1. General Description
The D634-1027 is a single‑stage, direct‑drive servo valve (DDV) with integrated 24 VDC electronics and LVDT closed‑loop spool position feedback. It uses a permanent magnet linear force motor—no pilot oil required—for high reliability and fast response. The valve is a 4‑way, spring‑centered, zero‑lap spool design, offering fail‑safe operation by returning to neutral when power is lost。
Series: D634 (ISO 4401 Size 05 / NG10)
Model: 1027 = extra‑high‑flow, standard‑dynamic response
Applications: High‑flow injection molding, hydraulic presses, machine tools, and precision closed‑loop motion control systems.
2. Hydraulic Specifications
Maximum working pressure for ports P, A, and B is
350 bar (5,000 psi)Moog Inc.. Port T withstands
50 bar (725 psi) without an external drain (Y port), and
350 bar (5,000 psi) when the Y port is connected
Moog Inc..
Rated flow:
110–120 L/min (29.1–31.7 gpm) at 35 bar pressure drop per land.
Max flow: approx.
220 L/min (58.1 gpm).
Internal leakage:
≤0.60 L/min.
Operating fluid: Mineral oil per
ISO 11158 / DIN 51524.
Fluid temperature:
−20 °C to +80 °C.
Recommended cleanliness:
ISO 4406 17/14/11.
3. Performance Characteristics
Step response (0→100%): 19–21 ms
Frequency response (−3 dB): ≥65–75 Hz
Hysteresis: <0.45% FS
Resolution: <0.15% FS
Null drift (60 K change): <1.2% FS
Repeatability: <0.25% FS
4. Electrical Specifications
Supply: 24 VDC (18–32 VDC)Moog Inc.
Max current: 3.0 A
Control signals (jumper selectable): ±10 V, ±10 mA, 4–20 mAMoog Inc.
Feedback: 0–10 VDC spool position output
Connector: M18, 6+PE, IP65Moog Inc.
Ambient temp: −20 °C to +60 °C
EMC: CE compliant (EN 61000‑6‑2/4)
5. Functional Principle
An LVDT continuously measures spool position and feeds the signal to the integrated electronics. The controller compares command and actual position, then drives the linear force motor to move the spool, adjusting flow rate and direction. Spring centering returns the spool to neutral on power loss for safe shutdown.
6. Installation
Mount per ISO 4401 Size 05 on a clean, flat surfaceMoog Inc.. Use specified torque; avoid shock and misalignment. Horizontal mounting preferred for air bleeding. Bleed all air from valve and lines before operation.
7. Wiring Definition
Use shielded twisted‑pair cables; ground shield at one end only.
8. Maintenance
Sealed integrated unit; no user‑serviceable parts. Monitor fluid contamination; replace filters to maintain ISO 4406 17/14/11. Inspect connector for damage/corrosion. Do not disassemble—unauthorized disassembly voids warranty。
Get a Quote