The gantry crane is a bridge crane supported on the ground track by legs on both sides. Structurally, it consists of the gantry, trolley running mechanism, hoisting trolley, and electrical parts. Some gantry cranes have legs only on one side, supported by the factory or pier on the other, known as semi-gantry cranes. The components of the gantry crane include the upper bridge girder (including the main beam and end beam), legs, lower cross beam, etc. To expand the crane's working range, the main beam can extend beyond the legs on one or both sides, forming a cantilever. An articulated trolley with a boom can also be used to increase the crane's working range through the boom's tilt and rotation.