Part Number Decoding (Z = special specification)

• D633：Series, ISO 4401 Size 03 / NG6, direct‑drive servo valve (DDV)

• Z：Special specification (non‑standard part number)

• 371：Internal factory code (corresponds to R16KA1M0NSX2)

• B：Version / release

Basic Identification

• Model：D633‑Z371B

• Brand：MOOG

• Type：Single‑stage, pilotless direct‑drive electro‑hydraulic servo valve (DDV)Moog Inc.

• Mounting：ISO 4401‑03‑03‑0‑94 (NG6)

• Weight：≈2.5 kg (5.5 lb)

• Protection：Connector IP67, body IP65

Hydraulic Specifications

• Rated Flow：16 L/min (at Δp = 35 bar per edge)

• Max Working Pressure：

  • P, A, B：350 barMoog Inc.

  • T (without Y)：50 barMoog Inc.

• Null Leakage：≤0.5 L/min (typical)

• Fluid：Mineral hydraulic oil, ISO 4406 18/15/12

• Viscosity：15–100 mm²/s (5–400 mm²/s allowed)

• Fluid Temp：−20 °C to +80 °C

Mechanical & Environmental

• Configuration：4/3‑way, permanent magnet linear force motor, integrated closed‑loop electronicsMoog Inc.

• Centering：Spring‑centered on power‑off (failsafe)Moog Inc.

• Ambient Temp：−20 °C to +60 °C

• Seal Material：FPM (fluoro rubber)

Electrical Specifications

• Supply：24 VDC (18–32 VDC)Moog Inc.

• Control Signal：±10 V, ±10 mA, 4–20 mAMoog Inc.

• Feedback：4–20 mA spool positionMoog Inc.

• Max Current：≤1.2 AMoog Inc.

• Connector：M12 (6+PE)Moog Inc.

Performance

• Step Response：≤12 ms (0–100%)Moog Inc.

• Hysteresis：≤0.2%

• Linearity：≤0.1%

• Resolution：≤0.05%

• Dynamics：Pressure‑independentMoog Inc.

Applications

• High‑flow precision closed‑loop controlMoog Inc.

• Material testing / fatigue rigsMoog Inc.

• 2‑axis synchronisationMoog Inc.

• Hydraulic robots, high‑precision positioningMoog Inc.

• Injection moulding / die‑casting machinesMoog Inc.