Abstract: Stopper pins are arranged on a path of movement of respective reaction-force receiving cam plates and are urged by urging forces of compression coil springs in a direction in which the stopper pins project from circular holes. As a solenoid is energized, the stopper pins are accommodated into the circular holes. The solenoid is operated by means of a stopper switch, and the solenoid in an energized state allows each combination socket to be fitted over a corresponding wheel-mounting nut. With the combination sockets fitted over all of the wheel-mounting nuts, the operation of the stopper switch causes the stopper pins to move to a projected position to prevent rotation of the reaction-force receiving cam plates, so that high torque is imparted to transmission shafts, allowing four wheel-mounting nuts to be simultaneously tightened or loosened.

Abstract: A nut runner can be moved along fixed rails and a moving rail. A tire, after being removed by using the nut runner, is supported on a tire dolly, and the tire is transported to an outer rail. Here, the tire is held by a hanger, and is transported to an operating machine. A movable block is provided with a sensor, and a plurality of stop points are set in each rail. Upon completion of the operation by the operating machine, the tire is held again by the hanger, and is transported to a predetermined position along the outer rail. The tire is then supported on the tire dolly, and is temporarily fixed to a vehicle. In this state, the nut runner is moved, and nuts are tightened by means of this nut runner, thereby completing the tire demounting and mounting operation.