1. Model Definition

• D634: ISO 4401 Size 05 direct drive servo valve series

• 391: Highest flow & maximum power rating in D634 series

• C: Revision C

2. Hydraulic Specifications

• Mounting: ISO 4401‑05 (NG10)

• Max working pressure (P/A/B): 350 barMoog Inc.

• T‑port pressure (no Y): ≤ 50 barMoog Inc.

• T‑port pressure (with Y): ≤ 350 barMoog Inc.

• Rated flow (Δp = 35 bar): 330 L/min

• Peak flow: approx. 440 L/min

• Internal leakage: ≤ 6.0 L/min

• Fluid: ISO 11158 mineral oil (DIN 51524)

• Fluid temperature: −20 °C ~ +80 °C

• Fluid cleanliness: ISO 4406 17/14/11

• Weight: approx. 9.0 kg

3. Dynamic Performance

• Full‑stroke step response: ≤15 msMoog Inc.

• −3 dB bandwidth: 70–80 Hz

• Hysteresis: <0.20% full scale

• Resolution: <0.10% full scale

• Null drift (ΔT = 55 K): <1.2% full scale

4. Electrical Specifications

• Supply: 24 VDC (18–32 VDC)Moog Inc.

• Max operating current: 4.8 A

• Standard command: ±10 VMoog Inc.

• Optional command: ±10 mA / 4–20 mAMoog Inc.

• Spool position feedback: 0–10 VDC

• Connector: M18, 6‑pin + PE, IP65Moog Inc.

• Ambient temperature: −20 °C ~ +60 °C

• EMC: CE compliant

5. Key Features

• Pilotless direct drive: Permanent‑magnet linear force motor, no pilot oil required穆格中国

• Highest flow density: Ultimate model for extreme high‑flow hydraulic systems

• Pressure‑independent dynamics: Stable response under varying loads穆格中国

• Closed‑loop control: Integrated LVDT for precise spool position feedbackMoog Inc.

• Fail‑safe: Spring‑centered, returns to neutral on power lossMoog Inc.

• Integrated electronics: Compact, rugged, PWM‑driven, EMI‑hardened designMoog Inc.

6. Typical Applications

• Ultra‑high‑force hydraulic presses, heavy forging & extrusion lines

• Large aerospace/automotive structural test benches

• High‑load vibration & motion simulators

• Industrial closed‑loop control (position/velocity/pressure) for extreme duty cycles

7. Pin Assignment

1. +24 VDC Power

2. Power Ground

3. Command +

4. Command −

5. Position Feedback Output

6. Feedback Ground

   PE: Protective Earth

   Shielded twisted pair recommended for signal wiring.