forcing the air out of the
upper end of the cylinder up under the discharge-valve 32, and away
through the proper passages to the main reservoir. At the same time the
lower end of the cylinder is being filled with air drawn through the
lower receiving-valve 34. During the downward stroke of the piston, the
air will be delivered through the valve 33, and the upper part of the
cylinder filled by air received through the upper valve 34.
AIR-PUMP DISORDERS.
An engineer who does not understand the principles of a locomotive’s
action, is not likely to prove a valuable runner. The men who are most
successful in getting trains over the road with solar regularity; the
men who make the best records on the mileage sheets for economy in
fuel and in lubricants; who are lightest in repairs, yet keep their
engine going longest,--are those who comprehend the functions of every
portion of the engine, and what relation the various parts bear to
each other. With this knowledge clearly established in the mind of the
runner, his power to detect any thing wrong with his engine becomes
instinctive. Trifling defects, which neglect would develop into serious
disabilities, are rectified in time, and the whole engine is maintained
in smooth working-order by the harmony of its individual sections. The
mere stopper and starter is losing his hold on the locomotive service.
When he drops off entirely, our mileage for each dollar expended will
be decidedly increased.
The principles which apply to the running of a locomotive are equally
applicable to the management of an air-brake, with all its perfected
connections. This apparatus can not be properly managed unless the man
who works it knows something about its action.
PUNY DIFFICULTIES VANQUISH THE IGNORANT ENGINEER.
A great many engineers who run passenger trains, and take an
intelligent interest in the working of the locomotive, whose
technicalities they have thoroughly mastered, display no desire
whatever to understand the air-brake, and are perfectly contented
with its action so long as it will stop the train. The air-pump,
so wonderfully interesting to those who understand its movements,
receives no more attention than is necessary to keep it going so that
the required air-pressure is maintained. They know how to start and
stop the machine, and they oil it regularly; but these are the limits
of their attentions. Should the pump happen to stop working, the cause
is mysterious, like many other mysteries; and the natural remedy
suggested, is to hit the thing on the head with a monkey-wrench. Should
it not respond to this treatment by renewed action, the hand-brakes are
resorted to for the rest of the journey; and the round-house foreman or
machinist is required to do the head-work which locates the trouble.
A belief prevails among men who labor principally with their hands,
that laziness is exclusively physical. This is a mistake. It is a
psychological fact, well known to metaphysicians, that mental laziness
is prevalent enough to dwarf the minds of half the human race. Men who
would willingly work with their hands during half their leisure time to
keep their engines in proper condition for running, have to be driven,
by fear or jealousy, before they will force their mental faculties to
do trifling labor in a new channel.
CAUSES THAT MAKE BRAKES INOPERATIVE OFTEN EASILY REMEDIED.
Any engineer of ordinary intelligence, who will spend one hour a day
for two weeks studying up the Westinghouse instruction book, will
understand the brake so well, from the pump to the hind end of the
train, that any imperfection happening to its working will be as
readily located as an ordinary defect in a locomotive. Yet it is an
intensely hard matter to induce men running passenger engines to go
through this trifling mental exercise. The consequence is, that the
brake sometimes becomes inoperative from causes so slight that men
should be ashamed to report them; and they would be so if they only
comprehended how small a mole-heap became their mountain. I knew a case
where all the train men--that is to say, engineer, fireman, conductor,
baggageman, and brakemen--wrestled for twenty minutes over a triple
valve, trying to find out how to cut the air off a car; and, when the
crowd was vanquished, a colored porter came, and showed them how the
thing was done. This was on a road where straight air was generally
used. One day some winters ago, a passenger train on the road I worked
for was delayed an hour or more at a station, waiting for something.
When the engineer tried to start the air-pump, it would not work.
He fumed and fussed over it for fifteen minutes, gave it a liberal
dose of copper hammer medicine, and saturated it with oil, but all to
no purpose. It would not pump a pound of air, so the old-fashioned
Armstrong was called into operation. In the course of its journey, this
train had to pass the round-house at headquarters; and the engineer
stopped to see if his pump could be given some quick remedy. I happened
to be the doctor consulted. On learning the particulars of how the pump
stopped working, I set fire to a piece of greasy waste, and held the
flame to the check-valve of the air-drum; and the pump went right to
work. All the trouble was, that the check-valve was frozen in its seat.
I felt sorry for that engineer, he appeared to be so thoroughly ashamed
and crestfallen at being baffled by such a small trouble.
CARE OF THE AIR-PUMP.
To run an air-pump successfully, the first requisite is that it should
be managed intelligently, and its wants attended to regularly. An
air-pump consists of numerous moving parts, which should operate with
the least possible amount of friction: consequently, it is important
that the machine should be properly lubricated,--not deluged with
grease for ten minutes, and then run on the interest of the excess
for two hours, but sparingly furnished with clean oil, which will
keep the moving parts moist all the time. To accomplish this, the
feeding-cup must be kept in proper working-order, so that it will pass
the oil regularly. I have found a leading cause for air-pumps working
unsatisfactorily to be in the intermittent feeding of the oil-cups.
Some dirt gets into the cup, obstructing its action, and greater
opening is given to make it feed; then the oil goes through by spasms,
and the pump works irregularly; for at one time the steam-piston is
churning the oil, and again it is working dry. There is also a common
abuse of the oil-can when any thing goes wrong with the pump; for
some men will then drench it with oil, expecting that to make it work
smoothly. Permanent injury is often done in this way, especially where
inferior oils are used, which frequently contain mineral substances in
suspension. This solid matter is separated from the oil by the heat,
and settles in the small passages, filling them up by degrees till
eventually there is no channel left for the steam to pass through to
reverse the steam-valve; so the pump stops. I once saw a runner trying
to doctor a sick pump by pouring the stickiest kind of gummy valve-oil
into an air-cylinder. He gave the thing its quietus, as other poor
doctors sometimes do with their patients.
PUMP PACKING.
The stuffing-box packing is not generally supposed to exercise an
important effect on the action of an air-pump; yet I have seen cases
where irregular action of the pump, and serious loss of air, resulted
from bad packing. Soapstone and asbestos, and other substances that
become compact and rigid when cold, are unsuitable for packing the air
end of a pump. After a little use, material of this kind becomes so
hard that no amount of screwing of the gland will make it tight; and
the greater part of the air at that end of the pump escapes through the
stuffing-box instead of passing into the drum.
HOW STEAM PASSAGES GET CHOKED.
Around the bushings of the cylinder, where the small reversing piston
20 works, are diminutive steam passages, very liable to get stopped up
when foreign matter is attempted to be run through the cylinder. Such
matter is occasionally introduced in various ways. When rubber gaskets
are used in the pipe connections leading to the cylinder, the rubber
often peels off in shreds, or breaks off in small pieces, which lodge
around the bushing in the passages, producing harassing annoyance. So
soon as those passages get obstructed, or reduced below their correct
size, the pump begins to work badly. Machinists not well versed in the
mysterious ways of air-pump disorders will now take that pump apart,
and find nothing the matter. Subsequent proceedings depend upon the
nature of the man who has the job in hand. If the machinist be of a
conservative disposition, he will put the apparatus together again
without making any alteration, and perhaps will relieve his mind by
expressing a belief that the engineer does not know when an air-pump is
in good shape. Another machinist, of a more enterprising stamp, must
find something to change, so he lengthens or shortens the reversing
valve-rod 12 (a favorite resort of small-knowledge tinkers), which
gives the pump the _coup de grâce_; and it has to be overhauled by a
competent machinist before it again supplies the air to stop a train.
This competent man goes direct to the root of the trouble. Skill in
this particular line of work convinces him, after an examination,
that the moving parts require no repairs; and knowledge begotten of
experience, supplemented by sound sense, directs him where to look for
the cause of defective operation.
SAGACITY NEEDED IN REPAIRING AIR-PUMPS.
Men who meet with good success in repairing air-pumps, and in
determining, from the action of the pump, the probable cause of defect,
have to do a great deal of deep and sagacious thinking. Sometimes a
defect, simple enough in itself, is extremely difficult to locate,
because it belongs to the unexpected order of occurrences.
Here was an instance. Some small jobs had been done one day to
the steam cylinder of a pump which had not been working quite
satisfactorily. When they tried to start it, after being put together,
the pump would not work at all. The machinist who did the job, an
eminently competent man at such work, took the machine apart again,
but could detect no defect or maladjustment about it. The steam
cylinder, with all its valves and rods and bushings, was critically
examined: the air-pump, with all its connections, got a thorough
inspection to no purpose. When an ordinary man goes through the
patient, thoughtful labor needed for an examination of this kind, and
finds nothing wrong, he is apt to get discouraged, and confess himself
beaten. This man did not recognize the word beaten as applied to his
work. He reasoned, “This pump would work if it were all right. It will
not work, so something must be wrong.” After exercising more patience
and perseverance, he discovered that the bushing 23 of the reversing
valve (usually called the kicking-rod valve) had become loose, and,
when the cap was screwed down, it twisted the bushing round, and closed
the passages that lead steam to the reversing piston. There are small
grooves round the sides of the small steam passages to provide for the
bushings being moved a little, but these grooves had become gummed up
so that they failed to serve their purpose of keeping the ports open.
GRADUAL DEGENERATION OF THE AIR-PUMP.
The working and stationary parts within the cylinders of the air-pump
are adjusted with nice exactness; and, when they remain in their normal
condition, the pump works smoothly, and compresses air rapidly. When
wear, or any other cause, alters the dimensions of these parts, the
effect immediately becomes apparent in unsatisfactory working of the
whole machine. Rods are adjusted so that valves or pistons shall cover
and uncover steam passages, and no superfluous movement is provided
for. The passages are so small that all the steam they convey is needed
for the work of reversing the motion; and if from any cause the valve
or piston only partly uncovers the opening, the necessary volume of
steam does not get through. A close observer of the pump’s action can,
day by day, perceive the gradual degeneration due to wear. Wear of the
steam-cylinder connections is generally indicated by reduced power. The
pump will not do its work satisfactorily, and has difficulty in keeping
up the pressure of air. This deterioration continues till the pump will
stop, unless its decay gets arrested by repairs. When the valves of the
air-pump are in correct order for doing good work, the discharge-valves
32 and 33 have 1/16″, and the suction-valves 34 ⅛″ lift. The continual
tapping of these valves on their seats has a tendency to wear out
valves and seats, making the lift greater than what is desirable. Any
material increase of lift for the discharge-valve has a most injurious
effect upon the motion of the pump, especially if the suction-valve
should happen to be leaky. Then the movement of the pistons will become
fluctuating, and subject to frequent stoppages. The up-and-down motion
of the piston is of a jerky character, that makes the beholder suppose
the thing is uncertain which way to go. Deterioration of air-valves is
not, however, the only cause for that jerky motion so often observed
in bad working pumps. A bent reversing valve stem (kicker-rod) acts on
the reversing valve with oblique pull and thrust, which tend to move
it away from the seat, letting the steam pass the wrong way. A broken
main steam-valve ring has a similar effect; for the steam passes to
the wrong end of the valve, destroying its equilibrium; and there is
nothing decisive about its reversal, or about its motion after it is
reversed. Its action resembles the movements of a vacillating human
being. It does not want to go in that direction, but goes, then keeps
trying to change its mind during the rest of the journey. Obstructed
steam passages will sometimes cause indecisive action of the pump
before it gets bad enough to stop it altogether.
CAUSES THAT MAKE A PUMP POUND.
Pounding on the heads is a somewhat common attribute of degenerated
air-pumps. Broken or badly worn air-valves very often cause the pump to
pound. If the trouble should happen to be in the upper air-valve, it
will demonstrate its disorder by causing pounding on the upper head;
and the lower valve’s malady will cause pounding on the lower head.
