Track Tensioner Seal Replacement on the Komatsu EX120-2

[MikePhua]

Introduction to Track Tensioners
Track tensioners play a crucial role in maintaining the proper tension of the tracks on a variety of heavy machinery, including excavators. For machines like the Komatsu EX120-2, track tensioners are responsible for keeping the tracks in place, ensuring that they run smoothly over the undercarriage and reduce the risk of wear. The track tensioner contains seals that prevent the hydraulic fluid inside from leaking, ensuring that the tension remains consistent under varying operating conditions.
However, over time, these seals can wear out due to continuous pressure, dirt ingress, and exposure to harsh working environments. If the seals are not functioning correctly, the hydraulic pressure can drop, resulting in improper track tension, uneven wear, and even track failure. Replacing the seals on the track tensioner is therefore a vital maintenance procedure that helps maintain the performance and longevity of the machinery.
Understanding the Komatsu EX120-2 Excavator
The Komatsu EX120-2 is a well-regarded hydraulic excavator, known for its durability and efficiency in various applications, from construction to demolition. Its undercarriage system, which includes the track tensioner, is essential for keeping the tracks properly adjusted. The EX120-2 is often used in both urban and rural environments, where the terrain can be demanding. Its robust design allows it to operate efficiently even under tough conditions.
Given that track failure or improper tension can lead to significant downtime and costly repairs, regular maintenance of the track tensioner system, including seal replacement, is important.
Symptoms of Faulty Track Tensioner Seals
Before diving into the replacement procedure, it’s important to understand the signs that indicate a problem with the track tensioner seals:

• Track Slippage: If the tracks are slipping more than usual or you notice uneven wear on the tracks, this could be a sign that the tension is not properly maintained due to a seal failure.
  
• Hydraulic Fluid Leaks: One of the most obvious signs that the track tensioner seals need replacing is the appearance of hydraulic fluid leakage around the tensioner area.
  
• Track Slack: A significant amount of slack in the tracks, especially when the machine is under load, can indicate that the tensioner is not holding pressure effectively due to worn-out seals.
  
• Erratic Track Behavior: If the tracks seem to become too tight or too loose during operation, this may point to a malfunctioning tensioner system that requires seal replacement.
  

Tools and Equipment Needed for Seal Replacement
Replacing the track tensioner seals on the Komatsu EX120-2 requires a specific set of tools and equipment to ensure a smooth and effective process. These tools include:

• Hydraulic Jack: To lift the machine and relieve pressure on the tracks.
  
• Track Wrench: Used for adjusting the track tension.
  
• Seal Puller: A tool designed to remove the old seals without damaging the housing or surrounding components.
  
• Torque Wrench: For ensuring bolts and components are properly tightened to the manufacturer’s specifications.
  
• Clean Rags and Solvent: For cleaning off any debris, oil, or old fluid before assembly.
  
• Replacement Seals: Ensure that the seals you are using are OEM parts or high-quality aftermarket seals that meet the manufacturer’s standards.
  
• Grease Gun: For lubricating the new seals during installation.
  

Step-by-Step Guide to Replacing Track Tensioner Seals

1. Lift the Machine and Remove Tracks
   • Before beginning, it’s essential to lift the excavator and secure it on stable ground. Use a hydraulic jack to raise the machine. Ensure that the tracks are not under any load.
     
   • Once the machine is elevated, you’ll need to remove the tracks by loosening the tension bolts using a track wrench. This step is critical because it relieves the pressure on the track tensioner, allowing you to work on the seals without risk of injury.
     
2. Drain the Hydraulic Fluid
   • If there is hydraulic fluid in the track tensioner system, it’s necessary to drain it to avoid spills and to ensure that the new seals are not contaminated by old fluid.
     
   • Use a drain pan to collect the fluid as it drains from the tensioner.
     
3. Remove the Old Seals
   • After draining the fluid, you can access the track tensioner assembly. Using a seal puller, remove the old seals from the tensioner. Be careful to avoid damaging the seal housing during this process.
     
   • Clean the tensioner housing thoroughly to remove any debris, dirt, or old fluid. This is crucial for preventing contamination when the new seals are installed.
     
4. Install New Seals
   • Lubricate the new seals with hydraulic oil before installing them. This ensures a smooth installation and prevents damage during assembly.
     
   • Carefully place the new seals into the housing, making sure they are seated properly. Use a seal installation tool if necessary to ensure the seals fit snugly and evenly.
     
5. Reassemble and Test
   • Once the new seals are in place, reassemble the track tensioner system. Tighten all bolts to the manufacturer’s recommended torque specifications.
     
   • Refill the hydraulic system with fresh hydraulic fluid, ensuring that the system is properly pressurized.
     
   • Reattach the tracks, adjusting the tension as needed. Operate the machine briefly to check for any leaks and to verify that the track tension is correct.
     
6. Final Check
   • After the replacement is complete, visually inspect the track tensioner for any signs of fluid leakage or improper operation.
     
   • It’s also advisable to test the excavator under working conditions to ensure the tracks remain properly tensioned during use. Pay attention to any irregularities such as slipping or excessive noise.
     

Preventive Maintenance Tips for Track Tensioners
To prolong the life of the track tensioner and prevent future seal failures, follow these maintenance tips:

• Regular Inspections: Periodically inspect the track tensioner seals for wear or leaks. Catching small issues early can prevent costly repairs later.
  
• Clean Environment: Keep the undercarriage of the machine clean from mud, dirt, and debris, as these can accelerate wear on the seals and other components.
  
• Proper Lubrication: Ensure the tensioner is properly lubricated to avoid friction that could damage the seals. Use high-quality hydraulic fluid and replace it at the recommended intervals.
  

Conclusion
The track tensioner seal replacement for the Komatsu EX120-2 is a manageable task for those with mechanical knowledge and the right tools. Proper maintenance of the track tensioner system ensures optimal performance and minimizes costly repairs in the future. By following the outlined steps for seal replacement and performing regular checks on the hydraulic system, operators can keep their Komatsu EX120-2 running efficiently in demanding environments.