Woodward | 8558-345 | PG-PL Hydraulic Governor Control System

Product Description

The Woodward 8558-345 is a PG-PL Series pressure-compensated hydraulic governor designed for mechanical speed control of engines and industrial turbine prime movers.

The governor uses a centrifugal flyweight mechanism, pilot valve assembly, hydraulic oil system, and power cylinder (servomotor) to regulate prime mover speed. It responds to changes in engine speed and adjusts the hydraulic output to maintain the selected operating speed.

This model features pneumatic speed setting and an integrated pressure relief valve. Its hydraulic power assembly provides the force required to position the engine or turbine fuel-control mechanism.

The 8558-345 is suitable for applications requiring dependable mechanical-hydraulic governing, including industrial engines, generator drive systems, and selected turbine installations. Correct configuration depends on the engine or turbine specifications and the governor’s original calibration.

Product Datasheet & Parameters

• Brand: Woodward
• Model: 8558-345
• Series: PG-PL
• Product Name: Pressure-Compensated Hydraulic Governor
• Product Type: Mechanical-Hydraulic Speed Governor
• Control Function: Prime Mover Speed Regulation
• Speed Setting: Pneumatic
• Governor Mechanism: Centrifugal Flyweight and Pilot Valve Assembly
• Hydraulic System: Pressure-Compensated Oil System
• Pressure Relief Valve: Yes
• Power Assembly: Hydraulic Power Cylinder / Servomotor
• Speed Control: Mechanical-Hydraulic
• Application: Engine and Industrial Turbine Speed Control
• Mounting: Engine or equipment-specific mounting arrangement
• Place of Manufacture: Verify from the product nameplate
• Country of Origin: Not confirmed; check the unit’s identification plate
• Dimensions: Confirm from the actual assembly and installation drawing
• Weight: Depends on the complete governor configuration; verify before shipping
• Product Condition: Confirm the actual item’s condition and test status with the seller
• Discontinued Status: Confirm current production and replacement availability with Woodward

 

Main Product Features

• PG-PL pressure-compensated governor design for mechanical-hydraulic speed regulation.
• Centrifugal flyweight mechanism provides speed-responsive control.
• Pneumatic speed-setting mechanism allows remote adjustment of the speed reference.
• Hydraulic power cylinder supplies the force required for actuator positioning.
• Integrated pressure relief valve helps control maximum hydraulic oil pressure.
• Oil pump and pressure storage arrangement support hydraulic governor operation.
• Compensation system helps stabilize governor response and reduce unwanted speed oscillation.
• Manual adjustment mechanism supports authorized setup and maintenance procedures.
• Designed for engine and turbine control applications requiring hydraulic governing.

 

Daily Maintenance and Care

1. Hydraulic Oil Inspection
   Check oil level, cleanliness, and condition. Use the oil grade specified for the governor and the associated prime mover.
2. Oil Filter and Pump Inspection
   Inspect the oil filter, pump, and supply passages. Replace contaminated filters and investigate abnormal oil pressure.
3. Pressure Relief Valve Check
   Inspect the relief valve for leakage or abnormal pressure behavior. Verify its setting using the approved maintenance procedure.
4. Pneumatic Speed-Setting Inspection
   Check the pneumatic supply, tubing, fittings, and speed-setting response. Look for air leaks or unstable pressure.
5. Linkage and Power Cylinder Inspection
   Inspect the output linkage, servomotor, mounting points, and connected fuel-control mechanism for wear or mechanical resistance.
6. Speed Stability Monitoring
   Monitor operating speed during startup, steady-state operation, and load changes. Investigate hunting, overspeed tendencies, or slow response.
7. External Cleaning
   Keep the governor housing and surrounding area clean. Prevent dust, moisture, and foreign material from entering the hydraulic system.

 

Troubleshooting and Common Problems

Problem: Unstable Engine Speed or Governor Hunting

• Check hydraulic oil level and cleanliness.
• Inspect the compensation system and governor linkage.
• Check for air in the hydraulic circuit.
• Verify that the pneumatic speed-setting signal is stable.
• Inspect the prime mover for load or fuel-system disturbances.

