Komatsu 155A (1975) Not Moving After an Hour: Troubleshooting and Solutions

[MikePhua]

Introduction
A common issue that can arise with older equipment like the 1975 Komatsu 155A is the failure to move after the machine has been running for some time. Operators often encounter situations where the vehicle runs for a while but suddenly loses its ability to move. This problem can stem from a variety of causes, such as hydraulic issues, transmission problems, or overheating. In this article, we will discuss potential causes and troubleshooting methods to help resolve this issue effectively.
1. Symptoms of the Problem
The main symptom reported is that the Komatsu 155A stops moving after about an hour of operation. This usually happens when the machine reaches a certain temperature or runs for a certain period. The issue doesn't present itself immediately but gradually worsens after the machine has been operating for a while.
2. Potential Causes of the Issue
Several factors can contribute to a machine losing its ability to move after running for some time. Here are the common causes:

• Hydraulic System Issues: One of the most common reasons for such behavior is a problem within the hydraulic system. Overheating of hydraulic fluid or a clogged filter could cause a loss of pressure, resulting in the machine failing to move.
  
• Transmission Problems: The transmission system might be experiencing issues, such as low fluid levels or internal wear. This could cause the vehicle to operate normally at first but fail to move after it heats up or operates for a while.
  
• Overheating: Excessive heat can affect various systems in the machine, including the hydraulic and transmission systems. Overheating might cause fluid to thin out, reducing pressure or causing internal seals to fail.
  
• Clogged Filters: A clogged hydraulic filter can restrict the flow of fluid, causing the system to lose pressure after extended use. This could explain the loss of movement after running for an hour.
  
• Fluid Contamination: Contaminants in the hydraulic fluid can cause damage to the hydraulic pump or other critical components. This can result in diminished performance, especially when the machine operates for an extended period.
  

3. Troubleshooting Steps
To diagnose the problem and resolve it, follow these troubleshooting steps:

• Check Hydraulic Fluid Levels: Begin by checking the hydraulic fluid levels. Low levels could lead to insufficient fluid pressure, preventing the machine from moving properly.
  
• Inspect Hydraulic Filters: Look for any signs of clogging in the hydraulic filters. If the filters are dirty or blocked, replace them with fresh filters to restore proper flow and pressure in the system.
  
• Examine the Transmission Fluid: Check the transmission fluid level and quality. Low or contaminated fluid could lead to transmission failure. Ensure that the fluid is clean and at the correct level, topping up or replacing it as necessary.
  
• Check for Leaks: Inspect all hydraulic hoses and lines for any visible leaks. Leaks can cause a loss of pressure, which might explain the lack of movement after some time.
  
• Coolant and Temperature Checks: Verify that the cooling system is functioning properly. Overheating can affect both the hydraulic and transmission systems, so ensure the radiator is clean and the coolant is at the correct level.
  
• Test for Fluid Contamination: If you suspect fluid contamination, perform a fluid sample test to check for metal particles or other contaminants. If contamination is detected, replace the fluid and flush the system.
  

4. Solution and Fixes
Once you’ve identified the cause of the issue, you can proceed with the following solutions:

• Hydraulic Fluid Replacement: If the fluid is low or contaminated, replace it with the recommended hydraulic fluid. Ensure the system is properly bled to remove any air pockets.
  
• Filter Replacement: Replace clogged filters to restore proper hydraulic fluid flow and pressure.
  
• Transmission Repair: If transmission fluid issues are identified, top up or replace the fluid as needed. In more severe cases, the transmission may need to be overhauled or repaired by a professional.
  
• Cooling System Repair: If overheating is the cause, clean the radiator and check for any leaks or blockages in the cooling system. You may need to replace worn-out components like fans or hoses.
  
• Regular Maintenance: Once the issue is resolved, ensure that regular maintenance is performed on the machine. This includes changing the hydraulic fluid and filters, checking fluid levels, and inspecting the transmission system to prevent future issues.
  

5. Conclusion
A Komatsu 155A (1975) that fails to move after an hour of operation is often the result of hydraulic or transmission system issues, overheating, or fluid contamination. By following the troubleshooting steps and performing the necessary repairs or replacements, you can restore the machine’s performance. Regular maintenance is key to ensuring the machine operates smoothly and avoids similar problems in the future. Always consult the owner’s manual and consider seeking professional help if the issue persists.