When a pump is suffering from indecisive motion, or is pounding, and
the machinist does not feel certain about where the trouble lies, he
may safely examine the condition of the air-valves,--for they can be
easily reached,--and in a great many cases the defect will be found
there. Wear of the pin whereon the bottom of the main valve-rod rests,
or of the rod itself, will induce pounding on the upper head by the
main piston. Some runners think, that, by keeping the drain-cock of the
steam-cylinder open all the time, they secure dry steam. The practice
is pernicious, and injurious to the pump: for the piston receives so
little cushion when the drain-cock is shut, that it can not afford the
decrease made by a permanently open cock; and consequently the loss of
cushion permits pounding on the lower head.
I have known of a disastrous effect being produced on a pump by putting
a new gasket, which proved too thick, on the upper head. It was the
thinnest copper that could be found, but it perceptibly lengthened the
upper end of the cylinder so that the bottom knob on the reversing stem
struck the reversing plate on the main piston before that action was
due. On several occasions I have had air-pumps reported to be working
badly, when all the trouble lay in the air-strainer being partly
choked up by floating vegetable matter that had been sucked in with
the air, and failed to pass through the meshes. In another case we had
much difficulty in locating the defect, with a pump that absolutely
refused to work. The boiler-makers had been working in the smoke-box,
and by some means the end of the exhaust-pipe got solidly stopped up
with cinders. As none of us had come across that particular cause of
obstruction before, we expended a good deal of labor searching for the
trouble before we thought to disconnect the exhaust-pipe from the pump.
THE TRIPLE VALVE.
This is the part whose operation gives the brake its automatic action.
Those who have opposed this form of brake have made great objection
to the complicated nature of the triple valve. But some familiarity
with the device shows that it is far from being complex, considering
the functions it performs. It is merely a piston-valve carrying a
slide-valve along with it.
The arrangement of the parts of the triple valve is shown in Fig. 34.
[Illustration: FIG. 34.]
The triple valve has a piston 5, working in the chamber _B_, and
carrying with it the slide-valve 6. Air enters from the main pipe
through the four-way cock 13 into the drain-cup _A_, and passes
to the chamber _B_, forcing the piston up, and uncovering a small
feeding-groove in the upper part of the chamber, which permits air
to flow past the piston into the auxiliary reservoir, while, at the
same time, there is an open communication from the brake-cylinder to
the atmosphere through the passages _d_, _e_, _f_, and _g_. Air will
continue to flow into the auxiliary reservoir until it contains the
same pressure as the main brake-pipe.
ACTION OF THE TRIPLE VALVE.
To apply the brakes with their full force, the compressed air in the
main brake-pipe is permitted to escape, when the greater pressure
in the auxiliary reservoir forces the piston 5 down below the
feeding-groove, thus preventing the return of air from the reservoir
to the brake-pipe. As the piston descends, it moves with it the
slide-valve 6, so as to permit air to flow directly from the auxiliary
reservoir into the brake-cylinder, which forces the pistons out, and
applies the brakes. The brakes are released by again admitting pressure
into the main brake-pipe from the main reservoir; which pressure, being
greater than that of the auxiliary reservoir, forces the piston 5 back
to the position shown in the engraving, recharges the reservoir, and at
the same time permits the air in the brake-cylinders to escape.
To apply the brakes gently, a slight reduction is made in the pressure
in the main brake-pipe, which moves the piston down slowly until it
is stopped by the graduating spring 9. At this point, the opening _l_
in the slide-valve is opposite the port _f_, and allows air from
the auxiliary reservoir to feed through a hole in the side of the
slide-valve, and through the opening _l_ into the brake-cylinder.
The passage _l_ is opened and closed by a small valve 7, which is
attached to, and moves with, the piston 5, provision being made for
a limited motion of these parts without moving the valve 6. When the
pressure in the auxiliary reservoir has been reduced by expanding into
the brake-cylinder until it is the same as the pressure in the main
brake-pipe, the graduating spring pushes the piston up until the small
valve 7 closes the feed opening _l_. This causes whatever pressure is
in the brake-cylinder to be retained, thus applying the brake with a
force proportionate to the reduction of pressure in the brake-pipe.
TO PREVENT CREEPING ON OF BRAKES.
To prevent the application of the brakes, from a slight reduction of
pressure caused by leakage in the brake-pipe, a semicircular groove is
cut in the body of the car-cylinder, 9/64 of an inch in width, 5/64
of an inch in depth, and extending so that the piston must travel
three inches before the groove is covered by the packing leather. A
small quantity of air, such as results from a leak, passing from the
triple valve into the car-cylinder, has the effect of moving the piston
slightly forward, but not sufficiently to close the groove, which
permits the air to flow out past the piston. If, however, the brakes
are applied in the usual manner, the piston will be moved forward,
notwithstanding the slight leak, and will cover the groove. It is very
important that the groove shall be three inches long, and shall not
exceed in area the dimensions given above. Heretofore leakage valves
have been used, and also a leakage hole. These leakage holes have been
found to be too uncertain in their operation; and consequently it is
recommended that these holes should be closed, and the grooves in the
cylinders substituted, as rapidly as possible.
When the handle of the four-way cock 13 is turned down, there is a
direct communication from main brake-pipe to the brake-cylinder, the
triple valve and auxiliary reservoir being cut out; and the apparatus
can be worked as a non-automatic brake, by admitting air into the main
brake-pipe and brake-cylinder, to apply the brakes. When from any cause
it is desirable to have the brake inoperative on any particular car,
the four-way cock is turned to an intermediate position, which shuts
off the brake-cylinder and reservoir, leaving the main brake-pipe
unobstructed to supply air to the remaining vehicles.
The drain-cup _A_ collects any moisture that may accumulate, and is
drained by unscrewing the bottom nut.
HOW TO APPLY AND RELEASE THE BRAKE.
The brakes, as has been explained, are applied when the pressure in
the brake-pipe is suddenly reduced, and released when the pressure is
restored.
It is of very great importance that every engineer should bear in
mind that the air-pressure may sometimes reduce slowly, owing to the
steam-pressure getting low, or from the stopping of the pump, or from
a leakage in some of the pipes when one or more cars are detached
for switching purposes, and that in consequence it has been found
absolutely necessary to provide each cylinder with the leakage groove
already referred to, which permits a slight pressure to escape without
moving the piston, thus preventing the application of the brakes, when
the pressure is slowly reduced, as would result from any of the above
causes.
This provision against the accidental application of the brakes must
be taken into consideration, or else it will sometimes happen that all
of the brakes will not be applied when such is the intention, simply
because the air has been discharged so slowly from the brake-pipe that
it only represents a considerable leakage, and thus allows the air
under some cars to be wasted.
It is thus very essential to discharge enough air in the first
instance, and with sufficient rapidity, to cause all of the leakage
grooves to be closed, which will remain closed until the brakes have
been released. In no case should the reduction in the brake-pipe for
closing the leakage grooves be less than four or five pounds, which
will move all pistons out so that the brake-shoes will be only slightly
bearing against the wheels. After this first reduction, the pressure
can be reduced to suit the circumstances.
On a long train, if the three-way cock be opened suddenly, and then
quickly closed, the pressure in the brake-pipe, as indicated by the
gauge, will be suddenly and considerably reduced on the engine, and
will then be increased by the air-pressure coming from the rear of the
train: hence it is important to always close the three-way cock slowly,
and in such a manner that the pressure, as indicated by the gauge, will
not be increased; or else the brakes on the engine and tender, and
sometimes on the first one or two cars, will come off when they should
remain on. It is likewise very important, while the brakes are on, to
keep the three-way cock in such a position that the brake-pipe pressure
can not be increased by leakage from the main reservoir; for any
increase of pressure in the brake-pipe causes the brakes to come off.
On long down grades, it is important to be able to control the speed of
the train, and at the same time to maintain a good working pressure.
This is easily accomplished by running the pump at a good speed, so
that the main reservoir will accumulate a high pressure while the
brakes are on. When, after using the brake some time, the pressure has
been reduced to sixty pounds, the train pipes and reservoirs should
be recharged as much as possible before the speed has increased to
the maximum allowed. A greater time for recharging is obtained by
considerably reducing the speed of the train just before recharging,
and by taking advantage of the variation in the grades.
There should not be any safety-valve or leaks in the main reservoir,
otherwise the necessary surplus pressure for quickly recharging can not
be obtained.
To release the brakes with certainty, it is important to have a higher
pressure in the main reservoir than in the main pipe. If an engineer
feels that some of his brakes are not off, it is best to turn the
handle of the three-way cock just far enough to shut off the main
reservoir, and then pump up fifteen or twenty pounds extra, which will
insure the release of all of the brakes; all of which can be done while
the train is in motion.
For ordinary stops, great economy in the use of air is effected by, in
the first instance, letting out from eight to twelve pounds pressure
while the train is at speed, taking care to begin a sufficient distance
from the station.
PUMP GOVERNOR.
This is an important attachment which ought to be connected to all
air-brake pumps. It not only prevents the carrying of an excessive
air-pressure by the engineers, which often results in the sliding
of the wheels, but it also causes the accumulation of a surplus of
air-pressure in the main reservoir, while the brakes are applied, which
insures the release of the brakes without delay. It also limits the
speed of the pump, and consequently the wear.
[Illustration: FIG. 34_b_.]
The pump governor is shown in Fig. 34_b_, the object of which is
to automatically cut off the supply of steam to the pump when the
air-pressure in the train-pipe exceeds a certain limit, say seventy
pounds.
The operation of this governor is as follows: the wheel 8 is screwed
down so as to permit the valve 10 to be unseated by the excess of
pressure on the upper side of the valve, permitting steam to pass
through the openings _A_ and _B_ to the pump. A connection is made from
the train-pipe to the upper end of the governor, and the compressed
air passes around the stem 14 to the upper side of the diaphragm plate
18, which is held to its position by the spring 16, which latter is of
sufficient strength to resist a pressure of, say, seventy pounds per
square inch on diaphragm. As soon as the air-pressure on the diaphragm
18 exceeds this amount, it forces the diaphragm down, unseating the
valve 13, and allowing the steam on the upper side of the valve 10 to
escape through the exhaust 6, which causes an excess of steam-pressure
on the lower side of the valve 10, forcing the valve against its seat,
and cutting off the supply of steam to the pump.
When the pressure in the train-pipe is diminished by applying the
brakes, the diaphragm is restored to the position shown by the action
of the spring 16. The valve 13 is seated by the spring 12; and the
steam-pressure, passing through the port _C_, accumulates on the upper
side of the valve 10, forcing it down, and opening the passage for
steam to the pump until the air-pressure is again restored to the
required limit of seventy pounds.
CHAPTER XXV.
_THE EAMES VACUUM BRAKE._
OPERATION OF THE BRAKE.
The Vacuum Brake, as the name implies, is operated by means of a vacuum
which is formed in the connections that act the part of the cylinder
in the air-brake. With an air-brake, compressed air is made to do the
work of applying the brakes by moving a piston to which the brake-lever
is attached, the air being carried throughout the train by means of
iron pipes and rubber hose: with the vacuum brake the work is done in
a similar way with similar connections; but, instead of compressed air
being forced inside the pipes and apparatus, all the air is exhausted
out, and the natural pressure of the atmosphere is made to do the work.
THE DIAPHRAGM.
[Illustration: FIG. 35.]
Under each vehicle of a train, as seen in Fig. 35, a diaphragm is
securely fastened which performs the combined duties of cylinder and
piston. It consists of a kettle-shaped casting with a loose disk of
heavy rubbered duck fastened over its mouth; the center of the disk
being provided with an iron plate, through which passes an eye-bolt for
forming connection with the brake-lever. The inside of the diaphragm
is connected to the pipe which passes along the train, and has its
front end connected with the ejector on the locomotive.
