What is the typical effect of adding a pilot-operated check valve on retract speed?

What is the typical effect of adding a pilot-operated check valve on retract speed?

• A. Increases retract speed
• B. Has no effect
• C. Slows or holds retract speed
• D. Reverses direction

Answer: (C)

A pilot-operated check valve mainly serves to control or slow the motion in one direction by adding a restricted path that must be opened by pilot pressure. In retract, the valve blocks flow back through the line until the pilot is pressurized; because the flow is metered by that valve, the cylinder retracts more slowly and can even be held in position if the load is large or the pilot isn’t activated. Only when you apply pilot pressure does the valve open enough to let retract occur, and even then the flow is still restricted compared to a direct, unrestricted path. So the typical effect is to slow or hold retract speed, not speed it up, not leave it unchanged, and not reverse direction.

A pilot-operated check valve mainly serves to control or slow the motion in one direction by adding a restricted path that must be opened by pilot pressure. In retract, the valve blocks flow back through the line until the pilot is pressurized; because the flow is metered by that valve, the cylinder retracts more slowly and can even be held in position if the load is large or the pilot isn’t activated. Only when you apply pilot pressure does the valve open enough to let retract occur, and even then the flow is still restricted compared to a direct, unrestricted path. So the typical effect is to slow or hold retract speed, not speed it up, not leave it unchanged, and not reverse direction.