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Title: The Use of Ropes and Tackle
Author: Pearl, W. A., Dana, H. J.
Language: English
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MONTHLY BULLETIN
OF THE STATE COLLEGE OF WASHINGTON
PULLMAN, WASHINGTON
VOLUME IV DECEMBER, 1921 NUMBER 7
The Use of Ropes
and Tackle
By H. J. DANA
Specialist in Experimental Engineering
and
W. A. PEARL
Instructor in Mechanical Engineering
[Illustration]
ENGINEERING BULLETIN NO. 8
Engineering Experiment Station
H. V. CARPENTER, Director
1922
Entered as second-class matter September 5, 1919, at the
postoffice at Pullman, Wash., under Act of Aug. 24, 1912
The ENGINEERING EXPERIMENT STATION of the State College of Washington
was established on the authority of the act passed by the first
Legislature of the State of Washington, March 28th, 1890, which
established a “State Agricultural College and School of Science”,
and instructed its commission “=to further the application of the
principles of physical science to industrial pursuits=.” The spirit
of this act has been followed out for many years by the Engineering
Staff, which has carried on experimental investigations and published
the results in the form of bulletins. The first adoption of a definite
program in Engineering research, with an appropriation for its
maintenance, was made by the Board of Regents, June 21st, 1911. This
was followed by later appropriations. In April, 1919, this department
was officially designated, Engineering Experiment Station.
The scope of the Engineering Experiment Station covers research in
engineering problems of general interest to the citizens of the State
of Washington. The work of the station is made available to the public
through technical reports, popular bulletins, and public service. The
last named includes tests and analyses of coal, tests and analyses of
road materials, testing of commercial steam pipe coverings, calibration
of electrical instruments, testing of strength of materials, efficiency
studies in power plants, testing of hydraulic machinery, testing of
small engines and motors, consultation with regard to theory and design
of experimental apparatus, preliminary advice to inventors, etc.
Requests for copies of the engineering bulletins and inquiries for
information on engineering and industrial problems should be addressed
to Director, The Engineering Experiment Station, State College of
Washington, Pullman, Washington.
The Control of the Engineering Experiment Station is vested in the
Board of Regents of the State College of Washington.
BOARD OF REGENTS
Hon. Louis F. Hart, Governor of the State, Olympia
R. C. McCroskey, Garfield
Adam Duncan Dunn, Wapato
Edwin A. Ritz, Walla Walla
A. W. Davis, Spokane
J. H. Hulbert, Mt. Vernon
E. O. Holland, Secretary Ex-Officio, President State College Pullman
ENGINEERING EXPERIMENT STATION STAFF
Director, H. V. Carpenter, B. S., M. S.
Experimental Engineering, Homer J. Dana, B. S., M. S., M. E.
Electrical Applications, Philip S. Biegler, B. S., M. S., E. E.
Electrical Standardizations, Harry F. Lickey, B. S.
Automotive Engineering Aschel C. Abell, B. S.
Steam Engineering, A. R. Nottingham, M. M. E.
Mechanical Design, E. B. Parker, B. S.
Engineering Materials, G. Everett Thorton, B. S.
Gas Power, William A. Pearl, B. S.
Steam Power, Robert L. Rhoads, M. S.
Mining Engineering, Louis O. Howard, A. B., M. E.
Metallurgical Engineering, Chester G. Warfel, M. E.
Economic Geology, Olaf P. Jenkins, A. B., A. M.
Irrigation and Structures, Osmar L. Waller, Ph. B., Ph. M.
Municipal Engineering, Morris K. Snyder, B. S.
Highway Engineering, Howard E. Phelps, B. S., C. E.
Topographical Engineering, Frederic W. Welch, B. S., C. E.
Architectural Engineering, Rudolph Weaver, B. S.
Agricultural Engineering, L. J. Smith, B. S.
Physics, Brenton L. Steele, B. A., M. A.
Chemical Engineering, Clare Chrisman Todd, B. S., Ph. D.
TABLE OF CONTENTS
LIST OF ILLUSTRATIONS 5
SOURCES OF MATERIAL 7
INTRODUCTION 8
KNOTS 9
SPLICES 25
HITCHES 28
LASHINGS 43
TACKLE SETS 45
HOISTS 53
TRANSMISSION CABLES 55
TEXTILE ROPE DATA 57
WIRE ROPE DATA 58
SPLICING TRANSMISSION CABLES 62
POWER TRANSMISSION TABLES 66
LIST OF ENGINEERING BULLETINS 68
LIST OF ILLUSTRATIONS
=Fastening Knots=.
1. Over-hand knot.
2. Double knot.
3. Figure 8 knot.
4. Double Figure 8 knot.
5. Square knot.
6. Reef knot.
7. Sq. served or whipped knot.
8. Slipped Square knot.
9. Open-hand knot.
10. Granny knot.
11. Fisherman’s knot.
12. Ordinary knot.
13. Ordinary knot whipped.
14. Weaver’s knot.
15. Hawser knot, or Sheet Bend.
16. Double Sheet Bend.
17. Garrick Bend knot.
18. Half-hitch and whipping knot.
19. Slip knot.
20. Bowline knot.
21. Running Bowline knot.
22. Loop knot.
23. Tom-fool knot.
24. Boat knot.
25. Surgeon’s knot.
26. Bowline on the bight.
27. Spanish Bowline.
28. Flemish Bowline.
29. Hawser knot with toggle.
=Ending Knots=.
30. Whipping.
31. Single Crown Tucked.
32. Wall knot Tucked.
33. Matthew Walker.
34. Double Wall or Crown knot.
35. Stevedore.
36. Chain knot.
=Shortening Knots=.
37. Whipped Shortening.
38. Three fold shortening.
39. Sheepshank.
40. Sheepshank for free end rope.
41. Sheepshank with toggle.
42. Sheepshank ends whipped.
43. Bow Shortening.
=Splices=.
44. Short Splice.
45. Eye Splice.
46. Long Splice.
47. Chain Splice.
48. Cut Splice.
=Hitches=.
49. Half hitch.
50. Timber hitch.
51. Clove or Builder’s hitch.
52. Rolling Hitch (A).
53. Rolling Hitch (B).
54. Snubbing hitch.
55. Timber hitch and half-hitch.
56. Chain hitch.
57. Twist hitch.
58. Twist and bow hitch.
59. Blackwall hitch.
60. Lark’s head with toggle.
61. Round turn and half-hitch.
62. Fisherman’s hitch.
63. Cat’s paw hitch.
64. Slippery hitch.
65. Double Blackwall.
66. Slip knot and half-hitch.
67. Fisherman’s bend.
68. Taut line hitch.
69. Jam hitch.
70. Scaffold hitch.
71. Studding sail bend.
72. Midshipman’s hitch.
73. Bale sling.
74. Hamburger hitch.
75. Sling a cask head up.
76. Well pipe hitch.
77. Hackamore hitch.
78. Halter tie.
79. Horse hitch or tie.
80. Manger Tie.
81. Figure 8 Manger tie.
82. Harness hitch.
83. Strap hitch or line.
84. Clevis hitch.
85. Two-man Diamond hitch.
86. Two-man Diamond hitch.
87. Two-man Diamond hitch.
88. Packer’s knot.
89. One-man Diamond hitch.
90. One-man Diamond hitch.
91. One-man Diamond hitch.
92. Two-man Diamond hitch.
93. Spar and Transom lashing.
94. Tripod lashing.
=Tackle Sets and Hoists=.
95. Single Whip.
96. Running Tackle.
97. Gun Tackle (A).
98. Gun Tackle (B).
99. Whip on Whip.
100. Luff.
101. Port Tackle.
102. Double Luff.
103. Single Burton (A).
104. Single Burton (B).
105. Three Fold Purchase.
106. Four Fold Purchase.
107. Double Burton (A).
108. Double Burton (B).
109. Double Burton (C).
110. Double Burton (D).
111. Luff on Luff.
112. Double Burton (E).
113. Geared Chain Hoist.
114. Differential Chain hoist.
115. Chinese hoist or Capstan.
116. Snatch Block on Hay Rope.
=Transmission Cables=.
117. Cable splice.
118. Cable Splice.
119. Cable Splice.
120. Cable Splice.
121. Cable Splice.
122. Splicing Tools.
123. Splicing Tools.
SOURCES OF MATERIAL
In the compilation of this bulletin free use was made of the
material given in the following books, bulletins, catalogs, etc.
Knotting and Splicing Ropes and Cordage,
Paul M. Hashuk--Cassel & Co., New York.
Knots, A. F. Aldridge, The Rudder Pub. Co., New York.
Knots, Splices, and Rope Work, A. Hyatt Verril,--Norman W. Henly
Pub. Co., New York.
Rope and its Use on the Farm, J. B. Frior--Ag. Exp. Sta. Bul.
No. 136, Univ. of Minn.
Knots, Hitches and Splices, Howard W. Riley,
Cornell Reading Courses, New York State College of Agriculture,
Ithaca, New York.
Story of Rope, Plymouth Cordage Co., North Plymouth, Mass.
Rope Knots and Hitches, MacGreggor Smith, College of Agriculture,
Univ. of Saskatchewan, Saskatoon, Canada.
Problems in Physics, War Department Committee on Education and
Special Training, Washington, D. C.
Kent’s Mechanical Engineers Hand Book, John Wiley & Sons, New York.
Encyclopedia Britannica.
Rope and Its Uses, Iowa State College of Agriculture and Mechanic Arts.
American Wire Rope, American Steel and Wire Company.
Boy Scout Manual.
Engineer Field Manual, Fifth Edition, Government Printing Office,
Washington, D. C.
Rope Work, L. M. Roehl, The Bruce Publishing Co., Milwaukee, Wis.
R. O. T. C. Engineer.
Columbia Knots and Splices, Columbia Rope Co., Auburn, New York.
American Boy Magazine--July 1917.
INTRODUCTION
Each year, old industries keep expanding and new ones are created. In
many of these, the use of hoists, tackle, rope transmissions, etc. is
ever increasing in extent and importance. Information on the selection
and use of ropes and tackles and the tying of knots is very scattering
and incomplete. The purpose of this bulletin is to collect information
from all the different sources possible and assemble it under one
cover, in the hope that it may be valuable to people in many different
fields of activity. It is not meant to be an advanced treatise for
those who consider themselves already proficient in the use of rope and
tackle but is designed as an aid and reference to those less skilled in
the art.
A variety of knots and splices are shown with occasional suggestions as
to their use and application. Some knots tie easily and are very secure
but are not so easy to untie; others are easily and quickly tied--are
secure and yet are not difficult to untie. Some knots are suitable for
small cords only, and others are adapted to large ship’s hawsers. For
these and other reasons, it is desirable to select the right knot for
the job in hand.
Nearly every individual at some time or other has gone camping. If he
chanced to select a remote or inaccessible mountain side for a vacation
trip, he probably had one or more pack animals to take in the supplies
and camp outfit. How many could use the famous Diamond hitch to fasten
the pack on the horse’s back so that it will not shift or fall off in
transit?
The desirability of correct selection with reference to the work to be
done is also true of tackle sets. One type of tackle will give great
mechanical advantage, but requires an excessive amount of rope or
requires frequent overhauling to complete the job, while another type,
using the same equipment, will not give such great mechanical advantage
but does not require overhauling so often during the progress of the
load.
Rope is coming more and more into favor for the transmission of
power--replacing gears and heavy leather belts. It is important that
the proper sized sheave wheel be used with a rope of given diameter in
order to secure the longest service from the transmission. It is also
important that speed be considered in the calculation for necessary
strength to transmit a certain amount of power. It is evident from
these two instances alone that it is desirable that the selection of
a rope transmission should be governed by the use of complete sets of
data on the subject.
Some of the knots, splices, etc. shown in this bulletin were found to
have more than one name, or were called by different names by different
authors. In such case only the most commonly used term was selected.
