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Undercarriage wear calculator
Grouser height is the one undercarriage measurement you can take yourself in two minutes with a steel rule. Put the numbers in and it will tell you what percentage of life is left — and roughly what that does to the price.
What the number means
Turning a percentage into a price
The reason to measure rather than eyeball is that a percentage is negotiable and an adjective is not. “The tracks look alright” cannot be taken off a price. “Shoes at 34% remaining, and the sprockets are hooking” can.
The right move is usually to price the work that is due, present it, and negotiate against that figure rather than against the machine as a whole. A seller can argue about whether a machine is worth ₹24 lakh. It is much harder to argue that an undercarriage due inside a year costs nothing.
On a full report this item appears with six others, each as a percentage, and the worst of them sets the undercarriage grade — which, if it is the worst major system on the machine, sets the overall grade too. That rule is published here.
Questions
About undercarriage measurement
How do you calculate undercarriage wear percentage?
Percentage of life remaining equals (current height − wear limit) ÷ (new height − wear limit), expressed as a percentage. The wear limit matters: measuring against zero rather than the manufacturer's limit overstates the life left, sometimes badly.
Where exactly do I measure grouser height?
On the grouser bar of a shoe at the middle of the track, on level ground, measuring from the top of the shoe plate to the tip of the grouser with a depth gauge or a steel rule against a straight edge. Take three shoes at different points and use the lowest — a single reading tells you about one shoe, not a track.
Why is undercarriage the number that matters most?
On a tracked machine it is usually the largest single deferred cost, and it is the item most often described rather than measured. A full undercarriage on a 20 tonne excavator runs to several lakh, which is why a seller would much rather you looked at the paint.
Is grouser height on its own enough?
No. It is one of roughly seven undercarriage measurements — link height, bushing condition and rotation, roller and idler flange and tread wear, sprocket tooth profile and track sag all carry information, and sprocket teeth that have hooked tell you the chain has already stretched. Grouser height is simply the one you can take yourself in two minutes.