Chapter II: Part 2

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.

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.

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.

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.

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.

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 97, 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.

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.

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.

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.

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.

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.

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.

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).

=_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.

College of Mechanic Arts and Engineering

Architecture, Civil Engineering, Electrical Engineering,
Hydro-Electrical Engineering, Mathematics, Mechanical Engineering,
Physics.

College of Sciences and Arts
Chemistry, Chemical Engineering, Botany, Zoology, English,
Economic Science and History, Foreign Languages.

College of Home Economics

College of Veterinary Science

School of Mines and Geology

Geology, Mining, Metallurgy, Metallography.

School of Education

School of Music and Fine Arts
Music, Oral Expression, Dramatic Art, Fine Arts.

School of Pharmacy

The Graduate School

Department of Military Science and Tactics

Department of Physical Education and Athletics

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