KNOTS
A knowledge of knots has saved many a life in storm and wreck, and if
everyone knew how to tie a knot quickly and securely there would be
fewer casualties in hotel and similar fires where a false knot in the
fire escape rope has slipped at the critical moment and plunged the
victim to the ground. Many an accident has occurred through a knot
or splice being improperly formed. Even in tying or roping a trunk,
few people tie a knot that is secure and quickly made and yet readily
undone. How many can tie a tow rope to a car so it will be secure and
yet is easily untied after the car has been hauled out of the mud? Or
suppose a rope was under strain holding a large timber in midair and a
strand in the derrick guy rope shows signs of parting. How many could
attach a rope each side of the weak spot to take the strain?
The principle of a knot is that no two parts which lie adjacent
shall travel in the same direction if the knot should slip. Knots
are employed for several purposes, such as, to attach two rope ends
together, to form an enlarged end on a rope, to shorten a rope without
cutting it, or to attach a rope to another rope or object. Desirable
features of knots are that they may be quickly tied, easily untied and
will not slip under a strain. In a number of cases a toggle is used
either to aid in making the knot or make it easier to untie after a
strain has been applied.
A number of terms are commonly used in tying knots. The “standing” part
is the principal portion, or longest part of the rope. The “bight” is
the part curved, looped or bent, while working or handling the rope in
making a knot, and the “end” is that part used in forming the knot or
hitch. The loose, or free end, of a rope should be knotted or whipped
to prevent it from raveling while in use.
Strength of Knots
If a knot or hitch of any kind is tied in a rope its failure under
stress is sure to occur at that place. Each fiber in the straight part
of the rope takes its proper share of the load, but in all knots the
rope is cramped or has a short bend, which throws an overload on those
fibers that are on the outside of the bend and one fiber after another
breaks until the rope is torn apart. The shorter the bend in the
standing rope the weaker the knot. The approximate strength of several
types of knots in percent, of full strength of a rope is given in the
table below, as an average of four tests.
1. Full strength of dry rope 100%
2. Eye splice over an iron thimble 90%
3. Short splice in rope 80%
4. Timber hitch, round turn and half hitch 65%
5. Bowline, slip knot, clove hitch 60%
6. Square knot, weaver’s knot, sheet bend 50%
7. Flemish loop, over--hand knot 45%
Fastening Knots
Fig. 1. The over-hand knot is the simplest of all knots to make. It is
made by passing the lose end of the rope over the standing part and
back through the loop.
Fig. 2. The Double knot is made by passing the free end of the rope
through the loop twice instead of but once as in making an over-hand
knot. This is used for shortening or for a stop on a rope, and is more
easily untied than the over-hand knot. It is also known as a blood
knot, from its use on whip lashes by slave drivers, etc.
[Illustration: _Fig. 1; Fig. 2; Fig. 3; Fig. 4_]
Fig. 3. The Figure Eight knot is similar to the over-hand knot except
that the loose end of the rope is passed through the loop from the
opposite side. It is commonly used to prevent a rope running through
an eye or ring or tackle block. It is also used as the basis for
ornamental knots, etc.
Fig. 4. The Double Figure Eight knot is made by forming a regular
figure eight and then following around with the end of the other rope
as shown.
Fig. 5. The Square knot is probably the commonest and most useful of
all knots. It is strong and does not become jammed when being strained.
Take the ends of the two ropes and pass the left end over and under the
right end, then the right end over and under the left. Beware of the
granny knot which is often mistaken for the square knot but is sure to
slip under strain.
Fig. 6. The Reef knot is a slight modification of the square knot. It
consists merely of using the bight of the left or right end instead of
the end itself, and is tied exactly as is the square knot. This makes
the knot easy to untie by pulling the free end of the bight or loop.
[Illustration: _Fig. 5; Fig. 6_]
[Illustration: _Fig. 7; Fig. 8; Fig. 9; Fig. 10_]
Fig. 7. If the Square or reef knot is used to join two ropes of unequal
diameter, the knot is apt to slip unless the ends of the rope are
whipped as shown.
Fig. 8. A Square knot joining two ropes of unequal size is apt to slip
with a result similar to that shown.
Fig. 9. The Open-hand knot is made by tying an over-hand knot with two
rope ends lying parallel. It is better than a square knot for joining
two ropes of unequal diameter. Grain binders use this knot.
Fig. 10. The Granny knot is often mistaken for a square knot and its
use should by all means be avoided as it is almost sure to slip when
a strain is applied, unless the ends are whipped. For large rope, a
granny knot with ends whipped will hold securely and is easy to untie.
[Illustration: _Fig. 11; Fig. 12; Fig. 13_]
Fig. 11. The Fisherman’s knot is a simple type of knot formed by two
simple over-hand knots slipped over the standing parts of the two
ropes, and drawn tight. It is valuable for anglers as the two lines may
be drawn apart by merely pulling on the loose ends of the rope.
Fig. 12. The Ordinary knot is used for fastening two heavy ropes
together and is made by forming a simple knot with the end of one rope
and then interlacing the other rope around it, as shown.
Fig. 13. Whipping the two ends of an Ordinary knot makes it more secure.
Fig. 14. The Weaver’s knot is used to join small lines or
threads and is made by forming a bight in one rope, passing the end
of the second rope around the bight, back over itself and through the
bight. Weavers use this knot in tying broken threads. When pulled
tight, both ends point backward, and do not catch when pulled
thru the loom.
[Illustration: _Fig. 14; Fig. 15; Fig. 16; Fig. 17_]
Fig. 15. The Hawser knot or sheet bend is used for joining stiff or
heavy ropes and is not to be confused with the weaver’s knot. It
resembles the bowline, and is easily untied.
Fig. 16. The Double Sheet Bend is similar to the Hawser knot and is
useful for the same purposes.
Fig. 17. The Garrick bend is commonly used for joining two heavy
hawsers which are too stiff to bend easily.
Fig. 18. Another method of joining stiff hawsers is to use the
Half-hitch and whipping. This is a satisfactory method of making a
joint to be used for a considerable time.
Fig. 19. The Slip knot as shown is a knot with many uses.
Fig. 20. The Bowline knot is useful for forming a loop on the end of a
rope. It is used frequently by stockmen to tie a horse or cow so that
they will not choke themselves. It is always secure and easily untied.
Use this knot in tying a tow rope to a car.
[Illustration: _Fig. 18; Fig. 19_]
Fig. 21. The Running Bowline is used for the same purposes as the slip
knot in Fig. 19, but is much more secure. It will always run freely on
the standing part of the rope, and is easily untied.
[Illustration: _Fig. 20; Fig. 21_]
Fig. 22. A Loop knot is useful for making fast to the middle of a rope
where the ends are not free. It will pull tight under strain, and is
not easily untied.
Fig. 23. The Tom-fool knot is formed in the middle of a rope and may be
used for the same purpose as the loop knot, except in this case either
standing part of the rope may be strained without the knot failing, or
slipping. It can be used for holding hogs. Place one loop over the
hog’s snout and hold onto one rope. Release by pulling other rope. Can
also be used from the ground for releasing hoisting tackle which has
been used on a flag pole or other tall object.
[Illustration: _Fig. 22_]
Fig. 24. The Boat knot is formed by the aid of a toggle on a rope whose
ends are not free, and is used for shortening or for stopping a ring on
a taut line.
[Illustration: _Fig. 23; Fig. 24; Fig. 25_]
Fig. 25. The Surgeon’s knot is a modified form of the square knot, and
if used with smooth cord, as in tying bundles, it holds very securely.
The object of the double twist is to make the knot easy to tie without
holding with the end of the finger.
[Illustration: _Fig. 26_]
Fig. 26. Bowline on the bight is easily made on the looped part of a
rope which is double. It is used where a loop is desired which will
not pull tight or choke and is easily untied. May be used for casting
harness for horses.
[Illustration: _Fig. 27_]
Fig. 27. The Spanish Bowline is a knot which may be made in the middle
of a long rope or in a bight at the end, and gives two single loops
that may be thrown over two separate posts or both thrown over one.
Either loop will hold without slipping and is easily untied.
Fig. 28. The Flemish loop is similar to the Fisherman’s knot, Fig. 11,
except that it is used for forming a loop on the end of a rope instead
of joining two ropes. The loop or eye will not close up when strained.
[Illustration: _Fig. 28_]
[Illustration: _Fig. 29_]
Fig. 29. The Hawser knot with toggle is formed exactly the same as the
regular Hawser knot except that the toggle is inserted for the purpose
of making it easy to loosen the knot after a strain has been applied.
Ending Knots
A group of knots somewhat different from those already described, are
those used for ending ropes. Ending knots not only serve the purpose of
giving a large end on the rope, but also take the place of whipping, in
that they prevent the rope from unraveling. Sometimes an ending knot is
also used for its ornamental value.
[Illustration: _Fig. 30_]
Fig. 30. A Whipping applied as shown is employed for keeping loose
ends from fraying or unraveling, where the use to which the rope is to
be put will not permit of a knot on the end. Strong cord is used for
whipping. In splicing ropes, the whipping is removed before the splice
may be considered complete.
Fig. 31. The Single Crown, tucked, makes the rope end but slightly
larger than the standing part, and serves to prevent the strands from
unraveling. This gives a neat appearing end. To make this type of knot,
leave the ends long enough so they can be brought down and tucked under
the strands of the standing part. After tucking them under the first
strand, as shown, halve each strand and tuck it again under the next
strand of the standing part and continue this until the ends are
completely tucked the whole length, thus giving a gradual taper to the
end of the rope and also giving a knot that will stand by itself. The
single crown not tucked, is not a good ending for a rope.
[Illustration: _Fig. 31_]
Fig. 32. The Wall knot is frequently used as an ending knot to prevent
unraveling. It is very satisfactory where the rope does not need to
pass through a block or hole which is but slightly larger than itself.
The Wall knot may be tucked similar to the Crown and makes a very
secure ending for a rope. For small ropes unlay the strands back, each
three inches, and on larger ropes in proportion. Hold the rope in the
left hand with the loose strands upward. With the right hand take the
end of strand number one and bring it across the loose end in position
with the thumb of the left hand, then take the rope, forming a loop and
allowing the end to hang free. Hold strand number two and pass it under
strand number one and hold it against the rope with the thumb of the
left hand. Again with the right hand take strand number three and pass
it under strand number two and up through the first loop formed. Then
draw each of the strands gradually until the knot is tightened.
Fig. 33. The Matthew Walker knot or Stopper knot is similar to the Wall
knot except the ends are inserted through two loops instead of one
as in the Wall knot. It can readily be made by loosely constructing
the Wall knot as explained before and continuing as follows: pass the
end number one through the loop with two, then end number two through
the loop with three, and number three through the loop with one, then
gradually tighten the knot by drawing in a little at a time on each
strand.
Fig. 34. The Double Wall or Crown knot is made exactly the same as the
Single Crown or Wall knot, but instead of trimming off or tucking the
ends in, they are carried around a second time, following the lay of
the first as shown, and then the knot is pulled tight. When completed,
the ends may be tucked in as was done in the Single Crown, or they may
be trimmed off.
[Illustration: _Fig. 32; Fig. 33; Fig. 34_]
[Illustration: _Fig. 35_]
Fig. 35. The Stevedore knot is similar to the Over-hand knot shown in
Fig. 1, except that the end of the rope is served around the standing
part two and half times before it is tucked through the bight. It is
used where a knot is desired to keep the rope from running through a
block or hole.
Shortening Knots
A third type of knots are those which are used where a rope is too long
and where it is awkward to have the free ends hanging loose or where
the ends are in use and the slack must be taken up in the middle of the
rope. These are known as shortening knots. They are also sometimes used
merely for ornament.
