Eaton Vickers SM4-20 SM4-40 Servo Valve | SM4-20(15)57-80/40-10-S182 | High Response Hydraulic Servo Control

LIC Hydraulic presents the Eaton Vickers SM4 Series Servo Valves (including SM4-20 and SM4-40 sizes), the definitive solution for high-precision closed-loop hydraulic systems. Designed for exacting control of position, velocity, and force, these valves utilize a sophisticated two-stage nozzle-flapper design to deliver exceptional dynamic response and minimal hysteresis. Our units are engineered for 100% Drop-in Interchangeability with original Assy Numbers such as 3025047. Every valve undergoes rigorous flow curve characterization and 100% simulated load testing in cleanroom conditions, ensuring laboratory-grade accuracy for industrial automation, simulation, and aerospace applications.

Technical Specifications (Bulleted List)

• Model Code Example: SM4-20(15)57-80/40-10-S182

• Rated Flow (@ 70 bar Δp): 3.8 L/min to 76 L/min (SM4-20) / Up to 151 L/min (SM4-40)

• Max Operating Pressure: 210 bar (3000 PSI) / 315 bar (4500 PSI) depending on build

• Rated Current: 10mA, 15mA, 20mA, 40mA (as per coil code)

• Hysteresis: < 3% of rated current

• Resolution: < 0.5%

• Frequency Response (90° Phase): Up to 100 Hz (standard for SM4-20)

• Mounting Interface: ISO 10372 standard

• Assy Number Reference: 3025047

Key Technical Advantages

• Balanced Two-Stage Pilot: The nozzle-flapper first stage combined with a mechanical feedback spring ensures high null stability and extremely low zero shift during high-frequency cycles.

• Jewel-Grade Material Construction: Internal orifices and critical contact surfaces utilize industrial-grade jewels and hardened alloys to resist erosion and maintain precision over long service intervals.

• High Power-to-Size Ratio: Optimized internal fluid geometry allows the SM4 series to control high hydraulic power within a compact footprint, ideal for integrated manifold blocks.

• Environmental Resilience: Coils are vacuum-potted for moisture and vibration resistance, ensuring stable linear output in environments with high electromagnetic interference or mechanical shock.

Application Areas

• High-End Industrial Machinery: Closed-loop injection molding, metal rolling tension control, and robotic arm actuators.

• Aerospace & Simulation: Flight simulator motion bases and structural airframe test rigs.

• Automated Testing: Dynamic test stands for hydraulic cylinders and automotive suspension testing.

Expert Maintenance Tips

• Strict Filtration Protocol: Servo valves require ultra-clean fluid. Oil must maintain ISO 4406 14/11 (NAS 5) cleanliness or better. A non-bypass 3-micron filter must be installed immediately upstream of the valve.

• System Flushing: Never install a servo valve on a new or dirty system. Use a flushing plate to circulate oil through the system for at least 12 hours before mounting the valve.

• Electrical Calibration: Verify that the amplifier’s output current matches the valve coil’s requirements. Pay close attention to polarity; reversed wiring will cause the feedback logic to fail.

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