1. Model Code (D634‑526)

• D634: Series, ISO 4401‑05 (NG10)

• 526: High‑flow model (higher than 525A)

• (suffix like A/B denotes electronics/control signal; base 526 is standard analog)

2. Basic Data

• Brand: MOOG

• Model: D634-526

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

• Mounting: ISO 4401‑05 (NG10)

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

• Power Supply: 24 VDC (18–32 VDC), max 2.2 AMoog Inc.

• Feedback: Integrated LVDT spool position closed‑loop

• Centering: Spring‑centered; fail‑safe neutral on power lossMoog Inc.

• Protection: IP65

• Weight: ~6.8 kg

• Connector: M18 6‑pin + PEMoog Inc.

3. Hydraulic Specifications

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

• Max T‑port pressure (internal drain): ≤50 barMoog Inc.

• Rated flow (Δp = 35 bar): ~140 L/min (higher than 525A’s 120 L/min)

• Peak flow: ~200 L/min

• Null leakage: 0.5–3.0 L/min

• Fluid: ISO 11158 mineral oil

• Fluid temperature: –20 °C to 80 °C

• Cleanliness: ISO 4406 17/14/11

4. Dynamic Performance

• Full‑stroke step response: ≤25 msMoog Inc.

• –3 dB bandwidth: 40–60 Hz

• Hysteresis: <0.25% full scale

• Resolution: <0.10% full scale

• Temperature drift: <1.5% full scale

5. Electrical Data

• Standard control signal: ±10 VDCMoog Inc.

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

• Spool feedback signal: 0–10 VDC

• Ambient temperature: –20 °C to 60 °C

• Certification: CE compliant

6. Key Features

• No pilot oil: Higher reliability, lower contamination riskMoog Inc.

• Integrated closed‑loop LVDT: High accuracy and repeatabilityMoog Inc.

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

• 24 VDC PWM electronics: Energy‑efficient, low null powerMoog Inc.

• Fail‑safe spring return: Safe shutdown on power lossMoog Inc.

7. Applications

• High‑flow hydraulic presses and heavy forging equipment

• Large‑tonnage injection molding and die‑casting machines

• High‑force, large‑displacement vibration test benches

• Heavy‑duty industrial hydraulics requiring 140 L/min+ flow

• Closed‑loop position/velocity/pressure control for large actuators