Pin shaft for circuit breaker, arc extinguish chamber using pin shaft and circuit breaker

The invention relates to a circuit breaker, in particular to pin shaft connection of parts in the circuit breaker, and provides a pin shaft for the circuit breaker, an arc extinguish chamber using the pin shaft and the circuit breaker. The pin shaft for the circuit breaker comprises a pin shaft main body and an anti-falling elastic sheet, one end of the pin shaft main body is a penetrating-out end, and the other end is a head part; the anti-disengaging elastic piece is provided with a fixed end and an elastic deflection part, and the fixed end is used for being fixedly connected to the penetrating-out end of the pin shaft body. When the anti-disengaging elastic piece is in a natural state, the elastic deflection part protrudes out of the peripheral face of the pin shaft body and is used for being matched with a to-be-connected piece in a stopping mode in the axial direction of the pin shaft body so that the pin shaft can be prevented from disengaging from the pin shaft hole. The elastic deflection part is use