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Sun Hydraulics RD*A Direct Acting Differential Area Pressure Limiting Relief Cartridges - Two Port

Direct-acting relief cartridges are normally closed, pressure-limiting valves used to protect hydraulic components from pressure transients. When the pressure at the inlet (port 1) reaches the valve setting, the valve starts to open to tank (port 2), throttling flow to limit the pressure rise. These valves are smooth and quiet, essentially zero leak, dirt tolerant, immune to silting and are very fast.


  • Relatively flat pressure rise (especially at high end of spring range.)
  • High flow capacity (100 to 800 L/min) relative to physical size (comparable to piloted operated valves).
  • Low hysteresis (reseats at 90% of valve setting) and very low leakage (10 drops/min at reseat).
  • Utilizes a seated design which makes the valve suitable for use in load holding applications.
  • Fast opening and closing (2 ms typical response time).
  • Insensitivity to varying oil temperature and oil-borne contamination.
  • Reliable cold oil closing and exceptional hot oil stability (no oscillation).
  • Rugged, robust, construction withstands high pressure shocks or back pressure.
  • Not suitable where frequent pressure adjustment is required, as they are difficult to adjust under pressure
Part Number Cavity Size Flow Capacity l/min) Pressure Adjustment Range (bar) Datasheet Link
RDDA-LCN T-10A 95 70-420 View Datasheet Buy Now
RDFA-LCN T-3A 200 70-420 View Datasheet Buy Now
RDHA-LCN T-16A 380 70-420 View Datasheet Buy Now
RDJA-LCN T-18A 760 70-420 View Datasheet Buy Now

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