The top roller (also known as the idler wheel) of an excavator is one of the core components of the chassis (Idler,bottom roller ,top roller ,sprocket ) of a tracked excavator. It is usually installed above the track frame, and the quantity varies depending on the size of the excavator model.
Its main functions can be divided into the following four points:
Support the upper track
The core task of the idler is to lift the upper branch of the track, avoiding excessive sagging of the track due to its own weight, and preventing friction or entanglement between the track and the excavator frame, hydraulic pipelines, and other components. Especially during uphill and bumpy road operations, it can effectively suppress the jumping of the track.
Guide the direction of track operation
Limit the lateral displacement of the track to ensure that it always runs smoothly along the axis of the driving and guiding wheels, greatly reducing the risk of track deviation and derailment during excavator turning and operation.
Reduce component wear and vibration
Optimize the meshing state between the drive wheels, guide wheels, and tracks to avoid local stress concentration caused by track sagging, thereby reducing wear on the track chains and gear teeth; At the same time, it can also alleviate the vibration during track operation, improve the smoothness of the whole machine’s travel and operation.
Assist in maintaining track tension
Cooperate with the tensioning device (spring or hydraulic tensioning mechanism) to keep the track within the appropriate tensioning range, which not only prevents gear jumping and chain detachment caused by looseness, but also avoids the wear and tear of the walking system components caused by excessive tension, and extends the service life of the track and four-wheel belt.
In addition, the supporting wheels of micro excavators have higher requirements for derailment prevention due to their small size and narrower operating scenarios (such as indoor demolition and orchard operations), and their structure is also more compact and lightweight.
Post time: Jan-16-2026