1. Overview

2. Basic Information

• Brand: MOOG

• Model: D634-508

• Type: Pilotless electro‑hydraulic direct‑drive servo valve (DDV)

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

• Drive: Permanent magnet linear force motor (no pilot oil needed)Moog Inc.

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

• Feedback: Integrated LVDT spool closed‑loop

• Reset: Spring‑centered; failsafe to neutral on power lossMoog Inc.

• Protection: IP65

• Weight: ~6.3 kg

• Connector: M18 6‑pin + PEMoog Inc.

3. Function & Positioning

• Core Function: Precision flow/direction control via analog signals; closed‑loop regulation of position, velocity, pressure, force; excellent repeatability, low hysteresis, and pressure‑independent dynamic responseMoog Inc..

• Positioning: Top‑grade high‑flow & ultra‑high‑dynamic model in D634 series, for applications requiring max flow + fastest response + highest precision.

4. Key Performance Parameters

Hydraulic

• Max Working Pressure (P/A/B): 350 bar

• Max T‑port Pressure: ≤50 bar (no Y port); ≤350 bar (with Y port)Moog Inc.

• Rated Flow (Δp = 35 bar): 100 L/min

• Max Flow: ~190 L/min

• Null Leakage: 0.2–1.5 L/min

• Fluid: ISO 11158 mineral oil

• Fluid Temp: −20 °C to 80 °C

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

Dynamic

• Step Response (0→100%): ≤10 ms

• −3 dB Bandwidth: 70–90 Hz

• Hysteresis: <0.12% full scale

• Resolution: <0.05% full scale

• Temp Drift: <1.0% full scale (ΔT = 55 K)

Electrical

• Control Signal (Std): ±10 VDCMoog Inc.

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

• Spool Feedback: 0–10 VDC

• Ambient Temp: −20 °C to 60 °C

• Certification: CE

5. Applications

• High‑speed & ultra‑high‑force hydraulic presses

• Large injection molding & die‑casting machines (high‑cycle)

• Dynamic material test systems (high‑frequency fatigue, vibration)

• Wind turbine pitch control (offshore, high power)

• Heavy‑duty forging & extrusion lines (fast stroke)

• High‑load motion simulation platforms (aerospace, automotive)