Patent ID: 8028949

Claim:
A webbing take-up device, comprising: a frame having a pair of leg plates that face each other, and a back plate, the pair of leg plates being connected integrally by the back plate; a take-up shaft that is rotatably supported between the pair of leg plates and that takes up a webbing belt for restraining a vehicle occupant by rotating in one direction around its axis with a base end portion of the webbing belt being engaged with the take-up shaft; a motor; a case fixed on a side of either one of the pair of leg plates; a cover that covers a side of the case opposite to a side at which one leg plate is fixed; a worm gear accommodated in the case and connected to the motor; a worm wheel accommodated in the case coaxially with the take-up shaft and meshing with the worm gear, the worm wheel being rotated by rotation of the worm gear, said worm wheel being coaxially connected to and axially movable with respect to the take-up shaft and in load bearing engagement with one of said side of said one leg plate and said case mounted on said side of one leg plate and having teeth disposed at an angle relative to an axial direction of the worm wheel; and a clutch accommodated in the case and mechanically interposed between the worm wheel and the take-up shaft, the clutch being provided so as to rotate the take-up shaft in a webbing take-up direction by directly transmitting rotating force of the worm wheel to the take-up shaft, and interrupting transmission of rotating force generated at the side of the take-up shaft, thereby preventing transmission of the rotation to the worm wheel, all of said clutch being on the same side of said one leg plate as said worm wheel, wherein helix angles of teeth of the worm gear and worm wheel are set so that a thrust force acting upon the worm wheel in the axial direction of the worm wheel acts against said one leg plate at a time when the take-up shaft is directly driven by said motor through said clutch in the webbing take-up direction to remove slack in said webbing due to an emergency condition.