US Patent 10556521 Seat sliding device for vehicle

A shaft housing hole has a shaft insertion hole into which the rotating shaft section of an engagement member is inserted. Also, the shaft housing hole has slits extending from the lower end of the shaft insertion hole along the side surface of the shaft insertion hole toward an upper connection wall section. The upper side wall section of an upper rail has shaft restriction sections formed by the shaft housing hole. The shaft restriction sections have front ends with which the side surfaces of the rotating shaft section are in contact.