THE EJECTOR.
[Illustration: FIG. 36.]
The position of the ejector in the cut can be clearly seen in Fig. 36,
where there is also a diaphragm to be seen under the deck where it is
located when used to operate driver brakes. The ejector is operated
on the same principle as the water injector, only it is used to lift
air instead of water. A cross-section of the injector is shown in
Fig. 36. When the engineer wishes to apply the brake, he pulls the
handle 41 (broken off in the cut), which opens the valve _B49_, and
admits steam to the body of the ejector _A1_. The steam rushes upward
round the end of the tube 5, its velocity being accelerated in
passing through the contracted opening left round the top of the tube.
Passing through tubes 3 and 6, the steam shoots up in the form of a
column with a hollow base; the tube 5, which is connected with the
pipes and diaphragms on the train, forming this base. The effect of
the steam passing out under these conditions is to induce a current
through the tube 5, which draws up the valve _B7_, and sucks the air
out of the pipes and diaphragms. A vacuum being thus formed in the
diaphragms, the atmosphere presses the flexible ends together. This
tendency to collapse is retarded by the brake-rod connections, and the
latter receive a pull equal to the combined atmospheric pressure on the
diaphragm. The brake-levers are arranged to transmit a proper tension
to the brake-shoes for making the brake effective. A vacuum gauge
placed on the front of the ejector enables the engineer to regulate the
power as he wants it. The brake is released by pushing on the lever
24, which opens the valve 8, and admits air into the brake-pipes. The
release-valve attachment is sidewise in vertical section cut through
the handle, and is put separate for convenience of illustration.
CARE OF THE BRAKE.
The valve _B7_ of the ejector needs grinding occasionally; and, if
the lift should be too great, the valve will hammer the seat out of
shape. Sometimes when waste or other fibrous impurities are sucked
through the pipe, they stick in this valve, keeping it away from the
seat. The valve is very easily reached by taking off the cap _O4_. The
steam-valve _B49_ needs about the same care as any other steam-valve,
and its troubles are of the same nature. The shoulder at the top of the
tube 5, which is used to obstruct the steam, thereby increasing the
velocity of the quantity that passes, sometimes gets cut into channels
with the fast moving steam striking it. This reduces the promptness of
the ejector’s action, but it is a form of deterioration that proceeds
very slowly. Care must be taken to keep the drip-valves _A_ and _B16_
in order, otherwise there may be trouble with the ejector throwing
water, or freezing up if the engine stands where that apparatus will
get cold in winter.
CHAPTER XXVI.
_POWER OF LOCOMOTIVES AND TRAIN RESISTANCES._
CALCULATING POWER OF LOCOMOTIVES.
The capacity of engines is generally expressed in horse-power, which
is a measurable quantity; but, for several reasons, that method of
indicating power has not been usually applied to the locomotive. When
practical railroad men hear the size of cylinders, the diameter of
driving-wheels, and the boiler dimensions of a locomotive, mentioned,
they understand what kind of service the engine is adapted for, and
about the weight of train it can haul. As it has been found necessary
for designing and other purposes, to estimate, with some degree of
accuracy, the work a locomotive is capable of doing, it has become
usual to reckon the power of a locomotive by the tractive force it can
exert upon the rails.
PROPORTION OF ADHESION TO TRACTION.
Tractive force is the power which the pistons of the engine are capable
of exerting through the driving-wheels, to move the engine and train.
The efficiency of the engine’s traction is dependent upon the adhesion
of the wheels to the rails; for, where the adhesion is insufficient,
the pistons will slip the wheels, and no useful effect will result. To
prevent the wheels of ordinary American engines from slipping on dry
rails, the weight resting on the drivers must be about five times the
power exerted by the pistons to slip the wheels. To prevent slipping on
wet, unwashed rails, more than double the above weight would be needed.
In practice, locomotives are not provided with weight enough to prevent
the wheels from slipping on a greasy rail: the sand-boxes provide the
means of obtaining adhesion where the rails are in bad order. A common
practice is to place upon the drivers weight equal to about six times
the power exerted to slip the wheels, which leaves a small margin for
wet rails. Many locomotives have power sufficient to slip the wheels
on dry rails; but such engines generally have boilers too small for
the cylinders, or the distribution of weight on the drivers is badly
effected.
ESTIMATING TRACTIVE POWER.
The easiest way of calculating the tractive power of a locomotive is by
use of the following simple formula, first propounded by Pambour:--
_d^{2}Lp_
_T_ = ---------.
_D_
_d_ = the diameter of the cylinder in inches.
_L_ = the length of the stroke in inches.
_D_ = the diameter of driving-wheels in inches.
_p_ = the effective mean pressure on the piston in pounds per
square inch.
_T_ = the equivalent tractive force at the rails in pounds.
This, given in plain terms, reads: Square the diameter of piston in
inches; multiply by the length of stroke in inches; multiply by the
mean pressure of steam per square inch, and divide by the diameter of
the drivers in inches.
We will apply the calculations to the case of the standard Buchanan
passenger engine; the cylinders being 17 by 24 inches, the drivers 68
inches in diameter, and the effective pressure on pistons about 80
pounds. The problem is worked thus:--
17 inches diam. of cylinders.
17
----
289 = square of diameter.
24 inches stroke of piston.
----
6936
80 lbs. per square inch.
------
Diam. of drivers, 68)554880(8160
This gives 8,160 pounds as the pressure exerted to turn the drivers,
which may be accepted as a close approximation to the truth. In using
this formula, the mistake has frequently been made of taking the
quotient to represent the power developed by one cylinder, when, in
fact, it gives the power of both.
A method of calculating the locomotive traction that is a good deal
followed by our engineers, is to ascertain the foot-pounds of work the
engine is doing during each revolution of the drivers. By dividing the
total thus found by the circumference of the drivers in feet, the force
exerted through each foot that the engine moves is found. Taking the
same engine, the pistons 17 inches diameter, give 226.98 square inches
area. This is multiplied by the mean effective pressure of steam,
giving 226.98 × 80 = 18158.4 pounds pressing on each piston through the
whole stroke of four feet.
18158.4
2 pistons.
-------
36316.8
4 feet of stroke.
--------
145267.2
These figures show that 145267.2 foot-pounds are exerted during each
turn of the wheel, whose circumference is 17.8024; therefore, 145267 ÷
17.8024 = 8160, the number of pounds exerted through each foot moved.
There is still another way of figuring out tractive power by
calculating the rotational force and the leverage through which it is
applied to the locomotive wheels. The pressure of steam on the piston
is productive of two strains on the crank-axle. When the crank is
on the dead center, the pressure upon the crank-pin forces the axle
against the axle-box without causing any tendency to rotate: but, when
the crank-pin is on the quarter, the full leverage of the crank is
available for rotation; the leverage increasing gradually as the crank
gets away from the center. The mean effort upon the crank-pin during
one revolution of the crank is to the effort of the piston as .6366 is
to 1.
Now, to find the traction of the locomotive, we multiply the length
of our crank, which is 12 inches, by .6366, which gives 7.64 as the
length of the crank receiving constant pressure from the pistons.
The aggregate steam-pressure has already been found to be for each
piston, 18158.4 pounds. This is multiplied by 7.64; and the product is
divided by the radius of the wheel, which is 34 inches, giving as a
quotient 4080, being the power exerted on one side of the engine. That,
multiplied by 2, gives 8160 pounds,--the same as was found by the other
two methods.
HORSE-POWER OF LOCOMOTIVES.
When people wish to find the horse-power developed by a locomotive, the
indicator is generally employed, and the calculations made from the
diagram. Others figure out locomotive horse-power as they do that of
other engines. By this method, the engine whose traction we have been
investigating might have the horse-power calculated as follows:--
226.98 square inches piston area.
80 pounds mean pressure.
-------
18158.4 piston pressure.
4 feet piston travel each revolution.
-------
72633.6
2 cylinders.
--------
145267.2
145 revolutions per minute.
--------
20063944 ÷ 33000 = 608 horse-power when running
at a speed of 30 miles an hour.
No allowance has been made for frictional losses in any of these
calculations.
One horse-power is equivalent to the work performed in raising 33,000
pounds one foot high in one minute. One pound raised 33,000 feet
high, or 330 pounds raised 100 feet high, would amount to the same
thing. One horse-power is usually spoken of as 33,000 foot-pounds; and
engineers in this country always calculate work by foot-pounds,--that
is, so many pounds raised a certain number of feet. To indicate the
capacity of any prime motor, the foot-pounds of work it is capable of
raising in a given time must be stated. Although the work is often done
without any thing being raised vertically, the power represented would
be capable of raising the equivalent weight in the stated time.
FORMULAS OF TRAIN RESISTANCES.
The work which a locomotive performs in pulling a train is expended in
overcoming the resistances due to wheel-friction, gradients, curves,
and atmospheric or wind pressure. Formulas have been propounded for
calculating all train resistances, but they are utterly untrustworthy
for American railroad trains. The best known formula of this kind is
that given by D. K. Clark in his _Railway Machinery_. One calculation
will show how misleading its figures are when applied to American
railroad train resistances. Figured by the Clark formula, the total
resistance per ton of a passenger train running at a speed of fifty
miles an hour on a straight level track, is 22.6 pounds. By accurate
records with his dynagraph car, Professor P. H. Dudley found the total
resistances of an express train running at a speed of fifty-one miles
an hour, to be 11 pounds. The resistances are so much different under
different conditions, that nothing closer than a loose approximation
can be calculated of the work done by a locomotive, unless indicator or
dynamometer tests are made.
EXPERIMENTS OF TRAIN RESISTANCES ON THE ERIE RAILWAY.
In experiments made with a freight train on the Erie Railway in
1881, reported by Mr. F. M. Wilder to the Railway Master Mechanics’
Association, it was found that the total resistance on a level track
was from 3.25 to 4.5 pounds per ton at speeds under twenty miles an
hour. These figures will approximately represent the resistance due to
wheel and axial friction in summer; but this resistance will be higher
during cold weather, when the oil in the axle-boxes gets frozen. Track
in bad condition will also tend to increase the wheel resistance, and
improperly constructed trucks and wheels will entail the use of more
power to move the train. Where trucks are so defective that they do not
maintain the wheels revolving in parallel planes, the flanges of some
of the wheels will rub on the rail, increasing the resistance. Wheels
out of round; those having the axle out of center, however slight;
wheels of different size on the same axle; and numerous other car-truck
disorders,--all contribute their share in making a train pull hard.
CONDITIONS THAT INCREASE TRAIN RESISTANCES.
In a calm day the atmospheric resistance is very slight under a speed
of twenty miles an hour. To a fast train, atmospheric resistance
becomes an important obstruction. The atmosphere acts on the train
in various ways, that are hard to calculate with any degree of
accuracy,--head resistance to the locomotive, which is presumably equal
to the exposed area of the front of the engine and cab in square feet
multiplied by the air-pressure due to the speed; then, various parts of
the cars present surfaces that the air strikes against, and increases
the resistance; the raised and projecting roofs of passenger coaches
offer an ample area for the wind to hold the train by; and every
opening between the cars permits the wind to obstruct, to some extent,
each individual car. Where wind is blowing freely in a direction to
strike the train on the side, the resistance is greatly increased; the
retardation being due to the wind pushing the car sidewise, so that the
wheel-flanges rub against the rail, and also to the wind obtaining a
strong hold on the front of each car. In the case of a freight train,
the resistance is greatly increased when the doors of cars are left
open; for every car in that condition acts like a parachute to reduce
speed. Freight trains arranged with box cars and flat cars mixed,
obtain more than a fair share of obstruction from the atmosphere; for
every box car that has a space opened in front by a flat car, gets
nearly the full pressure of the wind in its front. It pays in coal to
incur some trouble and delay in putting box cars together. That also
enables the brakemen to get along the train more rapidly than where the
cars are mixed.