Fig. 36. The Chain knot is frequently used for shortening and is made
by forming a running loop, then drawing a bight of the rope through the
loop, and a second bight through the first and so on until the rope has
been shortened sufficiently. The free end should then be fastened by
passing a toggle or the end of the rope through this last loop. To
undo this shortening is very simple as all that is necessary is to
either remove the toggle from the last loop or remove the end of the
rope if it were used, and then pull on the free end until the knot is
completely unraveled.
[Illustration: _Fig. 36_]
Fig. 37. The Whipped Shortening or Bend Shortening is one of the most
easily made and is well adapted to heavy ropes where a shortening must
be made quickly and where it is not to withstand a heavy strain.
Fig. 38. Three-fold Shortening is started by making an Over-hand knot
and continuing to tuck the end through the loop three more times, and
drawing tight.
Fig. 39. The Sheep-shank or Dog-shank as it is sometimes called, is one
of the most widely used of all shortenings. It is made in several forms
but the first form shown, while adaptable to fairly stiff ropes, will
not withstand much strain. It is used for shortening electric light
cords.
Fig. 40. Sheep-shank for free end rope is similar to the plain
Sheep-shank except the free end of the rope is passed through the
loop. This makes a secure shortening, but it can not be used where
the ends of the rope are not free.
[Illustration: _Fig. 37; Fig. 38; Fig. 39; Fig. 40; Fig. 41_]
Fig. 41. A Sheep-shank with toggle, is a plain Sheep-shank with the
toggle inserted as shown, and makes the shortening as secure as that
shown in Fig. 38. It is also easily untied.
[Illustration: _Fig. 42_]
Fig. 42. Sheep-shank with ends whipped is the same as in a plain
Sheep-shank except the loop is whipped to the standing part of the
rope. This makes the shortening as secure as those shown in Fig. 38,
and Fig. 39.
[Illustration: _Fig. 43_]
Fig. 43. Bow-shortening is an ordinary knot in the middle of a rope
in which a double bend has previously been made. It is not adapted to
heavy ropes nor will it stand a heavy strain successfully.
SPLICES
In the use of ropes, occasion arises, many times, where it is necessary
to join two ends together in such a way that the union is as strong
as the rest of the rope and still not too large or irregular to pass
through a hole or pulley block. Knots are unsuitable in that they will
not pass through a block; they are unsightly, and usually are not as
strong as the rest of the rope. The method of joining ropes to meet
the above requirements is called splicing. There are two general types
of rope splices known as the short splice and the long splice. Other
applications of the former are made in the eye splice and the cut
splice. The long splice is almost always used in splicing wire rope
which runs through a block or over a sheave.
[Illustration: _Fig. 44; Fig. 45_]
Fig. 44. The Short-splice is made as follows: the two ends to be joined
are untwisted for a few inches and the rope is whipped temporarily
to prevent further unwinding. The end of each strand is also whipped
temporarily to prevent unraveling. The strands may then be waxed if
desired. The two rope ends are then locked together or “married” so
that the strands from one end pass alternately between those from the
other end. The strands from opposite sides are now in pairs. Take two
strands from opposite sides as strands A and 1, tie a simple over-hand
knot in its right hand form. Similarly with a right hand knot tie
together the strands forming each of the pairs B and 2 and C and 3.
Draw the knots tight, then pass each strand of the rope over the strand
adjacent to it and under the next, coming out between two strands as at
first. Repeat until the ends of the strands have been reached--leaving
from half an inch to an inch and a half of ends hanging free so that
when the rope is put under repeated strain for the first few days, the
stretching of the splice will not pull the ends from under the last
strand under which they were tucked. After a few days service the free
ends may be safely trimmed even with the face of the rope. After the
splice has been completed by tucking the ends as above, remove whipping
on strands and lay the splice on the floor and roll it under the foot,
or in the case of a large rope, pound it with a mallet to make it round
and smooth. The appearance of the splice is improved if the strands are
divided in half just before the last tuck is made, and one-half is cut
off while the other half is used to complete the splice. This splice
may also be made by simply laying the ropes together and then tucking
them as above without first tying the simple Over-hand knots. A skilled
workman frequently dispenses with the whipping in making a splice.
Fig. 45. An Eye-splice is so much smaller and neater than a knotted eye
in the end of a rope that it is much to be preferred to the latter. The
Eye-splice is made similar to the short-splice except that the strands
on the end of the rope are unlaid for the full length of the splice.
The ends are tucked under, over and under, etc., the strands of the
standing part of the rope. Stretch well and cut off the loose ends of
the strands.
Fig. 46. Long splice. If it is desired to unite two rope ends so that
the splices will pass through a pulley as readily and smoothly as the
rope itself, what is known as a Long splice is used. This is best
suited as it does not cause an enlargement in the rope at the point
where the splice is made. To make it, unlay the ends of two ropes to
the length of at least five and a half times the circumference of the
rope. Interlace the strands as for the Short splice. Unlay one strand
and fill up the vacant space which it leaves with the strand next to it
from the other rope end. Then turn the rope over and lay hold of the
two next strands that will come opposite their respective lays. Unlay
one, filling up the vacant space as before, with the other. Take one
third out of each strand, knot the opposite one-thirds together and
heave them well in place. Tuck all six ends once under adjacent strands
and having stretched the splice well, cut off the ends. The ending of
successive pairs should occur at intervals in the splice as shown, and
not at the two ends as in the Short splice.
[Illustration: _Fig. 46; Fig. 47; Fig. 48_]
Fig. 47. A Chain splice is used for splicing a rope into a chain end
which is required to travel through a block or small opening. It is
also sometimes used for making an ordinary eye in the end of a rope.
Four or six strand rope lends itself more readily to this type of splice
than does a three strand rope. To make a chain splice, unlay the
strands more than for an eye splice, then unlay a little further one
strand in a three strand rope, and two strands in a four strand rope.
Bend the two parts together and tie an Over-hand knot so that the
divided strands will lay together again. Continue to lay the ends in by
passing them through the eye. When the eye has been completely laid up,
the remaining ends should be tucked in the standing part of the rope
as in a very short splice. This makes an eye which will not pull out
even if the ends of the strands are only whipped without first tucking.
It is especially valuable in forming smooth eyes in steel cable,
without the use of clamps. In this case, however, the eye must be made
considerably longer than in the case of hemp rope.
Fig. 48. The Cut splice is formed similar to the Eye splice, except
that the two rope ends are extended past each other and joined into the
standing part of the ropes. This type of splice is frequently used to
hold the rings in rope ladders. It can also be used where it is desired
to attach a spar or rod to the middle of a line.
HITCHES
The knots so far described are used mainly for fastening rope ends
together or for ending a rope. A quite different class of knots is that
used for fastening a rope to a stationary or solid object. This type of
knots is known as hitches.
Hitches as well as other types of knots should be easily made, should
not slip under strains and should be easily untied. If all ropes
were the same size and stiffness it would be possible to select two
or three knots which would meet all requirements. But, since this is
not true and since a knot suitable for a silken fish line will not be
satisfactory for a ship’s hawser, we find a great variety of knots,
each of which is designed to meet some special requirements of service.
The following illustrations show a variety of the most typical and
useful knots used on fiber or manila rope.
Fig. 49. The Half-hitch is good only for temporary fastenings where
pull is continuous. It is usually used as part of a more elaborate
hitch.
Fig. 50. The Timber-hitch is very similar to the Half-hitch but is much
more permanent and secure. Instead of the end being passed under the
standing part once it is wound around the standing part three or four
times as shown.
[Illustration: _Fig. 49; Fig. 50; Fig. 51; Fig. 52_]
Fig. 51. The Clove, or Builder’s-hitch, is more secure than either of
the above hitches. It will hold fast on a smooth timber and is used
extensively by builders for fastening the staging to upright posts. It
will hold without slipping on wet timber. It is also used to make the
scaffold hitch.
Fig. 52. The Rolling-hitch is made by wrapping the rope three or four
times around the object to which it is to be fastened and then making
two half-hitches around the standing part of the rope. It is then drawn
tight. This hitch is easily and quickly made and is very secure.
Fig. 53. This illustrates another type of Rolling-hitch very similar to
the above but which is not as secure under a heavy strain.
[Illustration: _Fig. 53; Fig. 54_]
Fig. 54. The Snubbing-hitch is made by passing the rope around the
object to which it is desired to fasten it, and then making what is
known as a Taut-line hitch, Figure 68, about the standing part of the
rope.
[Illustration: _Fig. 55; Fig. 56_]
Fig. 55. Timber-hitch and Half-hitch is a combination of the two
separate hitches shown in Fig. 49 and Fig 50. It is more secure than
either used alone.
Fig. 56. The Chain-hitch is a combination of the above hitch and two
or more half-hitches. It is used for hauling in a larger rope or cable
with a tow line, etc.
Fig. 57. The Twist-hitch is more secure than the Half-hitch and it is
suitable only where the strain is continuous.
Fig. 58. Twist-and-bow-hitch is similar to the Simple Twist-hitch but
is easier to untie.
[Illustration: _Fig. 57; Fig. 58; Fig. 59; Fig. 60; Fig. 61_]
Fig. 59. The Blackwall-hitch is widely used as illustrated. The greater
the strain the more securely it holds, but it is unreliable if the rope
is slack. This hitch can be used with chain as well as rope.
Fig. 60. The Lark’s-head with toggle is easily made and is
used as a rule where it is desired to have a type of hitch which is
easily and quickly released.
Fig. 61. Round-turn-and-half-hitch is suitable for a more or
less permanent method of attaching a rope to a ring. Whipping the
end to the standing part of the rope makes it quite permanent.
[Illustration: _Fig. 62; Fig. 63; Fig. 64; Fig. 65; Fig. 66_]
Fig. 62. The Fisherman’s hitch is used for fastening large ropes or
lines to rings and is very similar to the hitch shown in Fig. 61. It is
improved by whipping the free end to the standing part.
Fig. 63. The Cat’s-paw-hitch is suitable for attaching a hook to the
middle part of a rope where the ends are not free. Strain may be taken
on either or both ends. It is easily released.
Fig. 64. The Slippery-hitch is easily made, but has the objection that
it draws very tight under strain, making it hard to untie.
Fig. 65. The Double Blackwall is similar to the Single Blackwall and is
used for the same purpose.
Fig. 66. The Slip Knot and Half-hitch constitute a combination that
is used for the same purpose as the Flemish loop. It is made by first
tying a slip knot so that it will run on the short end of the rope.
Then complete by tying a half hitch with the short end as shown.
[Illustration: _Fig. 67; Fig. 68_]
Fig. 67. The Fisherman’s-bend is similar to the Fisherman’s-hitch
except that the half hitches are replaced with whipping.
Fig. 68. A Taut-line-hitch is used for attaching a rope to another rope
already under strain, where no slack is available for making any other
hitch. It is not secure unless pulled very tight. A few threads of hemp
or marlin served about the taut line for the knot to pull against will
improve the hitch.
[Illustration: _Fig. 69; Fig. 70; Fig. 71; Fig. 72_]
Fig. 69. The Jam Hitch is used in tying up light packages, such as
bundles of lath, small boxes, rolls of paper, and the like. It is a
hitch that will slide along a cord in one direction, but will jam
and hold against moving the other way and will be found exceedingly
convenient. The Jam Hitch will answer the requirements provided the
cord is large enough and of not too hard a body nor too smooth a
surface.
Fig. 70. The Scaffold-hitch is very useful for slinging a scaffold so
that it will not turn in the sling. It is started by making a Clove
hitch with the two free ends of the rope below the scaffold. Then draw
each rope back on itself and up over opposite sides of the board, where
the short end is joined to the other with a bowline. Plenty of slack in
the Clove will make it possible to draw the bight of each end out to
the edge of the scaffold as shown in the left of the figure. The two
illustrations at the right of the figure show another method of making
a Scaffold hitch. Wrap the rope around the scaffold plank so that it
crosses the top of the plank three times. Pull the middle loop as shown
by the arrow and fold it down over the end of the plank, resulting as
shown in the illustration immediately to the left of the arrow. This
is completed by attaching the free end to the standing part with a
bowline. Both hitches are equally good.