Problem: Governor Does Not Respond to Speed Changes

• Inspect the centrifugal flyweight and pilot valve assembly.
• Check the hydraulic oil supply and pump operation.
• Inspect the power cylinder for sticking or leakage.
• Verify the mechanical connection to the fuel-control mechanism.

Problem: Incorrect Speed Setting

• Check the pneumatic speed-setting supply.
• Inspect the adjustment mechanism and connecting lines.
• Verify the governor’s specified speed range and calibration.
• Compare the actual configuration with the engine or turbine requirements.

Problem: Low Hydraulic Pressure

• Check oil level and pump operation.
• Inspect the oil filter and hydraulic passages.
• Check for external leakage.
• Inspect the pressure relief valve for incorrect operation.

Problem: Slow Actuator Response

• Inspect the servomotor and output linkage.
• Check hydraulic oil viscosity and temperature.
• Look for restricted oil passages or contaminated components.
• Verify that the connected fuel-control mechanism moves freely.

Problem: Oil Leakage

• Inspect seals, gaskets, fittings, and hydraulic connections.
• Check for damaged threads or loose fittings.
• Replace worn sealing components using approved parts.
• Confirm that operating pressure remains within the specified limits.

 

Installation and Safety Precautions

• Verify the complete part number, serial number, and any suffix markings before installation.
• Confirm that the governor’s speed range, rotation, mounting arrangement, and calibration match the prime mover.
• Check the pneumatic speed-setting requirements before connecting the control lines.
• Flush and clean hydraulic piping before connecting the governor.
• Use the specified hydraulic oil and filtration arrangement.
• Ensure that the output linkage moves freely throughout its operating range.
• Do not adjust the pressure relief valve or compensation settings without the correct technical documentation.
• Perform commissioning and speed-response testing under controlled conditions.
• Maintain an independent overspeed shutdown system where required by the application.
• Installation and calibration should be performed by qualified governor technicians.

 

Frequently Asked Questions

Q1: What is Woodward 8558-345?

A: It is a PG-PL Series pressure-compensated hydraulic governor designed for engine and industrial turbine speed control.

Q2: Is 8558-345 a PLC module?

A: No. It is a mechanical-hydraulic governor assembly, not a programmable logic controller or electronic I/O module.

Q3: What type of speed setting does it use?

A: The 8558-345 is identified with a pneumatic speed-setting mechanism.

Q4: Does this model have a pressure relief valve?

A: Yes. The listed configuration includes a pressure relief valve in its hydraulic system.

Q5: What are its main internal components?

A: The standard PG-PL governor arrangement includes a centrifugal flyweight head-pilot assembly, hydraulic power cylinder, compensation system, oil pump, and speed-setting mechanism.

Q6: Can it be used on a generator engine?

A: It may be suitable for compatible generator prime movers, provided the governor’s speed range, output configuration, and calibration match the engine requirements.

Q7: What information is needed when replacing an existing governor?

A: Provide the full part number, serial number, nameplate details, engine or turbine model, rated speed, rotation direction, and mounting information. Special suffix markings can indicate application-specific modifications or calibration.

 

Recommended Woodward Models and Related Products

1. 8552-215 – PG-PL Series pressure-compensated governor for engine speed regulation.
2. 8552-623G – PG-PL governor assembly for compatible mechanical-hydraulic control applications.
3. 8554-585 – PG-PL Series governor for prime mover speed control.
4. 8558-253PS – PG-PL governor assembly for engine and turbine applications.
5. 8558-573HK – PG-PL governor assembly for compatible hydraulic governing systems.
6. 8558-852 – PG-PL Series governor for mechanical-hydraulic speed regulation.
7. 8571-102MH – Woodward governor assembly for engine control applications.
8. 8571-953 – Woodward governor for compatible prime mover speed-control systems.
9. D8558-560HK – PG-PL governor assembly for specified engine applications.
10. 8558-531 – PG-PL governor-related assembly.
11. 8559-019 – PG-PL governor-related assembly.
12. 8559-123 – PG-PL governor-related assembly.
13. 8559-273 – PG-PL governor-related assembly.
14. 8559-580 – PG-PL governor-related assembly.
15. 8559-660 – PG-PL governor-related assembly.

Note: These models belong to related Woodward governor product families. They are not necessarily direct replacements for 8558-345. Confirm the complete configuration and application requirements before ordering.