Model Code Decoding

• D635: Base series, NG06 (Cetop 3) pressure control valveMoog Inc.

• Z: Special specification (extended temperature, enhanced EMC, factory tuning)Moog Inc.

• 681:

  • 6: Rated flow 40 L/min (Δp=35 bar/land)Moog Inc.

  • 8: Rated pressure 350 bar (max 350 bar, high‑pressure)Moog Inc.

  • 1: 3‑way spool, linear, standard overlapMoog Inc.

• E (typical suffix): Revision E, FPM (Viton) seals, 24 VDC supply, enhanced EMCMoog Inc.

Technical Specifications

• Part Number: D635Z681 (full: D635Z681E)

• Valve Size: NG06 (Cetop 3 / ISO 4401‑03)Moog Inc.

• Control Function: 3‑way pressure control, spring‑centered (fail‑safe: A→T, P→B)Moog Inc.

• Rated Flow (Δp=35 bar/land): 40 L/min (±10%)Moog Inc.

• Max Flow: 50 L/minMoog Inc.

• Operating Pressure:

  • P/A/B ports: 350 barMoog Inc.

  • T port: 50 bar (standard) / 350 bar (Y‑port option)Moog Inc.

• Response Time (0→100% step): ≤12 msMoog Inc.

• Hysteresis: <0.1%Moog Inc.

• Linearity: <0.3%Moog Inc.

• Electrical:

  • Supply: 24 VDC (19–32 VDC), 1.2 A maxMoog Inc.

  • Signal: ±10 V (std) / ±16 V (P16 option)Moog Inc.

  • Feedback: 4–20 mA (integrated pressure sensor)Moog Inc.

  • Protection: IP67 (Z‑series, mated)Moog Inc.

• Fluid: Mineral oil (DIN 51524), viscosity 5–400 mm²/sMoog Inc.

• Temperature:

  • Ambient: −20°C to +65°C (extended Z‑range)Moog Inc.

  • Fluid: −20°C to +85°CMoog Inc.

• Mass: ~2.6 kgMoog Inc.

• Seals: FPM (Viton)Moog Inc.

Interface & Communication Configuration

• Electrical Interface: Analog command (±10 V / ±16 V) + 24 VDC; 4–20 mA pressure feedbackMoog Inc.

• Feedback: Integrated high‑accuracy pressure sensor (closed‑loop, no external transducer)Moog Inc.

• Mounting: 4‑bolt NG06 (Cetop 3, M5 screws, 8–10 Nm)Moog Inc.

• Porting: P, A, B, T; Y‑port available (350 bar return)Moog Inc.

Core Functions

1. 350 Bar High Pressure: For heavy‑duty industrial hydraulicsMoog Inc.

2. 40 L/min High Flow: Top flow in standard D635 lineupMoog Inc.

3. Z‑Series Upgrades: Extended temp, IP67, enhanced EMCMoog Inc.

4. Integrated Closed‑Loop: Onboard sensor + electronics, no external controllerMoog Inc.

5. Fast Dynamics: 12 ms response, low hysteresis/non‑linearityMoog Inc.

6. Fail‑Safe Spring Center: Safe position on power lossMoog Inc.

Application Scenarios

• High‑Pressure Presses: 350 bar stamping, forging, extrusionMoog Inc.

• Industrial Test Benches: Fatigue, pressure cycling, component durabilityMoog Inc.

• Injection Molding: High‑pressure clamping/ ejection controlMoog Inc.

• Oil & Gas: High‑pressure hydraulic power units (HPUs)Moog Inc.

• Heavy Machinery: Construction, mining, and marine hydraulicsMoog Inc.

Compatibility & Key Differences

• Base Model: D635Z681 = high‑perf version of D635‑681EMoog Inc.

• Z681 vs Standard 681E:

  • Z681: −20°C→+65°C, IP67, enhanced EMC, optional ±16 VMoog Inc.

  • 681E: −20°C→+60°C, IP65, ±10 V onlyMoog Inc.

• Interchangeability: Same NG06 mounting as D635‑640E/671E/681EMoog Inc.