To facilitate work for attaching a rolling bearing unit 5a for supporting a wheel to a knuckle 3a while ensuring durability.
A stop ring 27 is laid between an outer ring 6a and the knuckle 3a in the state that a part close to an axial inner end of the outer ring 6a constituting the rolling bearing unit 5a for supporting the wheel is internally fitted to a mounting hole 26 of the knuckle 3a. By this constitution, facilitation of the attachment work is realized. Further, the outer ring 6a is prevented from being rotated relative to the knuckle 3a by a whirl-stop engagement part 34 comprising an engagement recession part 35 and an engagement projection part 36. By this constitution, abrasion of a fitting surface of the knuckle 3a and the outer ring 6a is prevented and durability is ensured.
Nakai Shun
Kinzo Koyama