Patent ID: 8047722

Claim:
A vehicle wheel bearing apparatus comprising: a substantially cylindrical outer ring formed with double row outer raceway surfaces on its inner circumference, and formed with press-fitting surfaces on an outer circumference of the outer ring first cylindrical portions; a pair of inner rings formed with inner raceway surfaces on their outer circumferences; said inner raceway surfaces arranged opposite to the double row outer raceway surfaces, said inner rings formed with first cylindrical portions having fitting surfaces on their inner circumferences, said fitting surfaces of said inner rings fit onto a cylindrical portion of a wheel hub, said inner rings are adapted to be arranged so that end faces of the it cylindrical portions of the inner rings abut each other; double row rolling elements are freely rollably arranged between outer and inner raceway surfaces; at least the outer ring of the outer and inner rings is formed by pressing or rolling from a plate member or a pipe member; the outer ring and the inner rings have second cylindrical portions axially extending, respectively, from the outer raceway surfaces and the inner raceway surfaces, a thickness of the second cylindrical portions of the outer ring is thinner than that of the outer raceway surfaces; seals are arranged in annular spaces formed between the inner circumferences of the second cylindrical portions of the outer ring and the outer circumferences of the second cylindrical portions of the inner rings, the seals are adapted to be press-fit into the inner circumferences of the second cylindrical portions of the outer ring; and the double row outer raceway surfaces of the outer ring and the inner raceway surfaces of the inner ring are surface hardened.