MOOG D635-671E

Description

Technical Specifications:

• Product Model: D635-671E

• Manufacturer: MOOG Inc.

• Product Category: Two-Stage Electro-Hydraulic Servo Valve

• Rated Working Pressure: 210 bar (approximately 30 MPa)

• Control Signal: 0-10 V (analog)

• Power Supply: 24V DC

• Flow Range: 5 to 80 gpm (approximately 0.3 to 5 L/s) at 1000 psi (≈70 bar)

• Temperature Range: -26°C to +82°C (-15°F to +180°F)

• Environmental Temperature: -20°C to +80°C

• Fluid Temperature: -20°C to +100°C

• Valve Structure: Two-stage flow control – pilot section (dual nozzle baffle) + main valve section (closed center four-way slide valve)

• Installation Standard: ISO 10372-04-04-0-92

• Sealing Materials: Viton (V) standard, Buna-N (B), or EPR (E) optional

• Zero Flow Adjustment Range: ±10%

Functional Features:

• Two-stage pilot-main valve structure

• Dual nozzle flapper torque motor in pilot section

• Closed center four-way slide valve in main stage

• Mechanical zero adjustment via eccentric bushing

• External pilot supply (X port) for improved response speed

• Closed-loop control of position, speed, pressure, or force

• Dry torque motor with two-stage hydraulic amplifier

• Low-friction double nozzle flapper valve pilot stage

• ISO 4401 standard mounting dimensions

Performance Parameters:

• Rated Working Pressure: 210 bar

• Flow Range: 5-80 gpm at 1000 psi

• Hysteresis: ≤0.2%

• Linearity: ±1%

• Frequency Response (-90° phase): ≥85 Hz

• Step Response Rise Time (10%→90%): ≤3 ms

• Positioning Accuracy: 0.01 mm

Material Composition:
Industrial-grade hydraulic valve construction with Viton (standard), Buna-N, or EPR sealing materials. Dry torque motor design with corrosion-resistant internal components.

Structural Features:
The D635-671E features a two-stage architecture with a dry torque motor and two-stage hydraulic amplifier. The pilot stage uses a low-friction double nozzle flapper valve. The main stage is a closed center four-way slide valve. The valve body can be installed in any direction on fixed or movable flanges.

Working Principle:
The valve receives an analog control signal (0-10V) and 24V DC power. The torque motor in the pilot stage converts the electrical signal into mechanical movement of the flapper between two nozzles, creating a differential pressure. This pilot pressure shifts the main spool, which directs hydraulic flow to the actuator. Electrical feedback ensures precise proportional flow control. Zero flow adjustment is achieved through mechanical eccentric bushing and magnetic torque motor methods.

Advantages and Strengths:

• High dynamic response with ≥85 Hz bandwidth

• Ultra-fast step response ≤3 ms

• Zero flow adjustable within ±10% range

• High pressure capability up to 210 bar

• Wide power supply compatibility (24V DC with 0-10V control)

• Dual adjustment path (internal mechanical zeroing or external pilot oil circuit)

• Solves response lag and nonlinearity issues of conventional proportional valves

Applicable Industries:

• Aerospace (landing gear and slat hydraulic systems)

• Aviation manufacturing

• Industrial automation

• Injection molding

• Metal forming

• Six-degree-of-freedom flight simulators

• Material fatigue testing machines

• Gas turbine and steam turbine fuel/guide vane actuators

• Steel mills

Model Series:
MOOG D635 Series

Installation Requirements:

• Install in any direction on fixed or movable flanges

• Flange dimensions comply with ISO 10372-04-04-0-92 standard

• Requires ±10 V differential drive signal source

• System must have ≥10 μm filtration (β₁₀ ≥ 75)

• Oil cleanliness must meet ISO 4406 16/13 standard

• External pilot oil circuit (X port) optional for improved response

Usage Precautions:

• Fluid cleanliness strictly required (recommended ISO 4406 <13/10)

• Contamination is the primary cause of valve failure

• Sealing material selection based on fluid compatibility (Viton, Buna-N, or EPR)

• External pilot oil connection (X port) does not conform to ISO 4401 standard

• Verify flow/pressure parameters match system requirements; not interchangeable with D660/D661 direct-drive valves