20/10/2026
A guide to track rollers on excavators and compact track loaders: what bottom rollers and carrier rollers do, single-flange and double-flange designs, signs of a worn roller, and the details you need to order the right replacements.
Track rollers carry the weight of a tracked machine and keep the track running straight. Every excavator, mini excavator and compact track loader runs on them. This guide explains what track rollers do, how bottom rollers differ from carrier rollers, how to spot a worn roller, and what to check before you order replacements.
Key takeaways
Track rollers are the steel wheels that bolt to the track frame and run on the inside of the track. The sprocket drives the track, the idler guides it around the front of the frame, and the rollers carry the machine along the track in between. On a steel-tracked machine the rollers run on the rails of the track chain. On a rubber-tracked machine they run on the inside of the rubber track.
The term covers two kinds of roller. Most people mean the bottom rollers when they say track rollers, but the carrier rollers on top of the frame are part of the same system. Both are listed in our track rollers and carrier rollers ranges.
A roller is made up of a hardened shell that the track runs on, a shaft that the shell turns on, seals that keep the lubricant in and dirt out, and the mounting that bolts it to the frame.
| Bottom roller | Carrier roller | |
|---|---|---|
| Also called | Track roller, lower roller | Top roller, upper roller |
| Position | Along the underside of the track frame | On top of the track frame, between the sprocket and the idler |
| Job | Carries the weight of the machine on the track and guides the links | Supports the top run of the track and stops it sagging onto the frame |
| Load | Takes the full machine weight, plus digging and travel loads | Carries the weight of the track only |
| Number per machine | Several per side | Usually one or two per side, and none on some compact machines |
Range links: track rollers · carrier rollers. Quantities vary by model; check your machine's parts page.
Because the bottom rollers carry the machine, they do most of the work and usually wear first. Carrier rollers turn with the top run of the track, so a seized carrier roller drags on the track and wears a flat on its own shell. Carrier rollers come in different mounting styles, including shaft-type rollers that bolt to the side of the frame.
Flanges are the raised rims on the roller shell. They keep the track links in line as the machine travels and turns. A single-flange roller has a flange on one side. A double-flange roller has one on each side, which gives the track links more guidance.
Many undercarriages use a mix of single-flange and double-flange rollers on the same track frame. Dozers normally run a mix of the two. When you replace rollers, fit each type back in the position it came from.
Tip
Before you remove the old rollers, photograph each track frame and mark the position of every single-flange and double-flange roller. It makes refitting quicker and avoids mistakes.
The number of rollers depends on the length of the track frame, so it changes from model to model. These examples come from the quantities per machine in our catalog. Each figure covers both sides of the machine.
| Machine | Bottom rollers per machine | Carrier rollers per machine |
|---|---|---|
| Kubota U27-4 | 6 | 2 |
| Kubota U55-4 | 10 | 2 |
| CAT 305 CR | 10 | Not listed |
| Hitachi ZX130 | 14 | 2 |
Quantities from the Excavator Parts Direct catalog, October 2026. Always count the rollers on your own machine before you order.
Rollers wear as the track runs over them. On a steel-tracked machine the rollers run on the rails of the chain, so the rails and the roller shells wear down together. Contact between the roller flanges and the sides of the rails wears both. Check the rollers every time you inspect the tracks, and look for these signs:
Change all the bottom rollers on a track frame together where you can. A single new roller sits higher than the worn rollers around it. It takes more of the machine's weight and wears faster than it should, and the track runs unevenly over the frame.
Rollers are part of the undercarriage system, so check the rest of it while the rollers are off. Inspect the track or chain, the idlers, the sprockets and the track adjusters. Our guide to excavator undercarriage parts covers what to check on each one. Use the bolt grade and tightening torque given in your machine's operator's manual when you fit the new rollers.
Our advice
Plan roller changes with the next track change where the wear allows it. Replacing worn parts together means one job and one round of downtime, and it protects the new parts. The cheapest roller is the one that keeps the machine working.
Rollers are specific to the machine, and some models were built with more than one undercarriage. Gather these details before you order:
Machine details
Make, model and serial number. The serial number helps confirm which undercarriage the machine has.
Roller type and count
Whether you need bottom rollers, carrier rollers or both, and how many of each are fitted to the machine.
Flange type
Which positions take single-flange rollers and which take double-flange rollers.
Markings
Any numbers or letters cast or stamped on the old rollers. Photos help if the markings are hard to read.
Send us these details and our team will check the right rollers for your machine. Contact us with what you have.
Shop carrier rollers by make
Most roller wear comes from how and where the machine works. These habits reduce it:
A track roller, also called a bottom roller or lower roller, is one of the rollers bolted along the underside of the track frame. It carries the weight of the machine on the track and guides the track links as the machine travels.
Bottom rollers sit under the track frame and carry the weight of the machine on the track. Carrier rollers, also called top rollers or upper rollers, sit on top of the track frame and support the top run of the track between the sprocket and the idler. A machine has more bottom rollers than carrier rollers, and some compact machines have no carrier rollers at all.
It depends on the model. In our catalog, quantities per machine range from 6 bottom rollers on smaller mini excavators to 14 on the Hitachi ZX130 excavator, with 2 carrier rollers where they are listed. Count the rollers on your machine or check its parts page before you order.
Replace all the bottom rollers on a track frame together where you can. A single new roller sits higher than the worn rollers around it, takes more of the load and wears faster.
A single-flange roller has a guide flange on one side of the shell. A double-flange roller has one on each side, which gives the track links more guidance. Many undercarriages use a mix of the two, so note the position of each roller before you remove it.
Look for a roller that no longer turns, oil leaking from the seals, a worn or uneven shell, and worn or broken flanges. A track that jumps on the sprocket can also point to worn rollers. Measure the shell and compare it with the new dimension to judge how much wear is left.
Related guides
Need track rollers for your machine?
Tell us your machine and what you need. We will confirm the right rollers and send a quote.
Get a quoteTalk to the teamBobcat, CAT, Hitachi, John Deere and Kubota are trademarks of their respective owners. Manufacturer names and model numbers are used for identification only. Excavator Parts Direct is an independent supplier of aftermarket replacement parts. Our parts are not genuine manufacturer parts, and we are not affiliated with any manufacturer named.
Contact our helpful sales team today.
