Ship-mounted sea crane is the main tool of ocean engineering equipments to improve efficiency and safety.It lays its hook above cargo,picks up loads,rotates,and then puts down cargo on target ship through slewing and luffing movements.Compared with common crane,it hasn't travelling mechanism.So its key components include hoisting mechanism,slewing mechanism,luffing mechanism and wave compensation equipments.Hoisting mechanism loads or unloads cargo.Slewing mechanism can turn clockwise or counterclockwise ho...