MOOG D661-4849 Electro‑Hydraulic Servo Valve
May 29, 2026

MOOG D661-4849 Electro‑Hydraulic Servo Valve

Product Description The D661-4849 is a two‑stage, pilot‑operated ServoJet® servo valve from MOOG’s D661 high‑response series, featuring integrated 24 VDC amplifier and LVDT spool position feedback. It complies with ISO 4401‑05 (NG10) mounting standard, designed for high‑flow, high‑precision closed‑loop hydraulic control in industrial and test applications.

Description

Model Definition

D661 = Series (integrated electronics, 24 VDC, NG10)

4849 = Spool/sleeve assembly; rated flow 120 L/min @ ΔP=35 bar

Typical full config example: P120HAAM7NSX2‑A

P120 = High flow & high frequency response version

HAAM = Standard hydraulic layout, 24 VDC, ±10 V/±10 mA command, centered null

7 = 7+PE connector, IP65

NSX2 = NBR seals, wide temperature range, LVDT feedback 4–20 mA

A = Standard ServoJet® pilot stage

Technical Specifications

Hydraulic Parameters

Rated flow: 120 L/min (ΔP=35 bar)

Max working pressure: 350 bar (P/A/B); 210 bar (internal drain T) / 350 bar (external drain T)Moog Inc.

Step response: 8–12 ms (0→100%, 210 bar)

Hysteresis: <0.2%

Resolution: <0.1%

Null drift: <1.2% (ΔT=55 K)

Null leakage: <18 mL/min

Fluid cleanliness: NAS 1638 Class 6 / ISO 4406 18/15Moog Inc.

Electrical Parameters

Power supply: 24 VDC (18–32 VDC)Moog Inc.

Control signal: ±10 V (differential) or ±10 mAMoog Inc.

Feedback signal: 4–20 mA (LVDT spool position)Moog Inc.

Connector: 7+PE, IP65Moog Inc.

Current draw: ≤700 mA

Physical & Environmental

Operating temperature: −40 ℃ to +85 ℃

Weight: approx. 9.2 kg

Interface & Communication Configuration

Hydraulic interface: P/A/B/T, ISO 4401‑05 (NG10)Moog Inc.

Electrical interface:

Power: 24 VDC, GND, PEMoog Inc.

Command: ±10 V / ±10 mAMoog Inc.

Feedback: 4–20 mA (spool position)Moog Inc.

Status: Fault alarm output

Core Functions

ServoJet® pilot stage: Superior contamination resistance, low null drift, extended service lifeMoog Inc.

Integrated high‑response amplifier: Built‑in PID, dead‑zone compensation, overload protectionMoog Inc.

LVDT closed‑loop feedback: High linearity and precision across full stroke穆格中国

Fail‑Safe centering: Spool returns to neutral on power lossMoog Inc.

High‑flow dynamics: Optimized for 120 L/min with fast response for high‑flow precision applications

Application Scenarios

Metallurgy: High‑flow AGC roll gap control, tension control for thick plate mills

Test equipment: High‑precision dynamic material testers, large‑scale high‑frequency vibration tables

Industrial automation: Large CNC machine tools, heavy‑duty hydraulic presses, large injection molding machines

Energy & heavy industry: Wind turbine pitch control, marine main hydraulic systems, heavy‑duty industrial robot hydraulic drives

Usage & Maintenance

Installation: Horizontal/vertical mounting; avoid severe vibration

Fluid: ISO VG46 mineral oil; maintain cleanliness per NAS 1638 Class 6Moog Inc.

Commissioning: Apply 24 VDC power; connect ±10 V/±10 mA command; calibrate zero and gain via 4–20 mA feedbackMoog Inc.

Maintenance: Inspect fluid contamination regularly; calibrate zero/gain every 6 months; avoid long idle periods at high pressure


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