Wheel Bearing Apparatus

A wheel bearing apparatus comprising:

• an axle housing receiving a drive shaft connected to a differential gear, the axle housing is supported on a lower surface of a vehicle body;
• a wheel hub is joined with the drive shaft, the wheel hub includes an integral wheel mounting flange to attach a wheel, a cylindrical portion, forming an outer circumference of the wheel hub, extends in an axial direction from the wheel mounting flange;
• a wheel bearing is fit between the cylindrical portion of the wheel hub and an opening of the axle housing, the wheel bearing rotatably supports a wheel;
• an outer member of the wheel bearing includes, on an outer circumference, an integral body mounting flange to be attached to the axle housing, the outer member includes a pilot section fit into the axle housing at an end portion of an inner side, double row outer raceway surfaces are integrally formed in an inner circumference of the outer member;
• an inner member is press-fit on the cylindrical portion of the wheel hub, the inner member includes at least one inner ring with an inner raceway surface formed opposite to the double row outer raceway surface;
• double row rolling bodies are rollably accommodated between the inner member and both raceway surfaces of the outer member, via a cage;
• a seal is mounted in an annular space opening formed between the outer member and the inner member;
• and
• an annular groove is formed at the pilot portion of the outer member, a seal ring, formed of a synthetic rubber, is mounted in the annular groove, the seal ring elastically contacts the axle housing and a slight gap of a fitting portion between the outer member and the axle housing is blocked off.