Fig. 71. The Studding-sail-bend is frequently employed on shipboard for
attaching a rope or line to a spar.
Fig. 72. The Midshipman’s-hitch is somewhat similar to the Snubbing
hitch shown in Figure 54, but is perhaps a little easier to make if the
rope is under a strain while being tied.
[Illustration: _Fig. 73; Fig. 74; Fig. 75; Fig. 76_]
Fig. 73. A Bale-sling as shown is useful where it is necessary to hoist
an object to which it is difficult to attach the hoisting tackle. It
may be used on bales, sacks, kegs, etc.
Fig. 74. The Hamburger hitch is useful in connection with a bale sling
which is too long for the object it is carrying. It is also used to
balance the load where two slings are used. The sling is placed around
the load as in Fig. 73. Then with the loop end of the sling form a
second loop as shown. Where the two ropes cross start to tie a square
or Reef knot. Draw up the loops as shown, resulting in the Hamburger
hitch. This may be adjusted by running the knot up or down the rope
while slack, but it will not slip under strain.
Fig. 75. Sling for a cask, head up, is very useful where it is desired
to hoist an open barrel of water or lime or other material. Tie an
ordinary knot over the barrel lengthwise. Then separate the two ropes
in the middle of the twisted part and drop them over the head of the
cask or barrel. Fasten the two rope ends together above the barrel as
shown with a bowline.
Fig. 76. A Well Pipe Hitch is used in hoisting pipe, where no special
clamp is available for attaching the hoisting tackle to the pipe. The
hitch shown will pull tighter, the harder the strain, and is also easy
to untie. Pull up all slack possible in the coils when forming the
hitch, in order to prevent slipping when the strain is first applied.
[Illustration: _Fig. 77_]
Fig. 77. The Hackamore hitch is commonly known and used as an emergency
rope bridle or halter, in the western part of the United States. Among
sailors it is known as a running turk’s head, and it may be used in
carrying a jug or other vessel of similar shape. When used for a halter
about twenty feet will be required. The knot is started by forming a
bight in the center of the rope. Proceed as indicated in the successive
illustrations shown. The result will be a running turk’s head. Draw
together the two center ropes forming a bridle complete with bit,
nose piece, head piece and reins. Such a bridle is not suitable for
continuous use, to be sure, but it will be found useful in an emergency.
Fig. 78. The Halter Tie is a knot preferred by some persons for use in
hitching or in tying the halter rope in the stall. If properly set,
it is secure and may be used in some cases in place of the underhand
bowline knot. The halter tie should never be used around a horse’s
neck, because if the tie is not set up correctly it forms a slip knot
and its use might result in strangulation of the animal. In completing
the tie draw the end through and set the knot by pulling first on the
short end. This is important. If the long rope is pulled first and the
kinks in it are straightened out, the tie forms a slip knot, being
simply two half hitches around the rope.
Fig. 79. Horse-hitch or tie is commonly used by farmers and stockmen
to tie a horse or cow with a rope, so it will not choke itself. Tie
an overhand knot in the standing part of the rope and leave open. Tie
another overhand knot or a Stevedore knot in the end of the rope. Loop
the rope around the animal’s neck and insert the knotted end through
the open Overhand knot. This hitch will not slip and choke the animal.
[Illustration: _Fig. 78; Fig. 79; Fig. 80; Fig. 81_]
Fig. 80. The Manger tie is used for tying a horse or other animal to
a manger or stanchion or hitching rack. The end of the halter rope is
first passed through the hole in the manger with a bight or loop on the
free end of the rope, tie a slip knot on the standing part. Stick the
free end of the rope through the loop or bow as shown. This knot is
easily and quickly tied, but under great strain will pull tight, making
it hard to untie.
Fig. 81. The Figure Eight Manger Tie is superior to the ordinary Manger
Tie in that it will not pull tight under heavy strain such as would
occur if the animal became frightened and attempted to break away. Pass
the free end of the rope through the hole in the manger or around the
hitching rack. Form a bight or loop with the free end of the rope and
hold the loop along the standing part. With the free end form another
loop and serve around both the first loop and the standing part.
Complete the tie by inserting the second loop through the first loop
and secure by inserting the free end of the rope through the second
loop as shown. This is easily untied by first withdrawing the free end
from the loop and then pulling on same until knot is untied.
[Illustration: _Fig. 82; Fig. 83; Fig. 84_]
Fig. 82. The Harness hitch is employed for forming a loop on a rope
in such a way that strain may be applied to both ends and to the loop
without slipping. Start to tie an Over-hand knot as shown. Reach
through between the two twisted parts and draw the opposite side of the
loop through, following the arrow. The completed harness hitch appears
as shown.
Fig. 83. The Strap hitch or Line knot is used to join the free ends of
two leather driving lines on a team. It may be employed as an emergency
tie for a broken line or strap but is not to be recommended as a
permanent repair.
Fig. 84. The Clevis hitch is used for forming a loop on the end of a
rope which is both secure under strain and easily untied.
The Diamond Hitch
The present age of high speed transportation both on land and water,
and in the air as well, has served to crowd pack animal transportation
back into the hills and into those few regions where rail and sail have
not yet penetrated. As a consequence, pack trains are fast becoming
unknown, and the skill of the packer is fast being forgotten. The skill
of the experienced packer is little short of marvelous, where he can
catch a more or less wild pack animal and attach from 100 to 400 or
500 pounds of stuff to his back so securely that it will ride all day
without coming off. Different types of freighting, of course, gave
rise to different methods of binding on the load, but the more widely
used was, no doubt, some form of the famous Diamond Hitch. The early
trappers of the Hudson’s Bay Company are credited with introducing the
Diamond Hitch among the North-West Indians, and old trappers of the
period of 1849, engaged in freighting to California, claim that the
Mexicans used it at that time.
Different packers have modified and used the Diamond Hitch to suit
their needs. As an example, in rough country where there is frequent
trouble with pack animals falling with their load, some packers tie the
Diamond Hitch so that the final knot is on top of the animal’s back
where it can be easily reached and loosened with the animal down. Under
more favorable conditions, other packers use a Diamond Hitch in which
the final tie is made on the side of the animal near the cinch hook.
In fact, out of a group of old packers from different localities, the
probability is that no two would tie the Diamond Hitch alike in every
particular.
The following illustrations of the Diamond Hitch are shown only as
types actually in use by different men in the packing business. Other
packers may have different methods of tying it more suited to the type
of load they are handling. The cuts shown represent the appearance
of the Diamond Hitch if the cinch were cut under the animal’s belly
and the pack were flattened out and laid on the floor with the ropes
undisturbed. This method clearly shows in one picture all the different
parts of the hitch, so that those interested may follow it in making
the hitch for themselves. The Government uses a Spanish packsaddle, or
what is known as an aparejo--pronounced, ap-pa-ray-ho, but civilian
packers often use the cross tree saddle. It consists of a padded board
resting on each side of the animal’s backbone. These two padded boards
are usually fastened together with two cross trees resembling a saw
buck. There are different methods of placing the load on the saddle
preparatory to lashing it fast with the Diamond Hitch. No attempt will
be made to give complete instructions in packing. The hitches shown
are given with the hope they will serve the prospective camper on his
vacation to a retreat in the hills, or perhaps satisfy the interest of
those who have heard of the Diamond Hitch but have never seen it tied.
[Illustration: _Fig. 85; Fig. 86_]
The Two Man Diamond Hitch
Fig. 85. The Two Man Diamond Hitch is started by laying the middle of
the rope lengthwise over the pack from head to tail with the free end
of the rope at the head of the animal. Then the cinch hook is thrown
under the animal’s belly and caught by the off packer. The near packer
throws a bight over the pack and the off packer catches it in the cinch
hook. The near packer pulls up on the rope, making it tight over the
pack.
Fig. 86. The two ropes over the pack are then twisted one and a half
times and a loop pulled through as shown. In this case the loop first
formed between the rope lying lengthwise and the part crossing the pack
is lowered over the near side of the pack.
[Illustration: _Fig. 87; Fig. 88_]
Fig. 87. The hitch is then completed by the off packer, as shown. The
difference between the one-man hitch and the two-man hitch is that they
finish up on different sides of the animal. In the two Diamond Hitches
shown, the final tightening pull is taken toward the head of the
animal. Many packers tie the Diamond Hitch so that the final pull is
taken to rearward of the animal. This can be done by laying the middle
of the rope lengthwise of the pack with the end to the rear instead of
toward the front of the animal.
Fig. 88. The packer’s knot as shown consists of a clove hitch made
around a standing rope. The second half hitch is made with a bight
instead of the end of the rope. One or more half hitches are then
thrown over this loop to make it secure. This knot, if pulled tight in
making, will hold very securely, without slipping, and is easily untied
by loosening the half hitches, and pulling on the free end of the rope.
The One Man Diamond Hitch
Fig. 89. The one man Diamond Hitch is employed by one packer working
alone and requires that he make two trips around the animal in tying
it. The rope is braided into a ring on one end of the cinch. The other
end of the cinch carries a hook. Standing on the near side of the
animal at its shoulder he first lays the middle of the rope across
the pack from forward to back with the free end of the rope forward.
He then throws the cinch over the pack and catches the hook under the
animal’s belly. A loop of the rope is then caught under the cinch hook
and pulled tight. Some packers, in using the one man Diamond Hitch,
find it helps to hold the hitch tight if they take a double turn around
the hook in making the first tightening.
[Illustration: _Fig. 89; Fig. 90_]
Fig. 90. Proceeding with the hitch, the two ropes over the pack
crosswise are then twisted, lifting the forward strand up and back and
pulling the rear strand forward and under. Two turns are made and then
a loop of the rope lying forward and back over the top of the pack is
drawn up between the two twisted ropes as shown. The loop formed on
the off side between the part crosswise of the pack and the part of
the rope crossing lengthwise of the pack, is formed over both corners
of the off side of the pack. Then the loop drawn up between the two
twisted ropes is lowered over the corners of the near side of the pack.
Fig. 91. The final strain is taken on the free end of the rope passing
along the neck of the animal and tied at the forward point of the
diamond with a packer’s knot. If the animal should fall on either side,
the knot is easily reached and untied. The free end of the rope
is tucked under some part of the hitch or looped over the pack or
otherwise disposed of. In making the Diamond Hitch, at no time is the
end of the rope pulled through anywhere. This makes it easy to take off
without becoming snarled.
[Illustration: _Fig. 91; Fig. 92_]
Fig. 92. The Diamond Hitch as mentioned above is frequently tied so
that the knot occurs on the side of the animal opposite the cinch hook
instead of on top. This hitch is tied so that the first loop is lowered
over the rear corner only of the off side of the pack. In the two
other hitches described above, the first loop included both corners of
the pack, and finished with a knot on top. The Diamond Hitch shown is
thrown by two packers.
LASHINGS
Fig. 93. To lash a Transom to an upright Spar with the transom in
front of the upright. A clove hitch is made around the upright a few
inches below the transom. The lashing is brought under the transom, up
in front of it, horizontally behind the upright, down in front of the
transom, and back behind the upright at the level of the bottom of the
transom and above the clove hitch. The following turns are kept outside
the previous ones on one spar and inside on the other, not riding over
the turns already made. Four turns or more are required. A couple of
frapping turns are then taken between the spar and transom, around
the lashing, and the lashing is finished off either around one of the
spars or any part of the lashing through which the rope can be passed.
The final clove hitch should never be made around the spar on the side
toward which the stress is to come, as it may jam and be difficult to
remove. The lashing must be well beaten with handspike or pick handle
to tighten it up. This is called a square lashing.
[Illustration: _Fig. 93; Fig. 94_]
Fig. 94. To lash three spars together as for a Gin or Tripod. Mark on
each spar the distance from the butt to the center of the lashing.
