R900958570 4WRZ25W6-325-7X/6EG24N9K4/D3M Rexroth Germany servo proportional hydraulic valve

Key Differences & Selection Guide

1. Q: What is the main difference between 4WRZ and the previous 4WRZE valves?

   A:​ The 4WRZ​ series (R900958570) uses External Electronics (EE), meaning you need a separate amplifier card (e.g., VT-5000 series) to power it and provide the control signal. The previous 4WRZE models had On-Board Electronics (OBE)​ integrated into the valve plug. The 4WRZ is typically chosen for high-temperature environments where onboard electronics might fail.

2. Q: What does the /D3M suffix mean?

   A:​ The /D3​ suffix indicates an integrated pressure reducing valve (ZDR 6)​ for regulating pilot pressure. The /M​ suffix specifies standard NBR seals.

3. Q: How does the pilot oil configuration work?

   A:​ This valve (/6EG24N9K4) uses external pilot oil supply (X port) and external pilot oil return (Y port). You must provide clean, filtered pilot oil to the X port (typically 20–100 bar) and ensure the Y port drains directly to the tank with minimal backpressure (max 30 bar).

4. Q: Why choose this specific configuration?

   A:​ This model is ideal for high-flow applications (325 L/min) requiring external amplifier flexibility. The W6 spool​ provides smooth overlap characteristics. The integrated /D3 pressure reducer​ ensures stable pilot pressure even if the system pressure fluctuates.

5. Q: What is the critical installation note?

   A:​ Since this valve uses external electronics, you must correctly wire the LVDT feedback and solenoid coils to the external amplifier according to the pinout. Additionally, ensure the external pilot supply (X) is clean and within the 20–100 bar range. Maintain high oil cleanliness (recommended NAS 1638 Class 8 or better for the pilot stage).