If you’re spending $20,000 to $40,000 on a used excavator from China, the last thing you want is to discover the undercarriage is shot after the machine arrives at your site. The undercarriage is one of the most expensive components to repair, and it’s where a lot of dodgy dealers hide problems. Here’s what our team checks every time before we touch the paperwork.
Why the Undercarriage Matters More Than You Think
The undercarriage on a CAT 320 or Komatsu PC200 isn’t cheap to fix. A full track replacement can run $3,000 to $8,000 depending on the market. That’s why we always tell customers: never buy a used excavator without knowing exactly what you’re getting underneath. In our experience, about 1 in 4 machines that come through our yard has some level of undercarriage wear that wasn’t disclosed upfront.
For buyers in Africa, Southeast Asia, or Latin America, getting a machine with a worn-out undercarriage isn’t just an annoyance — it can shut down a job site. That’s why we’ve built a checklist our own mechanics use on every machine before it gets listed, and we’ll walk you through the key points so you can ask the right questions from day one.
Step 1: Check the Track Links and Bogie Wheels
Start by walking around the machine and visually inspecting the track links. You’re looking for cracked links, missing pins, or uneven wear patterns. Run your hand along the top of the track — it should feel smooth. If you feel steppage, where one link sits higher than the next, that’s a sign the track is worn unevenly and close to needing replacement.
Bogie wheels — the rollers that support the track — should spin freely without play. Grab each roller and try to rock it. Any detectable movement means the bushing is worn. On a machine with 3,000+ hours, some play is normal, but if it moves more than a few millimeters, factor that into your negotiation. Our maintenance team has 10+ years of experience reading these signs — we’re happy to share what we see on any specific machine you’re looking at.
Step 2: Measure the Track Tension
Track tension is one of the easiest things to check and one of the most commonly overlooked. Use a pry bar or a simple stick to push the track down — it should deflect about 20-30mm under normal tension. If it sinks 50mm or more, the track is loose. Loose tracks are often a sign the adjuster is failing, or worse, the pin and bush wear is excessive.
If the track is too tight — basically no deflection at all — that puts excessive stress on the final drive and can cause premature failure of the hydraulic motors. Either extreme is worth negotiating on price or asking the seller to fix before shipping.
Step 3: Inspect the Sprocket and Idler
The sprocket is the toothed wheel that drives the track. Look at the teeth — they should be full and not worn to points. Worn sprocket teeth mean the track has been slipping and putting extra load on the final drive. The idler wheel at the front of the track assembly should have even rubber coverage, not cracked or chunked rubber exposing the metal core underneath.
How can I remotely assess undercarriage condition before buying?
The most effective approach is to ask the seller for close-up photos of the undercarriage, especially the track links, bogie wheels, and sprocket. We’ve seen many machine photos deliberately avoid undercarriage angles — that’s a red flag. Professional China suppliers should be happy to provide these shots on request.
How much does undercarriage repair cost?
A single set of track links costs about $1,500-$3,000 (labor not included). A full undercarriage rebuild including sprocket, bogie wheels, and idler can reach $5,000-$12,000. This is a significant expense, which is why pre-purchase assessment matters.