Rope, a large cord, formed by twisting together a collection of vegetable or animal fibres or metallic wires. The smaller cords are called twines and lines, and all are included under the general name of cordage. The invention of ropes or cordage dates from the earliest times. The first ropes were probably made of the fibres of the inner bark of some kinds of trees or of grasses, and of thongs from the hides of animals. There are sculptures among the relics of the ancient Egyptians illustrating the manner of making ropes more than 4,000 years ago, and their most ancient records contain representations of well made ropes capable of transmitting the enormous power required in transporting their colossal statues and huge blocks of stone. It appears that they made use of flax, and also of the fibres of the date tree. The most celebrated ropes known to history are the cables used in the construction of the bridges of boats on which the army of Xerxes crossed the Hellespont (Herodotus, vii. 36). There were two bridges, and six cables were assigned to each bridge. Two of the cables were of white flax, while four were of papyrus. Both sets of cables were of the same size and quality, but the flaxen were the heavier, weighing not less than a talent the cubit.
If we assume the talent to be equal to about 56 lbs. and the cubit to be 22 in., the cables must have measured about 28 in. in circumference. The largest hemp cables ever made in the United States were 24 in. in circumference. The ancient Peruvians twisted together the strong fibres of. the maguey plant, forming them into cables as large as a man's body, used in the construction of the suspension bridges by which their paved highways were carried over ravines and rivers. Many rude savages, especially among the islands of the Pacific and Indian oceans, are celebrated for making beautiful cordage. In modern times, among civilized nations, the principal materials for ropes are hemp, flax, manila hemp, plantain leaf, jute, and metallic wire. Rope making was regarded as a matter of great importance to the early American colonists, and efforts were made to introduce it with other branches of manufacture in Virginia, where the climate and soil were found to be favorable to the cultivation of hemp and flax; but the culture was neglected for that of tobacco.
In New England it was regarded with more interest; crops were raised from seeds of the plant received in Salem in 1629, and in 1641 the general court of Massachusetts directed attention to the wild hemp which grew in the province, and was used by the Indians for making nets, mats, and lines. In the same year the manufacture of cordage was begun in Boston by John Harrison, and in 1662 in Charlestown by John Heyman. In Connecticut the government at Hartford in 1642 gave direction for the sowing of hemp and "for the better furnishing of the river with cordage toward the rigging of ships." In the " History of Pennsylvania and West New Jersey," by Gabriel Thomas (London, 1698), there is a notice of large ropewalks in Philadelphia, several of which were owned by Joseph Wilcox. - Rope Making.. In the United States there are four principal kinds of rope in common use: hemp rope, made of the fibres of the cannabis sativa or hemp plant; manila rope, made of the fibres obtained from the leaves of the musa textilis, or wild plantain; hide rope, made of long strips of green oxhide; and wire rope. The best hemp for rope making comes from Russia, the Riga Rein being the brand preferred. One reason assigned for the superior quality of Russian hemp is the practice of water-rotting it.
American hemp is dew-rotted. Manila hemp comes chiefly from the Philippine islands, taking its name from Manila, the principal town. The best brand is the Cebu, named from the island on which it is grown; Quilot is another good brand; the Leyte is of inferior quality, while Lupis is very fine, white and silky, and of too high a grade for rope making. Hemp purchased for government use is first tested by inspection. It should present a fair appearance to the eye, be clear, dry, and free from a musty smell. If the appearance is satisfactory, a sample is selected at random from the cargo or lot and sent to the ropewalk to be more thoroughly examined. A lot containing about 140 lbs. is given to the hackler, and divided into two parts of 70 lbs. each. One part is hackled sufficiently fine for the smallest yarn or that used for bolt rope; the other part for larger yarn or the size used for cables. After hackling the hemp is again weighed to ascertain the quantity of dressed hemp produced and the percentage of tow and waste taken from it; this should not exceed 20 per cent. The dressed hemp is then passed through the spreaders and drawing machine and taken to the spinners, where it is spun into yarns of 20 s. and 40 s.
