Hydrodynamic device is used to open or close the hydraulic pressure regulating valve drive device which consists of control, power and implementing agencies composed of three parts. The control part consists of pressure control valve, flow control valve, directional control valve and electrical control system. Power part of the motor or air motor, hydraulic pump, fuel tank and other components, is the electric or pneumatic motor rotation axis of the effective power into hydraulic transmission fluid pressure energy. There are two implementing agencies, one is the hydraulic cylinder actuator, to achieve reciprocating linear motion; the other is the hydraulic motor actuator, to achieve rotary motion, the advantages and disadvantages of hydraulic devices are as follows: (A) hydraulic valve device advantages 1 ) The structure is simple, compact, small size; 2) The transmission is stable and reliable; 3) Can get a great output torque; 4) The output torque can be precisely adjusted by constant pressure relief valve, including the opening and closing torque adjustment, Can be reflected directly by the hydraulic instrument; 5) speed adjustment is convenient; 6) in the event of a sudden power outage, you can still use the accumulator for one or several power operations. This long-distance pipeline automatic emergency shut-off valve and wellhead discharge valve has a special significance. (B) the shortcomings of the hydraulic valve device 1) the oil temperature is greatly affected by the ambient temperature, the oil temperature changes caused by the viscosity of the oil changes, affecting the operation; 2) piping trouble, easy to produce leakage; 3) is not suitable for signal generation Operation (such as signal amplification, memory, logic judgment and other operations) of the occasion.