Troubleshooting Weak Track Issues on the Hitachi EX 120-5 Excavator

[MikePhua]

The Hitachi EX 120-5 is a popular mid-sized excavator known for its reliability and performance in various construction, mining, and landscaping applications. However, like all heavy machinery, it can encounter issues that affect its performance. One of the common problems reported by owners and operators of the EX 120-5 is weak or underperforming tracks. This issue can significantly impact the machine's mobility and overall efficiency, leading to potential downtime and increased repair costs.
In this article, we will explore the possible causes of weak track issues on the Hitachi EX 120-5, provide a step-by-step troubleshooting guide, and discuss potential solutions to restore the excavator’s full functionality.
Understanding the Track System of the EX 120-5
The EX 120-5, like most tracked excavators, uses a complex track system designed to distribute the weight of the machine evenly across the ground for improved stability and mobility. The track system consists of several key components:

1. Track Chains: These are the continuous metal chains that run around the sprockets and rollers, providing traction.
   
2. Rollers and Idlers: These components support the weight of the machine and help to maintain the track’s alignment.
   
3. Track Tensioner: This mechanism is responsible for maintaining the proper tension on the track, ensuring it stays tight and functional.
   
4. Sprockets: The sprockets are connected to the drive motor and help in turning the track.
   

When one of these components begins to fail, it can result in weak or underperforming tracks. Now, let’s explore some of the common causes of weak track issues in the EX 120-5.
Common Causes of Weak Track Issues

1. Low Track Tension
   Track tension is critical for the proper functioning of the tracks. If the track tension is too loose, the track will not grip the sprockets properly, leading to poor traction and inefficient movement. On the other hand, excessive tension can cause unnecessary wear on the track components and reduce the overall lifespan of the tracks.
   Signs of Low Track Tension:
   • Sluggish or jerky movement when the excavator is in motion.
     
   • Track slipping off the sprocket, especially during high-load operations.
     
   • Increased wear on the rollers and sprockets.
     
2. Damaged or Worn Track Chains
   Track chains, which provide the primary traction for the excavator, can become worn over time due to regular use, exposure to harsh conditions, and lack of maintenance. Worn track chains can lead to weak tracks that struggle to grip the ground or propel the machine forward.
   Signs of Worn Track Chains:
   • Excessive vibration or noise during operation.
     
   • Uneven track movement or slipping.
     
   • Visible signs of wear or damage on the track links.
     
3. Faulty Track Tensioner
   The track tensioner plays an essential role in maintaining the proper tension on the track. If the tensioner is faulty, it can fail to keep the track tight, leading to sagging or weak tracks. A malfunctioning tensioner can be caused by internal seal failure, hydraulic pressure issues, or wear and tear on the tensioning mechanism itself.
   Signs of a Faulty Track Tensioner:
   • Uneven track tension, with one side of the track appearing tighter than the other.
     
   • Leaking hydraulic fluid from the track tensioner.
     
   • Difficulty in adjusting track tension.
     
4. Hydraulic Problems
   The tracks on the EX 120-5 are powered by hydraulic motors. If there is an issue with the hydraulic system, such as low hydraulic fluid levels, leaks, or pump failure, it can lead to weak track performance. Hydraulic problems can affect the efficiency of the drive motors, which in turn affects the movement of the tracks.
   Signs of Hydraulic Problems:
   • Lack of power or responsiveness when attempting to move.
     
   • Sluggish movement or delayed response when engaging the tracks.
     
   • Visible fluid leaks around the hydraulic components.
     
5. Worn or Damaged Sprockets
   Sprockets are essential components that help transfer the power from the drive motors to the track chains. If the sprockets become worn or damaged, they may not mesh properly with the track chains, leading to weak track performance and potential track slippage.
   Signs of Worn Sprockets:
   • Teeth on the sprockets appear rounded or excessively worn.
     
   • Tracks skipping over the sprockets or losing traction during operation.
     
   • Excessive noise or grinding sound when the tracks are engaged.
     

Step-by-Step Troubleshooting Guide
If you're experiencing weak track issues with your Hitachi EX 120-5, follow these troubleshooting steps to diagnose the problem:

1. Check Track Tension
   • Use the appropriate tools to measure the track tension. If the track is too loose, adjust the tension by using the track tensioning mechanism. Ensure that the track is neither too tight nor too loose.
     
   • If the tensioner is stuck or malfunctioning, it may need to be replaced or repaired.
     
2. Inspect Track Chains
   • Perform a visual inspection of the track chains to check for wear, damage, or broken links. Look for any signs of excessive stretching or metal fatigue.
     
   • If the track chains are excessively worn, they may need to be replaced.
     
3. Inspect the Track Tensioner
   • Check the track tensioner for any leaks or signs of hydraulic failure. If there is a visible oil leak, it could indicate a problem with the internal seals or hydraulic pressure.
     
   • Test the tensioner to ensure it is functioning correctly. If it cannot maintain track tension, it may need to be repaired or replaced.
     
4. Check the Hydraulic System
   • Inspect the hydraulic system for fluid leaks, low fluid levels, or damaged hoses. Ensure that the hydraulic pump is functioning correctly and providing adequate pressure to the track drive motors.
     
   • Top off the hydraulic fluid and test the system for any signs of sluggish movement or power loss.
     
5. Inspect the Sprockets
   • Visually inspect the sprockets for wear or damage. Check the teeth for rounding or uneven wear. If the sprockets are worn out, they will need to be replaced.
     
   • Ensure that the sprockets are properly aligned with the track chains and not causing misalignment.
     

Solutions for Weak Track Problems
Once you’ve diagnosed the cause of the weak track issues, here are potential solutions:

1. Adjust Track Tension: If the issue is caused by low track tension, adjust the tension using the track tensioner. Ensure the track is neither too tight nor too loose to avoid further damage.
   
2. Replace Worn Track Chains: If the track chains are excessively worn, replacing them with new chains will restore proper traction and performance.
   
3. Repair or Replace the Track Tensioner: If the tensioner is faulty, repair or replace it to ensure the track remains tight and functional.
   
4. Address Hydraulic Issues: If there are hydraulic problems, repair any leaks, replace damaged hoses, and ensure the hydraulic fluid is at the correct level.
   
5. Replace Worn Sprockets: Worn sprockets should be replaced with new ones to prevent track slippage and restore proper power transfer.
   

Case Study: Addressing Weak Tracks on a Hitachi EX 120-5
A construction company working on a large road project noticed that their Hitachi EX 120-5 was experiencing weak track performance, especially when working on rough terrain. The machine would often struggle to move or would lose traction, leading to delays in the project.
After a thorough inspection, the team found that the track tension was too loose, and the track tensioner was malfunctioning. The tracks were not maintaining proper tension, causing the machine to lose power during operation. They replaced the faulty tensioner and adjusted the track tension. After these repairs, the excavator regained its power, and the tracks performed as expected, allowing the team to complete the project on time.
Conclusion
Weak track issues on the Hitachi EX 120-5 can be caused by a variety of factors, including low track tension, damaged track chains, a faulty tensioner, hydraulic problems, or worn sprockets. By systematically diagnosing the issue and addressing the underlying cause, operators can restore the excavator’s full track performance and prevent costly downtime. Regular maintenance, including checking track tension, inspecting hydraulic systems, and replacing worn components, is essential to keep your machine operating at its best.