The Mechanical Handling and Storing of Material

CHAPTER XXIII ENDLESS ROPE AND CHAIN HAULAGE The principle of this system consists of a rail track on which the trucks are conveyed by means of an endless hauling rope, or sometimes a chain, to which they can be attached and detached at certain fixed points without the necessity of stopping the rope, thus keeping up a constant supply of trucks to or from the workings. The rope or chain generally engages automatically with the tubs or trucks as soon as it comes within reach of them, but disengages as soon as the tubs have reached the higher level where they come outside the reach of the chain. The empty tubs are returned on the second pair of rails and are lowered in a similar manner. Although endless rope and chain haulage is mostly used for short distances, it is also equally applicable for greater lengths of journey, and endless ropes or chains are frequently used for haulage over considerable distances. The difficulty about such installations lies chiefly in carrying the rope over uneven ground \ the change of level, of course, necessitates a change in the direction of the rope, and also in deviations from the straight line, where sharp curves have to be turned. The power can be supplied by a stationary engine or electro-motor, either direct or transmitted, or by an ordinary clutch and drum arrangement attached to a line shaft, or finally by the gravity of the material. The rails are laid on the ground, except where it is essential that the ground space should remain unobstructed, and in such cases they are raised on more or less lofty structures. Endless Chain Haulage.—Appliances of this description running up inclines, upon which the trucks are hauled by chains, are principally used in collieries and other mines, and very rarely for long distances. They are, however, often installed for the purpose of raising the trucks to a sufficient height for them to run down again for a longer distance on a gentle incline by gravity. They are usually termed tub-hauls, or creepers, and consist of an endless chain fitted with claws at intervals of about 12 ft. and having tension adjustment, a pair of chain wheels, main and back shafts, countershaft, driving gear, and channel or angle iron guides. The chains generally used are of the “ Ley ” or the “ Gaston ” type. Chain Haulage for Hand Carts.—An endless chain with suitable attachments is used on inclines to assist the labourers to ascend ramps by the chains engaging with the axles of their hand carts. Such an appliance is in use at the Pequonnock Dock at Bridgeport, Connecticut, U.S.A., and was built by the Remo Inclined Truck Elevator Co., of New York. The endless chain of this device runs in a well-lubricated channel iron 4 in. wide. Fig. 345 shows the arrangement in use, and it will be seen from this illustration that only the upper strand of the chain projects above the floor level of the ramp. The speed of the chain is about 18 in. per second, so that 960 trucks may be raised per hour. A 5 H.P. electro-motor furnishes the driving power. The installation is used for loading ships with miscellaneous goods, and the incline of the ramp varies with the tide. 2-15