Description
Product Introduction
The Woodward 47371-02 is an electro-hydraulic linear actuator built to replace legacy pneumatic pilots or mechanical linkages in engine governor systems. It accepts a standard 4–20 mA input from a governor or PLC to drive the fuel rack with repeatable precision, cutting out the hysteresis typical of older hardware.
This variant, Woodward 47371-02, provides 15 to 35 lb-in of torque across a 1.0 to 1.5 inch stroke. It holds operation from -40 to 70 °C. The internal spring-return forces a safe shutdown if the 24 Vdc supply drops—critical for preventing runaways on unattended skids.
Woodward 47371-01
Key Technical Specifications
- Supply Voltage: 12 Vdc or 24 Vdc (verify coil rating on nameplate)
- Control Signal: 4–20 mA (Current Controlled)
- Stroke Length: 1.0 to 1.5 in (25 to 38 mm)
- Force Output: 15 to 35 lb-in (Dependent on linkage ratio)
- Holding Current: 3.5 A @ 18 Vdc
- Operating Temp: -40 to 70 °C (-40 to 158 °F)
- Enclosure: IP54 (Dust and splash resistant)
- Fail-Safe: Internal spring return (Default to Fuel-Off/No-Load)
- Mounting: Flange mount with slotted holes for adjustment
- Connections: Screw terminals or Deutsch DT series (verify with OEM datasheet)
Quality Control Process (Engineer’s Perspective)
- Incoming Verification: Cross-check the serial number against Woodward shipping docs. Inspect the flange and slotted holes for impact damage or thread stripping. Manually push the shaft to ensure it isn’t seized.
- Live Functional Test: Mount on a test rig. Drive the coil with a variable 4–20 mA source. Cycle the shaft through full stroke >50 times while logging position lag—we demand <0.5% deviation.
- Electrical Parameter Test: Measure coil resistance with a Fluke 115 (typically low ohms). Hit the terminals with a 500 V Megger; insulation must hold >10 MΩ to the cast housing.
- Firmware Verification: N/A (Analog device). Photograph the nameplate data and any jumper settings for the build record—well, technically some batches have DIPs for gain, but most are fixed.
- Final QC & Packaging: Lubricate the shaft tip sparingly. Cap the Deutsch connector with dielectric grease. Seal in anti-static foam, apply “QC Passed – Bench Run” label with the date.
Replacement Pitfall Guide
❗ Voltage Application: Never apply raw 24 Vdc continuously to the coil lugs. This isn’t a solenoid; it needs a PWM driver or current-limiting circuit. Full voltage cooks the winding in minutes.
❗ Linkage Geometry: Mounting the Woodward 47371-02 even 5 degrees off-axis binds the shaft in the bore. Use a flexible ball-joint linkage to absorb vibration—rigid rods eat the internal bearings in <500 hours.
❗ Spring Return Logic: Verify the fail-safe direction beforefinal bolting. Most diesels default to fuel-off, but gas compressor skids sometimes configure “fail-open.” Getting this wrong risks a mechanical overspeed.
❗ Power Budget: The 3.5 A holding current is heavy. Calculate your 24 Vdc PSU load with 20% headroom; voltage sag below 18 Vdc causes the actuator to drop out under load.
❗ ESD & Environment: The coil is robust, but terminal corrosion is a killer. Slather dielectric grease on the Deutsch plugs, especially in dry, salty, or dusty shop environments—though your mileage may vary on climate control.
Keep these in mind and you’ll cut 90% of rework time.
Woodward 47371-01
Compatibility Matrix & Benchmarks
- Woodward 47371-02 → Woodward 47371-01 : Direct — Verify stroke length and mounting tab offset (minor revision diffs)
- Woodward 47371-02 → Woodward PG-PL Governor : Direct — Bolt-on replacement for pneumatic pilot
- Woodward 47371-02 → Generic 24V Solenoid : Incompatible — Requires closed-loop current driver, not simple on/off
- Step Response: ~120 ms (10% to 90% stroke, 4–20 mA step)
- Hysteresis: < 0.5% of full stroke (measured per ISO 12204)
- Thermal Stability: ±1% force variance across -40 to 70 °C range
