Gantry crane (also known as gantry crane) is a bridge type crane that is supported on the ground track by two legs on both sides of the bridge. Structurally, it consists of a gantry, a crane operating mechanism, a lifting trolley, and electrical components. Some gantry cranes only have legs on one side, while the other side supports the operation on the factory building or trestle, called semi gantry cranes. The upper bridge (including main beam and end beam), support legs, lower crossbeam, and other parts of the gantry crane are composed. In order to expand the operating range of the crane, the main beam can extend beyond the support legs to one or both sides, forming a cantilever. A lifting trolley with a boom can also be used to expand the operating range of the crane through the pitch and rotation of the boom.