When buyers assess a used excavator, the engine and hour meter often receive the most attention. However, the undercarriage can decide whether the machine remains economical after delivery. Track shoes, links, rollers, idlers, sprockets, and the tension system work together under constant load. If one area is heavily worn, the repair bill can change the real purchase cost.
This guide explains five practical used excavator undercarriage inspection checks for overseas buyers. It focuses on what can be seen, measured, and documented before payment. To compare available machines by brand and size, review Imachine’s crawler excavator category before requesting a specific inspection pack. This guide does not replace a model-specific service manual. Instead, it helps a buyer ask sharper questions and request better evidence.
Why the Undercarriage Changes the Buying Decision
The undercarriage carries the excavator’s operating weight and transfers engine power to the ground. It also absorbs impact when the machine travels over uneven surfaces. As a result, wear is not limited to one part. A worn sprocket can accelerate track-link wear. Loose track tension can increase movement between components. Uneven roller wear can point to alignment or operating issues.
That is why a low hour reading does not prove that the undercarriage is ready for work. The machine’s application matters too. Quarry work, demolition, rocky ground, and frequent travel can affect wear differently from light earthmoving. Ask for the machine’s operating history when it is available, then compare that history with the visible condition.
Imachine’s crawler excavator inventory includes SANY, Caterpillar, and HITACHI machines from 5 t to 50 t classes. The public product pages show different years, working hours, weights, and power ratings. These details help define the machine’s context, but the undercarriage still requires a separate visual and technical review. Once a unit is shortlisted, use the quality control process as a checklist for the supporting evidence you want to receive.
Track Shoes and Track Links
Begin at ground level. Walk along both sides of the excavator and compare the track shoes. Look for missing bolts, cracked shoes, bent edges, and severe grouser rounding. A shoe with a different shape from the rest may indicate a replacement or a previous repair. That is not automatically a problem, but the seller should explain the reason and provide close photographs.
Next, inspect the track links. The links should form a consistent line around the sprocket and idler. Excessive side movement, stretched appearance, or uneven contact deserves further checking. Do not judge the entire track set from one clean photograph. Ask for images of the full length on both sides, including the top rollers and the area around the final drive.
For a technical assessment, compare measurements with the manufacturer’s service limits for the exact model. Without those limits, avoid inventing a remaining-life percentage. A reliable report should identify the measured point, the tool used, and the reference standard.
Rollers, Idlers, and Guards
Lower rollers carry the frame as the excavator travels. Inspect their outer surfaces for deep scoring, oil leakage, flat spots, and abnormal gaps. Spin or move the machine only under controlled conditions. A roller that looks acceptable in a static photo may still need a closer inspection for noise, looseness, or leakage.
The front idlers maintain track direction and tension. Check the idler rim, guide surfaces, mounting area, and visible seals. Look for uneven wear on the left and right sides. Also inspect roller guards and frame areas for deformation. A bent guard can interfere with the track path, while damaged mounting areas may point to impact or prolonged heavy work.
Take one straight side photograph and one close photograph for each side. Matching image angles make comparison easier. If the seller supplies a walkaround video, ask for a slow pass over the rollers, idlers, and guards rather than a fast general tour.
Sprockets and Final Drive Area
The sprocket transfers power from the final drive to the track chain. Its teeth should have a consistent profile. Hooked, pointed, or heavily rounded teeth indicate wear. Compare both sides rather than looking at only the more attractive side of the machine. Check the bolts, hub area, and surrounding frame for oil, cracks, or fresh paint that could hide a repair.
The final drive area also deserves attention because a clean undercarriage does not guarantee a healthy drive. Ask whether the seller has checked for leakage, abnormal noise, and travel performance. If a test video is available, request straight travel in both directions and a controlled turn. The video should show the machine moving at a safe speed on a suitable surface.
Do not claim a final drive is healthy only because the excavator moves. A proper conclusion should state what was tested, under which conditions, and whether a service record or inspection sheet supports the observation.
Track Tension and Frame Alignment
Track tension affects how the chain, rollers, and sprocket work together. A chain that is too loose can move excessively. A chain that is too tight can increase pressure and accelerate wear. The correct setting depends on the model and operating conditions, so use the manufacturer’s procedure rather than a universal number.
Look along the track frame for signs of uneven alignment. Compare the chain line with the rollers and idler. Check for unusual contact marks, damaged guards, and wear that appears stronger on one side. If the machine has worked on slopes or hard ground, ask whether the seller has observed uneven travel or recurring tension adjustments.
For overseas purchases, request a short video that shows both sides of the excavator travelling forward and reversing. A second video can show a slow turn in each direction. These simple tests do not replace an inspection, but they create useful evidence before shipping.
Match Wear With the Machine Record
The final check connects the undercarriage with the rest of the machine. Compare the track condition with the stated year, working hours, paint, bucket, boom, arm, and hydraulic components. A 2020 CAT 320GX listed by Imachine is described with 4,000 operating hours, a 19.8 t total weight, and 110 kW engine power. Those published details identify the machine, but they do not by themselves confirm undercarriage life.
For comparison, the site also lists a 2023 HITACHI ZX240 with 2,000 hours, 24 t total weight, and 132 kW engine power, as well as a 2021 SANY SY55 with 3,500 hours and 5.78 t total weight. These machines belong to different size classes and applications. Therefore, buyers should not compare wear only by hour count. Review the model, weight class, job type, and visible component condition together.
| Evidence to request | What it helps confirm |
|---|---|
| Full-length photos of both tracks | Track shoe, link, roller, and alignment condition |
| Close photos of sprockets and idlers | Tooth shape, rim wear, seals, and damage |
| Travel and turning video | Basic movement, noise, and visible tracking behavior |
| Inspection sheet or measurement record | Whether observations follow a repeatable process |
| Model and service information | Which manufacturer limits and procedures apply |
How to Request Better Evidence Before Payment
Send the seller a short, specific checklist. Ask for the exact model and serial number, both-side undercarriage photos, close-ups of the sprockets and idlers, a travel video, and any available inspection record. Also ask the seller to identify replaced parts instead of describing every machine as “perfect.” Clear limits improve the quality of the decision.
After the inspection evidence is complete, buyers can review Imachine’s export cases for examples of how equipment is prepared for international delivery. The case material should be treated as supporting context, while the selected excavator’s own photos, videos, measurements, and records remain the basis for the purchase decision.
Frequently Asked Questions
Inspect the track shoes, links, rollers, idlers, sprockets, final drive area, tension, and frame alignment together. One component alone cannot describe the complete condition.
No. Working hours provide context, but application, ground conditions, travel frequency, maintenance, and visible wear must also be reviewed.
Request full-length photos of both tracks, close photos of rollers, idlers, sprockets, and guards, plus a model and serial-number confirmation. A travel video adds useful evidence.
No. Wear limits depend on the model and manufacturer procedure. Use model-specific measurements or state clearly that a remaining-life percentage has not been confirmed.
