Four-link Portal Crane is widely used in ports, docks, yards and other places to complete the loading, unloading and transshipment operations of ships and vehicles. Its design, manufacture and inspection implement DIN, FEM, IEC, AWS, GB and other domestic and foreign advanced standards and the latest national standards. Four-link Portal Crane is divided into two types: single boom and four-link boom type according to the structure of the boom. The four-link portal cranes use the combined arm frame system to achieve the horizontal movement. It has the characteristics of small horizontal gap, stable variable amplitude, and low power consumption.