In the experiments already alluded to on the Erie Railway, it was
found, in the absence of wind, that the first car of a freight-train
produced atmospheric resistance equal to a surface of sixty-three feet,
multiplied by the air-pressure due to speed; and that each subsequent
car offered a resistance of twenty per cent of that due to the first
car.
RESISTANCE OF CURVES.
Curved track increases the resistance of trains in direct proportion
to the shortness of curvature. In European railways, the character of
the curves is nearly always denominated by the length of radius: in
this country, a railroad curve is described as of so many degrees. The
degree of a curve is determined by the angle subtended at its center by
a chord of 100 feet. To those who think of a curve by its radius, it
may be well to explain that a curve of one degree has a radius of 5,370
feet, and the radius of any curve can be ascertained by dividing these
figures by the number of degrees.
WORK DONE BY A LOCOMOTIVE PULLING A TRAIN.
To pull a train up an ascending gradient, the locomotive has to perform
work similar to the operation of a pile-driving engine in raising its
driving-block. The train is the block raised by the locomotive; and
the lift is not vertical, but up an inclined plane; yet the amount of
work done is reckoned in precisely the same way. When the engine of a
pile-driver raises a block weighing 1,000 pounds a distance of 30 feet,
the work done is 1,000 × 30 = 30,000 foot-pounds: when a locomotive
pulls a train weighing 1,000 tons over one mile rising 30 feet, the
engine performs 30,000 foot-tons of work in that distance by raising
the load alone. The total amount of work done will also include the
energy expended in overcoming wheel-friction and other ordinary train
resistances.
To find the tractive force which the engine must exert through each
foot of the mile traversed in pulling the train described, we must
divide the foot-pounds of work done, by the distance over which the
power was exerted. Thirty thousand foot-tons of work is 60,000,000
foot-pounds. To this we will add 5 pounds additional for every ton of
the train for every foot advanced to cover wheel and wind resistances,
making 86,400,000 foot-pounds of work that the engine has to perform in
hauling the train one mile. This, divided by the number of feet in a
mile, will give 16,363 pounds as the work the locomotive must perform
through each foot,--an effort which is entirely within the capacity of
many consolidation engines.
RECORD OF FAST EXPRESS TRAIN MADE BY PROFESSOR P. H. DUDLEY’S DYNAGRAPH
CAR.
Engineers interested in finding an approximation of the work done in
taking a fast train over a railroad, can make a close estimate by
studying out the figures given below by Professor Dudley. The table
shows the performance of an ordinary locomotive upon a train composed
of three eight-wheel and six twelve-wheel cars; weight 250 tons;
working-weight of engine and tender, 126,000 pounds; cylinders of
engine, 17 by 24 inches; diameter of drivers, 72 inches; weight on
drivers, 48,000 pounds; blowing-pressure on boiler, 135 pounds.
In starting the train, the locomotive would record a tension of 11,000
to 12,000 pounds for one or two hundred feet of distance. After hooking
up, the tension would decrease to about 2,800 or 3,000 pounds; and,
with this pull, the speed of 50 miles an hour was attained in the
fifth mile. As the speed increases, the resistance of the air against
the locomotive becomes greater, and more of its own power is required
to move itself. In starting a train, the working adhesion of the
steel-tired drivers on dry steel rails is about 33 per cent of the
weight upon them, and reduces as the speed increases.
_Tabulation of Part of a Trip of the Dynagraph Car on a Fast Express
Train._
KEY:
1 Numbers of Miles.
2 Time in Minutes and Seconds per Mile.
3 Speed in Miles per Hour.
4 Velocity of the Wind in Miles per Hour.
5 Approximate Grades.
6 Foot-Pounds of Work shown by Dynametrical Curve per Mile.
7 Foot-Pounds of Work per Minute expressed in Horse-Power.
8 Approximate calculated Foot-Pounds of Work required to move the
Locomotive in Horse-Power.
9 Sum of Columns 7 and 8.
===+======+=======+=====+================+============+=====+=====+====
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9
---+------+-------+-----+----------------+------------+-----+-----+----
1 | 2 54 | 20.68 | | Level | 24,116,233 | 252 | |
2 | 1 34 | 38.31 | 6.0 | Down 5 ft 3 in | 20,035,253 | 369 | 221 | 590
3 | 1 22 | 43.90 | 4.0 | Down 5 ft 3 in | 17,763,214 | 398 | 292 | 690
4 | 1 16 | 47.34 | 3.0 | Level | 15,904,273 | 383 | 418 | 791
5 | 1 11 | 50.70 | 4.5 | Level | 14,871,528 | 382 | 406 | 788
6 | 1 13 | 49.31 | 6.0 | Up 13 feet | 15,284,616 | 383 | 406 | 789
7 | 1 11 | 50.70 | 6.0 | Down 18 feet | 14,458,430 | 369 | 426 | 795
8 | 1 08 | 52.89 | 5.0 | Down 13 feet | 13,219,136 | 354 | 451 | 805
9 | 1 07 | 53.70 | 5.0 | Down 8 feet | 11,566,744 | 319 | 483 | 802
10 | 1 09 | 52.10 | 5.0 | Down 5 feet | 11,773,293 | 310 | 441 | 751
11 | 1 08 | 52.89 | 4.2 | Level | 11,773,293 | 316 | 447 | 763
12 | 1 09 | 52.10 | 5.2 | Down 8 feet | 12,806,038 | 337 | 456 | 793
13 | 1 10 | 51.43 | 6.0 | Level | 12,392,940 | 324 | 443 | 767
14 | 1 10 | 51.43 | 4.5 | Level | 12,806,038 | 339 | 426 | 765
15 | 1 10 | 51.43 | 4.0 | Level | 13,425,685 | 351 | 420 | 771
16 | 1 10 | 51.43 | 3.5 | Level | 13,299,136 | 345 | 415 | 760
17 | 1 08 | 52.89 | 3.0 | Level | 13,838,783 | 371 | 443 | 814
18 | 1 08 | 52.89 | 5.0 | Down 6 feet | 13,219,136 | 354 | 464 | 818
19 | 1 08 | 52.89 | 3.0 | Down 2 feet | 13,219,136 | 354 | 443 | 797
20 | 1 11 | 50.70 | 3.5 | Up 10 feet | 14,838,783 | 379 | 406 | 785
21 | 1 13 | 49.31 | 3.0 | Up 10 feet | 14,458,430 | 362 | 384 | 746
22 | 1 08 | 52.89 | 3.1 | Level | 12,392,940 | 332 | 443 | 775
23 | 1 07 | 53.70 | 3.1 | Down 10 feet | 12,186,391 | 333 | 462 | 797
===+======+=======+=====+================+============+=====+=====+====
The following calculations have been made, to indicate the trains that
various locomotives ought to pull.
_Weights of Train which Locomotives can haul at a Speed
of 20 Miles an Hour under Ordinary Conditions, in Tons
of 2,000 Pounds (not including the Weight of Engine and
Tender)._
=========================+=============================
| TYPE OF LOCOMOTIVE.
+---------+---------+---------
|Type “A.”|Type “B.”|Type “C.”
-------------------------+---------+---------+---------
_On straight track_: | | |
Level | 1,096 |1,664 | 2,226
Grade 20 feet per mile | 547 | 840½ | 1,128
” 40 ” ” | 350 | 545 | 734
” 60 ” ” | 249 | 390½ | 522
” 80 ” ” | 188 | 302 | 410
” 100 ” ” | 148 | 242 | 330
| | |
_On 5-degree curves_: | | |
Level | 921 |1,401½ | 1,876
Grade 20 feet per mile | 464 | 716 | 962
” 40 ” ” | 310 | 485 | 654
” 60 ” ” | 227 | 360½ | 488
” 80 ” ” | 173 | 279½ | 380
” 100 ” ” | 137 | 225½ | 308
| | |
_On 10-degree curves_: | | |
Level | 662 |1,013 | 1,358
Grade 20 feet per mile | 401 | 621½ | 836
” 40 ” ” | 278 | 477 | 590
” 60 ” ” | 207 | 330½ | 448
” 80 ” ” | 160 | 260 | 354
” 100 ” ” | 128 | 212 | 290
=========================+=========+=========+=========
Under the most favorable conditions, loads about fifty per cent
greater than those given above may be hauled.
The calculations are for three types of engine, designated in the
column titles as Type “A,” Type “B,” and Type “C;” these being as
follows:--
_Type A._--American locomotive, with four driving-wheels, and 12,000
pounds weight on each wheel, the total weight of engine being 36 tons.
_Type B._--Mogul or ten-wheeled locomotive, with six driving-wheels,
and 12,000 pounds weight on each wheel, the total weight of engine
being about 42 tons.
_Type C._--Consolidation locomotive, with eight driving-wheels, and
12,000 pounds weight on each wheel, the total weight of engine being
about 54 tons.
CHAPTER XXVII.
_WATER FOR LOCOMOTIVE BOILERS._
HOW WATER GETS MIXED WITH LIME.
Throughout a very wide area of territory in the United States and
Canada, limestones, or various forms of calcareous rocks, constitute
the upper rock stratum immediately underlying the subsoil of the great
agricultural regions. During the stupendous operations of Nature in
building up this continent, the rocks have been subjected to vast
disintegrating agencies: they have been torn and eroded by huge masses
of ice; they have been burned by the rays of the unshadowed sun;
fractured by the congealing power resulting from deep-searching frost;
melted by water,--that most universal solvent in nature; then scattered
far and wide by ice and flood. This process has been so complete, that,
in the whole limestone territory, all the earth seems charged with
lime. Limestones are very sparingly soluble in pure water; but the
rain that falls from the clouds is not pure, but contains a charge of
carbonic acid that acts chemically upon the lime, forming salts, which
the water readily dissolves. Owing to this circumstance, there are few
streams, and fewer wells, in the calcareous districts that are not
contaminated with lime. The water that passes into streams, generally
runs over surfaces that have been washed partly free from lime; and, in
consequence of this, creeks and rivers are not so badly tainted with
lime-salts as the water in wells that stands saturating the rocks. The
appearance or taste of water gives no indication of the quantity of
lime held in solution; for the ice-cold well, or sparkling spring, that
supplies water so pleasant to drink, may yield so much lime-salts that
the water would be ruinous to sheets and flues when used for boiler
purposes.
EXPENSE ENTAILED BY USING BAD WATER.
Considering the financial influence of the matter alone, it might be
supposed that parties building railroads would exercise diligence in
selecting the best water that possibly could be secured for boiler
purposes, since the operating expenses are largely magnified by using
impure water; but for many years the subject appeared to receive no
attention whatever from those best able to regulate the water supply,
and water stations were established without any consideration as to the
character of the water available.
It is owing to the absence of care in the original locating of water
stations, that numerous tanks are to-day drawing their supply from
bad wells, where surface water could easily be obtained. Railroad
companies are peculiarly conservative about making changes that
entail expenditure of money: and existing evils in the water supply
arrangements are often continued, because some expense would be
incurred in making them; although no kind of money expenditure would
bring a more ample return in economy.
EFFORTS OF MASTER MECHANICS TO SECURE GOOD WATER.