Lay two of the spars parallel to each other with an interval a little
greater than the diameter. Rest their tips on a skid and lay the third
spar between them with its butt in the opposite direction so that the
marks on the three spars will be in line. Make a clove hitch on one of
the outer spars below the lashing and take eight or nine loose turns
around the three, as shown in Figure 94. Take a couple of frapping
turns between each pair of spars in succession and finish with a clove
hitch on the central spar above the lashing. Pass a sling over the
lashing and the tripod is ready for raising.
TACKLE SETS
The use of block and tackle affords at least two advantages to the
user. One is the advantage of position. The user may stand on the
ground and pull downward--the most easy and natural way of exerting
force, while the resulting forces may be developed upward as in the
case of a hoist. The other advantage is mechanical. By the use of a
combination of lines and sheaves, force applied by the user can be
multiplied many times before it is transferred to act upon the body.
But where there is gain in pounds force applied, there is always a
counteracting loss due to an increase in the distance required to apply
the force compared with the distance the weight or load will travel; as
in Figure 96, a force of 100 lbs. on the free end of the rope will give
a resultant on the object of 200 lbs. (neglecting loss by friction in
rope and pulley) but distance travelled by the user will be two feet to
one foot travelled by the object.
The illustrations are shown in each case with an arbitrary force of
100 lbs. applied to the free end of the rope. The resulting force
(neglecting or disregarding friction) is then shown in all parts of the
set. In actual practice the friction of the sheave and the resistance
of the rope to bending gives rise to a loss of about 5% of the force
applied to the rope passing through each sheave. For example in Fig.
95 the force applied on the barrel would be 95% of that applied to the
free end of the rope or 95 lbs. In Fig. 96 the resultant force would
be 100 + (100 - 5) = 195 lbs. and in Fig. 97, the lift on the armature
would be 185½ lbs. instead of 200 as shown.
[Illustration: Fig. 95]
The ropes are also separated in the illustrations in order to show each
part clearly. The ropes are assumed to pull parallel to each other and
the figures represent the pounds resulting in different parts of the
set under those conditions. The illustrations show some of the most
typical applications of block and tackle for mechanical advantage or
advantage of position or both.
Fig. 95. The Single Whip affords only advantage of position
commonly used on a crane or derrick or perhaps for hauling an object
up to a wall or to the water’s edge. Theoretical advantage 1:1.
[Illustration: _Fig. 96_]
Fig. 96. The Running tackle is similar to the Single Whip except that
the object to be moved is attached at a different place. This gives a
theoretical advantage of 2:1.
Fig. 97. The Gun tackle A affords an advantage of position since the
user stands on the ground and pulls down and the resultant force is
applied to the object vertically upward. Theoretical advantage 2:1.
Fig. 98. The gun tackle B is the same as gun tackle A except that its
application is different, giving a theoretical advantage of 3:1.
Fig. 99. Whip-on-whip multiplies the mechanical advantage by two, where
applied as shown. If inverted and the top block applied to the load
with the loop snubbed the mechanical advantage would be 4:1. In both
cases two single blocks are used.
Fig. 100. The Luff tackle has many applications aside from the one
shown. Ordinarily consisting of one single and one double block and a
single rope, it gives a theoretical mechanical advantage of 4:1 in
the case shown.
[Illustration: _Fig. 97; Fig. 98; Fig. 99; Fig. 100_]
[Illustration: _Fig. 101; Fig. 102_]
Fig. 101. The Port tackle, consisting of Single Whip and a Luff tackle
may be applied when the level of operations changes from time to time
and it is undesirable to apply the amount of rope necessary to make the
Luff part of the set long enough to serve for all levels. A bale sling
is also shown in use.
Fig. 102. A Double Luff tackle has a four part line instead of a three
part line as in the Single Luff.
Fig. 103. A Single Spanish Burton (A) using two single blocks and one
rope gives a greater mechanical advantage than the same equipment used
as in Figure 81, the Gun Tackle. This is useful in shifting cargo, etc.,
where the distance hoisted in not great.
Fig. 104. A Single Spanish Burton (B) using three single blocks and
two ropes, gives the same hoisting range as the Type A Burton, but a
greater mechanical advantage.
Fig. 105. Three Fold Purchase using a six part line, gives a
theoretical mechanical advantage of 6:1 and an actual advantage of
5·03:1, assuming a loss of 5% of the force on the rope passing over
each sheave.
[Illustration: _Fig. 103; Fig. 104_]
[Illustration: _Fig. 105; Fig. 106_]
Fig. 106. Four Fold purchase using two four-sheave blocks, is commonly
used in derricks and hoists. The illustration shows the possibility of
using four two-sheave blocks, where the larger sizes are not available.
Fig. 107. The Double Burton (A), for one rope and two single blocks and
one double block, gives a limited hoisting range which is desirable in
shifting heavy weights when it is necessary to lift them but a small
distance.
Fig. 108. The Double Burton (B), while using exactly the same equipment
as is used in Fig. 91, shows the large differences in mechanical
advantage between different methods of threading up the set. The
illustration also shows a box sling in use.
Fig. 109. Double Burton (C), is a further application of the principle
of the Spanish Burton, using two ropes.
[Illustration: _Fig. 107; Fig. 108; Fig. 109_]
[Illustration: _Fig. 110_]
Fig. 110. Double Burton (D), using but one rope, illustrates the
possiblity of using it to greater mechanical advantage than would be
possible in a six fold purchase. However, in this case the hoisting
range is less than would be possible in a six fold purchase.
Fig. 111. Luff on Luff illustrates a common application of tackle to
secure mechanical advantage. It will readily be recognized that the
major tackle must be four times as strong as the other set if both are
to be used anywhere near to capacity.
Fig. 112. Another Double Burton which also illustrates the possibility
of combining two blocks in place of one, with the required number of
sheaves.
[Illustration: _Fig. 111_]
[Illustration: _Fig. 112_]
CHAIN HOISTS
Frequent use is made in garages, machine shops and other places, of a
special device for hoisting heavy machine parts. The apparatus referred
to is known as a chain hoist. These are built to use chain instead of
rope and are designed to operate slowly, but with great mechanical
advantage. Different types embody different design of movements, some
being merely a train of gears attached to a sheave wheel and driven
by a worm gear. Others employ the differential principle in which the
hoisting chain is double, one end running over a small pulley and the
other end running in the opposite direction over a larger pulley on the
same shaft. As the small pulley unwinds one end of the chain slowly,
the other pulley winds up the other end faster--thus raising the lower
end of the chain loop. Chain hoists are made for various capacities,
and can be built to raise the load any desired distance, merely by
supplying chain long enough. A chain-hoist attached to a travelling
crane makes a very satisfactory equipment for a shop where heavy parts
are to be lifted and transferred and should be used wherever there is
enough such work to warrant the greater first cost.
Fig. 113. A Geared-chain-hoist showing a 1-ton hoist manufactured by
the Wright Mfg. Co., of Lisbon, Ohio, using two chains, one for lifting
and the other for operating.
Fig. 114. A Differential Chain hoist using a single continuous
chain running through a pulley at the bottom and over two different
sized wheels fastened on the same shaft at the top. As one unwinds
the other winds up and the difference in diameter causes one to wind
up faster than the other unwinds.
[Illustration: _Fig. 113; Fig. 114; Fig. 115_]
Fig. 115. A Chinese hoist or Chinese capstan, in which the differential
principle is used. The illustration shows the possibility of quickly
applying the principle to the hoisting of a well-casing. It has the
merit of being cheap and easy to construct and very efficient in
developing a large mechanical advantage. The necessary materials can
frequently be found around almost any farm or construction camp.
[Illustration: _Fig. 116_]
Fig. 116. A Snatch Block is used frequently in connection with hay
handling equipment on the farm. Hoisting hay from a loaded wagon to the
track located in the peak of the barn, requires much more force than is
required to move the load along the track. From then on, the snatch
block pulls away from the knot causing the load to travel on the
carrier track twice as fast as the team. The object is to utilize the
direct pull of the team while elevating the load and increase the speed
of the load and decrease the distance travelled by the team after the
load has been elevated and is to be transferred.
TRANSMISSION CABLES
Hemp and Manila
Ropes and cables have many uses and applications both in industry and
pleasure. Haulage, hoisting and the transmission of power are three
of the most modern applications to which ropes and cables have been
put, which require an intimate knowledge of their strength and life
in service, in order to secure satisfactory service. For instance,
a certain kind and size of rope is suitable for guy lines but would
not be able to compete with a different type of rope in service on a
rapid hoist. Similarly, a certain size of rope is being used on a rope
drive, but the power load is increasing to such a point it is necessary
to increase the size of transmission rope. If the sheaves are not
increased in diameter suitable to the increased size of rope, the acute
bending of the larger rope on the old sheave wheel will shorten its
life materially.
Following are tables of strength for a few different kinds and sizes
of ropes. It is not the purpose to make these tables complete and
exhaustive in scope, but rather to give a general conception of the
strength to be expected of different kinds and sizes of ropes in more
common use. Those interested in more complete information on this
subject should refer to the catalogs put out by manufacturers of ropes.
No accurate rule can be given for calculating the strength of rope
and any table giving the strength will only be approximately correct.
Four-strand rope has about 16% more strength than three-strand rope.
Tarring rope decreases the strength by about 25% because the high
temperature of the tar injures the fibers. The strength of a rope is
decreased by age, exposure and wear.
The breaking strength of a rope is the weight or pull that will break
it. The safe load is the weight you may put on a rope without danger
of breaking it. The safe load must be very much less than the breaking
strength, in order that life and property may not be endangered when
heavy objects are to be moved or lifted. The safe load is usually
regarded as 1/6 of the breaking strength. The breaking strength and
safe load for all ropes must be largely a matter of good judgment and
experience.
Calculation of Strength
For new manila rope the breaking strength in pounds may be found
approximately by the following rule: Square the diameter, measured in
inches, and multiply this product by 7200. Result obtained from this
rule may vary as much as 15% from actual tests. The safe load can be
found by dividing the breaking strength by 6.
Hemp rope is approximately 3/4 as strong as manila so that we use the
following rule for it: The breaking strength of hemp rope in pounds is
5400 times the square of the diameter in inches. The safe load is found
by dividing the breaking strength by 6 as we did for the manila rope.
Care of Rope
Keep rope in a dry place, do not leave it out in the rain. If a rope
gets wet, stretch it out straight to dry. Do not let the ends become
untwisted but fix them in some way to prevent it as soon as the rope is
obtained. A stiff and hard rope may be made very soft and flexible by
boiling for a time in pure water. This will of course remove some of
the tar or other preservative. Cowboys treat their lasso ropes in this
way.
Uncoiling Rope
1. Start with the end found in the center of the coil.
2. Pull this end out and the rope should uncoil in a direction opposite
to the direction of motion of the hands of a clock.
3. If it uncoils in the wrong direction, turn the coil over and pull
this same end through the center of the coil and out on the other side.
4. If these directions are followed, the rope will come out of the coil
with very few kinks or snarls.
SIZE AND STRENGTH OF TEXTILE ROPES
──────────────┬────────────────────────┬───────────────────────
│ Ultimate Strength, Lb. │ Working Strength, Lbs.
