The hydraulically pilot operated check valves series RH for in-line mounting are proven components of Parker's check valve product range which ensure a leak-free blocking of the flow and thus a reliable operation. They allow free flow in one direction (B to A), the counter flow is blocked (A to B). By applying pilot pressure the ball can be lifted from its seat and allows flow from A to B.

Most common use:
• Keeping cylinders leak-free in position, when spool type directional control valves are used
• Return line discharge, when return flow exceeds functional limits of directional control valve at differential cylinders
• As hydraulically activated drain or circulation valve

Markets:
• Industrial

Features/Benefits:
• Spring-loaded balI seated valve - enables zero leakage
• Proven, robust design - ensures reliable operation
• Flexible, versatile mounting in any orientation - makes integration easy
• Short delivery time for most variations - no warehousing necessary
• Maximum operating pressure up to 700 bar

Applications:
• Suitable for general hydraulic applications

Function:
The valves are available without and with hydraulic predischarging.

Without pre-discharging
These valves have a ball as valve element, which quickly enables the full flow cross-section proportionally during pilot operation. A metering position in the pilot port dampens the control movement of the pilot spool so that pressure shocks (unloading shocks) are mostly suppressed.

With pre-discharging
For valves with pre-discharging a spherical polished valve spool (seat valve function) is built-in instead of a ball. The additional check valve achieves a pre-opening which provides shock-free unloading of the fluid, especially at high working pressure and large volumes.