Crane Hoist Crab

The Crab includes the hoisting machinery placed on a frame, which is in turn fixed on at least four wheels and consists of suitable machinery for traversing the Crab to and fro motion along the main bridge girders of the crane. The crab wheels operate on two rail sections mounted on the top flange of the main bridge.The bridge is termed a crane bridge, crane girder, or crab girder. It spans the bay of the shop and moves in a longitudinal direction. To facilitate movement, wheels are attached to the ends of crane girders. These wheels move over rails placed centrally over the girders which are called gantry or crane gantry girders.