Undercarriage wear parts — track rollers, carrier rollers, idlers, sprockets and link assemblies — are built per machine class and identifiable from a short set of measurements: roller diameter and flange dimensions, idler wheel diameter and shaft bore, sprocket tooth count and pitch, link pitch and rail height. A part number helps when it survives, but dimensions identify the part when it does not, because the undercarriage is dimension-driven in a way the engine is not. Guangzhou Shenyue Machinery Technology Co., Ltd. quotes undercarriage from those measurements plus the machine model and serial, states the grade on every line, and holds 3,000+ part types on the shelf with 100,000+ part numbers available to order.
The measurement set for each family
| Part | What identifies it |
|---|---|
| Track roller | Tread diameter, tread width, flange height and spacing, shaft or bore at both ends |
| Carrier roller | Tread diameter, overall width, flange form, and the bracket or shaft fitting |
| Idler | Tread diameter, overall width, shaft diameter and length, recoil and adjuster thread type |
| Sprocket | Tooth count, bolt circle and bore, hub length, pitch — counted before anything else |
| Link assembly | Pitch center-to-center, rail height at the unworn shoulder, shoe bolt pattern |
How to confirm it
- Clean the part enough to read the wear, not to showroom standard
A wire brush on the end faces and the shaft bores reveals casting numbers and the wear surfaces that matter for grading. The number is often on the end cap or the flange face, not the tread.
- Measure a roller across the tread and the flanges
Overall diameter, tread width, flange height and flange spacing, plus the shaft or bore diameter at both ends. Those five numbers place most track and carrier rollers into their family, and the flange spacing separates the lookalikes.
- Measure an idler at the tread and the shaft
Idler tread diameter, overall width, and the shaft diameter and length if the shaft is integral. The recoil-spring side and the adjuster thread type matter too, because idlers are handed and thread types do not interchange.
- Count and measure a sprocket before anything else
Tooth count and bolt-circle: the number of teeth, the bolt pattern, the hub bore and the pitch. A tooth count plus bolt-circle identifies most sprockets faster than a photo, and a worn sprocket still counts its own teeth reliably.
- Measure link pitch and rail height for a link assembly
The pitch is center-to-center on adjacent link pins, the rail height is measured at the unworn shoulder if there is one, and the shoe bolt pattern follows from the link. One link measurement plus the machine serial usually resolves the chain family.
What to do about it
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Parts you may need, by grade
| Part | Grades commonly quoted |
|---|---|
| Rollers, idlers and carrier rollers | Genuine; OEM-quality; established aftermarket matched to the machine class. Sealed-for-life units are the ones worth paying for — the seal is the life. |
| Sprockets | Genuine or OEM-quality matched to tooth count and pitch. A sprocket wears with its chain, and a new sprocket on a worn chain is half a repair. |
| Track links and shoes | Genuine; OEM-quality; established aftermarket to the pitch and rail specification. The rail height and pitch are the fitment, and the shoe bolt pattern follows the link, not the shoe. |
Need the parts this covers?
Send the machine model, serial number and the part numbers you need. We confirm fitment before payment and state the grade of every line — genuine, OEM-quality or aftermarket.
Request a quoteFrequently asked
Can you identify a roller from photos alone?
Usually not, and the honest request is photos plus five measurements: tread diameter, width, flange height and spacing, and the shaft or bore diameter. Photos rule families out; dimensions rule the part in. Guangzhou Shenyue Machinery Technology Co., Ltd. confirms against the machine serial once the family is placed.
Should I replace undercarriage parts in sets?
As a rule, yes for rollers and idlers per side: wear is shared along the chain, and one new roller among worn neighbors carries the section until it matches them. Sprockets are the strongest case — a worn sprocket eats a new chain and a new sprocket on a worn chain is half a repair.
How do I know if a part is too worn to reuse?
Compare the tread with a new unit's specification and check the flanges for the sharp-shouldered profile they left the factory with. A tread worn flat or flanges worn to ramps no longer track the chain and belong on the scrap side of the decision. When in doubt, photos of the wear faces with a ruler in frame let us grade it before you order.