WOODWARD 8901-067 Product Description
I. Product Basic Positioning
Brand: Woodward (USA)
Full Category Name: Booster Servomotor – Series Hydraulic Assist Servo Motor / Hydraulic Amplifier
Series: 8901 Hydraulic Servo Amplifier Unit, compatible with PG series mechanical hydraulic governor for force amplification. It is a hydraulic execution amplification component for old steam turbine / diesel engine governor systems.
Manual Number: 36684 Revision M, and the covered models: 8901-065, 8901-067, 8901-091, etc. of the tandem (Tandem) structure assist servo
Structure and Working Principle
Structural Form: Tandem Booster (Double Cylinder Tandem)
Receiving the small torque output displacement from the PG governor, through hydraulic oil power amplification to output a larger thrust / stroke, directly driving the fuel valve stem of the steam turbine / diesel engine, and the main steam valve.
It belongs to the hydraulic amplification mechanism: mechanical small displacement → hydraulic pressure amplification → high-power execution output, solving the problem of insufficient output of the mechanical governor and inability to directly drive large-sized valves.
Hydraulic Driving Medium: Unit speed control anti-fuel oil / turbine oil, operating by relying on system control oil pressure.
Typical Matching Application Scenarios
Older PG mechanical centrifugal governors (PG-PL, PG-EG, etc.) steam turbines, marine main engines, diesel generator sets, industrial driving turbines
Original execution amplification components before the hydraulic speed control retrofit of old power plants
Application Industries: Thermal power self-owned power plants, marine power, oil pipeline compressor units, sugar factories / paper mills self-owned steam turbines
Key Structural Characteristics
Double-cylinder tandem structure, compared with single cylinder (8901-037/043/051), has greater output thrust and longer stroke, suitable for large-diameter steam regulating valves
Built-in piston, feedback connecting rod, reset spring, with built-in mechanical position feedback, forming closed-loop hydraulic servo control
Equipped with standard anchor bolt fixing holes, oil interface is in imperial thread, compatible with the original PG governor oil layout
Can be mechanically adjusted to zero position, stroke limit, feedback lever ratio
Lifecycle & Spare Parts Status
Original Factory Status: It belongs to an old mechanical hydraulic governor component, has already been discontinued by the original factory (EOL), and no longer produces new parts;
Market Circulation Form:
Disassembled second-hand parts, refurbished and inspected parts (replacement of sealing parts, piston rings, bearings)
Spare Parts Maintenance: Common faults include internal oil leakage, piston jamming, feedback mechanism wear, spring fatigue failure, etc. Can perform disassembly major repair to replace oil seals and wear parts;
Modern Replacement Solution:
Solution A: Retain the PG governor, replace with refurbished 8901-067 assist servo of the same specification
Solution B: Upgrade the entire system to Woodward 505/505E digital governor + electro-hydraulic converter (CPC/I/H), cancel the mechanical hydraulic amplification structure, digital speed regulation
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