Model Definition

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

• 4790 = Spool/sleeve assembly; rated flow 200 L/min @ ΔP=35 bar

• Typical full config example: P20HDAM6NSF2‑A

  • P20 = Medium‑high flow & high frequency response version

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

  • 6 = 6+PE connector, IP65Moog Inc.

  • NSF2 = NBR seals, wide temperature range, LVDT feedback 4–20 mA

  • A = Standard ServoJet® pilot stageMoog Inc.

Technical Specifications

Hydraulic Parameters

• Rated flow: 200 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: 8–14 ms (0→100%, 210 bar)

• Hysteresis: <0.2%

• Resolution: <0.1%

• Null drift: <1.5% (ΔT=55 K)

• Null leakage: <25 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: 6+PE, IP65Moog Inc.

• Current draw: ≤750 mA

Physical & Environmental

• Operating temperature: −40 ℃ to +85 ℃

• Weight: approx. 10.2 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 life

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

• LVDT closed‑loop feedback: High linearity and precision across full strokeMoog Inc.

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

• Medium‑high‑flow dynamics: Optimized for 200 L/min with stable response for high‑flow applications

Application Scenarios

• Metallurgy: Medium‑high‑flow AGC roll gap control, tension control for plate mills

• Test equipment: High‑force dynamic material testers, large‑scale vibration tablesMoog Inc.

• Industrial automation: Large CNC machine tools, hydraulic presses, heavy‑duty injection molding machinesMoog Inc.

• Energy & heavy industry: Wind turbine pitch control, shield machine main control, marine hydraulic systemsMoog Inc.

Usage & Maintenance

• Installation: Horizontal/vertical mounting; avoid severe vibrationMoog Inc.

• 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 pressureMoog Inc.