POWER TOOL

摘要

The invention provides a transmission assembly and a power tool. One form of the power tool includes a rotatable driven member for releasably gripping and rotating a working element and a transmission assembly for transmitting rotation from a motor to the driven member. The transmission assembly includes a rotatable input shaft and first and second rotatable output shafts. In a first speed setting the input shaft is selectively lockable together with the first output shaft so that the locked input shaft and first output shaft rotate in unison to drive rotation of the driven member at a first speed of rotation relative to a speed of rotation of the motor. In a second speed setting the input shaft is selectively lockable to the second output shaft so that the locked input shaft and second output shaft rotate in unison to drive rotation of the driven member at a second speed of rotation relative to the speed of rotation of the motor. Another form includes a torque controller operable for controlling torque supplied from the motor to the driven member to render the driven member stationary when the amount of torque supplied from the motor to the driven member exceeds a pre-determined level. Another form includes a switch mechanism for adjusting the transmission assembly between the first and second speed settings and for rendering the torque controller operable or inoperable. Another form includes a torque controller for use with a power tool and operable for controlling torque transmitted from an input shaft to an output shaft.