In a load-lock circuit, how many pilot-operated check valves are used when force can act in both directions?

• A. One
• B. Two
• C. Three
• D. Four

Answer: (B)

Holding a load that can be pushed from either side requires a mechanism that can lock in both directions. A pilot-operated check valve normally blocks flow back from the actuator to the load unless a pilot signal is applied, so it can hold the load in place when the opposing side pushes. To cover forces from both directions, you use two of these valves arranged in opposite directions—one valve blocks and locks when force comes from one side, the other does the same for the opposite side. This pair lets the load stay stationary no matter which direction the external force acts. Extra valves would add unnecessary complexity without improving the locking behavior in a typical load-lock circuit. So, two pilot-operated check valves are used.