Description
Product Introduction
The Woodward 47371-01 is an electro-hydraulic linear actuator designed 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, eliminating the hysteresis found in older equipment.
This unit provides 15 to 35 lb-in of torque (dependent on lever arm ratio) across a 1.0 to 1.5 inch stroke. It operates reliably from -40 to 70 °C. The internal spring-return mechanism forces a safe shutdown position if 24 Vdc power is lost.
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: Check the unit’s serial number against Woodward shipping docs. Inspect the flange and slotted holes for impact damage. Ensure the shaft isn’t seized by hand-pressure test.
- 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 look for <0.5% deviation.
- Electrical Parameter Test: Use a Fluke 115 to measure coil resistance (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 jumper settings (if equipped) for the build record.
- Final QC & Packaging: Lubricate the shaft sparingly. Seal the Deutsch connector with a dust cap. Bag 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 requires a PWM driver or current-limiting circuit. Full voltage cooks the winding in minutes.
❗ Linkage Geometry: Mounting the Woodward 47371-01 even 5 degrees off-axis binds the shaft against the bore. Use a flexible ball-joint linkage to absorb vibration—rigid rods trash the internal bearings fast.
❗ Spring Return Direction: Verify the fail-safe logic beforefinal bolting. The spring defaults to fuel-off on most diesels, but some gas skids configure it to “fail-open.” Getting this wrong risks a runaway.
❗ Power Budget: The 3.5 A holding current is significant. 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 windings are tough, but the terminal screws corrode fast in salt air. Use dielectric grease on the Deutsch plugs, especially in dry, dusty shops.
Keep these in mind and you’ll cut 90% of rework time.
Woodward 47371-01
Compatibility Matrix & Benchmarks
- Woodward 47371-01 → Woodward PG-PL Governor : Direct — Bolt-on replacement for pneumatic pilot
- Woodward 47371-01 → Woodward 47371-02 : Needs Adaptation — Verify stroke length and mounting tab offset
- Woodward 47371-01 → 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
