Which Track Roller Best Fits Bobcat MT50, MT52, MT55, and MT85 Models?

7109409 is the number that answers the question for a Bobcat MT50, MT52, MT55 or MT85: those four walk-behind and mini track loaders share the same bottom roller fitment, which is why one part number covers them all. The number is the fitment; the model list is the cross-check. Everything else about choosing a roller - material, seal, bearing - decides how long it lasts once it is on the machine.

Last updated: October 5, 2026

This guide covers what a track roller does on these machines, the numbers to confirm before ordering, what separates a durable roller from a cheap one, how to read the wear on the roller you are replacing, and what to check while the track is off.

What the bottom roller does

A track roller carries the machine's weight on the belt and guides the belt as the machine travels. On a compact machine like an MT series, each roller is small and carries a substantial share of the load, which is why the failure mode is so consistent: the seal is the first thing to go. Once grit or water gets past the seal, the bearing loses its lubrication, the roller stops turning, and the flat spot that develops starts hammering the belt and the frame - which is where a small part becomes an expensive repair.

That is also why the roller is worth inspecting at the same time as tension rather than separately. The two checks take the same few minutes, and the failure that ends a track usually starts at one of them.

The numbers to confirm before ordering

Four checks close the fitment question, and the first is the one that identifies the part.

The part number against your machine. 7109409 is the roller listed for the MT50, MT52, MT55 and MT85. Confirm it against your machine's serial number rather than assuming, because machines that share a family do not always share a roller. Roller dimensions: the running-surface diameter and width, taken from the roller you are removing. The bore or shaft diameter, measured with the mounting hardware off - this is the number that cannot be seen once the roller is assembled, and the one buyers most often get wrong. The mounting arrangement: the axle, bracket and retaining method, which have to match the frame the roller sits in.

Where the machine has been rebuilt at some point in its life, the dimensions of the part you are removing beat any catalogue drawing. Write all four down before you open a listing.

What separates a durable roller from a cheap one

Two rollers that measure identically can differ substantially in service life, and the difference is in three details.

Detail	Why it matters on an MT series machine
Seal design	The failure here is contamination, not load: a proper seal is what keeps the bearing alive
Bearing type and lubrication	The roller carries load continuously and cannot be re-greased in service if the design is sealed
Material and hardness of the running surface	The surface the belt runs on decides how the belt wears as well as how the roller wears

Ask for the specification in writing, along with the warranty terms - stated as a period plus an operating-hours cap, whichever comes first - and the freight responsibility on a claim. A roller you cannot document is a roller you cannot compare with any other.

Reading the roller you are replacing

With the machine raised and the track slack, turn each roller by hand. It should rotate smoothly with no flat spot, no roughness and no free play; a roller that will not turn is already transferring its load into the belt and the frame. Then look for a weep: oil or grease streaked along the undercarriage after the machine has stood is the earliest warning a sealed roller gives, and by the time it is visible the bearing has already begun to fail. Finally, compare the rollers side to side and along the frame - even, shallow wear is normal life; one-sided wear means alignment or tension rather than the part.

Two of those observations mean replace rather than watch. The third - uneven wear - means check tension and the idler before fitting anything, because a new roller will wear in the same pattern as the old one if the cause is still on the machine.

It is worth setting that check against the machine's own roll-call of parts. On an MT series machine the rollers are small and numerous, so a single failed roller is easy to miss until the belt starts running rough; the discipline is to turn all of them at each tension check rather than the one the operator can reach. That habit takes a couple of minutes and it is the difference between replacing a roller and replacing a roller plus the section of belt it damaged.

While the track is off

Inspect what the roller was hiding: the idler face for scoring or uneven wear, the sprocket teeth for hooks, and the belt's inner surface for damage from a seized roller. Where one roller has failed and the rest have run the same hours on the same ground, the set is usually close behind, and doing them together - with the track off and the tension released - costs less than the same job three times. The replacement procedure follows the same order of work as replacing tracks on a Bobcat mini excavator, and the same logic about matching a specific roller to a specific model appears across the range - what makes roller 7013577 right for a Bobcat E45 is the same exercise as this one, and why it also suits the E50 and E55 is the same cross-model reasoning that puts 7109409 on four MT models.

This article is part of the track rollers guide, which covers how bottom rollers are confirmed, how they wear and when to replace a set.

FAQs

Which track roller fits Bobcat MT50, MT52, MT55 and MT85?

Track roller 7109409 is the number listed for those four models. Confirm it against your machine's serial number, and against the dimensions of the roller you are removing, before ordering.

How do I know if a track roller needs replacing?

A flat spot or roughness when you turn it by hand, free play in the bearing, or an oil or grease weep at the seal. The first two mean the roller has stopped carrying its load; the third means the bearing has lost its lubrication and cannot be saved in service.

Can I replace one roller instead of all of them?

If one roller has been damaged early on an otherwise sound undercarriage, yes. Where the rollers have shared the same hours and ground and one has failed, the others are close behind - and replacing the set in one job usually costs less than repeating the labour.

What should I check on the roller before fitting it?

That it matches the dimensions and mounting of the part it replaces, that it turns freely with no play, and that the seal is intact and properly seated. Clean the mounting surface as well - a roller fitted onto packed material never sits square.

Does track tension affect roller life?

Yes, directly. A loose track slaps and rides the sprocket; a tight one loads the rollers, idler and bearings. Set tension to the figure in the machine's manual, measured the manual's way, and check both sides.