CABLEWAY. A hoisting and conveying de vice, employing a suspended cable as a trackway, and differing frolic ropeways (q.•.), which can not be used for hoisting, being limited to the sole function of conveying. While rope ways date hack to the early part of the Nineteenth Cen tury. the cableway had its origin practically in an inclined hoisting and conveying device in vented about ISM, and still extensively used in the slate-quarries of Vermont and Pennsylvania. These first cableways consisted of a winding engine with one drum, a suspended cable, a cable carriage traveling on the suspended cable, a fall block adapted to rise and fall from the cable carriage, and a hoisting-rope operating the same. The suspended cable or track cable of these cableways ran on an incline from the top of a trestle tower to a ground anchor. Horizontal cableways of short span were used in the con struction of the piers of the Saint Louis Bridge. As the span of cableways became greater the necessity arose of supporting the hoisting-rope or fall rope between the tower and the carriage. The devices for supporting the fall-rope are termed fall-rope carriers. One of the earliest arrangements of this sort consisted of a series of blocks, at the upper end of each of which was a sheave riding on the track cable and through the lower end of which was a hole for the fall rope. These blocks were connected by a light chain, one end of which was also connected to the head tower and the otber end to the carriage; as the carriage moved out from the head tower it strung the blocks at intervals along the track cable, and as the fall rope passed through a hole in each block it was supported and prevented from sagging unduly: as the carriage returned to the tower it gathered up the blocks into a hunch at the tower. This system of fall-rope carriers was objectionable chiefly because of the weight of the connecting chain. and although it is still used in its essential features, the heavy chains have been replaced by light steel wire con nections and other important reductions made in the weight.
A second form of fall-rope carrier arrangement much used may be described as follows: Anauxil iary rope is suspended above the main cable and held in a parallel position to the main cable by passing under wheels in the cable-carriage. On this rope a series of buttons are secured whose diameter increases with the distance from the head tower: slots in the heads of the carriers, corresponding to the diameter of the buttons, al each of the carriers in passing out from the head tower to be stopped at its proper button. The carriage distributes and picks lip the car riers in its forward and return journeys.
Described briefly, the modern cableway consists of a heavy steel cable called a track cable or main cable, suspended with a slight sag between the tops of two timber towers so placed that the main cable spans the quarry, canal, foundation pit, or other work on which it is to be used. On this
main cable a carriage runs, being drawn back and forth by an endless rope passing around suitable sheaves at the towe•-tops and operated by a spe cial hoisting-engine mounted at the bottom of one of the towers. from the same engine a hoisting or fall rope passes to the top of the engine tower and thence through the fall-rope carriers to the carriage, where it eonneets with a fall block by means of which the load is hoisted. The fall-rope carriers have already been described. The operation of the cableway is as follows: The carriage is run out on the main cable to a point directly over the place from which the load is to be picked up: the fall block is then lowered by running out the fall rope, and when it reaches the ground the load is attached; the fall rope is then hauled in, raising the load high enough to clear obstructions, and, finally. the carriage is hauled to the point of the main cable directly over the place where the load is to be deposited, and the fall rope then runs out, lowering the load “3 the ground. In work sueh as canal excava tion, for example, where the purpose is simply to hoist the load of earth or rock, convey it to the bank, and deposit it as quickly as the discharge of the load is effected in mid-air by special mechanism. In other eases the towers carrying the cables are mounted on wheels so that the whole cableway plant may be moved easily from one position to another.
The traveling cableway is particularly adapted to canal work, where the towers are placed on opposite banks. with the cables spanning the channel, and are moved along the banks as the excavation progresses. Cableways are built of varying capacities and lengths of span, depending in each ease upon the work which they are re quired to perform. They are sometimes, though seldom, used for passenger traffic. Mr. Spencer Miller, the inventor of the Miller cableway, places the following limitations on the practical applications of cableways: Span (single), 2000 feet ; load, 25 tons; speed of travel, 1800 feet per minute; and speed of hoist, 900 feet per minute. The average practice. however, is about as fol lows: Span, (100 to 1200 feet; loads, 3 to 7 tons; speed of travel, 500 to 1000 feet per minute; speed of hoist. 150 to 300 feet per minute. The files of the engineering journals and the excellent printed matter prepared by manufacturers of cableways should be consulted for further information on this subject.