The Mechanical Handling and Storing of Material

570 THE MECHANICAL HANDLING OF MATERIAL the tip. With this arrangement the winch may run idle during the raising or lowering of the cradle. There is also a third groove on the drum of this winch, for the purpose of keeping the tipping ropes taut. This winch' is very similar to the preceding one, but the electro- motor is .of 60 H.P., running at 530 revs, per minute, and the tipping portion of the cradle can be raised to an angle of 50°. As soon as the incline has been reached the current is automatically cut off, and the weight of the empty truck and of the tipping portion of the cradle is sufficient to return the former to the level position, the speed being regulated by the brake. Just before the level position is reached the brake is pulled up tight. When lowering the cradle both the brakes of the hoisting and tipping gear are released ; this is necessary as the winch has to run round idle again during the lowering of the cradle. 3 and 4. Winch for Raising or Lowering the Discharge Shoot, and Winch for Altering the Incline of the Discharge Shoot.—These are illustrated in Figs. 804 to 807. The apparatus is fitted with two independent sets of winding gear, which can be alternately coupled to the electro-motor, thus only one of the two operations can be performed at a time. The reversing of the coupling is done by hand. One of the winding gears serves to raise or lower the shoot, and the other to alter the incline. The rope connection between the winch and the tip is shown in Figs. 808 and 809, from which it will be seen how the ropes operate the shoot. The dotted lines which indicate ropes are clearly marked; the line composed of dashes and crosses controls the incline of the shoot, whilst the rope indicated by dashes and dots raises and lowers the shoot itself. The movement of this winch is designedly rather slow, as an alteration either to the height of the shoot or to its incline is only very occasionally made. The raising and lowering of the shoot is at the rate of 3 in. per second, whilst the movement of the end of the shoot to alter its incline is performed at the rate of 4 in. per second. The motor which drives this double winch is of 17 H.P., and runs at 700 revs, per minute, and as the difference in speed is so great a worm and worm wheel are used here. One of the two winches is fitted with a band brake, the weight of which is lifted or lowered by a small electro-motor, similar to all the other brakes on the winches. On either side of the frame of the tip, against two of the main supports, are