Reason:
1. The inertia force of the passive wheel is not taken into account.
2. Overload or passive wheel stop due to accident. Thus, the load force is greatly increased.
3. The pulley is too small. The belt bent forcibly.
Countermeasures:
1. Check the design.
2. Inspection design is replaced by more pulleys than the original minimum number of teeth.
3. Full attention and caution should be paid to handling, storage and installation.