The yarns are then weighed to ascertain the waste in spinning and the quantity of yarn produced. Half of the yarn is taken to the "laying" ground, where it is laid up into rope 1 3/4 in. in circumference. The other half is' first tarred and then laid up into ropes of each sized yarn, making in all four ropes: tarred and untarred of 20 s., tarred and untarred of 40 s. The ropes are then carefully weighed to ascertain the weight per fathom and the percentage of tar absorbed. The strength of the rope is then found by securing short pieces, cut in lengths of 6 ft. for convenience, in a testing machine. The dry or white rope should sustain a strain of 4,200 lbs.; the tarred, 3,200 lbs. The weight should be from .5 to .6 of a pound per fathom for the dry, and from .6 to .7 for the tarred. The hemp having passed the required inspection, the first step in the process of preparing it for the manufacture of rope is to hackle or hatchel it. The hackle or hatchel consists of a strong board in which are inserted long steel prongs sharply pointed and polished. The hackler, taking a wisp of hemp in his hand by one end, throws the other over the prongs and combs it out, cleaning it of dirt and tow and straightening out the fibres.
Having combed it out to where it was held, he reverses the wisp and combs out the other end. Much of the tow that is thus combed out is again hackled and spun into yarn for inferior kinds of rope. After hackling, the hemp is passed through the spreading and drawing machines, care being taken to regulate the supply so that the "sliver" or "roping" for the spinning machines shall be of suitable size; if too small, the yarn is liable to break in spinning; if too large, the spinning machine will clog up. The first of the " preparation machines " is the " spreader," which is in fact a finer method of hackling. Its office is to comb out and straighten the fibres. The largest one now in use at the government ropewalk is intended especially for the very long manila fibres, being 17 ft. long by 6 ft. wide. It will run off a bale of 270 lbs. of manila in nine minutes, or 60 bales in 10 working hours, taking it direct from the bale, or rather with the intermediate step of oiling. From this machine the manila passes to a smaller and finer one, where the fibres in the sliver are still further straightened, and the sliver itself evened and drawn down.
Thence it passes to a third, called the drawing frame, a machine built on precisely the same principle, but with one chain instead of two and with finer teeth, through which it is usual to pass it twice, the sliver at each successive step being reduced in volume, straightened and evened more thoroughly, to prepare it for the spinners. The course of preparation for the hemp is the same, though if the machines are properly geared and the draught correct, it will be found sufficient to run the hemp through the spreader only once, and through the drawing frame twice. From the preparation machines the hemp passes to the spinner, where it is spun into yarn and at the same time wound on a bobbin containing about 300 fathoms. In making rope, a three-inch rope is the key to the sizing of the yarn. Yarns of 20 s. are of such a size as to require 20 to make one strand for a three-inch rope, or to fill a tube half an inch in diameter; yarns of 26 s. require 26 threads to fill the same sized tube, and so on. If manila or white rope is to be made, the bobbins pass from the spinning room to the laying ground; if tarred rope, the next step is tarring.
The bobbins containing the yarn are taken from the spinners to the tar house, where they are placed on horizontal rods contained in a framework conveniently arranged with reference to the tar box; 160 bobbins is about the capacity of the frame. The end of each yarn is passed through a board or gauge perforated with holes sufficiently large to allow the yarns to run freely, thence through three or more similar gauges so arranged over the tar box that when all is ready they can be lowered to the bottom. The tar box should be about 30 ft. long, 2 ft. wide, and 3 ft. deep. Steam, admitted to copper steam pipes at the bottom, keeps the tar at the desired temperature. A thermometer is so arranged that the bulb is always immersed in the tar, which, after the evaporation of the watery parts, should be maintained at 220° F., and should never be allowed to get below 212° while tarring. The machinery is so regulated that the yarn is drawn through the tar at the rate of about 15 ft. a minute. After leaving the tar the yarn passes between two metal rollers attached to the further end of the box, the upper one carrying a heavy weight to press out the superfluous tar. Thence the yarn passes over a drum to cool it, when each separate yarn is led to, and evenly wound upon, its appropriate bobbin.
