Model Code Explanation (D661-4178)

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

4: High‑flow platform

17: 170 L/min nominal flow rating

8: Ultra‑high‑dynamic, single‑feedback, maximum‑response base

(No suffix): Standard electronics, premium null stability

Technical Specifications

Part Number: D661-4178

Mounting: ISO 4401‑05 (NG10), 4‑hole, M5 screws (torque 8 Nm)

Control Function: 4‑way/3‑position, spring‑centered, zero‑lap, closed‑loop control

Hydraulic

Nominal Flow (Δp = 35 bar): 170 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. 5.8–6.0 kg

Electrical

Supply: 24 VDC (18–32 VDC), quiescent 230 mA, dynamic 500 mAMoog Inc.

Command Signal: ±10 V differential (10 kΩ impedance); optional ±10 mAMoog Inc.

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

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

Step Response (0→100%): ≤8 ms @ 210 bar (faster than 4168)

Hysteresis: <0.18% (closed‑loop)

Linearity: <±0.20%

Resolution: <0.07%

Interface & Communication

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

Feedback: Single integrated LVDT (full‑stroke closed‑loop, high‑accuracy for 170 L/min flow)

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

Key Features

170 L/min Nominal Flow: Highest flow in 41xx series (higher than 4157B/4158B/4168)

Ultra‑High‑Dynamic Response: 8 ms step response for extreme high‑speed control

High‑Pressure Rated: 350 bar max working pressure for severe‑duty applicationsMoog Inc.

Premium Null Stability: Superior null shift performance for long‑term precision

Single‑LVDT Precision: Reliable closed‑loop feedback for consistent accuracy at maximum flow

Applications

Extreme‑dynamic test benches (high‑frequency fatigue, aerospace/defense component simulation)

Heavy‑duty industrial automation (large forging presses, heavy steel rolling mills)

Metallurgy (high‑precision roll gap control, high‑tension systems)

Heavy machinery (mining excavators, high‑tonnage die‑casting, large injection molding)

Energy (high‑flow hydraulic control, turbine governing systems)

Compatibility

Interchangeable with D661 (G/C/A), D662/D663 (ISO 4401‑05)Moog Inc.

Drop‑in upgrade for D661‑4168 (higher flow, faster response) and 4158B/4157B/4125E/4099

Requires 24 VDC supply, analog controller (±10 V in / 4–20 mA out), ISO 4401‑05 manifold