Basic Information

• Brand: MOOG

• Model: D634‑558

• Series: D634 (Direct Drive Valve, DDV)

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

• Mounting: ISO 4401‑05 (NG10)

• Drive: High‑thrust 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)

Hydraulic Specifications

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

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

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

• Rated flow (Δp = 35 bar): 180 L/min (47.5 gpm)

• Peak flow: ≈250 L/min (66.0 gpm)

• Null leakage: 4–10 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)

• Max current: 3.0 A

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

• Connector: 6‑core + PE, IP65

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

Dynamic Performance (Typical)

• Full‑stroke step response: ≤35 ms

• −3 dB bandwidth: 8–15 Hz

• Hysteresis: <0.35% of full scale

• Resolution: <0.20% of full scale

• Temperature drift (ΔT = 55 K): <2.0% of full scale

Key Features

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

• High‑flow & high‑thrust design: Optimized for max flow in D634 series; suitable for large‑scale hydraulic systems。

• LVDT closed‑loop feedback: Ensures high positioning accuracy and repeatability。

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

• Pressure‑independent dynamics: Stable performance under varying loads。

• Robust construction: Suitable for harsh industrial environments。

Applications

• Super‑large hydraulic presses and heavy forging equipment

• Ultra‑high‑tonnage injection molding and die‑casting machines

• High‑force & high‑flow vibration test benches

• Heavy‑duty industrial hydraulic systems requiring maximum flow

• Precision position, force & speed closed‑loop control