Patent ID: 8840313

Claim:
A wheel bearing apparatus comprising: an outer member formed with double row outer raceway surfaces on an inner circumferential surface of said outer member; an inner member formed with double row inner raceway surfaces on an outer circumferential surface of said inner member arranged opposite to the double row outer raceway surfaces; a counter portion (E, F, G, H) of each said raceway surface is rounded; double row ball groups freely rollably contained between the outer raceway surfaces and inner raceway surfaces of the inner members and the outer member; a pitch circle diameter of one of said double row ball groups near a wheel mounting flange is larger than a pitch circle diameter of another one of said double row ball groups away from the wheel mounting flange; a corner of each shoulder (A, B, C, D) of the outer and inner raceway surfaces is rounded as a smooth circular arc; the respective corner of the shoulder (A, C), raceway surface and counter portion (E, G) of the inner member are ground in place together at the same time and the respective corners of the shoulders (B, D), raceway surfaces and counter portions (F, H) of the outer member are ground in place together at the same time to suppress the generation of edge load when a large bending moment is applied to the wheel bearing apparatus; and wherein an axial chamfer and a radial chamfer dimensions of the corner portion of the shoulder are set in a range 0.15 to 0.8 mm, and the corner radius is set in a range 0.15 to 2.0 mm, and wherein the transition portion is smoothly formed, this prohibits scratching of the balls and an oval contact region of the balls from overriding the inner raceway surface.