Hydraulic equipment is a general term for hydraulic devices used to drive hydraulic anchors, steering gears, cargo lifts, hatch covers, and adjustable propellers. The power part is an oil pump, the execution part - the liquid engine (cylinder, oil motor), the control part - various pressure, flow, direction, etc., the control valve member and the auxiliary part, a fuel tank, a pipeline, and the like. Through these devices, the pressure and mechanical energy of the liquid medium in the system are converted to each other to achieve the purpose of transmitting motion, force and torque. The hydraulic equipment transmits a large range of energy and can realize stepless speed regulation in a wide range; it runs smoothly, especially when moving at low speed; it can be controlled remotely, easy to operate, easy to realize automation; good lubrication of moving parts and long service life .