Why Do Tracks Keep Getting Thrown Off and What Can Be Done About It

[MikePhua]

The Anatomy of a Thrown Track
A thrown track is one of the most disruptive failures in tracked equipment, whether it's an excavator, dozer, or compact track loader. It occurs when the track chain disengages from the sprocket or idler, rendering the machine immobile and often stranded in difficult terrain. While the event itself is sudden, the causes are usually cumulative—rooted in wear, misalignment, or improper tension.
Terminology Annotation:

• Track Chain: The continuous loop of steel links that forms the undercarriage track.
  
• Sprocket: A toothed wheel that drives the track chain via engine power.
  
• Idler: A non-powered wheel that guides and tensions the track at the opposite end of the sprocket.
  
• Carrier Roller: A roller mounted above the track frame that supports the top run of the track chain.
  
• Track Tensioner: A hydraulic or spring-loaded mechanism that maintains proper track tightness.
  

Thrown tracks are more common in machines operating on uneven ground, in muddy conditions, or with worn undercarriage components. Once thrown, reinstallation is labor-intensive and often requires jacking, prying, and sometimes disassembly.
Common Causes of Track Displacement
Several factors contribute to thrown tracks:

• Improper Track Tension: Tracks that are too loose can walk off the sprocket during turns or when backing up. Over-tightening, on the other hand, accelerates wear and increases the risk of component failure.
  
• Worn Sprockets or Rollers: As sprocket teeth wear down, they lose their ability to grip the track links securely. Carrier rollers that no longer rotate freely can cause the track to bind and jump.
  
• Bent Track Frame or Idler Misalignment: Impact damage or frame fatigue can shift the alignment of the idler, causing the track to drift off-center.
  
• Debris Accumulation: Mud, rocks, or ice packed between the track and frame can lift the chain off its path.
  
• Operator Technique: Sharp turns on slopes, sudden reversals, or pivoting with one track stationary can stress the undercarriage and promote derailment.
  

In one case from northern Alberta, a forestry contractor reported frequent track throws on a compact loader used in swampy terrain. Investigation revealed that the track tensioner had failed internally, allowing slack to build up unnoticed. After replacing the tensioner and adjusting the track to spec, the issue disappeared.
Field Recovery and Reinstallation Techniques
When a track is thrown, recovery depends on terrain, equipment availability, and operator skill. Recommended steps include:

• Clear debris from the undercarriage and track path
  
• Use a hydraulic jack or cribbing to lift the affected side
  
• Rotate the sprocket manually or with engine power to align the teeth
  
• Use a pry bar or come-along to guide the track back onto the idler and sprocket
  
• Re-tension the track using the grease fitting or hydraulic adjuster
  

For machines with spring-loaded tensioners, releasing the tension may require loosening a lock nut and retracting the adjuster manually. Always wear eye protection and use caution—stored energy in the spring can release suddenly.
Preventative Measures and Maintenance Strategy
To reduce the risk of thrown tracks:

• Inspect track tension weekly and adjust according to manufacturer specs (typically 1–2 inches of sag between the carrier roller and track)
  
• Replace worn sprockets and rollers every 1,000–1,500 hours or as needed
  
• Clean the undercarriage daily in muddy or rocky conditions
  
• Avoid pivot turns on steep slopes or soft ground
  
• Monitor track frame alignment during annual service
  

In high-wear environments, consider installing track guards or rock deflectors to keep debris out of the undercarriage. Some operators retrofit their machines with aftermarket tension indicators to simplify inspection.
Undercarriage Design and Manufacturer Variations
Different manufacturers use varying undercarriage designs, which affect how tracks behave under stress:

• Caterpillar and Komatsu often use elevated sprockets on larger dozers, reducing debris impact and improving alignment
  
• Bobcat and Case compact track loaders use rigid frames with spring or hydraulic tensioners, which require frequent adjustment
  
• Hitachi and Deere excavators rely on low-slung track frames with multiple carrier rollers, offering better stability but more exposure to mud
  

Understanding the design helps tailor maintenance and operating technique. For example, machines with single carrier rollers are more prone to track walk during side-hill travel.
Operator Stories and Lessons Learned
In Tennessee, a land-clearing crew experienced repeated track throws on a mid-size excavator. After replacing the idler and adjusting the track tension, the problem persisted. The breakthrough came when they discovered the carrier roller had seized, causing the top run of the track to bind. Replacing the roller resolved the issue permanently.
In another case in Queensland, a contractor modified his compact loader with custom track guides made from hardened steel. The guides prevented lateral drift and reduced track throws by 80% over a six-month period.
These stories underscore the importance of holistic inspection—solving track issues often requires looking beyond the obvious.
Conclusion
Thrown tracks are more than an inconvenience—they’re a symptom of deeper mechanical or operational issues. By understanding the anatomy of the undercarriage, maintaining proper tension, and respecting terrain limitations, operators can dramatically reduce the risk of derailment. Whether in forestry, excavation, or grading, keeping tracks aligned and engaged is essential to productivity. In the world of heavy equipment, traction is everything—and it starts with a track that stays where it belongs.