1. Safety Precautions

‌ (1) System Pressure Relief

Before operation, confirm that the hydraulic system pressure has been completely released (verify with a pressure gauge to ensure that the pressure is ≤ 0.5 bar). Disconnect the main power supply and padlock (LOTO procedure) to prevent accidental start-up.

 (2) Environmental Requirements

Working area temperature: -20°C to +50°C (adjusted according to the temperature range of the specific model). Avoid electromagnetic interference sources (inverter, high-power motor, etc.) from the proportional valve cable to less than 1m.

‌ (3) Medium Cleanliness

The hydraulic oil NAS grade must meet ISO 4406 18/16/13 or higher. It is recommended to install a 10μm high-pressure filter at the valve group oil inlet.

2. Preparation before installation

(1) Mechanical installation

‌① Valve body fixing‌

Use a torque wrench to tighten the mounting screws evenly according to the torque marked on the valve body (usually 20-35 N·m) to avoid deformation of the valve body. Sealing surface treatment: Clean with a lint-free cloth before installation. Do not use silicone-based sealants.

② Oil port connection‌

The oil port direction must comply with ISO 1219 standard (P: pressure oil port, T: return oil port, A/B: actuator port). When using SAE flanges or UNF threaded connectors, ensure that there is no radial stress on the pipeline.

(2) Electrical installation

‌① Cable selection‌

Shielded cable specifications: ≥0.75 mm² (AWG18 recommended), the shielding layer must be 360° looped. Wiring length limit: analog signal cable ≤30m, bus type (such as SSC/Profibus) ≤100m.

② Wiring Specifications

Control signal cables (±10V or 4-20mA) should be routed separately from power cables, with a spacing greater than 15cm. Ground the shield at a single point (recommended on the controller side).

3. Parameter setting and debugging process

(1) Initial configuration

‌① Control mode selection‌

Set the control mode (such as ±10V or PWM control of the directional valve) through the DIP switch or software. Set the ramp time (Ramp Time) to the initial value (50-100ms is recommended).

② Dead zone compensation‌

Use Rexroth dedicated software (such as IndraWorks) to calibrate the zero offset (Null Offset). The compensation value usually does not exceed ±5% of the rated current.

(2) Step response test

‌① Input step signal‌

Input a 10%-90% step signal and record the valve core displacement curve (it is recommended to use an oscilloscope or a dedicated diagnostic tool). Target value: response time ≤50ms (no load state).

‌② Adjust the gain parameter‌

Gradually increase the proportional gain (Kp) until the system has slight oscillations, and then reduce it to 80% of the critical value. Set the integral time (Ti) to 1/3~1/2 of the response time.

4. System Integration

(1) Pressure Characteristics Test

Set the proportional valve to pressure control mode and input step pressure commands (e.g., 25%, 50%, and 75% of rated pressure). Verify the deviation between the actual pressure and the set value: the steady-state error is required to be ≤±1.5% FS.

(2) Dynamic Characteristics Verification

Perform a sine sweep test (0.1Hz→10Hz) and analyze the phase margin (≥45°) and amplitude margin (≥6dB) using the Bode plot.

5. Common troubleshooting

(1) No valve spool response

Cable shield failure/power supply polarity reversed. Check shield grounding and verify 24V polarity.

(2) Pressure fluctuation > ±3%.

Oil contamination causes valve spool to become stuck. Check oil cleanliness and replace filter element.

(3) Step response overshoot > 10%.

Proportional gain too high. Reduce Kp value by 20% and re-adjust.

6. Maintenance Recommendations

‌ (1) Periodic Inspection

Check the valve core displacement sensor resistance value every 500 hours (standard range: 1-5kΩ). Replace the pilot filter element once a year.

‌ (2) Long-term out-of-service treatment

Drain the hydraulic oil in the valve cavity and inject Vg32 hydraulic oil as a rust prevention treatment.