The electro-hydraulic servo valve SM4-40 (40) 151-80/40-10-H919H is a key control component used in the DEH system of steam turbines, and the valve core of the servo valve plays a crucial role in controlling oil flow. The servo valve adjusts the oil flow through the movement of the valve core.

In the electro-hydraulic servo system, the position and motion speed of the SM4-40 (40) 151-80/40-10-H919H valve core need to be adjusted based on the input electrical signal to achieve precise control of the executing components (such as hydraulic motors, hydraulic cylinders, etc.). When the input electrical signal changes, the valve core will move accordingly, thereby changing the flow rate and pressure of the oil.

However, when the fire-resistant fuel is contaminated or the control system malfunctions, the servo valve spool may not operate. Generally speaking, the following reasons can easily cause the servo valve to not operate:

• Control signal failure: The operation of the servo valve is driven by the control signal. If the control signal malfunctions, the valve core may not function properly. It is necessary to check the transmission line, signal processor, and control program of the control signal for any issues.
• Valve core sticking: During the movement of the valve core, it may be worn and stuck due to impurities in the oil. In this case, it is necessary to clean the valve core and valve body, repair or replace worn parts.
• Hydraulic system malfunction: The operation of the servo valve is affected by the hydraulic system. If there are faults in the hydraulic system, such as insufficient oil, poor oil quality, blocked oil circuits, etc., the valve core may not function properly. It is necessary to check the working status and oil quality of various components of the hydraulic system.

Yoyik can offer other hydraulic pumps or valves for power plants as below:
Dual Solenoid Valve Z6206060
Single Row Ball Bearing 6310-Zz
Twin Screw Pump Hsnh210-36N
Industrial Water Vacuum Pump 30-Ws
Vacuum Pump Working Principle P-545
Thrust Bearing (Roll Bearing) 29332+ 6030
Solenoid Valve F3Dg5S2-062A-220Dc-50-Dfzk-V/B08
Stator Cooling Water Coupling Pump Ycz50-250B
Hydraulic Reversing Valve Mg00.11.19.01
Sequence Valve Hgpcv-02-B30