Ropeways and Cableways

The Double Ropeway.

This consists, as already stated, of an independent rail rope and a separate continuous hauling rope disposed parallel to one another. The carrier runs on the sta tionary rope which is fitted with running heads having grooved steel wheels. The load is borne by a hanger pivoted from the carrier and conveyed along the rail rope by the endless hauling rope at an average speed of 4 to 6 m. per hour. A great variety of clips have been introduced for the purpose of coupling the carriers to the hauling rope, but these are automatically connected and disconnected at the shunt rails of the terminals. The hauling is operated by driving gear at one end and controlled at the other by tightening gear, just as in the single rope system. The rail ropes of a double ropeway are sectionalized every 2 or 3 m., whilst the longest section for a hauling rope is about 9 miles. Such ropeways will support single loads of 6 cwt. to a ton or more.

Motive Power.

The power required for a ropeway will vary according to conditions but is relatively moderate. If the aggre gate down gradients exceed the up gradients the power consump tion may be nil or the ropeway may even produce power which may be harnessed to drive other machines; or it may have to be absorbed by some form of brake device. In a Japanese ropeway 1,80o yd. in length, which runs mostly at an incline of 1 in 11, the force generated is absorbed by a hydraulic brake, the revolv ing fan of which drives the water against fixed vanes which repel and heat it. In this way 5o h.p. is absorbed and the speed brought under the control of a hand brake.

The initial outlay for a ropeway is usually moderate, though of course it varies according to topographical conditions.

Ropeways are largely independent of weather conditions and their working need not be interrupted even by heavy snowfalls. Their construction is very simple and there is little to get out of order. Sound workmanship and good material will ensure a rela tively long life. The groundspaceoccupiedby ropeway installations, beyond that occupied by the terminals is exceedingly small and is confined to the emplacements of the standards which, in modern ropeways are few and far between.

Aerial Cableways.

The aerial cableway is a development of the ropeway and is a conveyor capable of hoisting and dumping at any desired point. The load is carried along a track consisting of a single span of suspended cable which covers a comparatively short distance as rope haulage goes. The trackway may either run in a more or less horizontal direction, i.e., the terminals may be on the same level, or it may be inclined at such an angle that the load will descend by gravity. The trackway or rail rope rests

upon saddles of hard wood or iron on the tops of terminal sup ports usually known as towers, which may likewise be constructed of wood or iron, and if the exigencies of the work render it de sirable they can be mounted on trolleys and rails, in which case the cableway is rendered portable and can be moved about, which is sometimes a great advantage in connection with dock and har bour work. The motive power may be either steam, gas, or elec tricity. The motor is situated in what is termed the head tower, which is occasionally a little higher than the tail tower. The span between the two towers sometimes extends to 2,000 ft., but this is exceptional. Objects weighing as much as 8 tons are handled by such devices. The load, which may be carried in a skip or tray, is borne by an apparatus called the carrier, which is a modification of a running head, consisting of pulleys and blocks and running along the main cable or trackway. This carrier is also fitted with pulleys or guides for the dump line, and is drawn along the main cable by an endless hauling rope which passes from the carrier over the head tower and is wound several times around the drum of the winding engine to secure frictional hold, then back over the head tower to the tail tower, returning to the rear end of the carrier. The hoisting rope passes from the engine to the fall block for raising the load. The dump line comes from the other side of the winding engine drum and passes to a smaller block attached to the rear end of the skip or tray. The whole weight of the skip is borne by the hoisting rope, while the dump line comes in slack but at the same rate of speed. Whenever it is desired to dump the load the dump line is shifted to a section of the drum having a slightly larger diameter, and being thus drawn in at a higher rate of speed the load is discharged. The engine is then reversed and the carriage brought back for the next load.

This is, in outline, the mode of operating all cableways. These appliances have rendered great service as labour-savers in navvy ing, mining and quarrying work; for instance in placer-mining cableways have been found very useful when fitted with a self filling drag-bucket which will take the place of a great number of hands. Cableways can be worked at a great speed ; a good mean speed, however, would be 50o to 75o ft. per min. for conveying, and 200 to 30o ft. per min. for hoisting. See also TELPHERAGE. BIBLIOGRAPHY.-G. F. Zimmer, Mechanical Handling and Storing of Material (1916) ; H. Blyth, Modern Telpherage and Ropeways (1926).

(G. F. Z.)