Rebuilding the Tensioner on a John Deere 655B Crawler Loader

[MikePhua]

John Deere 655B is a versatile, durable crawler loader known for its rugged performance in a variety of construction and agricultural tasks. However, like any piece of heavy machinery, regular maintenance is essential to keep it running efficiently and to extend its operational life. One of the critical components that may require attention over time is the tensioner system, specifically the tensioner used for the track drive system.
The tensioner plays an important role in maintaining the proper tension on the tracks, which ensures smooth operation and helps prevent premature wear of the undercarriage components. Over time, these tensioners can wear out, leading to inefficient operation or even mechanical failure. In this article, we will explore the process of rebuilding the tensioner on a John Deere 655B crawler loader, covering the signs of a failing tensioner, the tools and procedures required for a successful rebuild, and tips for maintaining the system to avoid future issues.
Understanding the Role of the Tensioner in the Track System
The tensioner is responsible for ensuring that the tracks on a crawler loader remain tight and properly aligned during operation. This tension helps distribute the weight of the loader evenly across the tracks, which reduces wear and tear on the undercarriage components and improves traction. If the tension is too loose, the tracks may slip or become derailed, leading to costly repairs and downtime. Conversely, excessive tension can put unnecessary strain on the track drive components, leading to premature failure.
On the John Deere 655B, the track tension is maintained by a spring-loaded or hydraulic tensioner, depending on the machine's configuration. These tensioners need to be periodically checked and rebuilt to maintain proper functionality.
Signs of a Failing Tensioner
There are several signs that may indicate the tensioner on your John Deere 655B is failing or needs rebuilding. These signs should be addressed promptly to avoid further damage to the undercarriage and to keep the machine running smoothly.

1. Loose Tracks: One of the most obvious signs of a failing tensioner is loose tracks. If the tracks feel too slack or the loader struggles to maintain traction, it could be a sign that the tensioner is no longer providing adequate pressure to keep the tracks properly tensioned.
   
2. Unusual Noises: A malfunctioning tensioner may produce unusual sounds, such as squeaking or grinding noises, especially when the tracks are moving. This can be a result of improper track alignment or a lack of lubrication in the tensioning mechanism.
   
3. Uneven Track Wear: Uneven wear on the tracks can be a symptom of improper tension. If the tensioner is not functioning correctly, it can cause one side of the track to be tighter than the other, leading to irregular wear patterns.
   
4. Hydraulic Leaks (for Hydraulic Tensioners): If your John Deere 655B is equipped with a hydraulic tensioner, leaking hydraulic fluid around the tensioner assembly is a clear indication that the seals are worn or damaged. Hydraulic fluid leaks can cause a loss of tensioning force, resulting in loose tracks.
   
5. Excessive Track Wear: If the tensioner is not maintaining the correct tension, it can accelerate track wear. This can result in premature track replacement, which can be costly for the operator.
   

Tools and Equipment for Rebuilding the Tensioner
Rebuilding the tensioner on a John Deere 655B crawler loader requires a variety of specialized tools to ensure the job is done correctly. Below is a list of essential tools for the rebuild process:

• Hydraulic Jacks and Lifts: To lift and secure the loader during the rebuild, a hydraulic jack or lift is necessary. This will provide sufficient clearance to access the tensioner and the track components.
  
• Wrenches and Socket Set: A complete set of wrenches and sockets will be needed to remove bolts and fasteners from the tensioner assembly.
  
• Torque Wrench: For ensuring that all components are tightened to the correct torque specifications, a torque wrench is essential.
  
• Seal Puller: If the tensioner is equipped with hydraulic seals, a seal puller will be necessary to remove old seals without damaging the components.
  
• Hydraulic Fluid: If the tensioner is hydraulic, fresh hydraulic fluid will be required for refilling the system after rebuilding.
  
• Replacement Seals and Gaskets: Be sure to have new seals, gaskets, and o-rings available for the rebuild. Worn seals are often the cause of hydraulic leaks and tensioner failure.
  
• Cleaning Supplies: Clean the components thoroughly before reassembly to ensure that no debris or contaminants enter the hydraulic system. This can be done using degreasers and lint-free cloths.
  

Steps to Rebuild the Tensioner
Rebuilding the tensioner on a John Deere 655B crawler loader is a straightforward process if you follow the correct steps. Here's a detailed breakdown of the procedure:

1. Preparation:
   • Park the crawler loader on a flat, level surface and engage the parking brake.
     
   • Use a hydraulic jack or lift to raise the machine, ensuring the tracks are off the ground.
     
   • Secure the loader with jack stands for safety.
     
2. Track Removal:
   • Depending on the configuration, you may need to remove the tracks to access the tensioner. Use the appropriate tools to release the tension on the track and remove the track assembly.
     
3. Tensioner Removal:
   • Locate the tensioner assembly, which is usually positioned near the idler wheel.
     
   • Disconnect any hydraulic lines if your tensioner is hydraulic.
     
   • Remove the bolts securing the tensioner to the frame of the machine.
     
4. Inspect the Tensioner:
   • Once removed, thoroughly inspect the tensioner for any signs of wear or damage. Check the springs, seals, and hydraulic components (if applicable).
     
   • Clean all components thoroughly to remove dirt and debris.
     
5. Rebuilding:
   • Replace any worn-out components, such as seals, o-rings, or springs.
     
   • If the tensioner is hydraulic, replace the hydraulic fluid and install new hydraulic seals.
     
   • Lubricate the moving parts with the recommended lubricant to ensure smooth operation.
     
6. Reinstallation:
   • Reinstall the rebuilt tensioner back into its original position on the loader frame.
     
   • Reconnect any hydraulic lines and ensure all connections are secure.
     
   • Reinstall the tracks and ensure they are properly tensioned before securing them in place.
     
7. Testing:
   • Lower the loader and test the tracks to ensure they are properly tensioned and that the loader operates smoothly.
     
   • Monitor for any signs of leaks or unusual sounds during operation.
     

Maintenance Tips to Extend Tensioner Life
To ensure the longevity of the tensioner system and avoid frequent rebuilds, regular maintenance is essential. Here are some maintenance tips to keep the tensioner in optimal condition:

1. Inspect the Tensioner Regularly: Check the tensioner system at regular intervals for signs of wear, leaks, or damage. This will help catch issues early before they lead to a breakdown.
   
2. Lubricate Moving Parts: Regularly lubricate the moving components of the tensioner to reduce friction and prevent premature wear.
   
3. Check Hydraulic Fluid: If your tensioner is hydraulic, monitor the fluid levels and check for any signs of leaks. Ensure that the hydraulic fluid is topped off regularly and replace it according to the manufacturer’s recommendations.
   
4. Adjust Track Tension: Periodically check the track tension and adjust it as needed. Over-tightening or under-tightening the tracks can cause unnecessary strain on the tensioner and other undercarriage components.
   
5. Replace Worn Components Promptly: If you notice any signs of wear or damage to the tensioner components, replace them immediately to prevent further damage to the track system.
   

Conclusion
Rebuilding the tensioner on a John Deere 655B crawler loader is a manageable task that requires attention to detail, proper tools, and the right replacement parts. By following the recommended steps and regularly maintaining the tensioner system, operators can extend the lifespan of their equipment and avoid costly repairs down the road. Ensuring that the tensioner functions properly will contribute to the overall performance and efficiency of the machine, ultimately leading to better productivity on the job site.