Abstract: A multi-usage electric tool includes an angle-changeable grip, a main body and an electric tool head. The grip and the main body are formed with corresponding inclined adjoining faces for movably connecting the grip with the main body. The inclined face of the grip is disposed with a guide rib and the inclined face of the main body is disposed with an arch guide slot. The guide rib is slidably fitted in the guide slot, whereby the grip can be rotated relative to the main body through a certain angle along the guide slot so as to change the angle contained by the grip and the main body. One end of the main body is disposed with an engaging mechanism and one end of the tool head is disposed with an engaging mechanism corresponding to the engaging mechanism of the main body for detachably engaging the tool head with the main body. The tool head is easily replaceably assembled with the main body, whereby a user can conveniently change the tool head for different usages.

Abstract: A tool head structure of power screwdriver, including an engaging clutch device for indirectly controlling the rotation of a driven member. The clutch device includes weight blocks which are subject to centrifugal force and thrown outward so as to indirectly press the leaf springs to further press the brake blocks. The brake blocks extend into an inner annular section of the rotary seat to drivingly engage with the driven member in the rotary seat. Therefore, when the rotary seat is coupled with a motor, at low rotational speed, simply the rotary seat is rotated. However, when the rotary seat reaches a certain high rotational speed, the weight blocks are subject to centrifugal force to indirectly press the brake blocks to drivingly engage with the driven member, whereby the driven member is rotated to tighten or untighten the screw.