The Mechanical Handling and Storing of Material

ELEVATORS FOR LARGE OBJECTS 31 but only two buckets instead of four are discharged with each revolution of the terminal. Rigid Arm Elevators.—The type of continuous elevator shown in Figs. 28 and 29 is extensively applied to the handling of bags, bundles, barrels, and rolls of linoleum, ■carpets, and felting. The first cost is low, the space occupied small, the power absorbed insignificant, .and the saving in labour enormous. A rigid arm elevator consists of two strands of chain running over two top and two bottom wheels of small diameter, together with the necessary shafts, bearings, reducing gear, and framing. Fastened to the chains at intervals of, say, 10 ft. are projecting arms and struts, shaped to suit the packages to be raised. These arms pick up the packages as fast as they can be placed on the loading grid, and dis- charge them as the arms pass over the top wheels. Obviously, with this type of elevator there can be only one loading point and one dis- charge point. Light packages, how- ever, may be removed by hand on the ascending side at any point before reaching the upper terminal. Similar elevators are used suc- cessfully on an incline for handling loose pieces of cloth in finishing factories, wood slats being arranged above the carrying arms to prevent the cloth coming in contact with the chains. It is sometimes required to dis- charge the packages on the ascend- ing side of an elevator instead of over the top shaft, and this neces- sitates a special artifice, as shown by Fig. 30. The top wheels are made of large diameter, and deflect- pjg 30 Type of Rigid Arm Elevator, showing ing wheels are added in order to Delivery. cant the carriers sufficiently for the package to slide off. This principle has been applied to an elevator transferring bales of paper pulp automatically to a slat conveyor erected at a large paper works. Swing Tray Elevators and Lowerers —A rigid arm elevator is not applicable when several floors have to be served, and where lowering is required as well as elevating. Further, some classes of goods would suffer injury if thrown oft' upside down