Reason:
1. The belt runs beyond the edge of the pulley.
2. The belt rolls up the side of the pulley.
3. When installing the belt, forcibly cross or drag into the side of the pulley.
Countermeasures:
1. Adjust the position of the pulley.
2. Strengthen the rigidity of the bearing and fix it firmly.
3. a: Remove the edge.
B: shorten the distance between axes and install epithelial bands.
C: Relax and tighten the wheel-mounted epithelial belt.