Patent ID: 8790210

Claim:
A power tool with a device for automatically switching transmission output, comprising: at least one stage of transmission part having a sun gear, a planetary gear carrier, and a gear ring for transmission; a sensing system having a sensing component for sensing variation of operating condition; and a control device cooperated with the sensing system for controlling the transmission output of the transmission part; wherein when the sun gear, the planetary gear carrier and the gear ring in the same stage of the transmission part are in a first transmission state, a first transmission output is generated by the transmission part; and when the variation of operating condition received by the sensing component reaches to a predetermined value and then being fed back to the control device by the sensing system, such that the sun gear, the planetary gear carrier and the gear ring in the same stage of the transmission part are in a second transmission state, a second transmission output is generated by the transmission part, wherein in the first transmission state, at least two of the sun gear, the planetary gear carrier, or the gear ring in the same stage of the transmission part have the same transmission state; and in the second transmission state, at least two of the sun gear, the planetary gear carrier, or the gear ring in the same stage of the transmission part have the different transmission states.