Diam. of Rope ├──────────┬─────────────┼─────────┬──────────────
Inches │ Cotton │ Manila Hemp │ Cotton │ Manila Hemp
──────────────┼──────────┼─────────────┼─────────┼──────────────
½ │ 1,150 │ 1,900 │ 50 │ 50
⅝ │ 1,800 │ 2,900 │ 78 │ 78
¾ │ 2,600 │ 4,100 │ 112 │ 112
⅞ │ 3,500 │ 5,500 │ 153 │ 153
1 │ 4,600 │ 7,100 │ 200 │ 200
1¼ │ 7,200 │ 10,900 │ 312 │ 312
1½ │ 10,400 │ 15,000 │ 450 │ 450
1¾ │ 14,000 │ 19,800 │ 612 │ 612
2 │ 18,400 │ 25,100 │ 800 │ 800
──────────────┴──────────┴─────────────┴─────────┴─────────────
STRENGTH OF MANILA ROPE
──────────────┬─────────────────
Diameter of │ Average Quality
Rope in Inches│ New Manila Rope
──────────────┼─────────────────
2 3/4 │ 26
2-1/2 │ 21-1/2
2-1/4 │ 18-1/2
2 │ 15
──────────────┼─────────────────
1-3/4 │ 12-1/2
1-5/8 │ 10
1-1/2 │ 8-1/2
1-3/8 │ 7-1/2
1-1/4 │ 6-1/4
1-1/8 │ 5-1/4
1 │ 4
──────────────┼─────────────────
7/8 │ 3-1/4
3/4 │ 2-1/4
5/8 │ 2
9/16 │ 1-1/2
1/2 │ 1-1/5
7/16 │ 3/4
3/8 │ 1/2
5/16 │ 3/8
9/32 │ 3/10
1/4 │ 1/4
──────────────┴─────────────────
STEEL CABLES
The modern demands of industry for speed and large capacity have called
for strengths exceeding that possible to attain from hemp or manila
ropes, which are not excessive in size or cost. As a result, steel
ropes and cables have been developed and perfected to a high degree of
strength and dependability. The majority of hoists and cranes use steel
rope. Logging industries depend for most part on steel cables. Cable
cars use special steel cables which in many cases are several miles
long. Long tramways use light steel cables, for long spans where manila
rope would scarcely maintain its own weight. High speed passenger
elevators maintain safe and dependable service day after day only
through the strength of the perfected flexible steel cable. However, as
stated above, each particular type of service calls for some special
type of cable. The following tables are not complete but will serve to
indicate the scope of the field covered by this subject.
CAST STEEL ROPE
Composed of 6 strands and a hemp center, 7 wires to the strand
──────────┬───────────────┬────────────┬──────────┬──────────
│ │ Approx. │ Proper │ Minimum
Diameter │ Approximate │ Breaking │ Working │ Size of
in │ Circumference │ Strain in │ Load in │ Drum or
Inches │ in Inches │ Tons of │ Tons of │ Sheave
│ │ 2000 lbs. │ 2000 lbs.│ in ft.
──────────┼───────────────┼────────────┼──────────┼──────────
1-1/2 │ 4-3/4 │ 63 │ 12.6 │ 11
1-3/8 │ 4-1/4 │ 53 │ 10.6 │ 10
1-1/4 │ 4 │ 46 │ 9.2 │ 9
1-1/8 │ 3-1/2 │ 37 │ 7.4 │ 8
1 │ 3 │ 31 │ 6.2 │ 7
7/8 │ 2-3/4 │ 24 │ 4.8 │ 6
3/4 │ 2-1/4 │ 18.6 │ 3.7 │ 5
11/16 │ 2-1/8 │ 15.4 │ 3.1 │ 4-3/4
5/8 │ 2 │ 13 │ 2.6 │ 4-1/2
9/16 │ 1-3/4 │ 10 │ 2 │ 4
1/2 │ 1-1/2 │ 7.7 │ 1.54 │ 3-1/2
7/16 │ 1-1/4 │ 5.5 │ 1.10 │ 3
3/8 │ 1-1/8 │ 4.6 │ .92 │ 2-3/4
5/16 │ 1 │ 3.5 │ .70 │ 2-1/4
9/32 │ 7/8 │ 2.5 │ .50 │ 1-3/4
──────────┴───────────────┴────────────┴──────────┴──────────
CAST STEEL ROPE
Composed of 6 strands and a hemp center, 19 wires to the strand
──────────┬───────────────┬────────────┬──────────┬──────────
│ │ Approx. │ Proper │ Minimum
Diameter │ Approximate │ Breaking │ Working │ Size of
of Rope │ Circumference │ Strain in │ Load in │ Drum or
in │ in Inches │ Tons of │ Tons of │ Sheave
Inches │ │ 2000 lbs. │ 2000 lbs.│ in ft.
──────────┼───────────────┼────────────┼──────────┼──────────
2-3/4 │ 8-5/8 │ 211 │ 42.2 │ 11
2-1/2 │ 7-7/8 │ 170 │ 34 │ 10
2-1/4 │ 7-1/8 │ 133 │ 26.6 │ 9
2 │ 6-1/4 │ 106 │ 21.2 │ 8
1-7/8 │ 5-3/4 │ 96 │ 19 │ 8
1-3/4 │ 5-1/2 │ 85 │ 17 │ 7
1-5/8 │ 5 │ 72 │ 14.4 │ 6-1/2
1-1/2 │ 4-3/4 │ 64 │ 12.8 │ 6
1-3/8 │ 4-1/4 │ 56 │ 11.2 │ 5-1/2
1-1/4 │ 4 │ 47 │ 9.4 │ 5
1-1/8 │ 3-1/2 │ 38 │ 7.6 │ 4-1/2
1 │ 3 │ 30 │ 6 │ 4
7/8 │ 2-3/4 │ 23 │ 4.6 │ 3-1/2
3/4 │ 2-1/4 │ 17.5 │ 3.5 │ 3
5/8 │ 2 │ 12.5 │ 2.5 │ 2-1/2
9/16 │ 1-3/4 │ 10 │ 2 │ 2-1/4
1/2 │ 1-1/2 │ 8.4 │ 1.68 │ 2
7/16 │ 1-1/4 │ 6.5 │ 1.30 │ 1-3/4
3/8 │ 1-1/8 │ 4·8 │ .96 │ 1-1/2
5/16 │ 1 │ 3.1 │ .62 │ 1-1/4
1/4 │ 3/4 │ 2.2 │ .44 │ 1
──────────┴───────────────┴────────────┴──────────┴──────────
CAST STEEL ROPE
Composed of 6 strands and a hemp center, 37 wires to the strand
──────────┬───────────────┬────────────┬──────────┬──────────
│ │ Approx. │ Proper │ Minimum
Diameter │ Approximate │ Breaking │ Working │ Size of
in │ Circumference │ Strain in │ Load in │ Drum or
Inches │ in Inches │ Tons of │ Tons of │ Sheave
│ │ 2000 lbs. │ 2000 lbs.│ in ft.
──────────┼───────────────┼────────────┼──────────┼──────────
2-3/4 │ 8-5/8 │ 200 │ 40 │
2-1/2 │ 7-7/8 │ 160 │ 32 │
2-1/4 │ 7-1/8 │ 125 │ 25 │
2 │ 6-1/4 │ 105 │ 21 │
1-3/4 │ 5-1/2 │ 84 │ 17 │
1-5/8 │ 5 │ 71 │ 14 │
1-1/2 │ 4-3/4 │ 63 │ 12 │ 3-3/4
1-3/8 │ 4-1/4 │ 55 │ 11 │ 3-1/2
1-1/4 │ 4 │ 45 │ 9 │ 3-1/4
1-1/8 │ 3-1/2 │ 34 │ 6.8 │ 2-3/4
1 │ 3 │ 29 │ 5.8 │ 2-1/2
7/8 │ 2-3/4 │ 23 │ 4.6 │ 2-1/4
3/4 │ 2-1/4 │ 17.5 │ 3.5 │ 1-3/4
5/8 │ 2 │ 11.2 │ 2.2 │ 1-3/4
9/16 │ 1-3/4 │ 9.5 │ 1.9 │ 1-1/2
1/2 │ 1-1/2 │ 7.25 │ 1.45 │ 1-1/4
7/16 │ 1-1/4 │ 5.50 │ 1.10 │ 1-1/4
3/8 │ 1-1/8 │ 4.20 │ .84 │ 1
──────────┴───────────────┴────────────┴──────────┴──────────
CAST STEEL ROPES FOR INCLINES
Six strands of 7 wires each--hemp center
────────┬─────────────────────────────────────────────────────────────
Diam. │ Diameter of Sheaves or Drums in Feet, Showing Percentage
of Rope │ of Life for Various Diameters
├─────────┬────────┬────────┬────────┬────────┬────────┬──────
Inches │ 100 % │ 90 % │ 80 % │ 75 % │ 60 % │ 50 % │ 25 %
────────┼─────────┼────────┼────────┼────────┼────────┼────────┼──────
1-1/2 │ 16 │ 14 │ 12 │ 11 │ 9 │ 7 │ 4.75
1-3/8 │ 14 │ 12 │ 10 │ 8.5 │ 7 │ 6 │ 4.5
1-1/4 │ 12 │ 10 │ 8 │ 7.25 │ 6 │ 5.5 │ 4.25
1-1/8 │ 10 │ 8.5 │ 7.75 │ 7 │ 6 │ 5 │ 4
1 │ 8.5 │ 7.75 │ 6.75 │ 6 │ 5 │ 4.5 │ 3.75
7/8 │ 7.75 │ 7 │ 6.25 │ 5.75 │ 4.5 │ 3.75 │ 3.2
3/4 │ 7 │ 6.25 │ 5.5 │ 5 │ 4.25 │ 3.5 │ 2.75
5/8 │ 6 │ 5.25 │ 4.5 │ 4 │ 3.25 │ 3 │ 2.5
1/2 │ 5 │ 4.5 │ 4 │ 3.5 │ 2.75 │ 2 │ 1.75
────────┴─────────┴────────┴────────┴────────┴────────┴────────┴──────
CAST STEEL HOISTING ROPES
6 strands of 19 wires each--hemp center
────────┬─────────────────────────────────────────────────────────────
Diam. │ Diameter of Sheaves or Drums in Feet, Showing Percentage
of Rope │ of Life for Various Diameters
├─────────┬────────┬────────┬────────┬────────┬────────┬──────
Inches │ 100 % │ 90 % │ 80 % │ 75 % │ 60 % │ 50 % │ 25 %
────────┼─────────┼────────┼────────┼────────┼────────┼────────┼──────
1-1/2 │ 14 │ 12 │ 10 │ 8.5 │ 7 │ 6 │ 4.5
1-3/8 │ 12 │ 10 │ 8 │ 7 │ 6 │ 5.25 │ 4.25
1-1/4 │ 10 │ 8.5 │ 7.5 │ 6.75 │ 5.5 │ 5 │ 4
1-1/8 │ 9 │ 7.5 │ 6.5 │ 5.5 │ 5 │ 4.5 │ 3.75
1 │ 8 │ 7 │ 6 │ 5.5 │ 4.5 │ 4 │ 3.50
7/8 │ 7.5 │ 6.75 │ 5.75 │ 5 │ 4.25 │ 3.5 │ 3
3/4 │ 5.5 │ 4.5 │ 4 │ 3.75 │ 3.25 │ 3 │ 2.25
5/8 │ 4.5 │ 4 │ 3.75 │ 3.25 │ 3 │ 2.5 │ 2
1/2 │ 4 │ 3 │ 3 │ 2.75 │ 2.25 │ 2 │ 1.5
3/8 │ 3 │ │ │ 2 │ │ 1.5 │
────────┴─────────┴────────┴────────┴────────┴────────┴────────┴──────
STANDARD HOISTING ROPE
Six Strands--19 wires to the strand--One hemp core
─────────────────────────────────┬────────────────────────────────────
│ Swedes Iron
──────────┬───────────┬──────────┼───────────┬───────────┬────────────
│ │ │ Approx. │ Proper │ Diam. of
Diam. │ Circum- │ Approx. │ Strain in │ Working │ Drum or
in │ ference │ Weight │ Tons of │ Load in │ Sheave in
Inches │ in │ Per Foot │ 2000 lbs. │ Tons of │ in ft.
