D634-381C
May 25, 2026

D634-381C

D634-381C is a member of MOOG D634 direct drive servo valve series with standard ISO 4401 Size 05 mounting interface. The spool is directly driven by permanent magnet linear force motor with no pilot oil needed. Built-in LVDT achieves closed-loop spool position control to ensure superior accuracy and repeatability. Dynamic performance stays stable regardless of pressure changes. Spring centering structure brings spool back to neutral position automatically for fail-safe protection upon power loss. This model features moderate flow and high dynamic response for high precision industrial control.

Description

1. General Description

D634-381C is a member of MOOG D634 direct drive servo valve series with standard ISO 4401 Size 05 mounting interface. The spool is directly driven by permanent magnet linear force motor with no pilot oil needed. Built-in LVDT achieves closed-loop spool position control to ensure superior accuracy and repeatability. Dynamic performance stays stable regardless of pressure changes. Spring centering structure brings spool back to neutral position automatically for fail-safe protection upon power loss. This model features moderate flow and high dynamic response for high precision industrial control.

2. Model Definition

D634: Direct drive servo valve series
381: Medium flow high dynamic configuration
C: Revision version C

3. Hydraulic Specifications

Mounting standard: ISO 4401 Size 05 (NG10)
Max working pressure of P, A, B ports: 350 bar
Max pressure of T port: 50 bar
Rated flow at 35 bar pressure drop: 90 L/min
Maximum flow rate: approximately 140 L/min
Internal leakage: ≤2.1 L/min
Applicable fluid: ISO 11158 mineral oil
Fluid temperature range: -20 °C ~ +80 °C
Required fluid cleanliness: ISO 4406 17/14/11
Total weight: approximately 6.9 kg

4. Dynamic Performance

Full stroke step response: ≤17 ms
-3dB frequency bandwidth: 62~72 Hz
Hysteresis: less than 0.20% full scale
Position resolution: less than 0.10% full scale
Null drift under 55K temperature change: less than 1.2% full scale

5. Electrical Specifications

Supply voltage: 24 VDC, working range 18~32 VDC
Maximum operating current: 2.7 A
Standard control signal: ±10 V
Optional signal: ±10 mA, 4-20 mA
Spool position feedback output: 0-10 VDC
Connector type: M18, 6 pins with PE terminal, IP65 protection grade
Ambient temperature: -20 °C ~ +60 °C
EMC certification: CE compliant

6. Key Features

Pilotless design reduces installation difficulty and maintenance cost
Fast dynamic response meets high-speed control requirements
Pressure independent characteristics maintain steady working state
High precision control realizes delicate motion adjustment
Automatic spring reset ensures safe operation under power failure
Integrated electronic drive owns compact structure and good durability

7. Application Scope

High precision hydraulic pressing equipment
Aerospace and automobile fatigue testing machines
High frequency vibration simulation platforms
Precision closed-loop position, velocity and pressure control systems

8. Pin Assignment

Pin 1: +24 VDC power
Pin 2: Power ground
Pin 3: Command signal positive
Pin 4: Command signal negative
Pin 5: Position feedback output
Pin 6: Feedback ground
PE: Protective earth
Shielded twisted pair cable is recommended for signal wiring


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