Check the listing for details. Hydraulic Double Overcentre Valve For Closed Centre VBCD, 1/4", 3/8, 1/2" BSP. Condition: New. Listed at 150.84 USD. USE AND OPERATION: These valves are used to control the actuator movements and block it in both directions. In order to have the descent of a load under control and avoid the load's weight being carried away the valve will prevent any cavitation of the actuator. These valves are ideal when normal overcentre valves doesn't work properly as it's not sensitive to back pressure. They also allow the system pressure to move multiple actuators in series. Type "A" is different due to the connection positions and the pilot ratio. MATERIALS AND FEATURES: Body: zinc-plated steel. Internal parts: hardened and ground steel. Seals: BUNA N standard. Leakage: negligible leakage. Standard setting: 320 Bar. Valve setting must be at least 1.3 times more than load pressure in order to enable the.