D634-1025
The D634-1025 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.
Description
1. General Description
The D634-1025 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: 1025 = 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 connectedMoog Inc.. Rated flow is 90–100 L/min (23.8–26.4 gpm) at a 35 bar pressure drop per land, with maximum flow reaching approximately 180 L/min (47.5 gpm). Internal leakage is ≤0.50 L/min.
The valve operates with mineral oil conforming to ISO 11158 / DIN 51524 standards. Fluid temperature ranges from −20 °C to +80 °C (−4 °F to +176 °F). Recommended system cleanliness is ISO 4406 17/14/11 to ensure long service life.
3. Performance Characteristics
Typical full‑stroke step response time (0 to 100%) is 18–20 msMoog Inc.. Frequency response (−3 dB) is ≥70–80 Hz. Hysteresis is <0.40% full scale (FS), with resolution better than 0.12% FS. Null drift is <1.0% FS under a 60 K temperature change, and repeatability is <0.20% FS.
4. Electrical Specifications
Supply voltage is 24 VDC, tolerating 18–32 VDCMoog Inc.. Maximum operating current is 2.7 A. Control signal options are jumper‑selectable: ±10 V, ±10 mA, or 4–20 mAMoog Inc.. A 0–10 VDC spool position feedback signal is provided as standard.
The valve uses an M18 connector with 6 signal pins plus protective earth (PE), rated IP65 for environmental protectionMoog Inc.. Ambient temperature ranges from −20 °C to +60 °C (−4 °F to +140 °F). Electronics comply with CE EMC requirements (EN 61000‑6‑2, EN 61000‑6‑4).
5. Functional Principle
An LVDT displacement sensor continuously measures spool position and sends a feedback signal to the integrated electronics. The electronic module compares the command signal with the actual spool position, then drives the linear force motor to move the spool, adjusting flow rate and direction. The spring‑centering mechanism ensures the spool returns to neutral upon power failure, providing safe shutdown.
6. Installation
Mount the valve on a clean, flat surface following ISO 4401 Size 05 mounting dimensions. Ensure the mounting surface is smooth and free of debris. Tighten mounting bolts to the specified torque to avoid misalignment or mechanical shock. Horizontal installation is preferred for optimal air bleeding. Bleed all air from the valve and hydraulic lines before initial operation.
7. Wiring Definition
Pin 1: +24 VDC power
Pin 2: Power ground (0 V)
Pin 3: Command signal +
Pin 4: Command signal −
Pin 5: Spool position feedback output
Pin 6: Feedback ground
PE: Protective earth (chassis ground)
Use shielded twisted‑pair cable for signal wiring, and ensure the shield is grounded at one end only.
8. Maintenance
The valve is a sealed, integrated unit with no user‑serviceable internal parts. Regularly check hydraulic fluid contamination and replace filters as needed to maintain ISO 4406 17/14/11 cleanliness. Inspect the electrical connector for damage or corrosion periodically. Do not disassemble the valve; unauthorized disassembly voids the warranty.
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