Crawler excavator and dozer undercarriages · Track chain, rollers, idlers and sprocket, wear at contact surfaces, hardness and case depth, fit by machine model, wear monitoring
An undercarriage is the crawler track system under an excavator, dozer or other tracked machine: a track roller frame carrying idlers, a drive sprocket and track rollers, around which a chain of linked track shoes runs. Ask three things first: which machine model and part numbers the parts must fit, what material, hardness and hardened depth the wearing surfaces have, and how wear will be measured so parts are replaced before they damage each other.
Complete crawler undercarriages and their wear parts for excavators, dozers and similar machines: track chains and shoes, track (bottom) and carrier rollers, idlers, sprockets and adjusters. Rubber tracks, wheeled axles and agricultural track systems are outside this page except where compared.
Start with your task
01
US patent 9,371,630 (Determination of undercarriage idler and roller wear based on final drive speed) describes an undercarriage track system with a track roller frame on each side carrying one or more idler wheels, a drive sprocket powered through a final drive by the machine's engine, and track roller assemblies between the idlers that guide and support a track chain. The chain is made of track links joined by track pins into a closed loop, with ground-engaging shoes fastened to the links or cast or forged with them; roller guides keep the links aligned on the rollers. [1]
CQC lists track roller assemblies by machine model and original part number, for example forged rollers with HRC 50–58 surface hardness and 10–12 mm hardened depth, weights of 58–100 kg and warranties stated as 2,000 or 4,000 working hours, or 12 months or 2,000 hours, depending on the model. [2]
Editorial note: undercarriage parts are model-specific; send the machine model, serial range and part numbers, and ask the supplier to confirm interchangeability and the drawing dimensions before ordering.
Give the supplier the machine make, model and serial range, part numbers, quantities, operating ground (rock, sand, clay), working hours per year, track shoe type and width, current wear measurements, and the hardness, case depth and warranty expected.
02
The patent states that contact between track links and rollers can create high stresses that wear the contact surfaces of rollers and links, that undercarriage wear has conventionally been measured by ultrasound, a measurement the patent calls "typically infrequent and time consuming", and that knowing roller and idler wear lets an operator or manufacturer predict further wear and schedule maintenance. It proposes comparing roller or idler speed with sprocket speed: because track speed is the same at each, r₂ = r₁ω₁/ω₂, so as a roller wears and its radius shrinks it turns faster. [1]
Editorial calculation: if a roller that turned at 70 rpm when new now turns at 74 rpm for the same sprocket speed (assumed figures), its rolling radius is 70 / 74 ≈ 0.946 of the original, about 5.4% smaller; compare such readings with the maker's wear limits rather than a fixed percentage. [1]
Editorial note: ask suppliers for the hardness and hardened depth of link rails, roller treads, idler treads and sprocket teeth, and keep wear records per component so worn parts are not run against new ones.
03
Suppliers linked to this page list undercarriage parts; each card links to the page reviewed.
The suppliers reviewed list track rollers, carrier rollers, idlers, sprockets, track links and shoes for excavators and dozers; ask each for material, forging or casting, hardness and hardened depth, seal and lubrication design, warranty hours and the machine models covered.
04
A 2026 study by researchers at Universitas Balikpapan, published in the Journal of Applied Mechanical Engineering and Renewable Energy, measured track link wear on a Caterpillar D8R dozer at a mine site in West Kutai, Indonesia, from May to June 2024, using field observation, a depth gauge and inspection records. It compared a Caterpillar track link on the left side with an OEM track link on the right. The new link height was 166 mm and the wear limit 149 mm; at the latest inspection the Caterpillar link measured 152 mm at SMR 46,102 and the OEM link 153 mm at SMR 45,723, giving wear-allowance utilisation of 82.35% and 76.47%. [3]
Editorial calculation: the usable wear allowance is 166 − 149 = 17 mm; the Caterpillar link had used 166 − 152 = 14 mm (14 / 17 = 82.35%) and the OEM link 166 − 153 = 13 mm (13 / 17 = 76.47%). The authors caution that recorded CTS indices should not be treated as equivalent to dimensional wear percentages when their calculation parameters are unavailable, so ask a supplier for the new and limit dimensions of each part in millimetres, not only a percentage. [3]
05
A 2022 study in Jurnal Teknologi Terpadu by Akbar, Randis and Anhar of Politeknik Negeri Balikpapan analysed track roller wear on three Komatsu D375A-5 bulldozers in the same soil-disposal area of the Batu Kajang coal mine. The machine has 8 track rollers per side, single-flange at positions 1 and 8, double-flange at 2 to 7. From undercarriage inspection records, in which each machine was "measured 8 times in every 400 hours of operation", the authors converted tread thickness into a wear rate in mm³ per hour. [4]
Average wear rates by roller position ran from 91 to 97 mm³/h. A two-way ANOVA found no effect of roller position (F = 0.16 against a critical F of 2.16) but a significant effect of machine unit (F = 3.97 against 3.06), whose averages were 103, 89 and 92 mm³/h, and no interaction. The authors conclude that track rollers should be replaced together, not partially. [4]
Editorial calculation: unit 1's 103 mm³/h is about 16% above unit 2's 89 mm³/h (103 / 89 ≈ 1.16) in the same working area, so compare replacement rollers on wear records from the same machine, and quote roller sets, not single rollers. [4]
06
This is a functional reference built from the sources cited; it is not one maker's design.
