Moog Proportional Valve

Moog Proportional Valve

3 week ago

2 0

Ningbo Hengnuo Hydraulic Drive Co.,Ltd

 3 year year

Product details

MOOG servo valve is a two-stage valve. The first stage is the nozzle baffle plate, and its outlet pressure is controlled by the control signal. The second stage is the slide valve type, which executes the pressure from the control stage to the brake cylinder. When there is no signal, the servo valve baffle rests against the oil return nozzle due to the oil pressure at the outlet of the pressure nozzle. At this time, the oil pressure at the pressure port acts on the spool valve, so that the brake port is directly connected with the metering oil port, and the pressure at the brake port is consistent with the metering oil pressure controlled by the pilot. When the wheel angular speed detects that there is a deviation between the taxiing speed and the reference taxiing speed, The torque motor receives the deviation electrical signal. At this time, the torque motor drives the baffle to deflect towards the pressure nozzle to reduce the oil pressure acting on the upper end of the valve core. Under the action of the oil pressure at the lower end of the valve core, the valve core moves up and the metering pressure oil port is closed down, which will lead to the reduction of the pressure at the control port. When the pressure at the control port is reduced to a certain value, there will be the corresponding braking pressure.

1. Product Overview

• Brand & Model:

• MOOG: Moog Inc. (USA), a global leader in electro-hydraulic servo control technology, with products widely used in aerospace, industrial automation, energy, and other fields.

• J761-003: A classic two-stage electro-hydraulic servo valve from MOOG, featuring anozzle-flapper pilot stage + power spool main stagefor high-precision hydraulic system control.

• Function:

Converts small electrical signals (e.g., ±10mA current) into hydraulic flow or pressure outputs, enabling precise control of hydraulic actuators (e.g., cylinders, motors) in terms of position, speed, or force.

------

2. Technical Specifications (Typical Values, Refer to Official Manual)

【表格】

Parameter Description

Model J761-003

Flow Range Nominal: ~15–30 L/min (depending on supply pressure and pressure drop)

Supply Pressure Typical: 21 MPa (3000 psi); Max Allowable: 35 MPa (5000 psi)

Input Signal Standard: ±10mA DC; Optional: ±100mA DC (customized)

Hysteresis ≤0.5% of rated signal

Linearity ≤±1% of rated signal

Frequency Response Bandwidth: ≥100 Hz (-90° phase lag)

Leakage Internal leakage: ≤1.5 L/min (@21 MPa)

Weight ~1.2 kg

Ambient Temperature Operating: -40°C to +70°C; Storage: -54°C to +125°C

------

3. Core Structure & Working Principle

• Two-Stage Control:

1. Pilot Stage: Nozzle-flapper design converts electrical signals into hydraulic pressure signals.

2. Main Stage: Power spool regulates output flow based on pilot-stage pressure.

• Feedback Mechanism:

Built-in mechanical feedback (e.g., springs) or electrical feedback (e.g., LVDT position sensors) ensures linear proportionality between output and input signals.

------

4. Applications

• Aerospace:

• Aircraft control surface actuation, engine fuel regulation, landing gear systems.

• Industrial Automation:

• CNC machines, injection molding machines, die-casting machine motion control.

• Energy & Testing:

• Wind turbine pitch control, structural fatigue test rigs, material testing machines.

• Defense & Military:

• Missile guidance systems, ship stabilization platforms, tank turret drives.

------

5. Common Faults & Diagnostics

【表格】

Symptom Possible Causes Solutions

No Output/Low Output Low supply pressure, clogged filter, stuck pilot stage Check oil pressure, replace filter, clean or replace servo valve

Sluggish Response/Oscillation Loose electrical connections, faulty feedback sensor, contaminated oil Tighten connections, calibrate/replace sensor, replace hydraulic oil & clean system

Zero Offset Spring fatigue, magnetic interference, temperature drift Adjust zero spring, shield interference sources, add temperature compensation

Excessive Internal Leakage Worn spool, aged seals Lap spool pairs, replace seals

Abnormal Noise Cavitation (insufficient supply), mechanical vibration Increase supply pressure, install vibration dampers

------

6. Maintenance & Care Recommendations

• Daily Checks:

• Monitor oil cleanliness (NAS 1638 Class ≤6).

• Inspect electrical connectors for looseness or corrosion.

• Periodic Maintenance:

• Replace hydraulic oil filters every 2000 hours.

• Conduct full performance tests (e.g., step response, frequency response) every 5000 hours.

• Critical Precautions:

• Never hot-swap electrical connectors to avoid arc damage to coils.

• Fully depressurize before disassembly; use dedicated tools to prevent spool damage.

• Store long-term with clean hydraulic oil in a dry environment.