A complete hydraulic system consists of five parts, namely, power component, executive component, control component, auxiliary component (accessories) and hydraulic oil. The function of the power element is to convert the mechanical energy of the prime mover into the pressure energy of liquid, which refers to the oil pump in the hydraulic system and provides power for the whole hydraulic system. The structural forms of hydraulic pump generally include gear pump, vane pump and plunger pump. The function of executive components (such as hydraulic cylinder and hydraulic motor) is to convert the pressure energy of liquid into mechanical energy and drive the load to do linear reciprocating motion or rotary motion. Control elements (i.e. various hydraulic valves) control and adjust the pressure, flow and direction of liquid in the hydraulic system. According to different control functions, hydraulic valves can be divided into pressure control valves, flow control valves and directional control valves. Pressure control valve is divided into beneficial flow valve (safety valve), pressure reducing valve, sequence valve, pressure relay, etc. The flow control valve includes throttle valve, regulating valve, shunting and collecting valve, etc. Directional control valves include one-way valves, hydraulically controlled one-way valves, shuttle valves, reversing valves, etc. According to different control methods, hydraulic valves can be divided into on-off control valves, fixed value control valves and proportional control valves. Auxiliary components include oil tank, oil filter, oil pipe and pipe joint, sealing ring, quick-change joint, high-pressure ball valve, hose assembly, pressure measuring joint, pressure gauge, oil level and oil temperature gauge, etc. Hydraulic oil is the working medium to transfer energy in hydraulic system, including various mineral oil, emulsion and synthetic hydraulic oil. The hydraulic system increases the force by changing the pressure. A complete hydraulic system consists of five parts, namely, power component, executive component, control component, auxiliary component (accessories) and hydraulic oil. The quality of a hydraulic system depends on whether the system design is reasonable, the performance of system components and the prevention and control of system pollution, and the last point is particularly important. In recent years, the domestic hydraulic technology in China has been greatly improved, and foreign hydraulic technology is no longer simply used for processing. A complete hydraulic system consists of five parts, namely, power component, executive component, control component, auxiliary component (accessories) and hydraulic oil. The function of the power element is to convert the original mechanical energy into the pressure energy of the fluid, become the pump in the hydraulic system, and provide power for the whole hydraulic system. The structure of hydraulic pump generally includes gear pump, vane pump and piston pump. Actuator (such as hydraulic cylinder and hydraulic motor) converts pressure energy in liquid into mechanical energy to drive load to make linear reciprocating motion or rotary motion. The control elements in the hydraulic system (i.e. various hydraulic valves) control and adjust the pressure, flow and direction of the fluid. According to different control functions, hydraulic valves can be divided into pressure control valves, flow control valves and directional control valves. Pressure control valves are divided into benefit flow valves (safety valves), pressure safety valves, sequence valves and pressure switches. ; The flow control valve comprises a throttle valve, a regulating valve and a diverter valve assembly; Directional control valves include check valves, check valves, shuttle valves, stop valves, etc. According to different control methods, hydraulic valves can be divided into switching control valves, proportional control valves and fixed value control valves. Auxiliary components, including oil tank, filter, oil pipe and pipe joint, seal, quick connector, high-pressure ball valve, hose assembly, pressure fittings, pressure gauge, oil level gauge, oil temperature gauge, etc. Hydraulic oil is the working energy transmission medium of hydraulic system, and there are many kinds of mineral oil, emulsion, hydraulic molding hopper oil and so on.