D634-317C
May 25, 2026

D634-317C

The D634-317C is a high-response, single-stage direct drive servo valve (DDV) from MOOG’s D634 series. It uses a permanent magnet linear force motor to drive the spool without pilot oil. An integrated LVDT provides closed-loop spool position control for excellent linearity and repeatability. Its direct-drive design offers pressure-independent dynamics, and spring centering ensures a fail-safe neutral position on power loss. This model is optimized for fast response (≈80 Hz) and 60 L/min rated flow, suitable for high-performance closed-loop motion control.

Description

1. General Description

The D634-317C is a high-response, single-stage direct drive servo valve (DDV) from MOOG’s D634 series. It uses a permanent magnet linear force motor to drive the spool without pilot oil. An integrated LVDT provides closed-loop spool position control for excellent linearity and repeatability. Its direct-drive design offers pressure-independent dynamics, and spring centering ensures a fail-safe neutral position on power loss. This model is optimized for fast response (≈80 Hz) and 60 L/min rated flow, suitable for high-performance closed-loop motion control.

2. Hydraulic Specifications

  • Mounting: ISO 4401 Size 05 (NG10)

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

  • T-Port Pressure: 50 bar (no Y port) / 350 bar (with Y port)Moog Inc.

  • Rated Flow (Δp = 35 bar per land): 60 L/min (15.9 gpm)

  • Max Flow: ≈110 L/min (29.1 gpm)

  • Internal Leakage: ≤1.0 L/min

  • Fluid: Mineral oil (ISO 11158)

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

  • Filtration: ISO 4406 17/14/11

  • Weight: ≈6.3 kg (13.9 lb)

3. Dynamic Performance (Typical)

  • Step Response (0→100% stroke): ≤12 msMoog Inc.

  • −3 dB Bandwidth: 75–85 Hz

  • Hysteresis: <0.2% full scale

  • Resolution: <0.1% full scale

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

4. Electrical Specifications

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

  • Max Current: 3.5 A

  • Control Signal (Optional): ±10 V, ±10 mA, 4–20 mAMoog Inc.

  • Feedback Output: 0–10 VDC (spool position)

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

  • Ambient Temperature: −20 °C to +60 °C

  • EMC: CE compliant

5. Key Features

  • Pilotless design: Simplifies installation and maintenance

  • High-response closed-loop: LVDT feedback for precision

  • Pressure-independent dynamics: Stable performance under varying loads

  • Fail-safe: Spring-centered on power loss

  • Compact & robust: Suits industrial environments

6. Applications

  • High-speed hydraulic presses

  • Material fatigue test benches

  • Industrial automation

  • Closed-loop position, velocity, and pressure control systems

7. Pin Assignment

  1. +24 VDC

  2. Power GND

  3. Command +

  4. Command −

  5. Position Feedback Out

  6. Feedback GND

    PE: Protective Earth

    Recommendation: Use shielded twisted-pair cable for signals.


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