Model Code Explanation (D661-4591C)

• D661: Series (ISO 4401‑05 mounting, integrated 24 VDC electronics)

• 4: 4‑way, zero‑lap, linear flow characteristic

• 59: Rated flow ≈ 200 L/min (Δp = 35 bar per land)

• 1: High dynamics, single LVDT feedback, enhanced null stability

• C: Command signal = ±10 VDC (differential), non‑explosion‑proof

Technical Specifications

Part Number

• D661-4591C

Mounting

• Standard: ISO 4401‑05 (NG10), 4‑hole, M6 bolts

• Torque: 13 Nm ±10%, diagonal tightening sequence

• Mounting Surface: Flatness ≤0.02 mm/100 mm; Ra <1 μm

Control Function

• 4‑way/3‑position, spring‑centered, zero‑lap, closed‑loop spool position control

Hydraulic Parameters

• Rated Flow (Δp = 35 bar): 200 L/min (±8%)

• Max Operating Pressure (P/A/B): 350 bar (5,000 psi)Moog Inc.

• Pilot Pressure (X): 21–280 bar (internal P or external X)

• T Port Pressure (Y internal): 210 bar; (Y external): 350 barMoog Inc.

• Fluid: Mineral oil (DIN 51524), viscosity 15–45 mm²/s

• Temperature: Ambient −20°C to +60°C; Fluid −20°C to +80°C

• Weight: Approx. 6.5–6.8 kg

Electrical Parameters

• Supply: 24 VDC (18–32 VDC), quiescent 270 mA, dynamic ~600 mAMoog Inc.

• Command Signal: ±10 VDC (differential, 10 kΩ impedance)Moog Inc.

• Feedback Signal: 4–20 mA (single LVDT spool position, ±0.02% FS accuracy)

• Connector: 6+PE (EN 175201‑804, IP65)Moog Inc.

• Step Response (0→100%): 7–8 ms @ 210 bar (high dynamics for 200 L/min)

• Hysteresis: <0.25% (closed‑loop)

• Linearity: <±0.30%

• Resolution: <0.05%

Interface & Communication Configuration

• Electrical: 6+PE connector; 24 VDC power, ±10 V differential command, 4–20 mA LVDT feedbackMoog Inc.

• Feedback: Single integrated LVDT (full‑stroke closed‑loop, high accuracy)

• Ports: P, A, B, T; optional external X (pilot) and Y (return)

• Seal Material: NBR (standard) or FKM (optional, high‑temperature)

Core Functions

• 200 L/min Ultra‑High Flow: For large‑scale, high‑throughput hydraulic systems

• High‑Dynamic Response: 7–8 ms step response, optimized for 200 L/min high‑speed operation

• ±10 V Differential Command: High‑noise‑immunity signal for industrial environmentsMoog Inc.

• Precision Closed‑Loop Control: LVDT feedback with ultra‑low hysteresis for accurate positioning

• ServoJet® Pilot: Jet‑pipe design reduces energy use and improves contamination resistance

Applicable Scenarios

• High‑Speed Heavy‑Duty Industrial Presses: Large stamping, forging, and extrusion presses requiring fast response

• High‑Capacity Hydraulic Test Benches: Aerospace, automotive, and structural testing with dynamic loading

• Metallurgical & Mining Machinery: Rolling mills, continuous casting, and heavy excavators needing rapid control

• Large‑Scale CNC & Machine Tools: Ultra‑precision large‑format machining centers with high‑speed positioning

Compatibility & Installation Notes

• Mechanical: Interchangeable with D661 (G/C/D/E), D662/D663 (ISO 4401‑05)

• Upgrade: Drop‑in replacement for D661‑4590C (standard dynamics) when faster response is needed

• System Requirements: 24 VDC supply, ±10 V differential analog controller, ISO 4401‑05 manifold

Usage & Maintenance Instructions

• Installation: Mount on flat surface (flatness ≤0.02 mm/100 mm; Ra <1 μm) with M6×55/60 bolts (13 Nm, diagonal)

• Fluid: ISO VG 32–46, NAS 1638 cleanliness class ≤8 (ISO 4406 17/14/11 recommended)

• Maintenance: Replace internal filter every 5,000 hours; inspect leaks/connectors periodically

• Precautions: Avoid voltage spikes/reverse polarity; do not open standard (C) models in field