The Mechanical Handling and Storing of Material

28 THE MECHANICAL HANDLING OF MATERIAL start it the driving band would most likely come off, or if driven by a chain, breakdowns might take place. The installation shown in Fig. 24 represents the feeding device driven from the lower terminal. This is all right as long as the elevator is a chain elevator, so that its bottom terminal must revolve with the elevator; but such an arrangement would not be suitable with elevators in which the buckets are fixed to a band, as these sometimes slip. Fig. ‘24. Mechanical Feeding Device for Elevators. Another device, which is illustrated in Fig. 25, consists of a small trough suspended under the delivery end of a bin by four wrought-iron hangers. This shoot is put into oscillating motion by levers attached to one or two of the suspended arms. As the trough swings backward the coal it may contain will not slide backwards with the shoot, but will fall forward through a spout on to the conveyor or elevator to be fed. At the forward Fig. 25. Oscillating Feeding Device for Elevators. movement of the shoot the coal from the bin above will slide down into the space that is now left vacant by the pieces that have moved forward, so that the material is gradually and evenly deposited with each backward and forward motion. This shoot is put in motion by a crank and connecting rod in such a way that the throw can be altered at will, and the feed regulated to a nicety. Similar appliances are used in which the shoots are supported on four small rollers moving backward and forward on suitable rails. In such cases the shoot is generally level instead of being at an incline. The speed at which such feeding devices are run depends to a great extent on the size of the material.