Measure four things: chain elongation, sprocket tooth wear, roller and idler diameters, and grouser height. Compare each against the machine's wear limits. What usually matters most is not any single measurement but how far apart the components are — a worn chain against a new sprocket, or the reverse, has a short life.
How to confirm it
- Prepare the machine and gather the right tools
Park on hard level ground, clean the undercarriage and have the wear limits for your machine to hand. A tape, a straight edge, a depth gauge and a wear gauge for the chain are normally sufficient. Measuring without the specified limits produces numbers that cannot be acted on.
- Measure track chain elongation
Measure across a fixed number of links with the chain tensioned to specification, or use the gauge provided for the chain series. Compare against the manufacturer's wear limit. Elongation is the measurement that most directly describes remaining chain life.
- Measure sprocket tooth wear
Measure the tooth profile or compare against a wear gauge. Teeth that have become hooked or pointed have passed their limit. Sprocket wear accelerates once the tooth profile no longer matches the chain.
- Measure roller and idler diameters
Measure the running surface diameter of bottom rollers and the idler. Diameters below the limit mean the chain path has dropped and the chain is running where it was not designed to run.
- Check every roller for rotation
A seized roller is not a wear measurement but it destroys the chain faster than wear alone. Check each one by hand with the side raised, and replace seized rollers urgently regardless of measured diameter.
- Measure grouser height
Measure remaining grouser height against the limit. Worn grousers reduce traction and increase track slip, which in turn accelerates the wear on everything else.
- Compare left and right and record everything
Measure both sides and write down every figure with the machine hours. The value of measurements is in comparing sides and in tracking the rate of wear between services, which is what lets you plan a replacement rather than react to a failure.
What to do about it
One component beyond its limit, the rest well within: replace that component, but check that its counterpart is in similar condition. A new chain on a worn sprocket destroys the chain; a new sprocket on a worn chain destroys the sprocket.
Chain and sprocket both near their limits: replace them together. This is almost always cheaper over the following period than either component alone.
Rollers or idlers below diameter limit, or seized: replace. Worn rollers change the chain path and accelerate chain wear, so this is rarely a measurement you can defer without cost.
Everything beyond limits: plan a full undercarriage replacement and plan it in advance. Doing it as a scheduled job is materially cheaper than doing it as an emergency, and the machine's availability improves as a result.
Need the parts this covers?
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Request a quoteFrequently asked
How do I measure chain elongation without a gauge?
Measure the distance across a fixed number of links — commonly four or five — with the chain tensioned, and compare against the specification for that chain series. Measuring the same span each time gives you a trend even if the absolute figure needs interpreting.
Can I measure undercarriage wear with the machine on a slope?
Not usefully. Measurements taken on a slope are distorted and will not compare with specification. Hard level ground is a requirement, not a preference.
When should undercarriage be replaced?
When measured wear reaches the limits, or when the cost of ongoing replacement of individual components exceeds the cost of doing the set. Recording measurements at each service is what makes that decision a calculation rather than an argument.