The tooth ring is镶入flywheel outer edge after heating, securing to the flywheel outer edge upon cooling. It is used to mesh with the starter gear, driving the crankshaft to rotate and start the engine.

1) When starting the engine, the starter gear may strike the flywheel gear ring or the teeth may not mesh properly, leading to damage to the gear ring.

2) The starter's power connection was too early, causing the starter gear to collide with the flywheel's toothed ring.