After tarring, the yarn should before use be allowed a few hours to harden, and attach more closely to the fibre. Should it be made into rope immediately after tarring, the tar would press through to the surface, giving it an unsightly appearance, and decay would soon set in at the centre of the rope. The passing of the yarn through the boiling hot tar at a certain rate is necessary to enable it to take up a sufficient quantity of tar, the rollers pressing out and returning to the trough the superfluity. Enough of the tar is retained in the yarn to coat over the fibre and preserve it from decay. Tarring protects cordage from injury by exposure to rain and immersion in water; but it makes its fibre rigid and impairs its strength. This fact has long been known, and many efforts have been made, hitherto unsuccessful, to improve the tar or find a substitute for it. It has been shown by experiment: 1, that white cordage in continual service is one third more durable than tarred; 2, that it retains its strength much longer when kept in store; 3, that it resists the ordinary injuries of the weather one fourth longer. Manila is judged by inspection, and is not tested by strain.
It is neither hackled nor tarred, with the single exception of the case of outside yarns of large hawsers, which are tarred. Having a harsher fibre, it is oiled before running through the preparation machines, the oil softening the fibre and relieving the machinery of much of the work it would otherwise have to perform. Care must be exercised, however, not to use too much oil, lest the manila turn yellow and the yarn become gummy. It should be well prepared before being taken to the spinners, as all the work required of them should be to put the twist into the yarn and wind it on the bobbin. The yarn having been spun of the size desired and wound up on bobbins, it is taken to the laying ground, where each bobbin is placed on an iron rod in frames convenient for reeling off in the process of forming the strands. The frames hold from 200 to 300 bobbins, one, two, or three frames being used, according to the size of the rope to be made. The number of yarns required for a strand are passed each through its proper hole in a metallic plate, brought together through a closely fitting iron tube in the tube board, and attached to the proper hook in the "former," a machine so called because it forms and equalizes the twist of the strand. The holes in the plate are made on concentric circles.
The tube inserted in the tube board opposite the centre of the plate is so made as to compress the yarns of each strand into a solid mass as they are drawn through and twisted into a strand. Each strand has a separate plate and tube. The "former" is drawn down the ropewalk by steam power, and is so constructed with "whelps" on drums, and gears, that at whatever rate it may travel the proper rotary motion is always given to the spindle to twist the yarns into strands. Power is applied to the former by means of an endless rope passing from one end of the walk to the other. The tube board is heated during cold weather by steam pipes, thus warming the tubes and keeping the tarred yarns soft and pliable. The next step is to put the strands into a rope, termed "closing." Two machines are used for this purpose, one at each end of the walk. The one at the lower end is termed a layer, as it lays up or closes the rope. The upper machine is stationary, and is used to keep the proper twist in the strand while laying. The strands are attached to the hooks of the machines separately. The machines being put in motion, the strands are brought to a proper degree of tension by means of a press attached to the lower or laying machine.
As the turn or twist is put into the strands they shorten in length; this is termed "hardening." After the strands become hard, they are placed on one hook of the laying machine, but kept separate in front by the insertion of the "top," a wooden cone with grooves cut in its surface of a size to admit the strands. The top has attached to it "rope tails," which are applied to the rope during the process of closing for the purpose of creating friction. The more turns taken with the tails, the more twist is given the rope, and consequently the harder it becomes. The machines are so geared that the lower one makes two revolutions to one of the upper; that is to say, it requires two revolutions of the rope to one of the strands, the additional revolution being requisite to overcome the friction caused by the top, tails, and stake heads, which are placed at every five fathoms to support the strands and the rope. To obviate the necessity for long ropewalks, a machine has been devised for reeling up the rope as it is made. In private establishments rope is made on these layers as large as 10-inch. They are known as " Woodworth's laying machines." The government ropewalk, in Boston, Mass., is 1,360 ft. long.
