1. General Description

2. Model Code (D634‑371C)

• D634: Series = Direct drive servo valve, ISO 4401 Size 05 (NG10)

• 371: Configuration = ultra‑high‑flow, medium‑dynamic spool, 24 VDC, industrial‑tuned

• C: Revision C (current production baseline)

3. Hydraulic Specifications

• Mounting: ISO 4401 Size 05 (NG10)Moog Inc.

• Max Working Pressure (P/A/B): 350 bar (5,000 psi)Moog Inc.

• T‑port Pressure (no Y port): 50 bar (725 psi)Moog Inc.

• T‑port Pressure (with Y port): 350 bar (5,000 psi)Moog Inc.

• Rated Flow (Δp = 35 bar/orifice): 180 L/min (47.5 gpm)

• Max Flow: ≈250 L/min

• Internal Leakage: ≤3.5 L/min

• Fluid: Mineral oil (ISO 11158 / DIN 51524)Moog Inc.

• Fluid Temp: −20 °C to +80 °CMoog Inc.

• Fluid Cleanliness: ISO 4406 17/14/11Moog Inc.

• Weight: ≈7.3 kg

4. Dynamic Performance

• Full‑stroke Step Response: ≤24 ms

• −3 dB Bandwidth: 45–55 Hz

• Hysteresis: <0.30% full scale

• Resolution: <0.15% full scale

• Null Drift (ΔT = 55 K): <1.8% full scale

5. Electrical Specifications

• Supply Voltage: 24 VDC (18–32 VDC)Moog Inc.

• Max Operating Current: 3.0 A

• Standard Command Signal: ±10 VMoog Inc.

• Optional Signals: ±10 mA, 4–20 mAMoog Inc.

• Spool Position Feedback: 0–10 VDC (or 4–20 mA)Moog Inc.

• Connector: M18, 6 pins + PE, IP65Moog Inc.

• Ambient Temp: −20 °C to +60 °CMoog Inc.

• EMC: CE compliantMoog Inc.

6. Key Features

• Pilotless direct drive: No external pilot supply, simpler installationMoog Inc.

• Ultra‑high flow: Highest flow in D634 series for high‑demand industrial systems

• Pressure‑independent dynamics: Stable under varying loadsMoog Inc.

• Robust & reliable: Designed for continuous high‑flow industrial operation

• Fail‑safe spring return: Protects machinery on power lossMoog Inc.

• Integrated PWM electronics: Compact, IP65 protectionMoog Inc.

7. Typical Applications

• Large industrial hydraulic presses & heavy‑duty injection molding

• High‑flow structural test rigs & fatigue testing machines

• Dynamic vibration tables (medium‑speed, high‑force)

• Closed‑loop control for large hydraulic actuators & motion simulators

8. Pin Assignment (6+PE)

1. +24 VDCMoog Inc.

2. Power GroundMoog Inc.

3. Command +Moog Inc.

4. Command –Moog Inc.

5. Position Feedback OutMoog Inc.

6. Feedback GroundMoog Inc.

   PE: Protective Earth

   Use shielded twisted pair for all signal wiresMoog Inc..

9. D634 Family Quick Compare (346C/358C/361C/362C/368C/371C)