US Patent 8256699 Webbing take-up device

A webbing take-up device includes a speed-reduction mechanism that reduces rotation speed of a motor to transmit rotation force to a take-up shaft. An overload release mechanism is disposed at a middle position of the speed-reduction mechanism. The overload release mechanism includes a large-diameter gear rotating with the rotation speed of the motor being reduced and the rotation force being transmitted, a spring member mounted to the large-diameter gear, and a small-diameter gear provided to rotate relatively to the large-diameter gear, rotating the take-up shaft when the rotation speed thereof is reduced and the rotation force is transmitted to the take-up shaft, engaging with the spring member to become a state where relative rotation with respect to the large-diameter gear is stopped, and slides with the spring member when the rotation force acts between the large-diameter gear to become a state where relative rotation to the large-diameter gear is allowed.