Motor having worm and worm wheel

摘要

A rotor of a motor includes an engaging portion that engages an annular portion of a yoke based on movement of a rotatable shaft in a thrust direction to brake the rotatable shaft. There is provided a Belleville spring that limits the movement of the rotatable shaft in the thrust direction to prevent engagement of the engaging portion with the annular portion when a thrust load applied on the rotatable shaft is equal to or smaller than a predetermined value. Furthermore, the Belleville spring allows the movement of the rotatable shaft in the thrust direction to allow the engagement of the engaging portion with the annular portion when the thrust load applied on the rotatable shaft is larger than the predetermined value.