The Mechanical Handling and Storing of Material

78 THE MECHANICAL HANDLING OF MATERIAL cases can be turned round a common centre by means of worm and worm wheel. hen out of use one guide pulley is above and one below the band, which runs through between them but without touching them. If delivery of the material is required at a certain point, the throw-off carriage is pushed into position and the guide pulleys are turned round the common centre in the direction of the arrow, so as to raise one part and lower the other part of the band as shown in Fig. 104. In this illustration the dotted circles a, B, indicate the guide pulleys when out of use, while those in full line Ax, Bx show the position of the pulleys when the throw-off carriage is in use. As soon as the grain arrives at the throw-off carriage, it leaves the band by its own momentum, and is received in a hopper which forms part of the apparatus. It is then spouted sideways to its destination clear of the band. This arrangement for withdrawing the grain from the band proved a complete success, and has been universally adopted. The throw-off carriage, designed for the use of the Liverpool Docks in 1868, was probably the first of these devices, and is shown in Figs. 105 and 106. It consists of a pair of wrought-iron rollers centred in gun-metal bearings in a Figs. 105 and J 06. Adjustable Throw-off' Carriage Designed for the Liverpool Docks. rocking frame, which is hung in a movable carriage running upon the top of the timbers of the wooden framing that supports the travelling band. The carriage is moved to any position along the length of the band where the grain is required to be discharged, and is there secured by wedges and. clamping screws. The rocking frame is rotated in either direction, by means of worm and worm wheel, to bring the pair of rollers into action in the proper, position for throwing the grain off in the same direction as that in which the band is running, while the rollers are turned back into a horizontal position to be clear of the band when the cai riage is required to be moved to any other point on the length of the band. A curved spout is attached to the carriage for receiving the stream of grain in its fall and leading it off on either side of the band. The throw-off carriage shown in Fig. 107 is of a very simple kind without adjust- ment. It has a clamp by means of which it can be secured in its position. The diagram shows also the receptacle for the grain and the alternate outlets on either side with valve arrangements. This appliance having no means of adjustment, when not in use must always be moved to the terminus. It is also sometimes made with a third outlet which delivers the grain back again on to the band if intermediate delivery is not required. In such