The Mechanical Handling and Storing of Material

HANDLING BLAST-FURNACE STOCK without moving the transporter upon its track. The total weight of each truss, including the supporting trolleys, is about 450 tons. The supports for each truss over the walls are as follows : On each trolley is a turntable, similar to a swing-bridge turntable, but the trusses also rest upon a nest of parallel rollers on the south walls, which permit of a variation in span length due to the obliquity resulting from the angular movement of the bridges. During the time the crane is traversing the length of the ore yard the work of excavating and delivering is not interfered with, both operations proceeding simultaneously. The furnace pockets shown in Fig. 500 have a capacity of 3,000 tons of ore, 1,000 tons of coke, and 500 tons of limestone. These are double pockets, the south tier being almost entirely used for the storage of coke and stone and the north tier for ore. A large portion of the ore is conveyed direct to the pockets by the crane, but as the ore Fig. 498. Plan and Section of Scraper used in connection with Hoover & Mason’s Ore-Handling Plant. yard could not be placed symmetrically to the furnaces, a transfer car became necessary. The body of this transfer car is 26 ft. long by 18 ft. wide. This bridge is of such large dimensions that the bridge operator can forthwith deliver his load of 10 tons taken from the trough or from the stock heap. The grab, when open, commands an area of 19 ft. by 6 ft. The skewing of the ore bridge, which brings the grab in position across the line of the axis of the pockets, necessarily affects the size of the car. The dumping or discharging is effected at the side, the opening of the doors being effected by gravity, while they are closed by a small motor. To avoid danger of collision with scattered lumps of ore the operator’s car is placed upon a sort of outrigger. The size of the car permits of the ore being delivered to either side of the pockets. The car body is of great weight, and thus the shock of receiving a mass of 15 tons is minimised. The car is electrically operated by one man who travels with it, controlling it by ordinary