Hydraulic Specifications

• Rated Flow: 1.9 to 57 L/min (0.5 to 15 GPM)
• Standard Configurations: 4, 10, 19, 38, 57 L/min (1, 2.5, 5, 10, 15 GPM)
• Maximum Operating Pressure: 210 bar (3,000 psi)
• Valve Design: 2-stage, with spool and bushing
• Pilot Stage: Nozzle-flapper
• Mounting Surface: ISO 10372-02-02-0-92

Performance Specifications

• 100% Step Response: 4 to 17 ms
• Frequency Response: 115 to 215 Hz (at 90° phase lag)
• Hysteresis: Low (improved accuracies for close tolerance applications)
• Resolution: High
• Linearity: Excellent

Electrical Specifications

• Rated Signal: 8 to 200 mA
• Standard Configurations: 8, 15, 20, 40, 200 mA
• Torque Motor: Dry type
• Electrical Connection: Various options available

Physical Specifications

• Size: Size 02 (ISO 10372-02-02-0-92)
• Weight: 0.86 kg (1.9 lbs)
• Storage Temperature Range: -40°C to +60°C (-40°F to +140°F)
• Ambient Temperature Range: -40°C to +135°C (-40°F to +275°F)
• Vibration Resistance: 30 g, 3 axis, 10 Hz to 2 kHz
• Shock Resistance: 30 g, 3 axis

Superior Performance

• High Dynamics: Enables increased production cycles and improved system response
• High Resolution: Provides precise control for close tolerance applications
• Low Hysteresis: Ensures accurate and consistent performance
• Fast Response Time: 4 to 17 ms for 100% step response

Robust Design

• 2-Stage Design: With dry torque motor for compatibility with many different fluids
• Double Nozzle Pilot Stage: Low friction design provides maximum stability
• High Spool Control Force: Ensures stable, consistent flows and increased accuracies
• Rugged Construction: Designed for long-life operation and reduced maintenance

Safety & Reliability

• Intrinsically Safe Versions: Available for hazardous environments
• Explosion Proof Options: Can be employed in most hazardous environments
• Failsafe Operation: Loss of electrical signal results in zero position
• Field Adjustable Null Bias: Allows perfect alignment when interchanging equipment

Installation & Maintenance

• Factory Setup: Allows easy installation and setup
• Compact Size: Small body size for space-constrained applications
• Multiple Mounting Options: Can be installed in any orientation
• Long Service Life: Reduces maintenance and downtime costs

Aerospace & Defense

• Flight control systems
• Missile launch systems
• Thrust vector control
• Turret control systems
• Naval vessel steering and stabilization
• Precision guided munitions

Industrial Automation

• Injection molding machines
• Steel mill rolling equipment
• Hydraulic presses
• Material testing machines
• Robotics and motion control
• Precision machine tools

Test & Simulation

• Flight simulators
• Structural testing equipment
• Shock and vibration testing
• Fatigue testing machines
• Automotive component testing
• Dynamic load simulation

Energy & Marine

• Wind turbine pitch control
• Hydroelectric power generation
• Offshore drilling equipment
• Ship steering systems
• Submarine control systems
• Marine propulsion systems

Valve Operation

The MOOG G771K202 servo valve is a 2-stage, flow control, mechanical feedback (MFB) servo valve. The first stage is a double nozzle-flapper pilot stage driven by a dry torque motor. The second stage is a sliding spool that controls the main flow to the actuator.

When an electrical current is applied to the torque motor, it creates a magnetic field that deflects the flapper between the nozzles. This deflection causes a pressure difference across the spool ends, moving the spool to a position proportional to the input signal. The mechanical feedback mechanism (cantilevered spring) provides stability and linearity by opposing the spool movement.

Fluid Compatibility

The G771K202 servo valve is designed to work with various hydraulic fluids, including:

• Mineral-based hydraulic oils
• Phosphate ester fluids
• Water-glycol solutions
• Synthetic hydraulic fluids

Proper fluid cleanliness is essential for optimal performance and longevity. MOOG recommends maintaining fluid cleanliness to ISO 4406 Class 16/13 or better (NAS 6-8).

Electrical Interface

The servo valve accepts a wide range of input signals, making it compatible with various control systems:

• Rated current: 8 to 200 mA (standard configurations: 8, 15, 20, 40, 200 mA)
• Input impedance: Depends on coil configuration
• Connector options: Various industry-standard connectors available
• Optional features: Reverse polarity protection, vented motor cap

Environmental Considerations

The G771K202 servo valve is designed to operate reliably in challenging environments:

• Temperature Range: -40°C to +135°C (-40°F to +275°F)
• Vibration Resistance: 30 g, 3 axis, 10 Hz to 2 kHz
• Shock Resistance: 30 g, 3 axis
• Ingress Protection: Various options available
• Corrosion Resistance: Stainless steel body and components

Electrical Options

• Various coil configurations
• Different connector types
• Reverse polarity protection
• Vented motor cap
• Magnetic null adjust

Safety Options

• Intrinsically safe versions
• Explosion proof options
• ATEX certification
• SIL3 certification

Performance Options

• Special flow configurations
• High-pressure versions (up to 350 bar)
• Low leakage options
• Custom null bias settings

Accessories

• Mounting hardware
• Test leads
• Filter assemblies
• Valve diagnostic tools
• Spare parts kits

Recommended Maintenance Practices

• Regular Fluid Analysis: Monitor fluid condition and cleanliness
• Filter Maintenance: Replace or clean filters according to schedule
• Visual Inspection: Check for leaks, damage, or contamination
• Performance Testing: Periodically verify valve performance
• Zero Adjustment: Recalibrate if necessary

Troubleshooting Guidelines

• Erratic Operation: Check fluid cleanliness, electrical connections, and valve alignment
• Slow Response: Inspect for contamination, worn components, or low supply pressure
• Leakage: Check seals, spool, and housing for damage or wear
• No Response: Verify electrical signal, check for coil damage, or mechanical binding