D062-191C Moog Servo Valve 62 Series 350 bar DDV

Product Overview

The D062-191C (Order Number H40DAGM4NAH) is a core model within the Moog Inc. 62 Series two-stage electrohydraulic servovalve family, belonging to the precision flow control valve product line with mechanical force feedback. The 62 Series flow control servovalves are throttle valves for 3- and preferably 4-way applications. They are a standard performance, two-stage design that covers the range of rated flows from 2.5 to 20 gpm at 1000 psi valve drop.

The D062-191C adopts Direct Drive Valve (DDV) technology, a high-performance servovalve with internal spool position electrical feedback, complying with ISO 4401-03 and ISO 4401-05 international standards. The valve achieves closed-loop control of spool position through integrated electronic devices, requires no external amplifier, and can be directly connected to a controller for operation, featuring simple wiring and convenient application.

The power stage is a closed-center, four-way sliding spool. The pilot stage is a symmetrical double-nozzle and flapper, driven by a double air gap, dry torque motor. Mechanical feedback of spool position is provided by a cantilever spring. The carbide ball at the end of the feedback wire is a critical design feature ensuring high precision, reliable operation, and long service life. The valve design is simple and rugged for dependable, long-life operation, suitable for electrohydraulic position, speed, pressure, or force control systems with high dynamic response requirements.

As a drop-in replacement, the D062-191C is fully compatible with the OEM Moog specification in mounting interface, electrical connection, and performance characteristics. Every unit undergoes 100% simulation-based testing prior to shipment, covering null stability, flow linearity, step response, and internal leakage.

Technical Specifications

All parameters below are based on Moog official 62 Series servovalve technical documentation and verified supplier technical pages:

• Complete Model: D062-191C

• Order Number: H40DAGM4NAH

• Brand: Moog Inc.

• Product Series: 62 Series two-stage electrohydraulic servovalve, Size 04

• Product Type: Two-stage mechanical feedback servovalve with internal spool position electrical feedback

• Nominal Size: Size 04 (ISO 10372-04-04-0-92 / ISO 4401-03 / ISO 4401-05)

• Mounting: Subplate mounting, any position (fixed or movable)

• Rated Flow: 75 L/min (19.8 gpm); standard configurations include 10, 20, 40, 60, 75 L/min

• Rated Pressure Drop: 70 bar (1000 psi) per metering land

• Max Operating Pressure (Ports P/A/B): 350 bar (5000 psi)

• Max Operating Pressure (Port T Internal Leakage): 50 bar (715 psi)

• Max Operating Pressure (Port T Drain): 350 bar

• Valve Port Diameter: 7.9 mm (0.31 inch)

• Response Time: < 12 ms

• Resolution: < 0.1%

• Hysteresis: < 0.2%

• Null Leakage: 0.15 – 1.2 L/min (0.04 – 0.32 gpm)

• Coil Rated Current: ≤ 2 times rated current (instantaneous)

• Supply Voltage: 24 V DC

• Rated Signal: 15 – 100 mA; standard configurations 30, 100 mA

• Hydraulic Fluid: Mineral oil-based hydraulic fluid per DIN 51524 parts 1-3 (ISO 11158)

• Recommended Viscosity: 15 – 100 mm²/s

• Fluid Temperature Range: -20°C to +80°C

• Seal Material: Viton

• Mounting Screws: M8 × 25, 4 pcs, torque 18 Nm

• Body Material: Cast steel

• Weight: 2.5 kg (5.5 lb)

• Protection Class: IP65 (with sealed connector)

Note: Specifications are based on Moog official 62 Series servovalve technical documentation (Catalog Rev. L, May 2024) and verified supplier technical pages (XRD Electric, Shenzhen Ouhang, XRJ PLC, etc.). The D062-191C is a specific configuration within the 62 Series; different models vary in rated flow, control signal, and electrical connector. Always verify against the complete model code during selection. This product is listed in Moog’s Legacy product catalog, with the 631 Series servovalve recommended as replacement.

Key Technical Advantages

1. Mechanical Force Feedback Closed-Loop Control with High Resolution and Low Hysteresis

The D062-191C core control architecture employs a cantilever spring mechanical force feedback system. When an electrical command signal is applied to the torque motor coils, a magnetic force acts on the pilot stage armature, causing deflection of the armature/flapper assembly. Deflection of the flapper restricts fluid flow through one nozzle, which is carried through to one spool end, displacing the spool. Movement of the spool also applies a force to the cantilever spring, creating a restoring torque on the armature/flapper assembly. Once the restoring torque becomes equal to the torque from the magnetic forces, the armature/flapper assembly moves back to neutral position, and the spool is held open in a state of equilibrium until the command signal changes. This mechanical feedback mechanism does not rely on electronic sensors, achieving resolution below 0.1% and hysteresis below 0.2%, with exceptional immunity to electromagnetic interference and long-term stability.