The paramount importance of the quality of water used in locomotive
boilers, has been long recognized by nearly all master mechanics;
for the effect of bad water is brought to their attention in an
unmistakable manner. The subject has been frequently before the Master
Mechanics’ Association for investigation. A report of a committee
appointed at an early meeting to investigate the subject, declares
that “Master mechanics have had the conviction forced home, that
impure water is the bane of good boilers;” and, even then, a vigorous
effort was being made to eliminate the injurious ingredients from
the water; and the work was carried on in a hopeful and confident
spirit, which was indicated by the words of a subsequent report, which
asserted that “Different waters differ widely in the component parts
of the impurities they contain, and each requires separate study and
treatment;” but the committee were satisfied that the engineering
and mechanical skill of railway men could readily devise a suitable
appliance for each particular case. In those days, railroad men thought
that they could, by mechanical and chemical means, purify bad water,
and render it suitable for boiler use. Purifying bad water proved
about as difficult an undertaking as reforming the average bad man is
recognized to be; and few railroad men can now be found who believe a
purifying process can be successfully performed on the large quantity
of water needed for locomotive boiler feeding.
LOSS OF FAITH IN PURIFYING METHODS.
The conclusion that artificial methods of purifying bad water can not
be carried out in railroad water supply, was not arrived at hastily. It
was reached by slow degrees, and through the convincing ordeal of many
disappointments, with methods and nostrums that promised to effect the
desired results.
Experience demonstrated, that, in the limestone regions, the proper and
only way to avoid trouble from lime incrustation in locomotive boilers,
is to obtain soft water from streams, or by collecting the rainfall in
ponds or reservoirs.
SCALE-MAKING AGENCIES.
Water, as has been mentioned, is the most universal solvent in nature;
and what is known as hard water contains many foreign ingredients,
but those that exercise such a pernicious influence upon locomotive
boilers are lime and magnesia. The scale-making lime appears in two
forms,--sulphate of lime, and carbonate of lime. The former is the
more dangerous and troublesome scale-making agent; the latter is most
frequently met with.
Ordinary well-water will be found to contain solid matter in solution
varying from 10 to 100 grains to the gallon. Under 20 grains to the
gallon of impurities may be considered fair water if the principal
ingredient is carbonate of lime, but that amount of sulphate will
make highly objectionable boiler water. Where the use of well-water
is unavoidable on a road, quite a saving to boilers can be effected
by ascertaining the quantity and character of the impurities received
from each water-tank, and directing the engineers to avoid those that
contain the worst scale formers.
TO ASCERTAIN THE QUALITY OF WATER.
The proper way to ascertain with accuracy the character of water, is
to send specimens to a competent analytical chemist for quantitative
analysis. But, as few railroad companies will incur the expense of
having the water of the water stations systematically tested, master
mechanics may, by a little labor, study, and practice, learn to make
tests for themselves that will indicate near enough for practical
purposes the character of each water station supply.
As master mechanics are the railroad officials most directly interested
in the kind of water supplied for locomotive use, they ought to have
direct control of all the water stations on the roads where they are in
charge.
APPLIANCES NEEDED IN TESTING WATER.
The chemical apparatus needed for the examination of well-water are,
a balance that will weigh accurately to half a grain; an oil stove
for evaporative purposes; a few pint porcelain evaporating dishes; a
sand-bath, which can be made from a piece of sheet-copper; a dozen
test tubes; half a dozen vials to hold solutions of chemically pure
chemicals; some pieces of glass tubing; a small mortar and pestle;
a supply of filtering-paper; and the vessels needed for measuring
accurately. For the solution of the chemical re-agents to be used, a
supply of distilled water is necessary; and water of this kind is also
necessary to make comparisons with. A piece of pure crystalline ice,
when melted, will generally produce water pure enough for experimental
purposes.
PREPARING FOR THE EXPERIMENTS.
In bringing in water for examination, it is best to have it drawn from
the water-tank into a perfectly clean jug, which should be corked and
labeled. Weigh an evaporating dish, noting down the exact weight, and
on a sand-bath evaporate one quart or half a gallon of the water to
be inspected. When the dish becomes dry, rub off all dust that may
be adhering to the bottom, and weigh the dish. The added weight will
indicate approximately the total amount of solid matter in the water.
Note that down, and every other detail of the experiments.
LIME HELD IN SOLUTION BY FREE CARBONIC ACID.
Sometimes a large quantity of bicarbonate of lime is held in solution
by free carbonic acid, which escapes as soon as the water is boiled,
leaving the lime to subside in the form of mud. Water of this kind may
appear very hard, yet not be very objectionable for boiler use; since
the deposit can be blown out if the blow-off cock is used freely.
To test this, boil a pint of water for two or three minutes in a
perfectly clean dish, then pass it through a filter paper that has been
previously dried and weighed. When the operation is finished, dry and
weigh the filter paper again; and the added weight will indicate the
amount of solid matter held in solution by free carbonic acid gas.
TEST FOR LIME SALTS.
Superficial tests that will indicate the condition of the water from
the coloring produced by the impurities combining with chemicals that
take them out of solution, can be made in the following manner: Five
test tubes are half filled with water to be tested. The first one will
be examined for lime in any form. A teaspoonful of aqua ammonia is put
in the water for the purpose of stimulating the chemical action, then
twenty drops of a solution of oxalate of ammonia are added. The degree
of turbidity will indicate the quantity of lime in the water. Should
the quantity of lime be very small, the test tube would have to be kept
in a warm place a few hours before the re-action showed itself.
TEST FOR SULPHATE OF LIME.
The water in the second test tube will be examined for sulphate of
lime. A few drops of hydrochloric acid are first put into the water,
then twenty drops of chloride of barium. A white precipitate, which
generally makes its appearance at once, indicates the presence of
sulphuric acid. In water belonging to the calcareous regions, it may
safely be concluded that the sulphuric acid is held in the form of
sulphate of lime. An exception has sometimes to be made for water drawn
from the vicinity of coal mines, and such places, where sulphate of
iron abounds. Water that holds sulphuric acid in this form is readily
identified by a test for iron salts.
When it is found that water gives a strong re-action indicating
sulphate of lime, the inference may safely be drawn that the tank it
came from should be avoided.
TEST FOR CARBONATE OF MAGNESIA.
The third test tube may be examined for carbonate of magnesia, which is
found freely mixed with the water of many wells. Put aqua ammonia in
this tube, and add twenty drops of a solution of phosphate of soda. A
crystalline precipitate will indicate the presence of magnesium. Where
carbonate of magnesia is present in considerable quantities in water,
it sometimes forms along with lime a thick, porous scale; and in other
cases it is apt to float on the top of the water, causing trouble by
making the boiler foam. If an engine boiler has got scale formed from
water free from magnesia, and goes on to a division where this impurity
abounds, the magnesia will take off the old scale before it begins to
form new incrustation. A few pounds of common salt put into the tender
daily will have a good effect in preventing trouble with magnesia;
since it forms chloride of magnesia, which is a decided preventive of
lime scale.
TEST FOR SALTS OF IRON.
In the fourth test tube we will search for iron salts. A solution of
potassa or ammonia will produce, should iron be present, a whitish
precipitate, which presently turns to a dirty green, and, ultimately,
a reddish-brown color, owing to its absorption of oxygen from the
air. A more delicate test for iron is ferro-cyanide of potassium, or
sulpho-cyanate of potassium; but other mineral combinations might
deceive a novice using these reagents into the belief that iron was
present when it was not. A light trace of iron in water is very common;
and, so long as it is in minute quantities, the salt seems quite
innocent. But occasionally water is found saturated with iron in the
form known by chemists as _FeSOᵥ{4}_. Then it is very objectionable for
boiler-feeding; since it exercises a strong corrosive action on the
plates, pitting and furrowing being a common result of its action.
Scale formed by water of this character is nearly always a hard, thin
substance, that sticks with intense tenacity, and generally takes away
part of the skin of the iron when it is taken off.
TEST FOR CHLORINE.
The fifth tube we will examine for common salt, which is nearly always
present in water. This test is done by dropping in some nitrate of
silver solution, which produces a white precipitate, caused by the
silver combining with the chlorine, which is the principal element
in common salt. This is an excessively fine test, and the nitrate of
silver will detect an incredibly small trace of common salt in water.
The worst effect that common salt has in water, is to cause priming.
Where it is present to any great extent, the blow-off cock should be
used frequently on the road; and a surface-cock is quite an aid in
keeping the boiler in order. Water that is taken from wells or streams
about cities, and found to give strong chlorine re-actions, is nearly
always contaminated with sewage.
LEARNING THE MANIPULATION OF TESTS.
Practice in making superficial qualitative tests of water, produces
skill in reading the meaning of the various chemical re-actions. This
skill can be rapidly developed by practice on prepared specimens. Water
for experiments on carbonate of lime can be prepared by dissolving
calcite crystals or marble dust in hydrochloric acid, or by mixing
chalk with clean rain-water, and filtering it till free from turbidity.
While the chalk is mixed with the water, and unfiltered, the specimen
will be made stronger by blowing air from the lungs through a glass
tube into the water. A preparation for testing sulphate of lime may
be made by dissolving some gypsum in distilled water. Fluid magnesia,
dropped into pure water, will provide carbonate of magnesia specimens;
and Epsom salts will give the magnesia re-action, with the addition
that it will indicate sulphuric acid under the chloride of barium
test. A grain of salt no larger than a pin-head dropped into a pint of
distilled water, will give a distinct chlorine test when nitrate of
silver solution is added. Stronger, or even weaker, salt solution can
be used by the experimenter while he is working into practice. A small
piece of sulphate of iron, dissolved in water, will provide a test for
iron.
MAKING QUALITATIVE TESTS.
While pursuing the apprentice practice of tests with these solutions,
care must be taken to have the test tubes perfectly clean. Go over the
tests in something like the following order. The carbonate of lime test
is to be made first. Four test tubes will be used. In the first we put
distilled water alone; in the second we put ten drops of the chalk
solution; in the third we put twenty drops of the solution; in the
fourth we put thirty drops, then add distilled water till all the test
tubes are about two-thirds filled. Drop into each tube about the same
quantity of oxalate of ammonia solution, and the degree of turbidity
will help to indicate the hardness of each specimen. The first tube,
containing pure water, will give no re-action if the chemicals are pure.
This process should be extended to all the other solutions, and will
be found very helpful. In carrying out experiments of this kind,
much assistance will be obtained from having a work like Stuckhardt’s
_Chemistry_ at hand for reference.
THE SOAP-TEST FOR HARDNESS.
Most people are aware that hard water has a peculiar effect upon soap,
making it curdle instead of lather when used for washing purposes. This
peculiarity was made use of some years ago by Dr. Clark of Aberdeen,
Scotland, in devising a test for the hardness of water, in which the
quantity of a standard soap solution needed to produce a permanent
lather on water, indicated the degree of hardness of the water. A
modification of the Clark process can be used very conveniently by
master mechanics in making superficial tests of the hardness of water,
and the plan has the advantage of being easily applied. With a test
tube and a small bottle of soap-solution, the investigator is ready
at any time or place to make tests; and a few minutes spent over each
specimen will give him an idea of the value of the water for boiler
purposes.
The original Clark soap-test was made with a soap-solution of known
strength, of which a certain measured quantity was required to
produce a permanent lather on a gallon of water containing a given
quantity of carbonate of lime. The degrees of hardness of other
specimens were computed according to the quantity of the soap-solution
required to produce a permanent lather. Preparing soap-solution of a
certain strength, and water of a certain hardness, for the purpose
of indicating a point for beginning the computations, is a tedious
operation; and the soap-test can be used in a much simpler way. While
making numerous tests of water on the Burlinglington, Cedar Rapids, and
Northern Railway some years ago, to ascertain the condition of water
tanks at different seasons of the year, and in examining the supply of
proposed water stations on extensions of the road, I used the following
modification of the Clark process:--
MODIFICATION OF THE CLARK SOAP-TEST.
