The Mechanical Handling and Storing of Material

TRANSPORTERS, BRIDGE OR CANTILEVER CRANES 445 gantry is designed for the sole purpose of The main support s, which also encloses the Fig. 624. Transporter by Bleichert. both mounted on wheels. The bridge or supporting the running head with its load, motor-house, rests on two lines of rails. The trestle p on the quay side is very light in comparison with the main support, and is so coupled to the gantry that it gives sufficiently to make allowance for any ex- pansion or contraction of the bridge through a change of temperature. The extension a is so hinged that it can be moved out of the way of the ship’s tackle, as shown by dotted lines. It can be raised by the small winch w, and lowered by its own weight and by the use of a brake. The skip, which runs the whole length of the gantry, can be unloaded either into a stock heap or into railway trucks, as may be seen from the illustration. Two inde- pendent ropes are used for the manipula- tion of the transporter, the one for lifting and the other for conveying. The action is as follows : — The skip, after being filled in the ship’s hold, is raised to its fullest extent, so that the fall-block, engages with the traveller, whereupon the lifting rope has no further load to carry. The conveying rope is then brought into action, and the traveller with its load is brought to the discharging point and there tipped. As the plant is mounted on wheels it can be moved forward or backward to discharge the ship without altering its position. I he operator’s cabin, marked h in the illustration, is so placed as to give a good view of the unloading operations. The time occupied by one skip in travelling from and returning to the ship is about one minute. The contents of the skip weigh 1| tons. In order to avoid any loss of time several skips are always in use. The average capacity is 500 tons in ten hours. This, of course, depends very much on the number of trimmers who fill the skips, and the nature of the material to be unloaded. It would be increased if a grab were used instead of the ordinary skip. Fig. 625 also illustrates a transporter designed by Bleichert, which is similar, to the one already described, but is much shorter, being only used for unloading ships into