Which valve is also known as 'running away' and traps fluid under pressure until conditions change?

Which valve is also known as 'running away' and traps fluid under pressure until conditions change?

• A. Counterbalance valve
• B. Flow control valve
• C. Meter-in
• D. One-way control valve

Answer: (A)

Preventing uncontrolled movement of a hydraulic actuator under load is achieved with a valve that holds fluid on the actuator side under a set pressure until the load conditions change. This is a counterbalance valve. It is placed so that the actuator’s load-side pressure must exceed a predetermined cracking pressure before fluid can move back, effectively trapping fluid under pressure and creating a braking effect that resists gravity or external forces. The valve holds the position until commanded or until the pilot pressure rises enough to open it. This is why it’s described as preventing “running away.” Other valves described don’t provide this holding function: a flow control valve throttles flow to control speed but doesn’t lock the load, a meter-in valve regulates inlet flow without locking, and a one-way (check) valve only allows flow in one direction without maintaining a holding pressure.