R900902095 4WRA6W30-2X/G24N9K4/V German Rexroth proportional valve

FAQs for Rexroth 4WRA6W30-2X/G24N9K4/V Proportional Directional Valve

1. Q: This valve is rated for 30 L/min, while the previous model was 15 L/min. What is the main difference?

   A:​ The primary difference is the nominal flow capacity. The 4WRA6W30​ valve is designed to handle approximately twice the flow​ (30 L/min vs. 15 L/min) at the same 10 bar pressure drop. This makes it suitable for controlling larger cylinders or motors​ that require higher speeds, or for applications where the same size actuator needs to move faster. The valve body size (6mm) is the same, but the internal spool and orifices are optimized for higher flow.

2. Q: The valve uses a "W" spool. What are the implications for system control?

   A:​ The "W" spool is a zero-overlap (critical center) proportional spool. This design provides: 1) No Dead Zone:​ The cylinder begins to move with the smallest command signal, allowing for very smooth, low-speed control. 2) High Resolution:​ Excellent for precise positioning applications. 3) Potential for Higher Leakage:​ In the center position, there is a small internal leakage path, which is typical for this spool type and provides lubrication. It is ideal for closed-loop velocity or position control systems.

3. Q: How do I interface this valve with my PLC or motion controller?

   A:​ This valve features On-Board Electronics (OBE). It is interfaced via a single, shielded multi-pin cable​ (e.g., with a 12-pin connector per DIN EN 175301-803). This cable carries: 24V DC power, the analog command signal​ (typically ±10V or 0-10V), and the LVDT feedback signal. The OBE interprets the command, drives the solenoid, and reads the LVDT, simplifying wiring. Your controller needs an analog output capable of supplying the command voltage/current.

4. Q: What is the purpose of the LVDT (Linear Variable Differential Transformer) feedback?

   A:​ The LVDT is a non-contact position sensor​ mounted inside the valve. It provides continuous, real-time feedback of the exact spool position​ to the OBE. This creates a closed-loop control system for the spool itself. The OBE compares the commanded spool position (from your input signal) to the actual position (from the LVDT) and instantly corrects any error. This ensures highly accurate and repeatable flow control, compensating for friction, pressure forces, and temperature changes.

5. Q: Can this valve be used for precise speed control of a hydraulic motor?

   A:​ Yes, it is an excellent choice for this application. The combination of proportional control, high resolution (W-spool), and closed-loop spool positioning (LVDT+OBE)​ makes it ideal for accurate speed control of hydraulic motors. By sending a precise command signal, you set a specific spool opening, which results in a controlled flow to the motor, determining its speed. For even more precise motor speed control, the valve would be part of an outer control loop using a motor speed sensor (e.g., an encoder) for true closed-loop velocity control.