Pettibone Extendo 88 Velocity Governor: Issues and Troubleshooting

[MikePhua]

The Pettibone Extendo 88 is a versatile telehandler, widely used in construction, industrial, and agricultural applications. One of its key features is the velocity governor, a critical component that regulates the speed of the machine, ensuring safe operation and preventing over-speeding. However, like any piece of machinery, the velocity governor can sometimes malfunction, causing a range of operational issues.
This article addresses the problems associated with the Pettibone Extendo 88's velocity governor, potential causes, and solutions. If you're experiencing issues with the velocity governor or related systems, this guide can help you troubleshoot and restore your machine’s performance.
What is a Velocity Governor?
The velocity governor is a control system that limits the speed of the machine, particularly in its drive and boom functions. The governor prevents the operator from exceeding a safe speed, which could potentially damage the equipment or pose safety risks. It is particularly useful for telehandlers, which can be prone to instability at higher speeds, especially when the boom is extended.
Common Issues with the Pettibone Extendo 88 Velocity Governor

1. Over-Speeding or Speed Limiting Failure
   

A common issue with the Pettibone Extendo 88's velocity governor is over-speeding or failure to limit the machine's speed. This typically occurs if the governor is malfunctioning, leading to the machine exceeding safe operational limits. When the governor doesn't work as intended, the telehandler may move too fast, which could affect its stability, especially when handling heavy loads.

• Cause: The governor may be failing due to an internal mechanical fault or issues with the sensors that measure the machine's speed. Worn or faulty parts, like the governor actuator or valve, could be responsible.
  
• Solution: Inspect the governor for any mechanical issues, such as damage to the actuator or linkage. Check if the sensors and valves are operating correctly. If any parts appear worn or broken, replace them with compatible components.
  

1. Erratic Speed Control or Inconsistent Operation
   

Another issue commonly reported is erratic speed control, where the machine either accelerates too quickly or slows down unpredictably. This can occur if the velocity governor is not accurately regulating the speed, resulting in a jerky or unstable operation.

• Cause: A malfunctioning governor valve or a worn speed sensor could be causing the inconsistency. Contaminated hydraulic fluid or air in the hydraulic system may also affect the governor’s performance.
  
• Solution: Start by checking the hydraulic system for any contamination or low fluid levels. Bleed the system to ensure no air is present. If the hydraulic fluid is dirty, replace it and install a new filter. Check the speed sensors for wear and replace them if necessary. Cleaning or replacing the valve may also help if the problem persists.
  

1. Inability to Engage Proper Speeds
   

Sometimes, the velocity governor might prevent the machine from engaging the desired speeds, either by keeping the machine in a slow mode or failing to adjust the speed settings. This could severely limit the machine's functionality, especially if it cannot operate at the required speeds for certain tasks.

• Cause: This problem might stem from a stuck or faulty governor actuator or a problem in the governor control module. A faulty electrical connection or sensor could also interfere with the governor's ability to detect and regulate the machine's speed.
  
• Solution: Examine the governor actuator and its electrical connections for any signs of malfunction. If the actuator is stuck, it may need lubrication or replacement. Test the governor’s control module to ensure it's receiving the correct input signals and can relay the information accurately to the machine.
  

1. Governor Not Responding to Changes in Load
   

In some cases, the velocity governor may not respond to changes in load. The governor is designed to adjust the machine's speed based on the weight of the load being carried. If it fails to do this, the machine could either move too slowly with a heavy load or too fast with a lighter load.

• Cause: The governor may have a malfunctioning load-sensing component or a calibration issue that prevents it from properly adjusting speed based on load weight. Additionally, a defective hydraulic pressure sensor may be contributing to the problem.
  
• Solution: Check the load-sensing system to ensure it's functioning correctly. Re-calibrate the governor if necessary to ensure it responds to changes in load. Inspect the hydraulic pressure sensors for signs of failure and replace them if required.
  

Steps to Diagnose and Fix Velocity Governor Issues

1. Check Fluid Levels and Quality
   

The first step in diagnosing issues with the velocity governor should be to check the hydraulic fluid levels. Low or contaminated fluid can affect the governor’s ability to function properly.

• Check fluid levels and top up as necessary.
  
• If the fluid appears dirty or contaminated, replace it with fresh hydraulic fluid and install a new filter.
  
• Ensure that the fluid is the correct type as specified by Pettibone for the Extendo 88 model.
  

1. Inspect the Governor Actuator and Linkage
   

The governor actuator controls the adjustment of the speed limits. Over time, wear and tear or dirt buildup can cause the actuator to become sluggish or unresponsive.

• Inspect the actuator for any signs of wear, rust, or dirt.
  
• Clean or replace the actuator if needed.
  
• Check the linkage to ensure there are no broken or disconnected parts.
  

1. Examine Speed Sensors and Electrical Connections
   

Speed sensors play a critical role in informing the velocity governor of the machine’s current speed. If these sensors are faulty or disconnected, the governor may not function as intended.

• Inspect the speed sensors for any signs of damage or wear.
  
• Ensure all electrical connections are secure and free of corrosion.
  
• Use a diagnostic tool to check for any electrical faults or codes that may indicate sensor problems.
  

1. Test the Governor Control Valve
   

The control valve is responsible for regulating the hydraulic pressure that powers the governor. If the valve is malfunctioning, it can cause erratic speed control or prevent the machine from reaching the correct speeds.

• Inspect the governor control valve for damage or leaks.
  
• Test the valve to ensure it is properly controlling hydraulic pressure.
  
• If needed, replace the valve or clean it to restore normal function.
  

1. Recalibrate the System
   

After addressing any mechanical or electrical issues, it’s important to recalibrate the velocity governor to ensure it operates properly. Consult the manufacturer’s manual for calibration instructions specific to the Pettibone Extendo 88.

• Follow the calibration procedure step by step.
  
• Ensure the governor is adjusting the machine’s speed correctly in response to changes in load or operating conditions.
  

1. Test the System
   

After making necessary repairs and calibrations, conduct a thorough test of the machine’s speed control system. Operate the machine under various load conditions to ensure the velocity governor is regulating speed as expected.

• Test the machine at different speeds, both with and without a load.
  
• Observe the machine’s performance and check for smooth, stable operation.
  

Conclusion
The velocity governor on the Pettibone Extendo 88 telehandler plays a vital role in ensuring safe and efficient operation. If you encounter issues such as over-speeding, erratic speed control, or failure to engage proper speeds, following a systematic diagnostic approach can help pinpoint the cause of the problem.
Common issues typically involve problems with the governor actuator, sensors, hydraulic system, or control valve. By carefully inspecting each component and performing necessary repairs, you can restore the functionality of the velocity governor and ensure that your machine operates safely and efficiently.
Regular maintenance, including checking fluid levels, cleaning sensors, and inspecting hydraulic components, is essential to prevent velocity governor malfunctions and extend the lifespan of your equipment. If you are unsure of any aspect of the troubleshooting process or need professional assistance, it’s always recommended to consult with a certified technician or reach out to Pettibone for expert support.