Sun Hydraulics RDDA LAN

The Sun Hydraulics Direct-Acting Relief Valve is a normally closed, pressure-limiting valve designed to safeguard hydraulic components from pressure transients. When the inlet pressure reaches the valve setting, it opens to the tank, throttling flow to limit pressure rise. This valve is known for its smooth, quiet operation, zero leakage, and dirt tolerance. It is immune to silting and offers rapid response times.

All 2-port relief cartridges are interchangeable, featuring the same flow path and cavity for a given frame size. The valve can handle maximum pressure at port 2, making it suitable for cross port relief circuits. The adjust screw seals are exposed to system pressure, so adjustments must be made with the pressure removed. The valve is relatively insensitive to oil temperature variations and contamination, ensuring consistent performance.

For optimal repeatability, select a spring range where the desired relief setting is mid to high between the minimum and maximum pressure. This valve is also suitable for load holding applications, with back pressure on the tank port directly additive to the valve setting at a 1:1 ratio. EPDM seal configurations are available for systems using phosphate ester fluids, but exposure to petroleum-based fluids will damage these seals.

Incorporating Sun's floating style construction, this valve minimizes the risk of internal parts binding due to excessive installation torque or machining variations. It meets or exceeds 90% reseat at test...