The Cedar River, during its normal flow in summer, contains about ten
grains of solid matter, mostly calcium carbonate, to the American
gallon of 58,373 grains. This I considered good boiler-water, and
made it the standard of comparison for my tests. Beside the shop,
there is a well, which the people who built the road dug for supplying
boiler-water; although the Cedar ran a few rods distant. This
well-water contained about forty grains of solid matter to the gallon,
one-fourth of the impurity being sulphate of lime. This water I made my
“awful example” standard of comparison, so that water approaching this
in hardness was condemned.
The soap-solution I made by dissolving seventy grains of castile soap,
or white soap-powder, in a pint of alcohol. Care must be taken that
all the soap is dissolved, and then it is best to keep the mixture in
an even temperature not below 60° Fahr. The tests can be made more
accurately by having the water under examination brought to the same
temperature as the soap-solution.
APPLYING THE SOAP-TEST.
In making the tests, a measured quantity of the Cedar water was put
into a stoppered bottle. One ounce of water put into a two-ounce bottle
is a convenient quantity. The soap-solution was then measured out with
a pipette made to hold thirty drops, and the bottle was well shaken
after each measure till it was found that a lather was formed which
held on for five minutes. The operation was then repeated; and the last
charge from the pipette was put in, drop by drop, till the point where
a permanent lather formed was noted. A similar performance was gone
through with the bad well-water, and very little practice enabled the
operator to ascertain where a specimen of water stood between the range
of the good and bad water.
The soap-solution must be kept in a properly stoppered bottle; and,
every time a new solution is made, its strength must be tested in the
above fashion. The solution deteriorates when kept longer than a month
or six weeks.
The degree of turbidity caused by the first charge of soap-solution, is
an indication to the practiced experimenter of the degree of hardness
of the water.
Most men interested in ascertaining the condition of boiler-water, can
devise means for obtaining water of known hardness wherewith to make
comparative tests.
If water under examination prove very hard, the test will be more
accurately done by diluting it with its own volume of distilled water.
The soap-test is good for lime in all its forms, and magnesia; but the
latter impurity uses up more soap than lime does. So, where magnesia
abounds in water, the specimen under trial will seem harder than it
actually is. Magnesia is also slower than lime in acting upon the soap.
Water that contains magnesia will produce a lather when enough solution
is put in to overcome the lime present; but if it be allowed to stand
a few minutes, till the magnesia acts, the lather will not then form.
The presence of certain alkaline salts in water, such as the carbonates
and sulphates of soda and potash, injuriously affects the soap-test by
making the water appear softer than it is; since they accelerate the
forming of a permanent lather. Keeping these facts in mind will often
prove of valuable service in making tests of water.
When the soap-test indicates that water contains hardening ingredients,
representing more than fifteen grains to the gallon, other tests should
be at once made to ascertain what the leading ingredients are.
DIFFICULTIES OF PURIFYING WATER FOR LOCOMOTIVES.
The nostrums offered to railroad managers for purifying feed-water
are legion, but it is doubtful if a single remedy has proved entirely
successful. In most instances, the material or means used have been
worthless or impracticable; but, in other cases, the appliances have
not received justice from those attending their application. Most
people underrate the magnitude of the task involved in undertaking to
render the impurities of feed-water innocent in locomotive boilers.
The case of a learned professor who undertook to doctor the feed-water
for locomotives on a prominent road, where he made his arrangements
for each engine using one thousand gallons of water a day, is
representative. When provision has to be made for some engines using
double that quantity each hour, the difficulty of the transaction
becomes apparent. As has already been said, I believe that obtaining
soft surface-water is the proper way to avoid trouble with locomotive
boilers; but, where this is impracticable, considerable saving can be
effected by “doctoring” the water if the operations are intelligently
conducted.
MUD.
Mud is the most universal impurity of feed-water; and, in many cases,
it causes the destruction or injury of sheets, particularly the
crown-sheets of fire-boxes. Where the water of a road is habitually
muddy, it would pay to filter the water, or to have two tanks at each
water station, so that a system could be followed of letting the water
settle in one tank while the other was in use. The settled mud, by this
means, could be washed out regularly before a tank were refilled.
CARBONATE OF LIME.
Dr. Clark, inventor of the soap-test, recommended a method of purifying
water containing carbonate of lime, which has been successfully
followed in many places, especially in England. It consists of adding
caustic lime to water containing carbonate of lime. By this process,
28 grains of caustic lime result in the precipitation of 100 grains
of lime carbonate. Or, to put it in a practical shape, where a tank
contains 30,000 gallons of water, each gallon being impregnated with 30
grains of lime carbonate, 36 pounds of caustic lime will be sufficient
to precipitate the whole of the impurity, making a total deposit of 164
pounds.
SULPHATE OF LIME.
Where the water impurity is principally sulphate of lime, the caustic
lime remedy will not work; but a precipitate of the objectionable
compound can be made by treating the water with caustic baryta or
caustic soda. In the first case, the baryta takes possession of the
sulphuric acid holding the lime in solution, allowing the latter to
fall down as mud: when the soda cure is applied, the sulphuric acid
deserts the lime, and combines with the soda, for which it has greater
affinity, leaving the lime to precipitate, unless it be preserved in
solution by the carbonic acid that accompanied the soda.
Where the water contains a mixture of lime sulphate and carbonate,
the soda treatment may be advantageously used in combination with the
caustic lime system.
Attempts have frequently been made to purify water by putting chemicals
into the locomotive tenders, the impurity being precipitated in the
boiler. The leading objection to this system is, that it leads to
enormous quantities of sediment being deposited inside the boiler;
since, in some instances, the purifying substance is as bulky as the
original impurity. In other cases, the chemical introduced into the
boiler causes foaming. Let us take the case of water that contains
fifteen grains of sulphate of lime to the gallon, and is treated with
sulphate of baryta. To do so properly, one grain of the chemical will
be required for each grain of lime. A freight engine uses seventy-five
gallons of water to the mile, and runs one hundred miles a day. This is
light service, both for water and mileage; yet, within ten days, nearly
three hundred pounds of solid matter is injected into the boiler.
To purify water by injecting chemicals into locomotive boilers, and
prevent the boiler filling up rapidly with mud, or giving trouble from
foaming, the blow-off cock and surface cock must be used so frequently
as to be felt on the consumption of coal. Where purifying of feed-water
_must_ be done, the right place to carry on the process is in the
station tanks, or in special appliances beside them. By carefully
watching the character of the impurities in the water, and treating
them with their proper precipitants, labor and expense devoted to the
purification of feed-water may bring in good returns: where attempts
are made to improve the water over a whole road by one method of
treatment, failure is certain.
CHAPTER XXVIII.
_EXAMINATION FOR LOCOMOTIVE ENGINEERS._
The following is the form of questions put to firemen on one of the
most prominent railroads in this country before they are admitted as
competent for promotion, and the kind of answers expected from those
who are considered eligible for the higher position. The form questions
are not adhered to strictly, and care is taken that a candidate for
promotion does not commit the answers to memory without properly
understanding the subject. No fireman is promoted who does not satisfy
the examiner that he understands the practical questions asked.
_Q._--What are the principal duties of an engineer before attaching his
engine to train?
_A._--To examine the engine carefully, to see that all set-screws
are in place, and rod-keys secure; that the engine is equipped with
all necessary signals, firing, and hand-tools; the necessary supply
of water, fuel, and stores. Also, to take a look at the flues and
crown-sheet.
_Q._--What is important, in carrying water in the boiler, as to height
and regularity?
_A._--To carry water and steam in the top gauge-cocks when working
steam, and as uniformly as possible.
_Q._--What is important in carrying water on grades, and approaching a
summit?
_A._--To carry the water sufficiently high to be sure that the front
ends of the tubes are not exposed, and, in pitching over a summit,
to have sufficient water to cover and protect the crown-sheet, after
finding its level from the front or low end of the boiler.
_Q._--Should it be necessary, after pitching over a summit, to pump up
a gauge or more of water, what should be the condition of the fire?
_A._--The fire should be kept bright, and burning freely.
_Q._--Why is this important?
_A._--To prevent chilling the flues, causing them to leak.
_Q._--Should you have ample water after pitching over, what should be
the condition of the fire?
_A._--It should be leveled and settled down, and covered over
sufficiently to prevent unnecessary waste of steam or fuel.
_Q._--Should the pump or injectors fail on the road, what would you do?
_A._--First, smother down the fire, stop promptly, take off the hose,
and raise the tank-valves to ascertain that they are connected; also
see that the strainers are clear. If all is found clear, then try the
injectors again; and, if the engine has a pump, take it down, and
see that the valves are free, and would also run water through the
feed-pipes. When all is open and free, put them up, and try them again.
_Q._--Should the water in the boiler get too low to allow you time for
the examination, what would you do?
_A._--Draw the fire, and send a messenger to the nearest telegraph
office for assistance.
_Q._--Should the water in the boiler become disturbed, and foam, what
would you do? And how would you ascertain whether it was foaming, or
being over pumped?
_A._--As soon as the water is discovered discharging from the stack,
would at once shut off, and ascertain the height of the water solid.
Should the water drop below the second or third gauge, would conclude
there was foaming, and would again gently open the throttle. Should
the water again rise, and discharge from the stack, would put on both
injectors, open the surface blow, and run carefully; allowing the bad
water to be worked off through the surface blow, being very careful not
to work the water in sufficient quantities through the cylinders as to
endanger knocking out the heads; and would occasionally shut off, to
see that the water was not being thrown off faster than the pumps or
injectors were supplying it. By this means, the bad water would, in
most cases, be worked out, and, with gentle usage, would again settle.
_Q._--Should the blow-off cock be blown out, or be broken off, or a
hole be broken in the boiler in any way, what would you do?
_A._--Draw the fire promptly, and send a messenger to the nearest
telegraph office for assistance. Would then disconnect, and get the
engine ready to be towed in when assistance arrived.
_Q._--What portions of the engine would you disconnect in such a case?
_A._--Take off main rods and valve-rods.
_Q._--What is important to observe in setting up or adjusting wedges?
_A._--To have them so neatly adjusted that there will be no thump of
the boxes, and, at the same time, not so tight as to cramp, and not
allow them full and free play in the pedestals.
_Q._--How would you go about setting them up?
_A._--Would place the engine at half stroke on the right side, block
the left wheels, admit a little steam, and thump the boxes hard away
from the wedges. Would then get under, and put the wedges up solid with
a short wrench, and make a side mark on the pedestals at top of wedge,
then draw them down equally a scant one-eighth of an inch. Go over the
left side in the same manner.
_Q._--How would you key up, or adjust, the side rods of a ten-wheel
engine?
_A._--Would place the engine on a level and straight track, and on a
dead center; then slack off all keys on that line of rods; would then
key the knuckle on center brass first, leaving it sufficiently free on
the pin to be moved laterally by hand. Then adjust the front and back
ends in the same manner.
_Q._--Why should you place the engine on exact dead center, and begin
by keying the center brass first?
_A._--In order to insure keying the rods of proper length, to allow
them to pass the dead, or rigid, points without strain.
_Q._--Can the side rods be keyed too long or too short when not
standing on dead center?
_A._--They can.
_Q._--If too long or too short, at what point of the stroke will the
strain be?
_A._--While passing the dead, or rigid, points.
_Q._--Should you slip the right back motion eccentric on the road, how
would you reset it?
_A._--Would place the engine on exact dead center on right side,
place the reverse-lever in full forward gear, and make a mark on the
valve-rod at the stuffing-box gland; then place the reverse-lever
in full back gear, and turn the slipped eccentric until the mark on
valve-rod came to its original position, being careful to see that the
full or throw of the eccentric was in position nearly opposite the
forward eccentric; then secure it there.
