Parker R4U Unloading Valves, Subplate Mounting


Parker R4U valves are subplate mounted unloading valves. They are used to unload a circuit at low pressure, even under high flow conditions. Typical applications are pump unloading in an accumulator circuit or unloading the low pressure stage of a double pump.

The mechanically adjustable pressure signal to unload the main stage has to be applied to port X. The pressure differential between opening and closing is nominal 15 or 28 % of the setting pressure: 28 % for pressure stages 105 and 210 bar, and 15 % for pressure stage 350 bar

Features and benefits of Parker R4U valves include:

  • Pilot operated
  • Subplate mounting interface to ISO 5781
  • High performance – maximum adjustable pressure of 350 bar
  • Flow capacity ranging from 150 to 650 litres / minute
  • Pilot stage design reduces pressure overshoot and cracking flow to a minimum
  • Precise adjustment and quick response – eliminate pressure variation and system shocks
  • 3 pressure stages for sensitive control
  • 2 vent valve functions; available with an electrical vent valve for unpressurised circulation
  • 3 adjustment modes: hand knob | acorn nut with lead seal | cylinder lock

Contact us for further technical details and configuration options.

Download the Parker R4U Technical Catalogue >>>

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