Strictly follow the mechanical principle design of excavator-the upper turntable and the lower chassis are connected by slewing bearing, which can simulate the real rotation function; The boom, stick and bucket of the working device are driven by hydraulic cylinders, and the joints are connected with clear pin shafts and bearing details to restore the flexion and extension trajectory during excavation. The crawler chassis is composed of metal chain links, driving wheels, guide wheels and roller wheels. The chain link texture and crawler tooth structure are clear, the supporting equipment is stable, and the overall structure conforms to the design principle of "power priority and accurate operation" of construction machinery.

An old railway crane on the Thames River at North Woolwich Wharf Road (Henry Road) in London.