_Q._--In what way does the mark you made on the valve-rod, while in
forward gear, aid you in setting the slipped eccentric?
_A._--The forward motion eccentric being in proper position by placing
the reverse-lever in full forward gear, the valve is brought into
proper position on the ports; and the mark gives the position of the
valve when the back motion eccentric is in its proper position, thus
setting the slipped eccentric by the good one.
_Q._--Should a valve-yoke break, how would you test in order to
determine which side was disabled?
_A._--Would first place the engine at half stroke on right side, and
admit a little steam to the cylinders; then move the reverse-lever from
back to forward motion, and, if the steam could be shifted from the
back to the forward cylinder-cock, would conclude that the right yoke
was good, and would test the left side in the same way.
_Q._--Why would you place your engine at half stroke on the side you
wished to test?
_A._--In order to get the full movement of the valve over the ports on
that side.
_Q._--After locating the broken yoke, how would you disconnect?
_A._--Would take off the steam-chest lid, place the valve over the
ports, and block it there securely; replace the lid, take off the
valve-rod, take off the main rod, block the cross-head, and proceed
with half train, if freight; if passenger, would take the full train to
the next telegraph office, report, and give judgment as to whether the
engine would take entire train to its destination.
_Q._--Should you blow or break out a cylinder-head, how would you
disconnect?
_A._--First, take off the valve-rod, and close the ports with the
valve, and secure it by cramping with the stuffing-box gland; take off
main rod, and block the cross-head.
_Q._--Should the cylinder packing drop and blow badly on the road, how
would you determine which side was down?
_A._--In starting from a station, would notice the right cross-head,
and, if the blow occurred when it was leaving each extreme end of the
stroke, would locate the blow in the right cylinder.
_Q._--Should it blow so badly as to make it necessary to set it out on
the road, what would be important for you to observe in setting it out?
_A._--Would be careful to set the piston central in the cylinder, using
calipers if at hand, and, if not, would use a stick of proper length,
and be careful only to set the packing to fill the cylinder neatly,
using as little power on the bolts as practicable; lock the nuts
securely, and replace the follower, being careful to screw the follower
bolts home solid.
_Q._--Should you be running an engine which had but one pump, it being
on the right side, and that side became disabled, so that it would be
necessary to disconnect it, the injector be too small or fail to supply
the boiler, what would you do to avoid drawing the fire, and being
hauled home?
_A._--Would disconnect the piston from the cross-head on the disabled
side, and take it out, put up the main rod, and work the cross-head,
which would give the use of the pump.
_Q._--Should you break the top rocker-arm, how would you disconnect?
_A._--Take off the valve-rod and broken arm, close the ports, and
secure the valve with the stuffing-box gland, and disconnect, as in
case of broken cylinder-head.
_Q._--Should the bottom rocker-arm break, how would you disconnect?
_A._--As a rule, would not take off eccentric-straps; but with an
engine badly worn, and loose in link-hanger, so that the link could
play about freely when running, would take off the eccentric-straps,
and disconnect, as in case of broken cylinder-head.
_Q._--Should you break a link-hanger, how would you disconnect?
_A._--If but a short distance to run, and no stopping or shifting to
do, would run in without disconnecting, after cautioning the crew to
keep the train under good control, and stop promptly when signaled to
do so. But, if a long distance to run, would disconnect, as in case of
broken cylinder-head.
_Q._--In what way would you have lost control of your engine with
broken link-hanger?
_A._--Would only be able to reverse one side of the engine.
_Q._--Should you break an eccentric-strap, how would you disconnect?
_A._--Take off both eccentric-straps on that side, and disconnect as in
case of broken cylinder-head.
_Q._--Should you break the back section of a side rod on a six-wheel
connected engine, what would you do?
_A._--Would take off both back sections, and run in with main and
forward wheels connected, with about two-thirds of train.
_Q._--Should you break a forward section, how would you disconnect?
_A._--Would take off all side rods, and run in without train.
_Q._--Should you break a main crank-pin close up to the wheel, how
would you disconnect?
_A._--Would take off all side rods and the main rod on disabled side,
and run in without train.
_Q._--Should you be running an engine which had a slide throttle-valve,
and it would strip or disconnect inside the boiler partly open, how
would you manage?
_A._--Would reduce the steam-pressure within easy control, and state
the trouble to the crew, and caution them to act promptly when called
upon to do so. Would work the train, if freight, to the nearest siding,
and back it off; if passenger, would keep the pressure within easy
handling, and work the train to the nearest telegraph office, report,
and ask for orders.
_Q._--Should one of the forward tires on a ten-wheel engine break, how
would you manage?
_A._--Would jack the wheel up the thickness of the tire, take out the
oil-cellar, and cut a block to fit the bottom of the box and journal
sufficiently thick to hold the axle up in its place when resting on the
pedestal-brace; would then run in without disconnecting, provided the
rod had not been bent or damaged by the broken tire. Would take in full
train.
_Q._--Should you break a main tire, how would you manage?
_A._--Would first send messenger to nearest telegraph office, and ask
for assistance. Would then block up the axle and wheel the thickness
of the tire, slack off the side-rod keys, and run in carefully without
train.
_Q._--Should the back tire break, how would you manage?
_A._--Would take off the back section of rods, block up the axle, run
very carefully, especially around curves, to nearest telegraph office,
report, and ask for orders.
INDEX.
Accidents to cylinders and steam connections, 162–171.
---- ---- eccentric-strap, 383.
---- ---- link-hanger, 383.
---- ---- running-gear, 172–181.
---- ---- valve-motion, 143–161.
Adhesion of locomotives, 346.
Air-pump disorders, 322.
Angularity of connecting-rod, 219.
Angularity of connecting-rod, effect of, in valve-motion, 220.
Appliances for testing water, 363.
Ash-pan, neglecting, 42.
Axles, broken, 179.
Baldwin locomotives, 284.
Boiler, blowing off, 139.
---- careful feeding preserves, 70.
---- care of, 136–138.
---- explosions, 137.
---- feeding, 65, 86, 103.
---- incrustation, 101, 362.
---- injudicious feeding of, 69.
---- inspection of, 36.
---- over-pressure on, 140.
---- precautions against scorching, 40.
---- preservation of, 138.
---- temperature of, 67.
---- water for locomotive, 359–375.
Boilers and fire-boxes, 136–142.
Books, prejudice against, 8.
---- mechanical, recommended, 9.
Brakes, advantage of good, 310.
---- atmospheric, 312.
---- Eames vacuum, 340–345.
---- to apply and release, 336.
---- to prevent creeping on of, 335.
---- Westinghouse air, 309–339.
Brooks locomotives, 284.
Chemicals for testing water, 363.
---- ---- purifying boiler water, 374.
Collisions, 173.
Connecting-rods, side rods, and wedges, 182–198.
---- ---- angularity of, 219.
---- ---- functions of, 182.
Crank, attempts to abolish, 217.
Cross-head, methods of securing, 157.
---- pin broken, 164, 383.
Curves, resistance of, 353.
Cut-off, ascertaining point of, 253.
---- adjustment of, 255.
Cylinders, accidents to, 162, 381.
---- action of steam, in reverse-motion, 224.
---- back pressure in, 211.
---- compression in, 213.
---- operation of steam in, 210.
Dampers, operating, 71.
---- loss of heat from, 73.
Dead center, 251.
Diagram, indicator, 306.
Diaphragm-plate, 99.
---- vacuum brake, 341.
Disconnecting engine, 379.
Draught appliances, 98.
---- obstructions to, 97, 98.
Driving-axles, broken, 179.
Driving-box, 179, 190, 196.
Driving-trusses, 193.
Driving-springs, broken, 177.
Dry pipe, broken, 166.
Dynagraph car, 355.
Eames vacuum brake, 340–345.
Eccentric, angular advance of, 218.
---- slipped, 234, 380.
---- description of, 214.
---- early application of, 215.
---- throw, influence of, 238.
---- position of, 152, 218.
---- rods, position of, 243.
---- rods slipped, 154.
---- strap broken, 155, 383.
Educating engineers, 25.
Ejector, Eames brake, 342.
Emergencies, dealing with sudden, 172.
Engineers, attributes that make good, 1, 89.
---- causes of anxiety to, 78.
---- education for, 25.
---- examination for, 376–384.
---- first duties of, 43, 376.
---- duties, growing importance of, 3.
---- how made, 11, 29.
---- illiterate men not wanted for, 3.
Engineers, individuality of, 3.
---- interest in valve-motion among, 149.
---- learning duties of, 20.
---- public interest in, 2.
---- their duties, 1–10.
Engines, hard-steaming, 92–108.
---- high-speed, 83.
---- essentials of good-steaming, 92.
---- slippery, 62.
---- power of different kinds of, 357.
---- rough-riding, 197.
Equalizer lever broken, 178.
Examination for engineers, 376–384.
---- ---- firemen, 24.
Exhaust, detecting cause of lame, 155.
---- locating the four sounds of, 144.
---- note, neglecting warning of false, 148.
---- watching sound of, 144.
Finishing the trip, 74–81.
Fire, attending to, 79.
---- effect of excessive air on, 72.
---- management of, 54.
---- making up, 84.
---- starting the, 40.
Fire-boxes and boilers, 136–142.
Firemen, bad, 59.
---- first duties of, 41.
---- first trips as, 18.
---- highest types of, 57.
---- learning duties of, 19.
---- make best engineers, 14.
---- medium, 58.
---- men chosen for, 16.
---- method of promoting, 23.
---- method of selecting, 17.
Firemen, misconception of duties of, 19.
---- qualifications for, 27.
Firing, conditions that demand good, 56.
---- good, 55.
---- effect of heavy, 72.
---- engine of fast train, 90.
---- scientific methods of, 57, 107.
---- whom to blame for bad, 59.
Flues, bursted, 141.
---- leaky, 102.
Frames, broken, 179.
Freight train, running a, 48–60.
Gauge, water-glass, 43.
Getting ready for the road, 39–47.
Getting up the hill, 61–73.
Grade, getting train up a, 61.
Grant locomotives, 285.
Grates, saving the, 42.
---- defects of, 100.
Giffard injector, 119.
Hancock inspirator, 134, 135.
Hard-steaming engines, 92–108.
How engineers are made, 11–29.
Ignorance, where disaster came of, 7.
Indicator, 303–308.
---- advantage of using, 308.
---- description of, 303.
---- diagram, 306.
---- operation of, 304.
---- Tabor, 304.
Injectors, chapter on, 119–135.
---- care of, 124–128.
---- choice of, for feeding, 66, 109.
---- disorders of, 125–127.
---- forms of, 123.
---- Hancock, 135.
Injectors, invention of, 109.
---- Korting, 133.
---- Monitor, 132.
---- principle of action of, 121.
---- repairing, 123.
---- Sellers, 129.
---- trying to learn philosophy of, 120.
Inspection of locomotives, 30–38.
Inspection of locomotives, neglecting, 31.
Inspirator, Hancock, 135.
Joy valve-gear, 292–302.
---- valve, action of, 296.
---- ---- advantage claimed for, 295.
---- ---- construction directions, 294.
---- ---- how applied, 292.
---- ---- rules for laying out, 298.
Knowledge and skill in engineering, 1.
---- _versus_ ignorance, 2.
---- practical, needed, 15.
---- of train-rights, 75.
Korting injector, 133.
Laying out link-motion, 257–286.
Lime, effects of its presence in water, 101, 359.
---- tests for salts of, 364.
Link-hanger, broken, 383.
Link-motion, adjustment of, 239.
---- conditions of laying out, 259.
---- hanger-stud, 241.
---- increase of lead, 243.
---- invention of, 230.
---- laying out, 257–286.
