Undercarriage Parts for 20-Ton Excavators: Match Track Rollers (CAT 320D / PC200)

How to Match Track Rollers, Idlers, Sprockets and Track Chain by Model

Technical Guides 2026-10-17

AIAI Search Summary

This article explains how to select undercarriage parts for 20-ton class excavators. It covers five component groups: Track Roller, Carrier Roller, Front Idler, Sprocket and Track Chain, and shows how CAT 320D and KOMATSU PC200 differ in pitch, flange type, shaft diameter, bolt-hole pattern and OEM part numbers. The guide advises buyers to confirm machine model, serial number and production year before ordering, then choose sealed structures and hardness levels according to site conditions such as earthwork, quarry, mud or long-distance travel. It also recommends requesting a fitment cross-reference, dimension drawing and pre-shipment photos to avoid mismatch and premature wear.

Undercarriage Parts for 20-Ton Excavators: How to Match Track Rollers

For 20-ton excavators, CAT 320D and KOMATSU PC200 are two of the most common machines. They look similar, but undercarriage parts are not freely interchangeable. Pitch, flange, shaft diameter, link count and tensioning design can all differ.

CAT 320D track roller selection

The Five Undercarriage Groups

Track Roller / Bottom Roller: carries machine weight and runs on the track chain
Carrier Roller / Top Roller: supports the upper return run and prevents chain sag
Front Idler: guides and tensions the track
Sprocket: driven by the final drive and engages the chain bushings
Track Chain / Link Assy: includes links, pins, bushings and track shoes

What to Check for CAT 320D vs PC200

Model and serial number: PC200-7, PC200-8, 320D and 320D2 use different rollers, links and idlers.
Pitch: 20-ton machines often use around 190 mm pitch, but always measure the existing chain.
Flange type: single or double flange affects chain centering; quarry duty needs thicker flanges.
Shaft diameter and bolt-hole pattern: most “does not fit” problems come from these two values.
OEM numbers: CAT uses codes such as 1XX-XXXX; KOMATSU uses codes such as 20Y-XX-XXXXX.

Match by Application, Not by Price

Earthwork / municipal: standard seals and standard flange are usually enough
Gravel / quarry: thicker flange, induction hardening, floating seals
Mud / snowmelt sites: triple-lip or duo-cone floating seals to block water and dirt
Long-distance travel: check pin, bushing and link heat-treatment reports

How to Avoid Wrong Orders

Do not just send “20-ton excavator track roller”. Send this instead:
Machine brand + model + serial number + old part photo + old OEM number + track shoe width + rollers per side

We can cross-match CAT 320D and PC200 items, then provide before shipment:

Fitment confirmation sheet
Key dimension drawing
Marked-part photos
Track chain pitch, link count and pin specification

One Practical Rule

Chain elongation, leaking track rollers and frequent track derailment are often caused by mixed old-and-new undercarriage wear. If you replace the chain, also evaluate the sprocket. A new chain on a badly worn sprocket creates uneven load and shortens the life of the new parts.

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