Patent ID: 7987922

Claim:
A power tool comprising: a prime mover; a tool shaft that is driven by the prime mover; a planetary gear mechanism that is disposed between the prime mover and the tool shaft, the planetary gear mechanism comprising a sun gear, at least one planet gear, an internal gear, and a carrier; a moving member that is configured to be at a first position while a torque applied to the tool shaft is less than a predetermined value and to move to a second position when the torque applied to the tool shaft reaches the predetermined value, wherein the moving member causes the internal gear to rotate integrally with the sun gear when being at the first position, and prohibits the internal gear from rotating when being at the second position; and at least one latch member that is configured to engage with the moving member when the moving member has moved to the second position and prohibit the moving member from moving back to the first position when the at least one latch member engages with the moving member.