The MG20t-320t U-shaped double beam gantry crane is a variation of the bridge crane, with a structure resembling a door, hence it is called a gantry crane. The metal structure of the electric double beam gantry crane is like a portal frame, with four support legs installed under the main beam, which can directly walk on the ground track. The two ends of the main beam can have outward overhanging cantilever beams. It consists of components such as bridge frame, large vehicle operating mechanism, small vehicle, electrical equipment, etc. The bridge adopts a box type single beam welded structure, and the large vehicle operating mechanism is driven separately. The institutions are all operated in the control room.