| Part | Role | Fix in the order |
|---|---|---|
| Track roller frame | Supports rollers and idlers. [1] | Model fit. |
| Track chain (links, pins, bushings) | Closed loop under the rollers. [1] | Pitch; links. |
| Track shoes | Ground contact. [1] | Type; width. |
| Track rollers | Guide and support the chain. [1] [2] | Hardness; depth; seals. |
| Idlers | Guide the chain. [1] | Tread hardness. |
| Drive sprocket and final drive | Drive the chain. [1] | Teeth; fit. |
07
An undercarriage quotation needs values for your machine. The table explains each field, gives published values where a reviewed source states them, and says what to obtain from the supplier.
| Field | What it means and published values | Ask the supplier for |
|---|---|---|
| Track Gauge (mm) | Centre distance between tracks. | Value for model. |
| Track Shoe Width (mm) | Shoes fastened to the links. [1] | Width; grouser type. |
| Ground Contact Length (mm) | Track on ground. | Value. |
| Ground Pressure (kPa) | Machine weight over track area. | Value. |
| Max Travel Speed (km/h) | Machine data. | Value. |
| Gradeability (%) | Machine data. | Value. |
| Hydraulic Oil Flow (L/min) | Travel motors. | Value. |
| Track Tension (kN) | Adjuster setting. | Procedure. |
| Material Grade | Forged roller, HRC 50–60 surface, 10–12 mm depth. [2] | Steel; hardness; depth. |
| Total Weight (kg) | E.g. 58–100 kg per roller. [2] | Weights. |
| Operating Temperature (°C) | Seals and lubricant. | Range. |
08
Paste it into your enquiry below or into an email to a maker, then replace every bracket.
Machine: [make; model; serial range] Parts: [part numbers; quantities] Ground: [rock; sand; clay] Wear: [current measurements; hours] Specification: [material; hardness; depth; seals] Warranty: [hours; terms] Delivery: [schedule; packing]
These companies list undercarriages and undercarriage parts.
Lists excavator track rollers, carrier rollers and track links.
Product scope checked 2026-10-11
Lists excavator and dozer undercarriage parts including track rollers.
Product scope checked 2026-10-11
Lists undercarriage parts including track and carrier rollers.
Product scope checked 2026-10-11
Lists track links, track rollers, upper rollers and idlers.
Product scope checked 2026-10-11
Lists undercarriage sprockets, track adjusters and springs.
Product scope checked 2026-10-11
Lists undercarriage track shoes, pads and claws with ground-engaging tools.
Product scope checked 2026-10-11
Lists undercarriage parts with attachments and ground-engaging tools.
Product scope checked 2026-10-11
Lists undercarriage parts with forged bucket teeth and cutting edges.
Product scope checked 2026-10-11
Describes itself as a maker of attachments and undercarriages for earth-moving machines.
Product scope checked 2026-10-11
Lists crawler track undercarriages and undercarriage parts.
Product scope checked 2026-10-11
Explore company information and manufacturing capabilities, then discuss the scope of your project with a relevant supplier.
US patent 9,371,630 notes that contact between track links and rollers creates high stresses that wear their contact surfaces. [1]
CQC lists forged rollers at HRC 50–58 or 52–60 surface hardness with 10–12 mm hardened depth. [2]
Conventionally by ultrasound; the patent proposes comparing roller speed with sprocket speed, since a worn roller turns faster. [1]
A 2026 D8R study in the Journal of Applied Mechanical Engineering and Renewable Energy measured link height (166 mm new, 149 mm limit) and reported wear as the share of that 17 mm allowance used. [3]
A 2022 Politeknik Negeri Balikpapan study of three Komatsu D375A-5 bulldozers, in Jurnal Teknologi Terpadu, found roller position did not affect wear rate and recommends replacing track rollers together, not partially. [4]
Sources checked 2026-10-11. The US patent describes undercarriage systems and a wear method in its own terms; CQC describes its own rollers. Wear limits for your machine come from the machine maker's data.
Ask for use case, specification boundaries, supplier type, and RFQ preparation information for this product.
Compare manufacturer profiles with relevant product and process capability.