The Mechanical Handling and Storing of Material

574 THE MECHANICAL HANDLING OE MATERIAL space for the counterweight. The ordinary position of the attendant is between a1 and B1, and with his right hand he manipulates the raising and lowering of the cradle, whilst with his left hand he controls the tipping operation. With the backward movement of the lever the load is raised, whilst with the forward movement it is lowered. There is a safety appliance which prevents the tipping lever from moving during the raising and lowering of the cradle, and vice versa. The normal position of the levers is in the centre of the index, and as soon as one of the levers is moved in either direction, the other lever is Figs. 820 to 822. Elevation, Plan, and Cross Section of Shoot. (The dimensions are in millimetres.) automatically locked until the former lever has again reached the central position. In addition to the operating levers, the cabin is fitted with the usual electrical instruments and cut-outs. An electrically driven tip, similar to the foregoing, was installed in 1901 in the Dutch harbour of Emden ; it has a capacity of fifteen trucks, together 225 tons, per hour. At Rotterdam the full trucks approach the tip, and the empty ones leaving have to pass the same turntable; this causes delay and reduces the capacity considerably. Two turntables are used at Emden, which is a decided improvement.