Rope can be made there, without resorting to unusual means, 170 fathoms (1,020 ft.) in length. - The Quality of Hope. The strength of rope depends mainly upon the quality of the material of which it is made. Hemp fibres vary from 3 to 3 1/2 ft. in length; the manila averages over 6 ft., and is often found as long as 12 ft. To make rope, these fibres must be overlapped among themselves, and compressed so as not to be drawn apart. This compression is obtained by twisting, the fibres being continuously drawn out from a bundle in quantities sufficient to produce the thread or yarn, as already described. It is customary to spin the yarn right-handed. Yarns are then combined by twisting, and form a strand which becomes left-handed, the twist being reversed at each successive step. Three or more strands are then combined by twisting, forming a rope, which in its turn becomes right-handed; and three or more ropes twisted together form a left-handed cable of nine strands. The proper twist to give the yarn averages about one turn and a half to the inch. The degree of twist to the rope may be determined by constructing a right-angled triangle, the base of which is the circumference and the height the length of one turn of the strand measured parallel to the axis.
The difference between this height and the hypothenuse is the quantity by which the rope is twisted. The rope maker's rule for a three-strand rope is to have one turn to as many inches as are contained in the circumference of the rope. A three-inch rope, for example, should have one turn in three inches, measured on a line paralled to its axis. Three-stranded right-hand rope is commonly called plain laid. Four-stranded rope is made with a smaller rope in its centre, called a heart. If in making a rope the twist of the strands, instead of being reversed, is made the same as the yarn, right-handed, then the rope itself becomes left-handed, commonly called backhanded rope. It is more pliable but not as strong as the plain laid. The continual twisting necessary to bind the fibres into a permanent bundle "shortens in" its length. Plain-laid rope takes up 46 fathoms of the original yarn for every 100 fathoms of rope. It requires 2,488.8 lbs. of hemp to produce one ton of rope of 20-thread yarn, or about 11 per cent. more hemp than yarn.
The size of rope is designated by its circumference; thus a six-inch rope measures six inches in circumference. - The Strength of Rope. The utmost strength of good hemp rope was formerly supposed to be about 6,400 lbs. to the square inch; but 9,200 lbs. is nearer the average strength. Tarred hemp ropes of 3 1/2 and 3 in., made at the government ropewalk, on a trial, required respectively a strain of 14,622 and 10,725 lbs. to break them, and therefore their utmost strength per square inch was 15,000 and 14,975 lbs., considerably more than double the strength ordinarily assigned to good hemp rope. These ropes were not made expressly for the trial. Rope stretches from one seventh to one fifth, and its diameter is diminished from one seventh to one fourth before breaking. A rough but safe rule for finding the breaking strain in tons of plain-laid rope is to square half the circumference. Thus, in a six-inch rope, the square of three is equal to nine tons, the table giving ten. A fore-handed rope is 25 per cent. stronger than one laid back-handed. A plain-laid rope is stronger than a cable-laid by about one sixth, owing to its having less twist. Four-stranded rope is weaker than three, about one thirteenth of its yarns going into heart.
The heart forms the centre round which the strands circle. On applying a breaking strain, the heart breaks first, when an unequal strain is brought on the strands, and they part in detail. The strength of manila rope is about one third less than that made of hemp. Repeated experiments show that there is a great variation in the strength of rope cut from the same coil, amounting sometimes in large ropes to several hundred pounds. - Hide Rope is made of strips of green oxhide. The hide is stretched on frames, and when partially dry is placed on a revolving table, the ragged edges stripped off, and the entire hide cut into one yarn or strip by a knife placed for the purpose, the table and knife being worked by machinery. Two or more strips are united by a rope yarn. These strips are then reeled upon bobbins placed in the frames on the laying ground, and without giving any twist to the hide yarn they are laid up into strands, etc., just as in making hemp rope. - Wire Rope. The best charcoal iron wire or steel is used. The first step in the process of manufacture is to wind the wires on bobbins, the ends of separate pieces of wire being joined by brazing or twisting.
