Gantry crane bridge crane is a kind of deformation, also called gantry crane. Mainly used for outdoor cargo yard, yard cargo, bulk cargo handling operations. Its metal structure is like a door frame, and two legs are installed under the main beam, which can be directly moved on the track of the ground. The two ends of the main beam can have overhanging cantilever beam. Gantry crane is widely used in port freight yard because of its high utilization ratio, large range of operation, wide adaptability and versatility.