The cantilever crane mainly uses the side width of the boom (pitching) to rotate around the vertical axis with the lifting of goods, the use of flexible action to meet the loading and unloading requirements, and its forms are fixed, mobile and floating. The fixed cantilever crane is installed directly on the pier of the wharf or depot and can only work in place. Some of them can only pitch but not turn, and some can both pitch and turn. Mobile boom crane can run along the track or ground surface, the main line of truck crane, tire crane, crawler crane and gantry crane. Among them, tire cranes and gantry cranes are commonly used in ports. Automobile, tire, track and other mobile cranes are also known as automatic cranes. The floating overweight crane is a cantilever crane mounted on the special flat boat, which is widely used in the loading and unloading of sea and river port gates and port construction.