Having seven bobbins- filled, six are put in a small machine, and one in a reel stand conveniently situated for leading the wire down through a fair leader and thence up through the vertical shaft; this single wire is for the heart, around which are wrapped the six wires placed on the horizontal disk. As the disk revolves the six bobbins turn on their own centres in an opposite direction, so as to avoid twisting the wires. The proper tension on the wire is maintained by friction bands attached to the bobbins. The six wires with the single wire in the centre are for the heart of the strands. Having formed the heart (which is wound up on a bobbin as it is made), it is placed in a reel stand as before. On the machine to form the strand are twelve bobbins filled with wire; the machinery is put in motion, the seven-wire heart drawn up the vertical shaft, and the twelve wires wrapped about it. As the strand is formed it is wound up on a bobbin, which at each successive step increases in size. When the required length of strand is on the bobbin, known by a register fitted for the purpose, the machinery is stopped, the strand cut, the full bobbin removed, and an empty one put in its place.
When seven bobbins are filled with strands, six are placed on another machine, a bobbin containing the heart being placed in the rear; the machinery is put in motion, the heart drawn through, and the six strands wrapped about it. The six strands of 19 wires each contain 114 wires, to which the 19 wires in the heart must be added, giving 133 wires to a rope. There are six wire-rope machines, made by Jackson and Wat-kins, London, and now in operation in the government ropewalk, known as A, the largest, B, C, D, E, and F, the smallest. A and B machines are for forming the rope, and are placed in a horizontal position; the others are for making strands and hearts, and are vertical. Wire hearts are used for bridge cables, etc. Hemp hearts are used instead of wire for standing rigging, as it makes the rope more pliable. The amount of twist to give to the strand and to the rope itself varies with the size, and requires much care and judgment on the part of the manufacturer. The numbers assigned to the various sizes of wires run from No. 22, the smallest, to No. 0, the largest. The heart of the strand must be of the same size as the single wire, and the heart of the rope the size of a strand. The softer hemp permits the inside wires to become imbedded, as in the preceding figure.
The foregoing description of wire-rope making applies to the fine wire of 133 to a rope. A stiffer kind of rope is made of coarser wire having seven to a strand and 49 to the rope. The sizing of the wire will be understood from the annexed diagram. Wire rope is applicable to all the general purposes of ordinary rope, except running rigging on board ship, and has many advantages over that made of hemp or hide. Its first cost is less than that of hemp rope of equal strength, the only correct mode of comparison; and, as a general rule, it will last three times longer than hemp rope. Its utility and economy have been fully demonstrated on inclined planes and slopes, to which purposes its application has become very general, and for hoisting, in warehouses, machine shops, founderies, mines, etc. It has also been substituted with perfect success for staying or guying derricks, suspension bridges, cranes, shears, masts, chimneys, etc., and for these purposes, not being affected by the weather, it never requires resetting, saving thereby a large amount of labor.
For ferries, tow lines, tiller ropes, suspending gasometers, lightning conductors on vessels or houses, hauling logs in saw mills, for transmitting power to a distance in place of belting, and for all other purposes of this kind, where safety, durability, and economy are necessary, wire rope is far superior. Wire rope must not be coiled or uncoiled like hemp rope. When mounted on a reel, the latter should be turned on a spindle to pay off the rope. When in a coil without reel, roll it over the ground like a wheel, and run off the rope in that way. All untwisting or kinking must be avoided. To preserve wire rope, apply raw linseed oil with a piece of sheepskin, wool inside, or mix the oil with equal parts of Spanish brown or lampblack. To preserve wire rope under water or under ground, take mineral or vegetable tar, add a bushel of fresh slacked lime to a barrel of tar (to neutralize the acid), and boil it well, then saturate the rope with the boiling tar. The grooves of cast-iron pulleys and sheaves should be filled with well seasoned blocks of hard wood, set on end, to be renewed when worn out; this end wood will save the rope and increase adhesion. The small pulleys or rollers which support the ropes on inclined planes should be constructed on the same plan.
Steel wire is to a certain extent taking the place of iron wire in ropes, where it is a special object to combine lightness and strength.
Wire Rope with Hemp Heart.
Wire Rope with Wire Heart.