Model Code Explanation (D661-4027)

• D661: Series code (ISO 4401-05, integrated 24 VDC electronics)

• 4: Flow rating code (high flow)

• 02: Spool/pressure/configuration combination code

• 7: Electrical/feedback variant (command: ±10 V; feedback: 4–20 mA, fault-safe)

Technical Specifications

Electrical

• Supply: 24 VDC (18–32 VDC), quiescent 200 mA, dynamic 350 mA

• Command Signal: ±10 V (differential, 10 kΩ impedance)

• Feedback Signal: 4–20 mA (LVDT spool position)

• Connector: 6+PE (EN 175201-804)

• Protection Class: IP65 (connected)

Hydraulic

• Fluid: Mineral oil (DIN 51524), viscosity 15–45 mm²/s

• Temperature:

  • Ambient: −20°C to +60°C

  • Fluid: −20°C to +80°C

• Weight: Approx. 5.7 kg

• Seals: Standard NBR; optional FPM (fluorocarbon rubber)

Interface & Communication

Key Features

• ServoJet Pilot: Contamination-resistant, low leakage (<15 ml/min), long service life

• Integrated Closed-Loop Electronics: On-board PID, high accuracy and repeatability

• High Dynamic Response: ≤12 ms step response for high-speed, high-precision applications

• Low Null Leakage: Energy-efficient, suitable for long-term pressure-holding/standby systems

• Fail-Safe Design: Spool centers on power loss/fault; custom safe position available

Applications

• Industrial Automation: High-precision machine tools, CNC centers, robotic hydraulic systems

• Test Equipment: Material testing machines, fatigue test benches, hydraulic simulation platforms

• Metallurgy: Roll gap control, tension control systems

• Aerospace: Ground simulation equipment, flight test benches

Compatibility

• Series Compatibility: Interchangeable with D661 (G/C/A types), D662/D663 (ISO 4401-05)

• Upgrade Replacement: Direct drop-in for older D633/D634 servovalves for improved dynamic performance

• System Requirements: 24 VDC supply, analog controller (±10 V input/4–20 mA output), ISO 4401-05 standard manifold