How to Confirm Compatibility of Komatsu PC200 Bottom Rollers?

Two PC200 excavators working the same site can take different bottom rollers. The model badge on the side of the machine is not the fitment - the build series and the serial number are - which is why compatibility on these rollers is settled by four measurements and a part number rather than by the model name. Get those four right and the roller fits; guess at any one and the roller either will not mount or will wear out quickly because it is loading the track wrongly.

Last updated: October 5, 2026

The roller in the photograph above is listed for a different Komatsu class, which is exactly the point: a part number that looks right has to be checked against your machine, not against the family name.

This guide covers the four numbers that decide whether a bottom roller fits, how to measure each of them, how to read the wear on a roller you are replacing, and what to have in writing before you order.

The four numbers that decide whether it fits

Compatibility on a PC200 bottom roller comes down to four things, and all four are checkable on the machine you are working on.

The part number. Start from the number in the machine's parts book for your exact variant, then cross-reference it against the supplier's listing. Komatsu changed roller part numbers across the PC200 build series, so a roller that is correct for one variant is the wrong part for another - and the serial number is what identifies which series your machine is. The roller width and outside diameter. The width has to suit the link width and the roller has to sit correctly against the track; measure the roller you are removing rather than trusting the size to be standard. The bore or shaft diameter. The roller's bore has to match the shaft or pin it mounts on, and this is the dimension buyers get wrong most often, because it is the one that is not visible once the roller is assembled. The mounting and flange type. Single-flange and double-flange rollers are not interchangeable, and the mounting arrangement - bracket, bolt pattern, retaining method - has to match the frame the roller sits in.

How to measure a roller before you order

Take the old roller off and measure it, even if you are confident about the part number. Three measurements cover it: the overall width across the roller, the outside diameter of the running surface, and the bore or shaft diameter with the mounting hardware removed.

While it is off, check the components that decide how the new roller will wear. A worn idler face or a hooked sprocket will wear a new roller the same way it wore the old one, and a frame that has been running with a seized roller usually shows poor alignment. Cleaning the area first matters more than it sounds: packed material hides the seating surfaces, and a roller that is fitted on top of debris never sits square.

Measure with the tools that suit the dimension. The running surface diameter is easiest with a caliper or a large vernier across the face; the width across the roller is a straight measurement; and the bore or shaft diameter needs the mounting hardware off, because that is the number that cannot be seen once the roller is assembled. Write all three down, along with the flange configuration and the number of mounting holes, before you open a catalogue - a written set of dimensions is what makes a purchase reversible if the first part you are sent is wrong.

Reading the roller you are replacing

The condition of the old roller tells you whether the replacement is the whole fix or only part of it.

What you see	What it usually means	What to do
Flat spots on the running surface	The roller stopped turning, usually because the bearing has failed	Replace it, and turn the other rollers on the same side by hand
Oil or grease weeping around the seal	Seal failure; the bearing is losing its lubrication	Replace it now - a sealed roller cannot be re-greased in service
Even, shallow wear across the face	Normal life being used up	Plan a set, rather than reacting to one roller
Uneven wear, or wear on one side only	Alignment or track tension, not the roller itself	Check tension and the idler before fitting anything new
Rust staining or pitting	Water getting past a compromised seal	Replace, and check the rest of the undercarriage for the same pattern

Two of these five are worth acting on immediately - a flat spot and a weeping seal - because both mean the roller has stopped doing its job, and every hour it runs in that state it is transferring load into the track and the frame.

What to check in the roller you buy

Two rollers that fit identically can still differ in how long they last, so the specification matters as much as the dimensions. Ask about the bearing type and whether it is sealed, the hardness and finish of the running surface, the seal design and how it is protected against contamination, and corrosion resistance if the machine works in wet or salty conditions. On a roller that runs against a steel track link, the interface between the hardened surface and the link is where life is decided - so "it fits" is only the first question.

Warranty terms and return policy belong in the same conversation: a roller that arrives with the wrong bore is a return, not a fitment problem, if the supplier cross-referenced the part number for you. Installation itself is straightforward but unforgiving - prepare the undercarriage and relieve track tension before you lift the machine, use the correct lifting points, follow the manufacturer's torque figure, and confirm the roller seats properly before the machine moves.

If you are working through the whole undercarriage rather than one roller, replacing a carrier roller on a Komatsu PC200 shows how the top rollers relate to the bottom ones, and the bottom roller range lists the part numbers and machine fits in one place.

OEM or aftermarket, and what to ask for

The honest answer is that the deciding factors on a roller this size are fit, documentation and support rather than the badge. A dealer supplies the OEM part with the factory's warranty behind it; an aftermarket specialist supplies an equivalent fitment with a shorter supply chain and, usually, better availability of the surrounding wear parts - CAT, Kubota, Doosan, Hyundai, LiuGong, XCMG and Komatsu among them.

Four items belong in writing either way: the part-number cross-reference against your variant and serial number; the four measurements above; the warranty terms as a period plus an operating-hours cap; and the stock position and lead time, because a machine waiting on a roller is the most expensive part of the job. Compare total landed cost - part, freight, tax and the days the machine stands - rather than the sticker price alone.

Lead time deserves more weight than it usually gets. A roller that is a little dearer and in the country is worth more to a machine that is standing still than a cheaper one arriving in five weeks, and for a contractor running a schedule the calculation is not close: at a day's machine rate, the difference between a three-day and a five-week delivery dwarfs any saving on the part itself. Confirm the position before ordering rather than after, and ask for the shipping date in writing.

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

Can I use a roller listed for another PC200 variant?

Only if the part number cross-references to your machine's build series. Komatsu changed roller part numbers across the PC200 range, so the correct way to check is against the parts book for your serial number, then against the measurements on the roller you are removing - not against the model badge.

What are the three measurements I should take?

Overall width across the roller, outside diameter of the running surface, and the bore or shaft diameter with the mounting hardware removed. Together with the flange type and the mounting arrangement, those are the numbers that decide whether a roller fits and sits correctly.

How do I know if a bottom roller is failing?

The two symptoms that mean stop rather than watch are flat spots on the running surface, which mean the roller has stopped turning, and oil or grease weeping around the seal, because a sealed roller cannot be re-greased in service. Uneven wear across the face points at tension or alignment instead.

Should bottom rollers be replaced as a set?

Judge by wear rather than by count. If the rollers on one side have run the same hours on the same ground and one has failed, the rest are close behind - and doing the job once, with the track tension released, is cheaper than doing it twice.

How long should a PC200 bottom roller last?

That depends on ground, tension and the state of the rest of the undercarriage, so the useful reference is your own maintenance records rather than a general figure. What you control is the fit: the correct part number, correct tension, and replacing a failed roller before it takes the track with it.