A pilot-operated check valve is used instead of a DCV with a closed center spool to hold a cylinder because ____________.

A pilot-operated check valve is used instead of a DCV with a closed center spool to hold a cylinder because ____________.

• A. They are cheaper
• B. The check valve requires less maintenance
• C. The DCVs spool leaks
• D. The DCV the spool sticks at high pressure

Answer: (C)

Holding a cylinder in a fixed position relies on stopping backflow from the rod side to the pressure side when no drive signal is present. A DCV with a closed-center spool can still allow small leakage through the internal pathways even when centered, so the cylinder may creep or drift under load. A pilot-operated check valve, on the other hand, provides a true one-way seal that blocks backflow when not piloted, giving a reliable hold. Movement is only possible when a pilot signal opens the valve, and otherwise the cylinder stays locked in place. This is why a pilot-operated check valve is chosen to hold a cylinder instead of relying on a closed-center DCV—the spool leakage of the DCV is the limiting factor.

Holding a cylinder in a fixed position relies on stopping backflow from the rod side to the pressure side when no drive signal is present. A DCV with a closed-center spool can still allow small leakage through the internal pathways even when centered, so the cylinder may creep or drift under load. A pilot-operated check valve, on the other hand, provides a true one-way seal that blocks backflow when not piloted, giving a reliable hold. Movement is only possible when a pilot signal opens the valve, and otherwise the cylinder stays locked in place. This is why a pilot-operated check valve is chosen to hold a cylinder instead of relying on a closed-center DCV—the spool leakage of the DCV is the limiting factor.