D634-322C
May 25, 2026

D634-322C

D634-322C is a single-stage pilotless direct drive servo valve of MOOG D634 series. Adopting permanent magnet linear force motor, the valve drives spool directly without pilot oil supply. Built-in LVDT realizes closed-loop spool position control with outstanding linearity and repeatability. Dynamic performance keeps stable against pressure variation. Spring centering structure returns spool to neutral position safely when power cuts off. This model fits medium flow and medium dynamic closed-loop hydraulic control.

Description

1. General Description

D634-322C is a single-stage pilotless direct drive servo valve of MOOG D634 series. Adopting permanent magnet linear force motor, the valve drives spool directly without pilot oil supply. Built-in LVDT realizes closed-loop spool position control with outstanding linearity and repeatability. Dynamic performance keeps stable against pressure variation. Spring centering structure returns spool to neutral position safely when power cuts off. This model fits medium flow and medium dynamic closed-loop hydraulic control.

2. Model Definition

D634: Direct drive servo valve series
322: Basic flow and structure configuration
C: Product revision version

3. Hydraulic Specifications

Mounting standard: ISO 4401 Size 05 (NG10)
Max working pressure(P,A,B): 350 bar
T port maximum pressure: 50 bar
Rated flow at 35 bar pressure drop: 60 L/min
Maximum flow rate: approx 180 L/min
Internal leakage: ≤1.2 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: approx 6.3 kg

4. Dynamic Performance

Full stroke step response: ≤20 ms
-3dB frequency bandwidth: 45~55 Hz
Hysteresis: less than 0.2% full scale
Resolution: less than 0.1% full scale
Null drift under 55K temperature change: less than 1.5% full scale

5. Electrical Specifications

Supply voltage: 24 VDC, working range 18~32 VDC
Maximum operating current: 3.5 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 working temperature: -20 °C ~ +60 °C
EMC certification: CE compliant

6. Key Features

No pilot oil required, simple installation and maintenance
High precision closed-loop position control
Stable dynamic response under variable load
Fail-safe protection with spring centering design
Integrated electronic drive, compact and durable structure

7. Application Scope

Medium flow hydraulic press equipment
Material dynamic and fatigue testing machine
Industrial automatic motion control system
Position, speed and pressure closed-loop control hydraulic system

8. Pin Assignment

Pin 1: +24 VDC
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
Signal wiring suggestion: Use shielded twisted pair cable


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