1. Product Brief

2. Basic Information

• Brand: MOOG

• Model: D634-405C

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

• Mounting: ISO4401-05 (NG10)

• Drive: Permanent magnet linear force motor (no pilot oil required)

• Power: 24VDC (18–32VDC operating range)

• Feedback: Integrated LVDT spool position closed‑loop

• Reset: Spring centering (failsafe to neutral on power loss)

• Protection: IP65

• Weight: Approx. 12.8 kg

• Also known as: Extra‑high‑flow DDV servo valve, high‑pressure hydraulic control valve

3. Function & Positioning

• Core Function: Precise hydraulic flow/direction control via analog signals; closed‑loop control of position, velocity, pressure, and force. Low internal leakage, excellent contamination resistance, and pressure‑independent dynamics.

• Positioning: Top‑tier, maximum‑flow model in D634 series; replaces complex multi‑stage valve assemblies for extreme heavy‑load hydraulics.

4. Core Performance Parameters

Hydraulic

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

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

• Rated flow @35 bar Δp: 740–780 L/min

• Peak flow: Approx. 900 L/min

• Null leakage: ≤12.5 L/min

• Fluid: ISO 11158 mineral oil

• Fluid temp: −20°C to 80°C

• Cleanliness: ISO 4406 17/14/11

Dynamic

• Full‑stroke step response: ≤6.5 ms

• −3dB bandwidth: 125–135 Hz

• Hysteresis: <0.10% full scale

• Resolution: <0.02% full scale

• Temperature drift: <0.4% full scale

Electrical

• Max operating current: 8.0 A

• Standard control signal: ±10 VDCMoog Inc.

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

• Spool feedback signal: 0–10 VDC

• Connector: M18 6‑pin + PEMoog Inc.

• Ambient temp: −20°C to 60°C

• Certification: CE compliant

5. Recommended Accessories

• Shielded twisted‑pair signal cable

• M18 waterproof mating connector

• ISO4401-05 standard manifold

• High‑precision hydraulic filter

• 24VDC low‑ripple power supply

• Servo controller, displacement/pressure sensors

6. Applications

• Heavy forging, extrusion, and ultra‑high‑pressure hydraulic presses

• Aerospace & automotive structural test benches

• High‑load vibration test systems & motion simulators

• Marine & offshore hydraulic control systems

• Large construction machinery & wind turbine hydraulic units