Track Stretching in Steel Tracked Equipment: Myths, Mechanics, and Maintenance

[MikePhua]

Understanding the Basics of Steel Track Systems
Steel track systems, found on excavators, bulldozers, and other crawler-type equipment, rely on a carefully balanced arrangement of components. These include the track links, pins and bushings, sprockets, idlers, rollers, and track shoes. Over time, these components wear—particularly the pin and bushing interfaces—resulting in a phenomenon commonly referred to as "track stretching." While the term “stretching” is often used by operators and mechanics, the tracks do not actually elongate like elastic. Instead, wear between the pin and bushing causes increased pitch length (distance between pins), which leads to an overall longer chain.
What Really Happens: Pin and Bushing Wear
Track chains are composed of alternating steel pins and bushings, creating pivot points that allow the chain to bend around sprockets and idlers. Over time, as the machine operates in dirt, sand, and rock, these joints experience internal wear. The bushing's inner surface and the pin’s outer surface slowly grind against each other, especially if lubrication is poor or absent. This creates a longer pitch and effectively makes the track “grow.”
Symptoms of this wear include:

• Difficulty maintaining proper track tension
  
• Excessive sag in the bottom track span
  
• Jumping or skipping sprockets
  
• Accelerated sprocket tooth wear
  
• Noisy or rough undercarriage performance
  

Eventually, the increased pitch can prevent the track from properly engaging the sprocket, leading to “walking out” or derailing under load.
Common Misconceptions About Track Stretching
One common myth is that improper tension or overloading causes the steel to stretch. While these factors can cause accelerated wear, they do not stretch steel. The visible elongation of the track is mechanical—not structural. It’s a function of internal joint wear, not metal deformation.
Another frequent misconception is that once a track stretches, it must be replaced. In reality, most OEM tracks can be turned or rebuilt. This involves rotating the pins and bushings 180 degrees (commonly called a "turn") to place fresh surfaces in contact, extending the track’s life. Some operators skip this procedure, unaware that it can provide thousands more hours of service.
Environmental and Operational Factors
Certain conditions accelerate pin and bushing wear:

• Abrasive soil types like sand or decomposed granite
  
• Water and mud, which wash away lubricants
  
• Frozen ground, where impact loads are higher
  
• High-speed travel, which increases articulation wear
  
• Improper tensioning, either too tight or too loose
  

A contractor working in Florida described how their machines required undercarriage rebuilds nearly twice as often as comparable units used in the Pacific Northwest, purely due to the sand-heavy coastal soils. Another in northern Alberta reported excessive wear after a winter season due to frozen ground operations with over-tensioned tracks that could not adjust naturally to debris buildup.
When to Rebuild or Replace
Eventually, all track chains reach the end of their serviceable life. The question becomes: is rebuilding cost-effective?
Consider rebuilding when:

• The track frame and shoes are in good condition
  
• Sprockets have been recently replaced or are still within spec
  
• Chain wear is within acceptable turning limits
  

Consider full replacement when:

• Links are cracked, severely worn, or bent
  
• Pins and bushings are beyond turnable limits
  
• Sprockets and rollers are also worn out
  
• The machine has over 80% undercarriage wear and needs multiple components replaced
  

A practical rule of thumb: if the cost to rebuild exceeds 60–70% of new, replacement becomes more economical—especially when considering downtime and labor.
Track Tension: The Double-Edged Sword
Proper track tension is one of the most misunderstood maintenance items. Operators often run tracks too tight, mistakenly believing it helps with stability or performance. In reality, overtight tracks create excessive friction, which accelerates wear on:

• Pins and bushings
  
• Carrier rollers
  
• Idler bushings
  
• Final drives (due to added load resistance)
  

Conversely, tracks that are too loose risk derailing, especially during side loading, turning, or when material gets packed between the sprocket and track chain. One logging operator reported three derailments in a single day after clearing deep brush with under-tensioned tracks that let branches wedge into the idler area.
Best Practices for Track Care
To maximize the life of steel tracks:

• Inspect tension daily, especially in muddy or shifting conditions
  
• Clean undercarriage regularly to prevent material buildup
  
• Operate smoothly, avoiding excessive spinning or abrupt turns
  
• Use travel reduction when possible—tracking is the most wearing action on any machine
  
• Track in reverse occasionally, to help even out wear patterns
  
• Turn pins and bushings at recommended intervals
  

Some contractors also paint a white mark across one link to visually track chain movement and identify skipped pitches. While primitive, this method helps detect early pitch growth before it becomes a derailment risk.
Stories from the Jobsite

• A pipeline crew in Texas kept losing tracks on their 345-class excavator. After investigation, they found a previously repaired track link had failed and deformed slightly. This increased the pitch just enough to make engagement with the sprocket unreliable. The repair was simple, but the lost hours weren’t.
  
• In the Midwest, a highway grading company had been religiously over-tensioning their dozers, thinking it reduced blade chatter. They ended up blowing out three final drives in 18 months. After retraining the crew and adopting OEM tension specs, their rebuild frequency dropped significantly.
  
• A mining operation in Australia invested in automatic track tensioning systems for their fleet. While expensive, the real-time adjustment based on load and terrain increased track chain life by over 20%.
  

Modern Advances in Undercarriage Design
Some manufacturers now offer sealed and lubricated track chains that extend wear life by keeping contaminants out and oil in. Others use carburized bushings and induction-hardened pins that resist wear more effectively. However, these systems still require monitoring, as seals can fail and allow dirt to enter, leading to internal grinding that mimics traditional wear patterns.
Telematics systems are beginning to include undercarriage wear monitoring through vibration and resistance sensors. These systems aren’t yet widespread, but as repair costs grow, they are likely to become standard on premium machines.
Conclusion: Respect the Chain, Preserve the Machine
Track systems are the unsung heroes of crawler equipment. They bear the load, endure the terrain, and often suffer silently until failure strikes. Misunderstanding “track stretching” can lead to misdiagnosis, premature replacement, or dangerous operation.
With a solid maintenance program, attentive operators, and informed decision-making, steel tracks can deliver thousands of productive hours. But when overlooked, even the strongest chain can become the weakest link.