Track rollers – what role do they play in tracked machines?

Continuous track

It is a mechanism that allows vehicles to move using tracks. They increase the contact surface of the vehicle with the ground – reduce the unit pressure and improve the road passability. The caterpillars are of course used in excavators, but also in tanks, bulldozers and armored personnel carriers. In general, tracks are used on machines that maneuver over unrestrained surfaces. The basic track system consists of an endless track belt which surrounds the load wheels. Most designs include a track drive wheel and a guide wheel separately. Additionally, support rollers as well as a tension wheel can be used.

The figure on the right shows a diagram of an example of a caterpillar track system:
1. track roller
2. carrier roller
3. front idler
4. sprocket
5. track link
6. final drive

Track rollers

Track rollers are an essential part of the overall undercarriage system as they carry a whole host of tracked machines. The size of the rollers is selected so that the machine can work without any problems in normal working mode. And the temperature resulting from prolonged loading is safely removed from all components (bearings, seals, etc.). The maximum resistance to abrasion of the rollers is achieved thanks to appropriate castings, precise machining and induction hardening. Moreover, good parameters are obtained thanks to tempering, increasing durability and extending the life of the rollers through their even wear.

Rollers failures

Premature failure of the rollers may be caused by their uneven load. E.g. when working with rollers that are worn to varying degrees (when they were not completely replaced during repair work).

What’s more, the rollers also degrade when driving at higher speeds for longer. Then there are leaks, from which oil leaks, which leads to incorrect lubrication of the bearings, and this leads to failure of the rollers. If the track rollers lack the right amount of oil, the bearings get stuck and are not able to rotate around their axis inside the roller. As a result they are seriously damaged.

Track rollers with leaking or blocked bearings should be replaced immediately to prevent damage to other track components, such as the link chain, because non-rotating rollers lead to rapid wear of the track chains. This is due to an increase in the frictional force on the roller shell and the contact surface of the chains.

Sources:
https://www.ketral.pl/pl/tagi/rolka-jezdna-do-koparki/elementy-podwozia/51-8/?fbclid=IwAR3EEZwxg2U01vVnyvxj_r9tXOEOGiMGUU61Q9PqUgSWFd9kDFz_CgFO4-k
https://www.wirtgen-group.com/media/01_wirtgen_group/03_broschueren_7/03_customer_support_1/parts_and_more/wg_brochure_pam-compact_crawler-units_1218_v1_pl.pdf