│ Inches │ │ │ 2000 lbs. │ Advised
──────────┼───────────┼──────────┼───────────┼───────────┼────────────
2-3/4 │ 8-5/8 │ 11.95 │ 111 │ 22.2 │ 17
2-1/2 │ 7-7/8 │ 9.85 │ 92 │ 18.4 │ 15
2-1/4 │ 7-1/8 │ 8 │ 72 │ 14.4 │ 14
2 │ 6-1/4 │ 6.30 │ 55 │ 11 │ 12
1-7/8 │ 5-3/4 │ 5.55 │ 50 │ 10 │ 12
1-3/4 │ 5-1/2 │ 4.85 │ 44 │ 8.8 │ 11
1-5/8 │ 5 │ 4.15 │ 38 │ 7.5 │ 10
1-1/2 │ 4-3/4 │ 3.55 │ 33 │ 6.5 │ 9
1-3/8 │ 4-1/4 │ 3 │ 28 │ 5.5 │ 8.5
1-1/4 │ 4 │ 2.45 │ 22.8 │ 4.56 │ 7.5
1-1/8 │ 3-1/2 │ 2 │ 18.6 │ 3.72 │ 7
1 │ 3 │ 1.58 │ 14.5 │ 2.90 │ 6
7/8 │ 2-3/4 │ 1.20 │ 11.8 │ 2.36 │ 5.5
3/4 │ 2-1/4 │ .89 │ 8.5 │ 1.70 │ 4.5
5/8 │ 2 │ .62 │ 6 │ 1.20 │ 4
9/16 │ 1-3/4 │ .50 │ 4.7 │ .94 │ 3.5
1/2 │ 1-1/2 │ .39 │ 3.9 │ .78 │ 3
7/16 │ 1-1/4 │ .30 │ 2.9 │ .58 │ 2.75
3/8 │ 1-1/8 │ .22 │ 2.4 │ .48 │ 2.25
5/16 │ 1 │ .15 │ 1.5 │ .30 │ 2
1/4 │ 3/4 │ .10 │ 1.1 │ .22 │ 1.50
──────────┴───────────┴──────────┼───────────┴───────────┴────────────
│ Crucible Cast Steel
──────────┬───────────┬──────────┼───────────┬───────────┬────────────
│ │ │ │ Proper │
Diam. │ Circum- │ Approx. │ Approx. │ Working │ Diam. of
in │ ference │ Weight │ Strain in │ Load in │ Drum or
Inches │ in │ Per Foot │ Tons of │ Tons of │ Sheave in
│ Inches │ │ 2000 lbs. │ 2000 lbs.│ ft. Advised
──────────┼───────────┼──────────┼───────────┼───────────┼────────────
2-3/4 │ 8-5/8 │ 11.95 │ 211 │ 42.2 │ 11
2-1/2 │ 7-7/8 │ 9.85 │ 170 │ 34 │ 10
2-1/4 │ 7-1/8 │ 8 │ 133 │ 26.6 │ 9
2 │ 6-1/4 │ 6.30 │ 106 │ 21.2 │ 8
1-7/8 │ 5-3/4 │ 5.55 │ 96 │ 19 │ 8
1-3/4 │ 5-1/2 │ 4.85 │ 85 │ 17 │ 7
1-5/8 │ 5 │ 4.15 │ 72 │ 14.4 │ 6.5
1-1/2 │ 4-3/4 │ 3.55 │ 64 │ 12.8 │ 6
1-3/8 │ 4-1/4 │ 3 │ 56 │ 11.6 │ 5.5
1-1/4 │ 4 │ 2.45 │ 47 │ 9.4 │ 5
1-1/8 │ 3-1/2 │ 2 │ 38 │ 7.6 │ 4.5
1 │ 3 │ 1.58 │ 30 │ 6 │ 4
7/8 │ 2-3/4 │ 1.20 │ 23 │ 4.6 │ 3.5
3/4 │ 2-1/4 │ .89 │ 17.5 │ 3.5 │ 3
5/8 │ 2 │ .62 │ 12.5 │ 2.5 │ 2.5
9/16 │ 1-3/4 │ .50 │ 10 │ 2 │ 2.25
1/2 │ 1-1/2 │ .39 │ 8.4 │ 1.68 │ 2
7/16 │ 1-1/4 │ .30 │ 6.5 │ 1.30 │ 1.75
3/8 │ 1-1/8 │ .22 │ 4.8 │ .96 │ 1.50
5/16 │ 1 │ .15 │ 3.1 │ .62 │ 1.25
1/4 │ 3/4 │ .10 │ 2.2 │ .44 │ 1
──────────┴───────────┴──────────┼───────────┴───────────┴────────────
│ Plow Steel
──────────┬───────────┬──────────┼───────────┬───────────┬────────────
│ │ │ Approx. │ Proper │ Diam. of
Diam. │ Circum- │ Approx. │ Strain in │ Working │ Drum or
in │ ference │ Weight │ Tons of │ Load in │ Sheave in
Inches │ in │ Per Foot │ 2000 lbs. │ Tons of │ ft. Advised
│ Inches │ │ │ 2000 lbs. │
──────────┼───────────┼──────────┼───────────┼───────────┼────────────
2-3/4 │ 8-5/8 │ 11.95 │ 275 │ 55 │ 11
2-1/2 │ 7-7/8 │ 9.85 │ 229 │ 46 │ 10
2-1/4 │ 7-1/8 │ 8 │ 186 │ 37 │ 9
2 │ 6-1/4 │ 6.30 │ 140 │ 28 │ 8
1-7/8 │ 5-3/4 │ 5.55 │ 127 │ 25 │ 8
1-3/4 │ 5-1/2 │ 4.85 │ 112 │ 22 │ 7
1-5/8 │ 5 │ 4.15 │ 94 │ 19 │ 6.5
1-1/2 │ 4-3/4 │ 3.55 │ 82 │ 16 │ 6
1-3/8 │ 4-1/4 │ 3 │ 72 │ 14 │ 5.5
1-1/4 │ 4 │ 2.45 │ 58 │ 12 │ 5
1-1/8 │ 3-1/2 │ 2 │ 47 │ 9.5 │ 4.5
1 │ 3 │ 1.58 │ 38 │ 7.6 │ 4
7/8 │ 2-3/4 │ 1.20 │ 29 │ 5.8 │ 3.5
3/4 │ 2-1/4 │ .89 │ 23 │ 4.6 │ 3
5/8 │ 2 │ .62 │ 15.5 │ 3.1 │ 2.5
9/16 │ 1-3/4 │ .50 │ 12.3 │ 2.4 │ 2.25
1/2 │ 1-1/2 │ .39 │ 10 │ 2 │ 2
7/16 │ 1-1/4 │ .30 │ 8 │ 1.6 │ 1.75
3/8 │ 1-1/8 │ .22 │ 5.75 │ 1.15 │ 1.50
5/16 │ 1 │ .15 │ 3.8 │ .76 │ 1.25
1/4 │ 3/4 │ .10 │ 2.65 │ .53 │ 1
──────────┴───────────┴──────────┴───────────┴───────────┴────────────
STRENGTH OF WIRE ROPE
in tons of 2,000 pounds
──────────┬───────────────────────────────────────────────
│ Wire Transmission Rope. One Hemp core
│ surrounded by six strands of
Diameter │ seven wires each
in ├────────┬────────────┬───────────────┬─────────
Inches │ │ Crucible │ Extra Strong │ Plow
│ Iron │ Cast │ Crucible Cast │ Steel
│ │ Steel │ Steel │
──────────┼────────┼────────────┼───────────────┼─────────
2-3/4 │ │ │ │
2-1/2 │ │ │ │
2-1/4 │ │ │ │
2 │ │ │ │
1-3/4 │ │ │ │
1-5/8 │ │ │ │
1-1/2 │ 32 │ 63 │ 73 │ 82
1-3/8 │ 28 │ 53 │ 63 │ 72
1-1/4 │ 23 │ 46 │ 54 │ 60
1-1/8 │ 19 │ 37 │ 43 │ 47
1 │ 15 │ 31 │ 35 │ 38
7/8 │ 12 │ 24 │ 28 │ 31
3/4 │ 8.8 │ 18.6 │ 21 │ 23
5/8 │ 6 │ 13 │ 14.5 │ 16
9/16 │ 4.8 │ 10 │ 11 │ 12
1/2 │ 3.7 │ 7.7 │ 8.85 │ 10
7/16 │ 2.6 │ 5.5 │ 6.25 │ 7
3/8 │ 2.2 │ 4.6 │ 5.25 │ 5.9
5/16 │ 1.7 │ 3.5 │ 3.95 │ 4.4
9/32 │ 1.2 │ 2.5 │ 2.95 │ 3.4
1/4 │ │ │ │
──────────┼────────┴────────────┴───────────────┴─────────
│ Wire Hoisting Rope. One Hemp core
│ surrounded by six strands of
Diameter │ nineteen wires each
in ├────────┬────────────┬───────────────┬─────────
Inches │ │ Crucible │ Extra Strong │ Plow
│ Iron │ Cast │ Crucible Cast │ Steel
│ │ Steel │ Steel │
──────────┼────────┼────────────┼───────────────┼─────────
2-3/4 │ 111 │ 211 │ 243 │ 275
2-1/2 │ 92 │ 170 │ 200 │ 229
2-1/4 │ 72 │ 133 │ 160 │ 186
2 │ 55 │ 106 │ 123 │ 140
1-3/4 │ 44 │ 85 │ 99 │ 112
1-5/8 │ 38 │ 72 │ 83 │ 94
1-1/2 │ 33 │ 64 │ 73 │ 82
1-3/8 │ 28 │ 56 │ 64 │ 72
1-1/4 │ 22.8 │ 47 │ 53 │ 58
1-1/8 │ 18.6 │ 38 │ 43 │ 47
1 │ 14.5 │ 30 │ 34 │ 38
7/8 │ 11.8 │ 23 │ 26 │ 29
3/4 │ 8.5 │ 17.5 │ 20.2 │ 23
5/8 │ 6 │ 12.5 │ 14 │ 15.5
9/16 │ 4.7 │ 10 │ 11.2 │ 12.3
1/2 │ 3.9 │ 8.4 │ 9.2 │ 10
7/16 │ 2.9 │ 6.5 │ 7.25 │ 8
3/8 │ 2.4 │ 4.8 │ 5.30 │ 5.75
5/16 │ 1.5 │ 3.1 │ 3.50 │ 3.8
9/32 │ │ │ │
1/4 │ 1.1 │ 2.2 │ 2.43 │ 2.65
──────────┴────────┴────────────┴───────────────┴─────────
SPLICING TRANSMISSION CABLES
Wherever wire rope transmissions are used it is necessary to splice the
rope or cable so that it will run smoothly over the sheave wheels. For
this purpose a long splice is invariably used. (Taken from “American
Wire Rope” published by American Steel and Wire Company). The tools
required are a small marlin-spike, nipping cutters, and either clamps
or a small hemp rope sling with which to wrap around and untwist the
rope. If a bench vise is accessible, it will be found very convenient
for holding the rope.
“In splicing a rope, a certain length is used up in making the
splice. An allowance of not less than 16 feet for ½ inch rope, and
proportionately longer for larger sizes, must be added to the length
of an endless rope, in ordering. The length of splice relation to the
diameter of the rope is approximately 50:1.”
This extra length is equal to the distance EE´ in Fig. 117. The
additional length recommended for making a splice in different sizes of
wire rope is as follows:
───────────────┬──────────────────────────
Diam. of Rope │ Extra Length Allowed for
in Inches │ the Splice, Feet
───────────────┼──────────────────────────
⅜ │ 16
½ │ 16
⅝ │ 20
¾ │ 24
⅞ │ 28
───────────────┼──────────────────────────
1 │ 32
1⅛ │ 36
1¼ │ 40
1½ │ 44
│
───────────────┴──────────────────────────
Fig. 117. Having measured carefully the length the rope should be after
splicing and marked the points M and M´, unlay the strands from each
end E and E´, to M and M´, and cut off the hemp center at M and M´.
