The Mechanical Handling and Storing of Material

COAL TIPS OR HOISTS 567 thrown in and out of gear by small electric motors. The following six winding gears have been erected :— 1. For lifting and lowering the cradle ; 2. For tipping the cradle ; 3. For raising or lowering the discharge shoot; and 4. For altering the incline of discharge shoot; 5. For lifting or lowering the anti-breakage skip; 6. For turning the anti-breakage crane. The electric driving gears have been very carefully constructed, and the wiring has been insulated so as to resist the damp climate at Rotterdam. A continuous current of 500 volts is used, and the lowering of the cranes is effected by means of electrical brakes. Figs. 794 to 796. Winch for Raising and Lowering the Cradle. 1. Winch for Lifting and Lowering the Cradle.—The weight of the cradle, including the heaviest full coal truck, is 50 tons, and this is raised at the rate of 1 ft. pei second. The action is illustrated by Figs. 797 and 798, which also shows the arrange- ment of the balance weights. The rope used is a steel wire rope, both ends of which wind on and off the grooves of the winding gear (Figs. 794 to 796), so that there is always the same tension on either end of the rope. The electric motor driving this winding gear is of 130 H.P., runs at 370 revs, per minute, and is mounted on the same bed-plate as the winding gear. The drum has a diameter of 40 in., which is necessary as the wire rope has a diameter of 1 | in. The gearing for reducing the speed from the motor to the winding drum consists of two countershafts and spur wheels. The gear wheels are of cast steel, except the pinion of the motor, which is of raw hide. The first of these countershafts is fitted with a brake at each end, which enables the operator to stop the load in free suspension, when the current is cut off. As soon as the cradle has