The Mechanical Handling and Storing of Material

the mechanical handling oe materlal down to the lower part of the structure, where they pass over sheaves and up again to the end of the balance beam. The travelling gear of the carriage of the unloader is connected to a 100 H.P. electro-motor (at 250 revolutions). The grab is so supported on its column that it can revolve around its vertical axis 418 Fie. 591. Hulett Unloaders in Hold of Vessel. 2 of a revolution in either direction, so that altogether a movement of 1| revolutions can be performed; this motion is given by a 35 H.P. electro-motor. The opening and closing of the grab are controlled by chains, which wind and unwind on three drums on one common spindle. The axis of the grab does not coincide with that of its column, but is eccentric by 2 ft. The spindle of the drum for manipulating the grab is con- nected by two intermediate gear-driven spindles, and by two cables which connect them with the winding gear at the rear end of the balance beam, and are manipulated by a 100 H.P. electro-motor. This gear is a flexible coupling, which absorb any stresses ight be caused by the closing of the grab. The weight of the grab and its support ■ in this htest installation is such that the ore can be deposited in a also fitted with an electro-magnetic brake and which mi^ is balanced to within 4 tons by a balance weight. The arrangement in -------------------- Fig. 592. Perspective View of Hulett Unloaders. portable bunker so that very little time is lost, the grab in order to unload only having to travel back a short distance. This portable bunker is connected with a weighing mechanism, and its contents may be drawn off into railway trucks, etc. Fig. 590 shows