Guide · 6 Min Read
Buying a Used Excavator? How to Check the Undercarriage
The undercarriage is up to 50% of a used excavator's repair bill. A 15-minute inspection routine — what to measure, the seller tricks to spot, and how to price wear into your offer.
01Why the undercarriage decides the deal
Two identical-looking 20-tonne excavators can differ by the price of a car in undercarriage condition alone. A machine at 80% undercarriage wear needs a five-figure spend within a year; the same model at 30% has thousands of hours left. Yet most buyers spend their inspection time on the engine and hydraulics — sellers know it.
02The 15-minute routine
Walk both sides with a tape and calipers. Measure chain pitch over 4 links against nominal, link height, and bushing OD at the shiniest point. Spin-check carrier rollers, look for oil weep at every roller and the idlers, and check for flat-spotted or scalloped roller treads. Sight the sprocket teeth against a photo of a new one — sharpened or hooked teeth mean chain AND sprocket money. Check shoe grouser height and look for welded-up repairs, cracked shoes and mismatched hardware. Finally sight down each chain line for alignment and check the frame for impact damage and bent guards.
03Seller tricks to spot
Fresh paint on rails and rollers hides wear measurement points — insist on measuring, paint tells you nothing. Over-tensioned tracks make a stretched chain look tight; measure pitch, not sag. A single new component (one new idler, a few new shoes) often marks a recent failure, not generosity. And 'we just serviced the undercarriage' should come with measurement records — no records, assume the worst.
04Pricing wear into your offer
Convert your measurements to rough percent worn, then get a real quote for what's within a year of replacement — chains, sprockets, and any component over ~70%. Deduct it. VANROCK prices a complete undercarriage for any of 5,300+ models, which makes a powerful negotiation document to bring to the seller.
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VANROCK manufactures OEM-specification undercarriage parts for 5,300+ machine models — direct manufacturer pricing.
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What percent undercarriage wear is acceptable when buying used?+
Under 50% is comfortable; 50–75% means budget for major parts within a year; over 75% should be fully priced into the offer using a real replacement quote for that model.
Can I judge the undercarriage by hours on the meter?+
No — application matters more than hours. 3,000 gentle landscaping hours can leave less wear than 1,500 demolition hours. Always measure; never infer from the hour meter.
Which undercarriage part is most expensive to ignore?+
The chain–sprocket pair. A stretched chain destroys a sprocket and vice versa, so discovering one worn usually means buying both. Check those two first on any used machine.
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