In hydraulic crane operations, what component prevents the extension from retracting after deployment?

• A. Locking pin
• B. Control valve
• C. Piston seal
• D. Counterweight

Answer: (A)

A positive mechanical lock is used to hold the extended section in place. When the extension reaches its deployed position, a locking pin (or similar locking mechanism) is engaged to physically secure the extension, preventing it from moving back even if hydraulic pressure drops or an external load tries to cause retraction. This ensures the crane remains stable during lifting.

The control valve governs the direction of hydraulic fluid flow and enables extension or retraction but does not by itself lock the position. The piston seal keeps fluid contained within the cylinder but doesn’t stop movement if pressure changes. The counterweight helps balance the crane for stability but doesn’t prevent the extension from retracting.