US Patent 8378242 Circuit breaker with rebound preventer

A circuit breaker having a stopping groove engaged with part of the main shaft and a rebound preventer rotatably installed in the circuit breaker. The stopping groove includes first and second contact surfaces contactable with the part of the main shaft upon the rotation of the main shaft. Further, an extending line of a force applied from the part of the main shaft to the second contact surface passes through the center of the rotation of the rebound preventer upon a reverse rotation of the main shaft.