Fig. 118. First. Interlock the six unlaid strands of each end
alternately, cutting off the hemp centers at M and M´, and draw wire
strands together, so that the points M and M´ meet, as shown.
[Illustration: FIG. _117_; FIG. _118_; FIG. _119_;
FIG. _120_; FIG. _121_]
Fig. 119. Second. Unlay a strand from one end, and following the unlay
closely, lay into the seam or groove it opens, the strand opposite it
belonging to the other end of the rope, until there remains a length of
stand equal in inches to the length of splice EE´ in feet, e. g., the
straight end of unlaid strand A on one-half inch rope equal 16 inches
for 16 foot splice. Then cut the other strand to about the same length
from the point of meeting, as shown at A.
Fig. 119. Third. Unlay the adjacent strand in the opposite direction,
and following the unlay closely, lay in its place the corresponding
opposite strand, cutting the ends as described before at B.
The four strands are now laid in place terminating at A and B, with
eight remaining at M and M´ as shown in Fig. 119.
It will be well after laying each pair of strands to tie them
temporarily at the points A and B.
Fig. 120. Pursue the same course with the remaining four pairs of
opposite strands, stopping each pair of strands so as to divide the
space between A and B into five equal parts, and cutting the ends as
before.
All the strands are now laid in their proper places with their
respective ends passing each other.
[Illustration: FIG. _122_; FIG. _123_]
All methods of rope splicing are identical up to this point; their
variety consists in the method of securing the ends.
Fig. 121. The completed splice with ends secured results in a cable
with scarcely any enlargement at that point. A few days’ use will make
it difficult to discover at all.
The final part of the splice is made as follows:
“Clamp the rope either in a vise or with a hand clamp at a point to the
left of A (Fig. 119), and by a hand clamp applied near the right of A
open up the rope by untwisting sufficiently to cut the hemp core at A,
and seizing it with nippers, let your assistant draw it out slowly.
Then insert a marlin spike under the two nearest strands to open up
the rope and starting the loose strand into the space left vacant by
the hemp center, rotate the marlin spike so as to run the strand into
the center. Cut the hemp core where the strand ends, and push the end
of hemp back into its place. Remove the clamps and let the rope close
together around it. Draw out the hemp core in the opposite direction
and lay the other strand in the center of the rope in the same manner.
Repeat the operation at the five remaining points, and hammer the rope
lightly at the points where the ends pass each other at A´, B´, etc.,
with small wooden mallets, and the splice is complete, as shown in Fig.
121.”
A rope spliced as above will be nearly as strong as the original rope,
and smooth everywhere. After running a few days, the splice, if well
made, cannot be pointed out except by the close examination of an
expert.
Fig. 122. If a clamp and vice are not obtainable, two rope slings and
short wooden levers may be used to untwist and open up the rope.
Fig. 123. A marlin spike is absolutely necessary in order to separate
the strands in making a splice in steel cable.
POWER TRANSMITTED BY WIRE ROPE
Wire Rope Drives
────────────────────┬────────────────────┬──────────┬──────────────
Diam. of Wheel │ No. of Revolutions │ Diam. of │ Horse Power
in Feet │ Per Minute │ Rope │
────────────────────┼────────────────────┼──────────┼──────────────
3 │ 80 │ 3/8 │ 3
3 │ 100 │ 3/8 │ 3 1/2
3 │ 120 │ 3/8 │ 4
3 │ 140 │ 3/8 │ 4 1/2
4 │ 80 │ 3/8 │ 4
4 │ 100 │ 3/8 │ 5
4 │ 120 │ 3/8 │ 6
4 │ 140 │ 3/8 │ 7
5 │ 80 │ 7/16 │ 9
5 │ 100 │ 7/16 │ 11
5 │ 120 │ 7/16 │ 13
5 │ 140 │ 7/16 │ 15
6 │ 80 │ 1/2 │ 14
6 │ 100 │ 1/2 │ 17
6 │ 120 │ 1/2 │ 20
6 │ 140 │ 1/2 │ 23
7 │ 80 │ 9/16 │ 20
7 │ 100 │ 9/16 │ 25
7 │ 120 │ 9/16 │ 30
7 │ 140 │ 9/16 │ 35
────────────────────┼────────────────────┼──────────┼──────────────
8 │ 80 │ 5/8 │ 26
8 │ 100 │ 5/8 │ 32
8 │ 120 │ 5/8 │ 39
8 │ 140 │ 5/8 │ 45
│ │ 9/16 │ 47
9 │ 80 │ 5/8 │ 48
│ │ 9/16 │ 58
9 │ 100 │ 5/8 │ 60
│ │ 9/16 │ 69
9 │ 120 │ 5/8 │ 73
│ │ 9/16 │ 82
9 │ 140 │ 5/8 │ 84
10 │ 80 │ 5/8 │ 64
│ │ 11/16 │ 68
10 │ 100 │ 5/8 │ 80
│ │ 11/16 │ 85
10 │ 120 │ 5/8 │ 96
│ │ 11/16 │ 102
10 │ 140 │ 5/8 │ 112
│ │ 11/16 │ 119
12 │ 80 │ 11/16 │ 93
│ │ 3/4 │ 99
12 │ 100 │ 11/16 │ 116
│ │ 3/4 │ 124
12 │ 120 │ 11/16 │ 140
│ │ 3/4 │ 149
12 │ 120 │ 7/8 │ 173
14 │ 80 │ 1 │ 141
│ │ 1 1/8 │ 148
14 │ 100 │ 1 │ 176
│ │ 1 1/8 │ 185
────────────────────┴────────────────────┴──────────┴──────────────
MINIMUM DIAMETERS OF SHEAVES FOR POWER TRANSMISSION BY WIRE ROPES
(All Dimensions in Inches)
────────┬──────────────────┬──────────────────
Rope │ Steel │ Iron
Diam. ├────────┬─────────┼────────┬─────────
│ 7-Wire │ 19-Wire │ 7-Wire │ 19-Wire
────────┼────────┼─────────┼────────┼─────────
1/4 │ 20 │ 12 │ 40 │ 24
5/16 │ 25 │ 15 │ 50 │ 30
3/8 │ 30 │ 18 │ 60 │ 36
7/16 │ 35 │ 21 │ 70 │ 42
1/2 │ 40 │ 24 │ 80 │ 48
9/16 │ 45 │ 27 │ 90 │ 54
5/8 │ 50 │ 30 │ 100 │ 60
11/16 │ 55 │ 32 │ 110 │ 66
3/4 │ 60 │ 35 │ 120 │ 72
7/8 │ 70 │ 41 │ 140 │ 84
1 │ 80 │ 47 │ 160 │ 96
1 1/8 │ 90 │ 53 │ 180 │ 108
1 1/4 │ 100 │ 58 │ 200 │ 120
1 3/8 │ 110 │ 64 │ 220 │ 132
1 1/2 │ 120 │ 70 │ 240 │ 144
────────┴────────┴─────────┴────────┴─────────
DIAMETER OF MINIMUM SHEAVES IN INCHES, CORRESPONDING TO A MAXIMUM SAFE
WORKING TENSION.
─────────────┬────────────────────────────┬───────────────────────────
Diam. of Rope│ Steel │ Iron
in Inches ├────────┬─────────┬─────────┼────────┬─────────┬────────
│ 7-Wire │ 12-Wire │ 19-Wire │ 7-Wire │ 12-Wire │ 19-Wire
─────────────┼────────┼─────────┼─────────┼────────┼─────────┼────────
1/4 │ 19 │ 15 │ 11 │ 39 │ 31 │ 23
5/16 │ 24 │ 19 │ 14 │ 49 │ 38 │ 29
3/8 │ 29 │ 22 │ 17 │ 59 │ 46 │ 35
7/16 │ 34 │ 26 │ 19 │ 69 │ 54 │ 41
1/2 │ 38 │ 30 │ 22 │ 79 │ 61 │ 47
9/16 │ 43 │ 33 │ 25 │ 89 │ 69 │ 52
5/8 │ 48 │ 37 │ 28 │ 99 │ 77 │ 58
11/16 │ 53 │ 41 │ 31 │ 109 │ 84 │ 64
3/4 │ 58 │ 44 │ 34 │ 119 │ 92 │ 70
7/8 │ 67 │ 52 │ 39 │ 138 │ 107 │ 81
1 │ 77 │ 59 │ 45 │ 158 │ 123 │ 93
─────────────┴────────┴─────────┴─────────┴────────┴─────────┴────────
ENGINEERING BULLETINS PUBLISHED BY THE STATE COLLEGE OF WASHINGTON
ENGINEERING EXPERIMENT STATION.
1. Sewage Disposal for the Country Home.
Septic tanks and underground distribution systems.
By O. L. Waller and M. K. Snyder. Mar. 1914, July 1916.
2. How to Measure Water.
Construction of weirs and tables for same.
By O. L. Waller. Oct. 1915.
3. Water Supply for the Country Home.
Water Sources, pumps, filters, storage tanks and cost data.
By M. K. Snyder. Jan. 1916 (out of print).
4. Construction and Maintenance of Earth Roads.
Grades and grading, drainage and dragging.
By L. V. Edwards. April 1916.
5. Cost of Pumping for Irrigation.
Cost of equipment and operation of same,
with tables of efficiency.
By O. L. Waller. Aug. 1916 (out of print).
6. Fuel Economy in Domestic Heating and Cooking.
Fuel Tables, heating equipment and care of same.
By B. L. Steele. Dec. 1917.
7. Thawing Frozen Water Pipes Electrically.
Method of Thawing and list of equipment needed.
By H. J. Dana. Oct. 1921.
8. The Use of Ropes and Tackle.
Illustrations of application to different jobs.
By H. J. Dana and W. A. Pearl. Mar. 1922.
9. Well and Spring Protection.
By M. K. Snyder. (In preparation).
10. Water Purification for the Country Home.
By M. K. Snyder. (In preparation).
11. Farm Water Systems.
By M. K. Snyder and H. J. Dana. (In preparation).
12. Commercial and Economic Efficiency of Commercial Pipe Coverings.
By H. J. Dana. (In preparation).
[Illustration: Mechanics Arts Building--Headquarters Mechanical
Engineering Experiment Station]
=_The State College of Washington_=
Founded and Maintained by the National Government and the
State of Washington
College of Agriculture and Experiment Station
Farm Crops, Soils, Animal Husbandry, Dairy Husbandry, Poultry
Husbandry, Horticulture, Landscape Gardening, Forestry, Farm
Management, Plant Pathology, Agricultural Engineering.
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Architecture, Civil Engineering, Electrical Engineering,
Hydro-Electrical Engineering, Mathematics, Mechanical Engineering,
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Economic Science and History, Foreign Languages.
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Geology, Mining, Metallurgy, Metallography.
School of Education
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Music, Oral Expression, Dramatic Art, Fine Arts.
School of Pharmacy
The Graduate School
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The Summer Session (six weeks)
Short Courses from one to twelve weeks, beginning early in January,
are offered in Farming, Gas Tractors, Automobiles, Home Economics,
and Mining.
The Department of Elementary Science offers three-year vocational
courses in agriculture, horticulture, mechanic and industrial arts,
commerce, and domestic economy, from which young men and
women can, if they desire, be admitted to the Freshman class of
the College.
The College Year Begins Monday, September 18, 1922.
Address all inquiries to:
THE REGISTRAR, Pullman, Wash.
Extension Service, under the Smith-Lever Act, is in charge of the
demonstration and correspondence work in Agriculture, Home
Economics, Boys and Girls Club Work, and County Work.
Address: The Director.
The Division of General College Extension gives correspondence
courses, organizes extension classes, supplies lectures and
educational motion picture films.
Address: Director.
MANY DEPARTMENTS PUBLISH SPECIAL BOOKLETS
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