Hydraulic control is the control of a pressurized liquid as a control signal transmission method. A control system constructed with hydraulic technology is called a hydraulic control system. Hydraulic control typically includes hydraulic open loop control and hydraulic closed loop control. Hydraulic closed-loop control is also hydraulic servo control, which constitutes a hydraulic servo system, usually including electro-hydraulic servo system (electro-hydraulic servo system) and mechanical hydraulic servo system (machine fluid servo system, or machine fluid servo mechanism).
A complete hydraulic system consists of five parts, namely the energy device, the actuator, the control regulator, the auxiliary device, and the liquid medium. The hydraulic pressure is widely used in industrial and civil industries due to its large transmission power, easy transmission and configuration. The actuators of the hydraulic system (cylinders and hydraulic motors) are used to convert the pressure energy of the liquid into mechanical energy to achieve the desired linear reciprocating or swiveling motion. The function of the energy system (hydraulic pump) of the hydraulic system is to convert the mechanical energy of the prime mover into the pressure energy of the liquid.