excavator Track Bottom Roller double track D20 roller track roller undercarriage
The supporting wheel is used to support the weight of the tractor while rolling on the track's guide rail (rail link) or track surface. It is also used to limit the track and prevent lateral slipping. When the tractor turns, the supporting wheels force the track to slide on the ground.
The supporting wheel is often in mud, water, and dust, and can withstand strong impacts, so it is required to be sealed reliably and the wheel rim is wear-resistant