Abstract: An exchange power hand tool includes a power section having a motor encased in a housing and two tool sections, respectively serving as a wrench and a jack actuator, alternately and exchangeably engageable with the power section to be driven thereby so as to provide one power hand tool with two functions. The power section has an output pinion mounted on the motor spindle to be engageable by a driving gear chain of the tool sections for transmission of torque from the power section to the tool section for selectively performing wrenching operation or jack actuation.

Abstract: A torque transmission mechanism to be used in a power wrench includes a body driven by a motor, having a central bore to rotatably support therein a toothed end of an output shaft. The toothed end of the shaft has a pair of diametrically opposite teeth, each defined by two circumferentially opposite contact faces that extend along radii of the output shaft. The body has a radial notch communicating the bore with a coupling member pivotally received therein. The coupling member has two opposite wings alternately movable into the bore with the rotation thereof to selectively engage one of the teeth for driving the shaft. A centrifugal clutch is provided between the body and the motor to control the movement of the wings.