How to determine if excavator undercarriage components (four wheels and one track) need replacement?

Excavators endure the elements on construction sites, working tirelessly in the sun and rain. The most strenuous and demanding components are undoubtedly the chassis's "four wheels and one track"—namely, the track rollers, carrier rollers, drive sprockets, idler rollers, and tracks. These support the entire machine's weight and bear the most intense friction. As the owner or operator, being able to promptly identify when these components are "tired" or "due for retirement" not only prevents breakdowns and lost work time but also saves considerable repair costs.

So, without the aid of precision instruments, how can we use the naked eye and common sense to determine whether these parts need to be replaced? Here are a few key points to consider.

Track rollers: Check for oil leaks and wear

The track rollers are the "feet" of the entire machine, bearing the majority of its weight. First, check for oil leaks. If you find black sludge on the edge of the track rollers, or obvious oil seepage, it means the floating oil seal inside is damaged. Once there is an oil leak, the internal gear oil will gradually leak out, causing the bearing to dry-grip. In this case, do not hesitate, it is recommended to replace them immediately, as they may seize up at any time.

Secondly, check the wear of the track roller. Inspect the guide groove where the track roller contacts the track chain to see if it is worn sharp or if its diameter has decreased significantly. If the outer edge of the roller is worn into a sharp, knife-like shape, it means that it can no longer effectively support the track chain and may even cut it, so it must be replaced.

Track rollers: Check for rotation and whether they are stuck

The track roller is located above the track and its main function is to support the track and prevent it from sagging. During inspection, the machine can be moved slowly to observe whether the track rollers rotate normally. If a roller stops rotating, or rotates erratically or jerks, the bearing is damaged. A non-rotating track roller will be worn down by the track, creating a flat surface, which not only accelerates track wear but also increases rolling resistance.

Drive wheel: Look at the tooth profile

The drive sprocket is like a gear in a car; its teeth engage with the track links to propel the machine forward. Pay close attention to the shape of the drive sprocket teeth. New drive sprockets have full, thick teeth. If the teeth are worn very sharp, like an eagle's beak, or if the tooth surface is severely worn, or even if slippage (track skipping teeth) occurs, then it must be replaced. Excessively worn drive sprockets will severely damage the track links of new tracks; replacing the drive sprocket while changing the track is often counterproductive.

Guide wheel: Check clearance and uneven wear

The idler wheel, located at the very front of the track, guides the track's direction and works with the tensioning cylinder to adjust track tension. The idler wheel also has a groove in the middle. During inspection, check if this groove is unevenly worn, for example, one side is more worn than the other. Additionally, shake the idler wheel by hand or observe if it shows any signs of swaying from side to side. Excessive swaying indicates wear on the internal bushings or sliding plates, which can cause the track to wobble or even derail.

Tracks: Check the height and look for cracks

Tracks consist of track links and track shoes. For track shoes (commonly known as "shoe shoes"), the main thing to look at is the traction teeth (track spikes). If the originally high track spikes are almost worn down, like a bald tire, the machine will lack power on mud or slopes, moving weakly and veering off course. In this case, it needs to be replaced. For track links, focus on checking the joints (pins and sleeves) for severe wear or cracks. If you notice unusual noises from the track while moving, or if the track pitch becomes significantly longer (causing the track to drag), it indicates that the track links have reached their lifespan limit. In summary, judging the condition of excavator chassis components can be summarized in a simple rhyme: check for oil leaks in the wheels, sharpness in the tooth tips, wear on the tracks, and replace them if they slip or jam.