---- position of rocker, 264.
Link-motion, position of crank-pin and eccentrics, 265.
---- problems of laying out, 260.
---- radius, 242.
---- slip, 240.
---- weak points of, 235–258.
Links, hooking up, 50.
Locomotives, adhesion of, 346.
---- difficulty of running at night, 14–21.
---- dimensions of, 284–286.
---- hard-steaming, 92.
---- high-speed, 83.
---- horse-power of, 350.
---- importance of, steaming freely, 92.
---- inspection of, 30–38.
---- learning to keep, in order, 22.
---- power of different kinds, 357.
---- running worn-out, 143.
---- slippery, 64.
---- traction of, 347.
Mason locomotives, 286.
Monitor injector, 132.
Mud-drums, 102.
Mud in boilers, 101, 139, 373.
Nathan injector, 132.
Netting choked with oil, 98.
Night, difficulty of running at, 14.
Nozzles, exhaust, 105.
Off the track, 172–181.
Oil-cups, inspection of, 34, 84.
Oil, quality of, needed for machinery, 45.
Passenger train, running fast, 82–91.
Petticoat-pipe, influence on steam-making of, 93.
---- ---- size and position of, 94.
Piston, clearance, 104, 184.
---- events of stroke, 222.
---- irregular speed of, 215.
---- setting out packing, 382.
Pittsburg locomotives, 285.
Point of suspension of link, 241.
Pounding of working-parts, 168–170.
---- in driving-boxes and wedges, 190.
Power of locomotives, 357.
Pumps, care of air, 326.
---- ---- ---- water, 113.
---- causes that induce pounding in air, 331.
---- choice of, for feeding water, 66.
---- disorders of air, 322.
---- disorders of water, 109–118.
---- gradual degeneration of air, 329.
---- lift of valves for water, 115.
---- sand in chambers, 116.
---- testing water, 113.
---- Westinghouse air, 318.
Raising steam, 39.
Radius of link, 242.
Relief-valve on dry pipe, 227.
Reversing motions, early, 229.
Road, acquaintance with the, 79.
---- getting ready for the, 39–47.
Rocker-arm, broken, 158.
---- position of, 264.
Rocker-shaft, broken, 158.
Rods, eccentric, 154, 243, 248, 268.
---- keying up, 186, 189, 379, 380.
---- main, 164, 182, 183.
Rods, side, 182, 187, 188.
---- watching, on road, 185.
---- valve, 250.
Rough-riding, cause of, 197.
Running-gear, inspection of, 35, 197.
---- understanding the, 176.
Running fast freight train, 48–60.
---- ---- passenger train, 82–91.
Saddle-pin, center of, 271.
Sand, use of, 63.
---- in pump-chamber, 116.
Scale agencies that make lime, 362.
---- effects on steam-making, 101.
Schenectady locomotives, 286.
Self-improvement, methods of, 5.
Sellers injector, 129–131.
Setting the valves, 246–256.
Shop, observing work in, 6.
Soap-test for hard water, 369–372.
Short of water, 109–118.
Smoke-box, extended, 99.
---- temperature of, 106.
Shifting-link, 229–245.
---- action of, 233.
---- construction of, 232.
---- slip, 240.
Side-rods, 182, 187, 188.
---- adjustment of, 187, 189, 379, 380.
Slide-valves, clearance, 208.
---- described, 200.
---- detecting leakage of, 145.
---- effect of changing travel, 236.
---- increase of lead, 243.
---- invention of, 199.
---- lap, 202–205, 212.
---- lead, 209.
---- primitive form of, 201.
Slide-valves, movement of, 217.
---- setting of, 246–256.
---- testing for leaks, 161.
Speed, average of fast train, 82, 86–88.
---- requisites of high, 83.
Springs, broken driving, 177.
Smoke-stack, badly proportioned, 105.
---- functions of, 97.
Steam-engine indicator, 303–308.
Steam, action of, in reverse-motion, 244.
---- back pressure, 211.
---- causes detrimental to making, 93.
---- chest-cover broken, 159.
---- compression of, 213.
---- operation in cylinders, 210.
---- pipes broken, 160.
---- pipes leaking, 100.
---- pressure best for economy, 52.
---- raising, 39.
---- running with low pressure of, 54.
---- working expansively, 51.
Stephenson link, 231.
Stevens valve-gear, 287–291.
Stevens valve-gear, control of exhaust-lead, 290.
Stevens valve-gear, description of, 287.
---- ---- valve-movement, 289.
Strainers, 113.
Supplies, 42.
Tests of feed-water, 363–372.
---- ---- valves, 161.
Throttle, accidents to, 167.
---- disconnected, 165, 166, 383.
Throttle, position of lever, 54.
Tires, broken, 179–384.
Track, engine off the, 172.
---- operating single, 77.
---- replacing engine on, 174.
Traction of locomotives, 346.
Train, conditions that increase resistance of, 352.
Train, fast passenger, 82.
---- knowledge of rights of, 75.
---- resistance formula, 351.
---- resistances, 346–358.
---- running freight, 48.
Travel of slide-valve, 236.
Triple valve, 332.
Trucks, accidents to, 178.
Tumbling-shaft, broken, 157.
---- length of arms, 277.
Valve, Allen, 206.
Valve-motion, accidents to, 143, 150, 158.
---- aids to study of, 221.
---- chapter on, 199–228.
---- compression, 213.
---- effect of excessive inside lap, 212.
---- effect of main-rod angularity on, 220.
---- interest in, 149.
---- Joy’s, 292–303.
---- locating defects of, 151.
---- of fast passenger engine, 235.
---- Stevens, 287–291.
Valve-setting, 246–286.
---- best way to learn, 247.
---- cut-off, 253.
Valve-setting, lead-opening, 252.
---- men who learn, 246.
---- preliminary operations, 247.
Valve-stem, broken, 158.
---- marking, 249.
Valve-travel, effect of changing, 235.
Valve-yoke, broken, 158, 380.
Water, expense of using bad, 360.
---- for locomotive boilers, 359–375.
---- how carried, 89, 376.
---- how to avoid getting short of, 111.
---- loss of faith in purifying methods, 361.
---- master-mechanics’ attempts to purify, 361.
---- soap-test for hardness, 369–372.
---- short of, 110, 112, 377, 378.
---- tests of quality, 363–372.
Watching the exhaust, 144.
Wedges, 182, 190, 192, 194–196.
Wheels, broken, 179.
---- slipping, 63.
Westinghouse brake, 309–339.
---- air-pump, 318.
---- air-pump disorders, 322.
---- air-brake, essential parts, 317.
---- air-brake, first trials of, 311.
---- air-brake, invention of, 309.
Working-parts, harmony of, 239.
---- pounding of, 168.
WM. SELLERS & CO. (INCORPORATED),
[Illustration]
SOLE PATENTEES AND MAKERS OF
THE
SELF-ACTING
INJECTOR
OF 1887.
Range of capacity over 60 per cent., and can therefore be regulated
to work continuously for the lightest or heaviest trains. Never fails
to lift promptly hot or cold water. No service on a locomotive is
sufficiently severe to permanently stop its working. Should the jet
break from any interruption of the steam or water supply, the Injector
will RESTART ITSELF as soon as the supply is resumed. ADJUSTS ITSELF to
varying steam pressures without waste of water. Increases quantity of
water with increase of steam, and _vice versa_. Very simple to operate.
Started by pulling out the lever. Stopped by pushing in the lever.
Descriptive Circular Price List sent on application to office and works,
PHILADELPHIA, PA.
Established, 1831. Annual Capacity, 600.
Baldwin Locomotive Works
BURNHAM, PARRY, WILLIAMS & CO.,
PROPRIETORS,
PHILADELPHIA, PA.
[Illustration]
Broad and Narrow Gauge Locomotives.
Mine Locomotives.
Plantation Locomotives.
Compressed Air Locomotives.
Logging Locomotives.
Noiseless Motors and Steam Street Cars.
All important parts made to Standard Gauges and Templates. Like parts
of different engines of same class perfectly interchangeable.
GEO. WESTINGHOUSE, JR., President.
JOHN CALDWELL, Treasurer.
T. W. WELSH, Superintendent.
W. W. CARD, Secretary.
H. H. WESTINGHOUSE, General Agent.
THE WESTINGHOUSE AIR BRAKE
COMPANY,
Pittsburgh, Pa., U.S.A.,
MANUFACTURERS OF THE
WESTINGHOUSE AUTOMATIC BRAKE,
WESTINGHOUSE LOCOMOTIVE DRIVER BRAKE,
VACUUM BRAKES (Westinghouse & Smith Patents),
WESTINGHOUSE AIR BRAKE.
The Automatic Freight Brake is essentially the same apparatus as the
Automatic Brake for passenger cars, except that the various parts are
one piece of mechanism, and is sold at a very low price. The saving
in accidents, flat wheels, brakemen’s wages, and the increased speed
possible with perfect safety, will repay the cost of its application
within a very short time.
The “AUTOMATIC” has proved itself to be the most efficient train
and safety brake known. Its application is instantaneous; it can be
operated from any car in the train, if desired, and should the train
separate, or a hose or pipe fail, it applies automatically. A GUARANTEE
is given customers against LOSS from PATENT SUITS on the apparatus sold
them.
FULL INFORMATION FURNISHED ON APPLICATION.
PITTSBURGH
LOCOMOTIVE AND CAR WORKS,
PITTSBURGH, PA.
MANUFACTURERS OF
LOCOMOTIVE ENGINES
FOR
BROAD OR NARROW GAUGE ROADS
From standard designs, or according to specifications,
to suit purchasers.
TANKS, LOCOMOTIVE OR STATIONARY BOILERS
Furnished at Short Notice.
D. A. STEWART, Pres’t.
D. A. WIGHTMAN, Sup’t.
WILSON MILLER, Sec. and Treas.
[Illustration]
BROOKS LOCOMOTIVE WORKS
DUNKIRK, N. Y.
H. G. BROOKS, President and Superintendent.
M. L. HINMAN, Secretary and Treasurer.
R. J. GROSS, Traveling Agent.
Builders of all classes of LOCOMOTIVE ENGINES. All work constructed
accurately to Standard Gauges and Steel-Bushed Templates. We guarantee
the interchangeability of like parts of different Engines of the same
class.
[Illustration:
THE STANDARD STEEL WORKS.
TIRES STANDARD TIRES
PHILADELPHIA
]
STEEL CASTINGS
From 1-4 to 15,000 lbs. weight,
True to pattern, sound and solid, of unequalled strength, toughness,
and durability. An invaluable substitute for forgings, or for cast-
iron requiring three-fold strength. Gearing of all kinds, Shoes,
Dies, Hammer-Heads, Cross-Heads for Locomotives, etc.
40,000 Crank Shafts, and 30,000 Gear Wheels of this
Steel now running, prove its superiority over
other Steel Castings.
SPECIALTIES:
CRANK SHAFTS, CROSS-HEADS, AND GEARINGS,
Steel Castings of Every Description.
_Please send for Circulars. Address_
CHESTER STEEL CASTINGS CO.,
_Works, CHESTER, PENN._
Office, No. 407 LIBRARY STREET, PHILADELPHIA.
Transcriber’s Notes
Punctuation and spelling were made consistent when a predominant
preference was found in the original book; otherwise they were not
changed. Inconsistent hyphenation was not changed.
Simple typographical errors were corrected; unbalanced quotation
marks were remedied when the change was obvious, and otherwise left
unbalanced.
Illustrations in this eBook have been positioned between paragraphs,
outside quotations, and usually close to their first reference in the
text.
The index was not checked for proper alphabetization or correct page
references.
Text uses both “employés” and “employes”.
Some tables have been rearranged to make them narrower.
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