Patent ID: 8887831

Claim:
A power tool comprising: a housing; a motor contained in the housing; an output shaft extending proximate a front of the housing; an end effector coupled to the output shaft, the end effector configured to hold an accessory; and a transmission disposed in the housing between the motor and the output shaft, the transmission including a variable ratio gear set and a constant ratio gear set, wherein the variable ratio gear set is configured to transmit power from the motor to the output shaft via a first power path such that, when power is transmitted through the variable ratio gear set, a ratio of an output speed of the output shaft to an input speed of the motor varies while transmitting power through the first power path, the constant ratio gear set is configured to transmit power from the motor to the output shaft via a second power path at a substantially constant speed ratio, and the transmission is selectively operable in: (a) a first mode where power is transmitted from the motor to the output shaft through the constant ratio gear set via the second power path, bypassing the variable ratio gear set, at the substantially constant speed ratio; or (b) a second mode where power is transmitted from the motor to the output shaft through the variable ratio gear set via the first power path.