US Patent 9205547 Electric power tool with vibration mechanism

An impact driver with a vibration mechanism includes a vibration switching ring externally fitted to a second cam in the forward position in such a manner that an inner protrusion on the inner circumference is latched a protrusion on the outer circumference of the second cam so that the rotation of the second cam is restricted. Further, a coil spring is provided for biasing the vibration switching ring to the forward position. A link plate provided between the mode switching ring and the vibration switching ring latches onto the front surface of the vibration switching ring and engages an engaging protrusion at the rear end with a mode switching ring. The link plate moves forward or backward to a first position where the vibration switching ring moves to the forward position or a second position where the vibration switching ring moves to the backward position.