Troubleshooting Track Speed and Direction Issues in a 1996 Komatsu PC60-6

[MikePhua]

When dealing with heavy equipment, issues related to track speed and direction can cause significant disruptions on the job site. One common problem reported by owners of the Komatsu PC60-6 excavator is a malfunction where the left track moves backwards while the right track moves at full speed, or when the left track moves forward very slowly. This type of malfunction not only hinders the equipment’s performance but can also pose a safety risk if left unaddressed.
This article explores potential causes for this specific problem, how to diagnose the issue, and the steps required to resolve it, focusing on the Komatsu PC60-6 excavator and its hydraulic systems.
Understanding the Komatsu PC60-6 Excavator
The Komatsu PC60-6 is a mid-size hydraulic excavator widely used in construction, landscaping, and utility work. Known for its reliability and power, this machine is built with a hydraulic system that controls its movement and various functions. The travel motors connected to the tracks are part of a complex hydraulic system that allows the machine to move forward, backward, and turn efficiently.
One of the common issues in hydraulic machines like the PC60-6 involves the loss of movement control in one or more of the tracks. The malfunction mentioned, where the left track operates incorrectly, is an example of such a hydraulic or mechanical failure.
Causes of Track Speed and Direction Problems

1. Hydraulic System Issues
   The primary cause of uneven track movement is often linked to the hydraulic system. In the Komatsu PC60-6, each track is controlled by a hydraulic motor. These motors receive fluid from the hydraulic pump, which is responsible for regulating the flow and pressure of the fluid to the travel motors.
   If there is an issue with the hydraulic fluid pressure, it can cause one side to operate much slower than the other. A low hydraulic fluid level, clogged filters, or a damaged hydraulic pump can prevent adequate fluid pressure, resulting in the sluggish or reversed movement of the left track.
   • Low fluid levels can cause a lack of lubrication and cooling in the hydraulic components, leading to underperformance of the travel motor.
     
   • Clogged filters or debris in the hydraulic system can restrict fluid flow, resulting in uneven movement between tracks.
     
   • A worn-out hydraulic pump can fail to deliver adequate pressure to one track, causing the movement to be slow or erratic.
     
2. Travel Motor Malfunctions
   Each track in a tracked excavator is driven by a hydraulic motor. If one of the travel motors is malfunctioning or has worn-out components such as seals or bearings, it can cause slow or reversed motion. A faulty travel motor may not receive enough fluid or may have internal issues that prevent it from functioning correctly.
   • Internal leaks within the motor can cause reduced pressure on one track, leading to slow or irregular movement.
     
   • Damaged seals can cause hydraulic fluid to leak out, reducing pressure and resulting in sluggish operation.
     
3. Control Valve Failure
   The control valve is responsible for directing hydraulic fluid to various parts of the machine, including the travel motors. If the control valve malfunctions, it may send incorrect amounts of hydraulic fluid to the tracks, causing uneven speeds. This can occur due to internal wear or external damage to the valve.
   
4. Electrical or Sensor Problems
   Many modern excavators, including the Komatsu PC60-6, rely on electrical sensors to monitor and adjust hydraulic pressures and movement. If these sensors fail or become misaligned, the hydraulic system might not function as expected, resulting in issues like slow movement or backward movement on one track. In some cases, sensor malfunctions can also lead to inconsistent movement patterns.
   

Steps to Diagnose and Fix the Issue

1. Check Hydraulic Fluid Levels
   Start by checking the hydraulic fluid levels to ensure they are within the proper range. Low fluid levels can significantly affect hydraulic performance. If the fluid is low, top it up with the recommended type of fluid as per the manufacturer's specifications. Also, inspect the condition of the fluid; dirty or contaminated fluid should be replaced.
   
2. Inspect Hydraulic Filters
   The hydraulic filters are responsible for removing debris and contaminants from the fluid. Over time, these filters can become clogged, reducing fluid flow and causing problems with track movement. Replace the filters if they are dirty or damaged.
   
3. Examine the Travel Motors
   The travel motors are critical to track movement, and any issues with them can lead to uneven performance. Inspect both motors for leaks, damage, or signs of wear. If a motor is malfunctioning, it may need to be repaired or replaced. In some cases, disassembling the motor to inspect its internal components, such as seals, bearings, and pistons, may be necessary.
   
4. Test the Control Valve
   The control valve regulates the flow of hydraulic fluid to the travel motors. If the valve is malfunctioning, it may need to be cleaned or replaced. Start by inspecting the valve for any visible damage or wear. If the valve seems to be functioning incorrectly, consult the service manual for troubleshooting steps or have it tested by a professional.
   
5. Check Electrical and Sensor Systems
   If all the hydraulic components seem to be in good condition, the issue may be related to the electrical system or sensors. Inspect the wiring and connectors for any signs of corrosion, damage, or loose connections. Faulty sensors can cause the machine to behave erratically, so check for any diagnostic codes using an onboard diagnostic tool to identify any electrical or sensor-related faults.
   

Preventive Maintenance for Future Issues
To avoid similar track movement issues in the future, it's crucial to implement a solid maintenance schedule. Here are some tips for maintaining the Komatsu PC60-6 to prevent hydraulic and track-related issues:

1. Regularly Check Hydraulic Fluid Levels
   Keep an eye on the hydraulic fluid levels and ensure they remain consistent. Regularly check the condition of the fluid to detect any signs of contamination early on.
   
2. Replace Filters Periodically
   Hydraulic filters should be replaced at regular intervals to ensure proper fluid flow and to keep contaminants out of the system.
   
3. Monitor Travel Motor Performance
   Periodically test the travel motors to ensure they are operating smoothly. Any unusual noises, slow movements, or leaks should be addressed immediately to prevent larger issues from developing.
   
4. Perform Electrical System Diagnostics
   Regularly check the electrical system and sensors, especially if the machine is experiencing erratic movement or performance. Catching small electrical issues early can save time and money on larger repairs later.
   
5. Consult the Manufacturer’s Service Manual
   The service manual for the Komatsu PC60-6 provides essential guidelines on maintenance intervals, recommended parts, and troubleshooting steps. Regularly referring to the manual can help keep the machine in top condition and prevent issues like slow or reverse track movements.
   

Conclusion: Keeping Your Komatsu PC60-6 Running Smoothly
Dealing with a left track moving backwards or moving slowly while the right track operates at full speed can be frustrating, but it's often a sign of an issue within the hydraulic system or the travel motor. By following a systematic approach to diagnosing and fixing the problem, you can restore the excavator’s performance and ensure it operates safely and efficiently. Regular maintenance is the key to preventing future issues, so taking the time to inspect and maintain your Komatsu PC60-6 regularly will help keep it running smoothly for years to come.