2. DDV Direct Drive Design with Dynamic Response Independent of Supply Pressure

The valve employs Direct Drive Valve (DDV) technology. The power stage is a closed-center, four-way sliding spool, and the pilot stage is a symmetrical double-nozzle and flapper driven by a double air gap dry torque motor. The DDV design eliminates pilot stage leakage loss, and its dynamic response performance is independent of oil supply pressure, achieving more stable and reliable hydraulic control. Response time is less than 12 ms, satisfying high-frequency dynamic loading, rapid directional switching, and precision velocity control requirements.

3. Tungsten Carbide Coating and Self-Flushing Filter for Long-Life Design

The spool surface employs laser cladding tungsten carbide coating technology, tripling service life while enhancing wear and corrosion resistance. The pilot stage is equipped with a self-flushing filter that is detachable and cleanable, effectively reducing impurity blockage and improving equipment durability. The carbide ball at the end of the feedback wire is a critical design requirement ensuring high accuracy, reliable operation, and long service life.

4. High Pressure Rating with Wide Media Compatibility

Maximum operating pressure at ports P, A, B reaches 350 bar (5000 psi), with port T internal leakage rated at 50 bar and port T drain rated at 350 bar, allowing direct integration into high-pressure hydraulic circuits. Seal material is Viton (FKM), providing excellent resistance to mineral oil-based hydraulic media. Recommended operating viscosity range is 15 – 100 mm²/s, with fluid temperature range of -20°C to +80°C, accommodating a wide range of industrial hydraulic applications.

5. 100% Simulation-Based Testing and Drop-In Interchangeability

Every D062-191C undergoes 100% simulation-based testing prior to shipment. Test protocols cover null stability, flow linearity, step-response verification, and internal leakage detection. As a drop-in replacement, the valve is fully compatible with the OEM Moog specification in mounting dimensions (ISO 10372-04-04-0-92 interface), electrical connection, and performance characteristics, enabling direct replacement without hydraulic circuit or control wiring modification.

Application Areas

• Injection Molding Machines: Closed-loop control of injection velocity and hold pressure for consistent part quality

• Die Casting Equipment: High-speed dynamic pressure regulation and real-time switching control

• Steel & Metallurgy Equipment: Rolling mill hydraulic gap control (AGC), continuous casting mold level control

• Material Testing Systems: Flow and pressure closed-loop control for electro-hydraulic servo loading systems

• Turbine Control Systems: Precision control of electro-hydraulic servo actuators

• Mining Equipment: Hydraulic directional and flow control for supports, drilling rigs, and related equipment

• Heavy Machinery: Precision flow control for electro-hydraulic control circuits

• Industrial Automation Lines: Integration with PLC and motion controllers for precision position, velocity, or force control

• D631 Series Replacement: Transitional replacement for Moog 631 Series servovalves

Expert Maintenance Tips

Pre-Installation Checks:

• Verify the manifold mounting surface conforms to ISO 10372-04-04-0-92 standard; flatness deviation not exceeding 0.01 mm over 100 mm, surface roughness Ra < 0.8 μm

• Flush all piping with clean hydraulic fluid prior to installation; ensure system cleanliness meets requirements

• Inspect Viton O-ring seals for damage and confirm compatibility with the hydraulic fluid in use

• Use M8 × 25 socket head screws (4 pcs), tightened diagonally in sequence to 18 Nm torque

Operational Maintenance:

• Use precision pressure filters matched to the servovalve; replace filter elements at regular intervals

• Recommended fluid: mineral oil-based hydraulic fluid per DIN 51524 parts 1-3 (ISO 11158)

• Maintain operating viscosity within 15 – 100 mm²/s

• Maintain fluid temperature within -20°C to +80°C; avoid overheating that degrades fluid quality

• Periodically verify electrical connector contact integrity; confirm 24 V DC supply is stable

• Valve may be mounted in any orientation (fixed or movable); ensure secure installation free of vibration

• Except for regular visual inspection for exterior leakage and filter change, no maintenance work on the valves is required

Troubleshooting Guide:

• Spool fails to actuate or responds abnormally: Check 24 V DC supply, verify command signal (15 – 100 mA) reaches the valve correctly, confirm electrical connector engagement is reliable

• Null-point drift: After ruling out fluid contamination, inspect cantilever spring feedback wire for deformation; mechanical null adjustment can be performed via the null adjust screw on the motor cap (clockwise rotation increases valve opening)

• Insufficient flow: Confirm system supply pressure is within the 350 bar allowable range; check spool metering edges for partial blockage by contaminant particles

• Pilot stage clogging: Check self-flushing filter for blockage; disassemble and clean if necessary

• Slow response: Check system cleanliness level; verify pilot stage nozzles are not partially blocked by contaminant particles