1. There are marks on the side of the track or the inside of the wheel rim. In severe cases, there are burrs or iron filings on the marks.
2. When the crane is traveling, the gap between the wheel flange and the track changes significantly in a short distance.
3. When the crane is running, the car body is skewed and the wheels are off.
4. When the cart is running, it will emit a loud "hissing" sizzling sound.
5. When the stern track is particularly serious, the running of the cart will emit a "slap" impact sound, and even climb the track.