The Mechanical Handling and Storing of Material

CONVEYING BY GRAVITY 201 conveyors cost only ,£500. Hence it was easy to understand the satisfaction experienced by the purchasers. Automatic Lowerers.—A vertical swing tray elevator is often used successfully for lowering through several floors, as well as for elevating. When required for lowering only, a belt drive is convenient for regulating the rate of lowering and acting as a brake, although the consumption of power is practically nil. Where no motor or other source of power is available, however, an automatic brake, controlled by a governor, may be fitted instead, and the lowering done entirely by gravity. The main objection is that the swing trays will seldom come to rest in the most suitable position for loading, a fault from which positively driven lowerers are free. Fig. 269 shows a modification of an ordinary inclined shoot, in which the rate of descent of the packages is automatically controlled by means of an endless chain, fitted with skidders, and a centrifugal governor geared to the top shaft-. These inclined automatic lowerers are sometimes hinged at the top, although usually fixed. Other examples of conveying' by gravity may be found in the chapters on “ Endless Chain and Rope Haulage,” “Ropeways,” and “Cableways.'’