Dam top gantry crane is employed to lift floodgate, Hydro-generating unit and trash rack on dams. The working area is a line or belt area along its running rails. The structure is plate girder or box girder. The lifting mechanism, gear box which hoist and crane traveling mechanism are driven by motors. There is a closed operation room on main beams. The slings is a hoisting beam powered by flexible cable device. The foot is protected by Buffer device and Windproof rail clipping device.

There are two kinds of dam top gantry crane: 1. Single direction: The lifting mechanism (slings/hook) is fixed on trolley and only travel along the rails direction on main beams, thus it can only lift one side floodgate/trash rack. 2. Double directions: The lifting mechanism on trolley can move vertically against the main beam rails direction, thus it can be used to lift 2 sides’ floodgates/trash racks of upstream and downstream.