CHAIN (OF. chains, Fr. ehaine, Dutch kete», ket t ing, Al LG. kcdenc, kede, Ger. Ket te, 0111% eliciting, from Lat. catcau, chain). A series of flexibly connected links of metal or other material designed for ornament or to sere the purpose of cord, rope, or cables. Chains are evidently of very ancient origin. Nearly all old writers speak of their use, and they are re peatedly referred to in the Bible. Remnants of chains of Itoman manufacture are preserved in museums and they show a variety of link forma tions and excellent workmanship. The uses made of chains by the ancients were few and unimpor tant compared with the multitude of uses to Which they are applied at present. They served for ornament, as emblems of investiture and badges of office, and as fetters for captors, but cordage was employed for all other purposes to which chains are now extensively applied. Chairs are now employed as ornaments and for the various purposes of a band, cord, rope, or cable in hoisting and hauling operations, in transmitting power, and in connecting, confining, and restraining objects. The modern chain of commerce, therefore, embraces chains in size and material, from the thread-like article of pure gold to the ship's cable of iron, each link of which weighs from 100 to 200 pounds. and will withstand a breaking strain of many tons.
Structurally, chains may lie somewhat roughly divided into those whose separate links are each composed of a single piece of metal and those whose links are (ma made up of several sepa rate pieces of metal. The ordinary oval link hoisting chain is an example of the first class, while the bicycle chain exemplifies quite well the second class. Chains may be also divided into hand-made and ma•hine-made chains, hut the division is not a sharp one. It is also common practice to define chains by special names based upon the form of the link, as stud chains, open link chains, and twisted-link chains; or upon the use to which the chain is put, as crane chain, chain cable, and bicycle chains, or upon the mane of the inventor or some other real or apparent peculiarity. This form of definition so fir as it
is practiced is neither nor systeniatie.
Chains are made in a variety of ways depend ing upon the material used, the size, the link formation. the purpose to which the article is to be put, etc. Chains for cranes, ship's cables, dredges, etc- are always hand-made. that is, each link is welded by hand and often is both formed and welded by hand from rolled bar iron. The various stages of operation are substantially as follows: The workman, taking a round bar or rod of iron of the proper diameter, heats it in a forge and then by means of a chisel cuts off a piece long enough to form a single link. This piece is again heated and then bent by hammer blows around a suitably shaped nose until it has a U shape. The U-shaped piece is then hooked into the last completed link of the chain and the unconnected ends thrust again into the forge to receive a welding heat. The final process is to weld together the unconnected ends around a nose of suitable shape and to bring the link to perfect form and dimnsions. In chains made as just described, the weld is usually at the end of the link. When making large ship's cables the chain-maker often uses presses for bending the bars into link form and the bending is so done as to bring the weld at the side of the link. The welding may also be done by power hammers in making very large cables.
In making stud elmins or twisted-link chains the only change in the mode of procedure de scribed above is the introduction of the ne•es sary additional operation of inserting the brace or stud or of twisting the link, just previous to closing tip the ends of the U-pieve for the final welding operation. A stud chain is an open-link chain, in each link of which a transverse stud or brace is played to prevent the sides of the links from closing up or drawing together when the chain is subjected to a heavy pull or load. Twisted links are of great advantage when a chain has to be wound on a drum, since they lie flat and smooth on the drum.