Excavator Undercarriage Parts: Fit by Brand & Model
The undercarriage is the single most expensive wear item on any excavator. Track rollers, sprockets, idlers and chains can account for up to half of your lifetime ownership cost. Yet buyers routinely order the wrong part because one model year uses a different roller shaft, a slightly changed link pitch, or a redesigned final drive. This guide shows you how to match excavator undercarriage parts to the correct brand and model, with real part numbers you can quote directly.
On a typical 20-ton machine the undercarriage can cost USD 8,000-15,000 to rebuild, and an unplanned track failure can idle the machine for days. A few minutes spent confirming fitment before you order pays for itself many times over.
Why Undercarriage Compatibility Matters
A mismatched roller or sprocket does not just fail early - it accelerates wear on the entire track system. Wrong pitch chews the idler; wrong shaft size walks out under load. Getting the fit right the first time protects the chain, the hydraulic travel motor, and your downtime budget.
Manufacturers revise undercarriage geometry across model years even when the external model badge looks identical. A roller that drops into a 2015 unit may not seat in a 2019 unit because the shaft collar changed. Always treat the stamped part number as the source of truth, not the model name alone.
The Core Undercarriage Components (the Four Wheels and One Track)
Track Rollers (Bottom Rollers)
Bottom rollers carry the machine weight and run in mud, grit and water. Part numbers vary by roller diameter and shaft. Examples from stock: 056-6892, 058-7708 and 060-3590 for compact-class rollers, and 1757725 / 1767771 for mid-size carriers.
We supply each roller with the correct seal group, so you are not tempted to reuse a hardened, brittle seal on a fresh roller. A new roller on an old seal is the fastest way to lose grease in a week.
Carrier Rollers (Top / Upper Rollers)
Upper rollers support the track return. They fail quietly until the track starts to sag. Stock top-roller references include 1785421, 1785501 and 1785753.
Because upper rollers see less load, they are easy to ignore - until the track starts to whip. Replace them in pairs per side so tension stays even across the loop.
Drive Sprockets
The sprocket transfers power from the final drive to the chain. Tooth count and bolt-circle must match the drive motor flange. Typical references: 1785814, 1785856 and 1785919.
When you fit a new chain, fit a new sprocket at the same time. A worn sprocket reshapes a new chain in a few hundred hours; a new sprocket on a stretched chain does the same in reverse.
Front Idlers
The idler tensions and guides the track. Wrong diameter changes track tension across the whole loop. References: 1786026, 1786114 and 1787189.
Idler wear shows as a narrowed guide flange. Once the flange can no longer centre the chain, the track climbs and throws. Catch it early, before it damages the chain itself.
Track Links & Shoes
Links and pads define ground contact. Pitch and shoe width are model-specific. Stock link and shoe references: 1875886, 202-10451, 202-15777, 202-19066 and 202-51958.
Pitch is the deciding number. Measure centre-to-centre across an even number of links; if it exceeds the service limit, the whole loop must be changed together rather than link by link.
Final Drive / Travel Gearbox (Verified Fit)
The travel gearbox is the most mis-quoted undercarriage item. We keep verified fitment for the major brands:
· Hitachi ZX200 / ZX200-3 travel gearbox - part 9233692 / 9134825
· Kobelco SK200-6E final drive - part YN15V00011F4
· Komatsu PC130-7 / PC120-6 travel gearbox - part 203-60-63111
Brand-by-Brand Fit Reference
|
Brand |
Typical Models |
Component |
Reference Part |
|
CAT |
305 / 307 / 320 |
Track roller / sprocket |
056-6892, 1785814 |
|
Komatsu |
PC120 / PC130 / PC200 |
Travel gearbox / roller |
203-60-63111, 1785421 |
|
Hitachi |
ZX200 / ZX240 |
Travel gearbox / idler |
9233692, 1786026 |
|
Kobelco |
SK200-6E / SK200-8 |
Final drive / roller |
YN15V00011F4, 1785501 |
|
Hyundai |
R55 / R225 |
Link / shoe |
202-10451, 202-15777 |
|
Doosan |
DH220 / DX225 |
Idler / roller |
1786114, 1767771 |
|
Volvo |
EC210 / EC240 |
Sprocket / link |
1785856, 202-51958 |
5 Steps to Verify the Right Undercarriage Part
1. Read the tag on the old part - the stamped number (e.g. 058-7708) is your fastest match.
2. Confirm machine serial and model year, not just the marketing model.
3. Measure roller diameter, shaft size and link pitch with calipers.
4. Match tooth count and bolt pattern on sprockets and final drives.
5. Send us the old-part photo plus the machine plate; we cross-check against our fitment database before shipping.
Common Mistakes Buyers Make
Ordering by machine type alone (e.g. 20-ton excavator) instead of serial; mixing brands of links and shoes on the same loop; reusing worn bolts on a new sprocket. Each of these shortens service life by months.
FAQ
Q: How do I know if a roller fits my excavator?
A: Match the stamped part number first, then confirm model and serial. If the tag is gone, send the roller diameter and shaft size - we map it to the correct reference, such as the 056-6892 family or its equivalent.
Q: Can I replace just the sprocket, or must I change the whole chain?
A: If tooth wear is even and pitch is still in spec, a sprocket alone is fine. If the chain is stretched, fit sprocket and chain together so they wear as a matched set.
Q: Do you supply complete undercarriage kits?
A: Yes - rollers, sprockets, idlers, links and shoes can ship as a matched set per model. Send your model and we quote the full kit with real part numbers.
Get the Right Fit, Fast
Correct undercarriage fitment is the cheapest insurance for your excavator. Browse our undercarriage category - track rollers, sprockets, idlers and track links - or message us the part number and machine plate. Get a matched quote on WhatsApp at +86 18758866446, or request a quote and we reply within 4 hours.
