Gantry crane is a kind of bridge crane deformation, also called gantry crane. Mainly used for outdoor goods yard, cargo, bulk cargo yard handling operation. Its metal structure like the door frame, bearing the main girder, the installation of two supporting feet, can be directly on the ground of walking on the orbit, both ends can be overhanging cantilever girders. Gantry crane with high space utilization, wider range of operation, adaptation of wide and strong commonality, is widely used in port yard.
Door crane is a bridge on both sides by supporting leg on the ground track or foundation of crane boom type. Have orbits along the ground, below but by rail vehicles or other ground vehicles. Rotating lifting device is installed on the door form mounts a boom type of crane. Portal of mount 4 legs 4 "the gate", for rail cars and other vehicles pass. Mostly along the floor or building a door crane crane orbit, crane loading and unloading operations. "" on the door a glyph of half door crane, crane said one side of its orbit in the ground, on the other side is located in the top of a building above the ground.