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D634-335C

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D634-335C
May 25, 2026

D634-335C

The D634-335C is a single-stage, pilotless direct drive servo valve (DDV) from the MOOG D634 series, built to the ISO 4401 Size 05 (NG10) mounting standard. It uses a permanent magnet linear force motor to drive the spool directly—no pilot oil required. An LVDT provides closed-loop spool position feedback for outstanding linearity and repeatability. Direct drive makes dynamic performance independent of pressure; spring centering ensures a fail-safe return to neutral on power loss. Compared to the 331C: higher flow (100 L/min), same high bandwidth, robust industrial configuration.

Description

1. General Description

The D634-335C is a single-stage, pilotless direct drive servo valve (DDV) from the MOOG D634 series, built to the ISO 4401 Size 05 (NG10) mounting standard. It uses a permanent magnet linear force motor to drive the spool directly—no pilot oil required. An LVDT provides closed-loop spool position feedback for outstanding linearity and repeatability. Direct drive makes dynamic performance independent of pressure; spring centering ensures a fail-safe return to neutral on power loss.
Compared to the 331C: higher flow (100 L/min), same high bandwidth, robust industrial configuration.

2. Model Definition (D634-335C)

  • D634: Series = Direct drive servo valve, ISO 4401 Size 05 (NG10)

  • 335: Configuration code (100 L/min, high-flow spool, 24 VDC industrial electronics)

  • C: Revision C (latest baseline)

3. Hydraulic Specifications

  • Mounting: ISO 4401 Size 05 (NG10)

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

  • T Port Pressure (no Y port): 50 bar (725 psi)Moog Inc.

  • T Port Pressure (with Y port): 350 bar (5,000 psi)Moog Inc.

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

  • Maximum Flow: ≈180 L/min

  • Internal Leakage: ≤2.0 L/min

  • Fluid: Mineral oil (ISO 11158 / DIN 51524)

  • Fluid Temp: -20 °C to +80 °C

  • Fluid Cleanliness: ISO 4406 17/14/11

  • Weight: ≈6.5 kg

4. Dynamic Performance

  • Full-Stroke Step Response: ≤20 ms

  • -3 dB Bandwidth: 50–60 Hz

  • Hysteresis: <0.2% full scale

  • Resolution: <0.1% full scale

  • Null Drift (ΔT=55 K): <1.5% full scale

5. Electrical Specifications

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

  • Max Operating Current: 2.2 A

  • Standard Command Signal: ±10 VMoog Inc.

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

  • Spool Position Feedback: 0–10 VDC

  • Connector: M18, 6 pins + PE, IP65Moog Inc.

  • Ambient Temp: -20 °C to +60 °C

  • EMC: CE compliant

6. Key Features

  • Pilotless design: Easy installation, no external pilot supply

  • High flow & precision: 100 L/min with closed-loop position control

  • Pressure-independent dynamics: Stable response under varying loads

  • Fail-safe: Spring-centered, returns to neutral on power loss

  • Integrated electronics: Compact, protected, and ready for use

7. Applications

  • High-tonnage hydraulic presses

  • Large-scale fatigue test systems

  • High-speed industrial automation

  • Closed-loop position/velocity/pressure control for heavy machinery

8. Pin Assignment (6+PE)

  1. +24 VDC

  2. Power Ground

  3. Command +

  4. Command –

  5. Position Feedback Out

  6. Feedback Ground

    PE: Protective Earth

    Use shielded twisted pair for all signal wires.


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