• Brand: MOOG

• Model: D634-544A

• Series: D634 (ISO 4401‑05 / NG10)

• Structure: Pilotless, single‑stage, direct‑drive valve

• Drive: Permanent magnet linear force motor

• Feedback: Integrated LVDT spool position closed‑loop

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

• Signal Interface: ±10 V, ±10 mA, 4–20 mAMoog Inc.

• Protection Class: IP65

• Weight: Approx. 6.8 kg

• Mounting: ISO 4401‑05 (NG10)

Function & Positioning

Core Functions

• Precise Flow/Direction Control: Four‑way servo with spool closed‑loop for accurate position, speed, pressure, force regulation.

• Pilotless Operation: Eliminates pilot oil supply, simplifying circuits, reducing leaks, improving reliability.

• Spring Centering: Returns spool to neutral on power loss for safe, fail‑safe shutdown.

• Pressure‑Independent Dynamics: Direct‑drive design maintains stable response regardless of system pressure fluctuations.

Product Positioning

• Ultra‑high‑flow, high‑pressure hydraulic system core control component.

• Top‑tier performance alternative to traditional pilot‑operated servo valves, offering lowest maintenance, highest stability, ultimate precision.

• Optimized for 400 L/min nominal flow and 350 bar high‑pressure industrial closed‑loop applicationsMoog Inc..

Core Performance Parameters

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

• Max. T‑Port Pressure: ≤ 50 bar (without Y port); 350 bar (with Y port)Moog Inc.

• Rated Flow (Δp = 35 bar): 400 L/min

• Peak Flow: 480 L/min

• Null Leakage: 2.0–6.5 L/min

• Full‑Stroke Step Response: ≤ 28 ms

• ‑3 dB Bandwidth: 22–38 Hz

• Hysteresis: < 0.25% of full scale

• Resolution: < 0.10% of full scale

• Working Fluid: ISO 11158 mineral hydraulic oil

• Fluid Temperature: ‑20 °C to 80 °C

Universal Matching Accessories

• ISO 4401‑05 standard mounting manifold

• M18 6+PE‑pin electrical connector (IP65)Moog Inc.

• High‑precision hydraulic filter (10 μm)

• Special sealing kit (for ‑20 °C to 80 °C)

• Pressure sensor (0–350 bar)Moog Inc.

Applicable Equipment Fields

• Super‑large‑tonnage hydraulic presses and heavy forging lines

• Ultra‑high‑speed injection molding and large die‑casting machines

• Multi‑axis high‑load vibration test benches and fatigue rigs

• Heavy‑duty industrial hydraulic systems (steel, mining, marine, aerospace)

• High‑precision automatic closed‑loop control equipment requiring maximum flow