The Mechanical Handling and Storing of Material

TRANSPORTERS, BRIDGE OR CANTILEVER CRANES 427 In 1913 a similar installation with longer span bridges was erected on the Pittsburg Coal Co.’s Dock No. 5 in Superior, U.S.A. Electric Travelling- Trolley of the Brown Hoisting Machinery Co.— A most important part in high-level cranes is the trolley with its motor. It can, of course, travel on any gantry or bridge of suitable construction. Fig. 598 represents an electric travelling trolley. The illustration explains itself. This rrolley is used to draw ore and limestone for blast-furnace purposes from the ore bins, and convey it to the furnace hoist, where the bottom door of the receptacle is opened and the ore discharged into the skip of the furnace hoist. Electric Travelling Trolley of the Temperley Transporter Co.—Fig. 599 illustrates a travelling trolley fitted with a Hone grab. It is shown with its electro-motor, also the cable from which the current is taken. The illustration also shows the operator’s seat, and the levers, by means of which the trolley as well as the grab are manipulated. Fig. 598. Electric Travelling Trolley as used for Feeding Furnaces. The capacity of the grab is 3 tons; it rises 50 ft. per minute, and the trolley travels at a speed of from 400 to 500 ft. per minute. For other examples see chapter on “Storing Coal and other Minerals in Stock Heaps and Silos,” page 650. TRANSPORTERS WITH STATIONARY WINDING GEARS These transporters undoubtedly owe their origin to American enterprise, and are largely used in the United States in a variety of forms, similar in appearance and general operation to that in which the winch accompanies the load, but the structure need not be so substantial, as smaller loads are generally dealt with, and in addition to the load the weight of the traveller or running head only need be taken into account as against the weight of the movable cabin with the winch and motor. But as this type is sometimes built from 60 to 80 yds. in length, the construction must be sufficiently rigid to resist, in addition to its own weight, the influence of high winds. It has also this advantage,