Description
Product Introduction
The Woodward 47371-02M is an electro-hydraulic linear actuator designed for engine governor retrofits requiring metric hardware. It translates a 4–20 mA input from a governor or PLC into precise fuel rack movement, removing the slop inherent in aging pneumatic or mechanical linkages.
Distinct from the standard 47371-02, this Woodward 47371-02M features metric-threaded adjustment slots on the flange. It delivers 15 to 35 lb-in of force over a 1.0 to 1.5 inch stroke. Operation is rated for -40 to 70 °C with a spring-return to fuel-off on power loss.
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 (Linkage ratio dependent)
- Holding Current: 3.5 A @ 18 Vdc
- Operating Temp: -40 to 70 °C (-40 to 158 °F)
- Enclosure: IP54 (Dust/Splash Resistant)
- Fail-Safe: Internal spring return (Fuel-Off/No-Load)
- Mounting: Flange mount with Metric slotted holes (M8 or M10 verify with OEM datasheet)
- Connections: Screw terminals or Deutsch DT series
Quality Control Process (Engineer’s Perspective)
- Incoming Verification: Check the serial against Woodward docs. Inspect the metric flange slots for thread damage or burrs. Hand-cycle the shaft to ensure it moves freely without binding in the bore.
- Live Functional Test: Rig it to a variable 4–20 mA source. Cycle full stroke >50 times. Log position lag with a dial indicator; we reject anything >0.5% hysteresis.
- Electrical Parameter Test: Check coil resistance via Fluke 115 (low ohms typical). Megger the terminals at 500 V; insulation to housing must exceed 10 MΩ.
- Firmware Verification: N/A (Analog device). Photograph the nameplate, specifically the “M” suffix and metric thread callouts, for the commissioning file.
- Final QC & Packaging: Lightly grease the shaft tip. Cap the Deutsch plug. Bag in anti-static foam, tag with “QC Passed – Bench Run” and the date.
Replacement Pitfall Guide
❗ Metric vs Imperial: The “M” suffix means metric threads (M8/M10) in the slotted flange. Forcing 5/16″ UNC bolts from a standard 47371-02 mount strips the aluminum housing immediately—drill/tap or use adapters.
❗ Voltage Application: Do not land raw 24 Vdc on the coil terminals. This requires a PWM/current driver. Continuous DC cooks the winding in minutes—seen it happen on midnight startups.
❗ Linkage Geometry: Mounting the Woodward 47371-02M off-axis by 5 degrees side-loads the shaft. Use a ball-joint rod end; rigid links destroy the internal bearings inside 500 operating hours.
❗ Spring Return Logic: Confirm fail-safe direction before final bolt-up. Most diesels fail-to-fuel-off, but gas compressors sometimes fail-open. Wiring this wrong invites an overspeed event.
❗ Power Budget: 3.5 A inrush is heavy. Size the 24 Vdc PSU with 20% headroom. Voltage sag below 18 Vdc makes the actuator drop out under load—common in daisy-chained panels.
Keep these in mind and you’ll cut 90% of rework time.
Woodward 47371-01
Compatibility Matrix & Benchmarks
- Woodward 47371-02M → Woodward 47371-02 : Needs Adaptation — Flange threads (Metric vs Imperial)
- Woodward 47371-02M → Woodward PG-PL Governor : Direct — Requires metric adapter plate for legacy mounts
- Woodward 47371-02M → Generic 24V Solenoid : Incompatible — Needs closed-loop current driver, not on/off
- Step Response: ~120 ms (10% to 90% stroke, 4–20 mA step)
- Hysteresis: < 0.5% of full stroke (ISO 12204 cyclic test)
- Thermal Stability: ±1% force variance across -40 to 70 °C range
