The Mechanical Handling and Storing of Material

 7° THE MECHANICAL HANDLING OF MATERIAL The horse power consumed by these conveyors cannot be given, as they are mostly used on a downward gradient, when they may even produce power. If on a'level or is about the same Fig. 88. Retarding Cable Trough Conveyor at the Mines of the Logan Consolidated Coal and Coke Co., Matewan, W. Va., U.S.A. Jeffrey slightly downward incline the power consumed the same as for ordinary scraper conveyors of capacity. Cable Trough Conveyor of the Manufacturing Co.—Cable trough conveyors may also be used as inclined retarding conveyors for lowering coal from higher to lower levels, work which, as a rule, is performed by means of a system of colliery tubs. The plant here illustrated (Fig. 88) is of special interest, because it replapes the old tram system, and has several points of advantage in its favour. Its first cost is less, while it is simple and requires practically no power or attendance. In the plant illustrated the coal is discharged over the ordinary tippler at the head into a hopper, from which it is fed on to the conveyor, which in this case is a Jeffrey wire rope with disc-shaped attachments running over special sheaves at the terminals and operating in a V-shaped trough. When the conveyor is loaded and working with a continuous feed, it acts as a retarder in keeping the coal from running away by itself. A small motor is generally necessary to start the conveyor, while when running with a full feed a brake is used to keep it in check. By this system coal may be carried to the shoots or cars below with but little breakage, and at the rate of 100 to 140 tons per hour. In the plant illus- trated the distance from the upper to the lower level is 500 ft. Formerly colliery tubs were used, but as this MECHANICAL HANDLING Fig. 89. General View of Meat Conveyor.