Patent ID: 6892611

Claim:
A screwdriver, comprising: a motor, a first rotating member that receives rotating torque of the motor, a second rotating member that is adapted to rotate by receiving the rotating torque of the first rotating member, a tool that performs a screw tightening operation by receiving the rotating torque via the first rotating member and the second rotating member, a torque transmission spring that is closely wound around the first rotating member and the second rotating member when the motor drivingly rotates the first rotating member in a predetermined rotating direction, so that the torque transmission spring transmits the rotating torque of the motor from the first rotating member to the second rotating member, a torque transmission releasing device that moves in the axial direction of the first rotating member or the second rotating member in response to the screw-tightening torque, so that the torque transmission releasing device releases the close winding of the torque transmission spring around at least one of the first rotating member and the second rotating member so as to release the transmission of the rotating torque of the motor from the first rotating member to the second rotating member, and a third rotating member that is disposed adjacent to the second rotating member and in the vicinity of the tool, the second rotating member being connected to the third rotating member via a clutch member, the clutch member being adapted to move toward the first rotating member in the axial direction in response to the screw-tightening torque, wherein the close winding of the torque transmission spring around the first rotating member is performed or released in response to the axial movement of the clutch member.