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D634-346C

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D634-346C
May 25, 2026

D634-346C

The D634‑346C is a single‑stage, pilotless direct drive servo valve (DDV) in the MOOG D634 family, built to ISO 4401 Size 05 (NG10). It uses a permanent magnet linear force motor to drive the spool directly — no pilot oil required. An internal LVDT provides closed‑loop spool position feedback for excellent linearity and repeatability. Dynamic performance is pressure‑independent, and spring centering ensures fail‑safe return to neutral on power loss. Compared to 345C: highest flow in D634 series, slightly lower bandwidth, heavy‑duty industrial rating.

Description

1. General Description

The D634‑346C is a single‑stage, pilotless direct drive servo valve (DDV) in the MOOG D634 family, built to ISO 4401 Size 05 (NG10). It uses a permanent magnet linear force motor to drive the spool directly — no pilot oil required. An internal LVDT provides closed‑loop spool position feedback for excellent linearity and repeatabilityMoog Inc..Dynamic performance is pressure‑independent, and spring centering ensures fail‑safe return to neutral on power lossMoog Inc..Compared to 345C: highest flow in D634 series, slightly lower bandwidth, heavy‑duty industrial rating.

2. Model Code (D634‑346C)

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

  • 346: Configuration = maximum‑flow spool, 24 VDC industrial electronics, top‑flow rating

  • C: Revision C (current production baseline)

3. Hydraulic Specifications

  • Mounting: ISO 4401 Size 05 (NG10)Moog Inc.

  • 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): 200 L/min (52.8 gpm)

  • Max Flow: ≈280 L/min

  • Internal Leakage: ≤4.0 L/min

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

  • Fluid Temp: −20 °C to +80 °C

  • Fluid Cleanliness: ISO 4406 17/14/11

  • Weight: ≈7.2 kg

4. Dynamic Performance

  • Full‑stroke Step Response: ≤30 msMoog Inc.

  • −3 dB Bandwidth: 35–45 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: 3.0 A

  • Standard Command Signal: ±10 VMoog Inc.

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

  • Spool Position Feedback: 0–10 VDC (or 4–20 mA)

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

  • Ambient Temp: −20 °C to +60 °C

  • EMC: CE compliant

6. Key Features

  • Pilotless design: Simple installation, no external pilot supplyMoog Inc.

  • Max flow in D634 series: 200 L/min rated, for extreme‑demand hydraulic systems

  • Pressure‑independent dynamics: Stable response under varying loadsMoog Inc.

  • Fail‑safe: Spring‑centered; returns to neutral on power lossMoog Inc.

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

7. Typical Applications

  • Ultra‑high‑flow hydraulic presses

  • Large‑scale structural fatigue test rigs

  • Heavy‑duty industrial automation

  • Closed‑loop position/velocity/pressure control for large 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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