D634-554A
May 25, 2026

D634-554A

D634‑554A is a single‑stage, pilotless direct drive servo valve (DDV) in the MOOG D634 line (ISO 4401‑05 / NG10). It uses a permanent magnet linear force motor and integrated LVDT spool feedback, designed for medium‑high‑flow, high‑pressure, high‑response industrial closed‑loop control

Description

Basic Information

  • Brand: MOOG

  • Model: D634‑554A

  • Series: D634 (Direct Drive Valve, DDV)

  • Type: Single‑stage, pilotless, direct‑operated servo valve

  • Mounting: ISO 4401‑05 (NG10)

  • Drive: Permanent magnet linear force motor

  • Feedback: Built‑in LVDT spool position closed loop

  • Electronics: Integrated 24 VDC PWM drive

  • Protection: IP65

  • Weight: Approx. 6.3 kg (13.9 lb)Moog Inc.


Hydraulic Specifications

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

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

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

  • Rated flow (Δp = 35 bar): 100 L/min (26.4 gpm)

  • Peak flow: ≈180 L/min (47.5 gpm)

  • Null leakage: 2.5–7 L/min

  • Fluid: ISO 11158 mineral hydraulic oil

  • Viscosity: 15–100 mm²/s (allowable 5–400 mm²/s)

  • Fluid temperature: −20 °C to +80 °C


Electrical Specifications

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

  • Max current: 2.2 A

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

  • Connector: 6‑core + PE, IP65Moog Inc.

  • Electronics: SMD technology, PWM current output, EMC certified


Dynamic Performance (Typical)

  • Full‑stroke step response: ≤20 msMoog Inc.

  • −3 dB bandwidth: 15–25 Hz

  • Hysteresis: <0.25% of full scale

  • Resolution: <0.10% of full scale

  • Temperature drift (ΔT = 55 K): <1.5% of full scale


Key Features

  • Pilotless direct drive: No pilot oil needed; simpler piping, lower leakage, higher reliability.

  • Linear force motor: High, stable force; pressure‑independent dynamics.

  • LVDT closed‑loop feedback: High positioning accuracy and repeatability.

  • Spring centering: Fail‑safe return to neutral on power loss.

  • Low power consumption: Minimal heat at null.

  • High contamination resistance: Suitable for harsh industrial environments.


Applications

  • Medium‑large hydraulic presses & forging machines

  • Injection molding & die‑casting equipment

  • Vibration & fatigue test benches

  • Heavy‑duty industrial hydraulic systems

  • Precision position, force & speed closed‑loop control


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