起重机的类型英文.docxVIP

Type of Cranes Cranes can be classified into four kinds, namely, (a) overhead traveling crane; (b) jib crane; (c) bridge or gantry crane; and (d) cantilever crane. Overhead traveling crane. Consists of a girder and a trolley. The girder is supported at each end on trucks capable of traveling on elevated fixed tracks. The trolley is equipped with hoisting and other mechanism, capable of traversing from end to end of such girder. The girder and associated end carriages are known as the bridge. Such cranes vary in lifting capacity from about 2 tons to 400 tons, and in span from 20 ft to 150 ft,or more. Depending on the purpose for which it is to be used, the crane can be operated either from a cabin fixed to the bridge or the trolley, or from the ground. When two trolleys are furnished, these may run on a common tracks arranged side-by-side or one above the other so that each trolley can?traverse the entire span. Jib crane Consists of an inclined member, or jib, capable of suspending a load at its outer end. The jib is supported by a rope or other member attached to a vertical mast of frame. The out reach of the jib can be constant or variable, and the crane as a whole may be either fixed or movable. Included in this kind are: mobile and caterpillar cranes, builders tower cranes, wharf cranes, and movable cranes mounted on high pedestals, gantries, pontoons and barges. Lifting capacities vary from 1/2 ton to 300 tons or more, and outreaches from a few feet to 150 ft. Cranes required for handling heavy machinery and equipment in shipyards and at ports are frequently mounted on pontoons.Bridge or gantry crane Bridge or gantry crane. Consists of a bridge girder, connected at near both ends to upright members, which may be fixed or arranged to travel on a fixed track, and the load is suspended from a trolley or crane, capable or traversing from end to end of the bridge. Cranes of this kind have lifting capacities varying from end to end of the bridge. When used in general