Driving tool for fastening fasteners

The present invention relates to a driving tool for fastening fasteners, more particularly to a tool for electrically fastening or unfastening fasteners, such as the bolts used for mounting tires on an automobile. A driving tool includes a hammer which hits instantaneously a connecting member for connecting the hammer with a spindle provided with a wrench at an end thereof. A housing has an on-off switch provided at a grip thereof and is divided into a part chamber in which parts are disposed and a motor chamber in which a motor is disposed. An inertial wheel is installed rotatably in the part chamber and engaged with a shaft of the motor, and a spindle is installed rotatably between the part chamber and the inertial wheel and provided with a connecting member on an outer circumference thereof and a wrench on one end thereof. The hammer is pivotally installed at the inertial wheel to hit the connecting member by centrifugal force according to the rotation of the inertial wheel and returned an initial position by a return spring positioned between the inertial wheel and the hammer. A pair of balls contained in holes are formed at both sides of the inertial wheel and arc shaped grooves formed at the hammer, respectively. Each of springs presses the balls into the holes inwardly, and screws are threaded to the holes for adjusting the pressing force of the balls by the springs, respectively.