Patent ID: 7641393

Claim:
A mounting structure of mounting a hub unit on an axle of a vehicle, comprising: the axle including: a hub mounting portion formed at an axially distal end portion thereof, and a large-diameter portion continuous to the hub mounting portion through a step portion therebetween having a larger outside diameter than an outside diameter of the hub mounting portion; and the hub unit mounted on the hub mounting portion of the axle, including: an outer ring which is stationarily mounted on a vehicle body, a hub wheel having a shaft hole disposed concentrically with the outer ring and attached to a wheel so as to rotate together with the wheel, an inner ring which is securely fitted around at least a vehicle inner side end portion of the hub wheel, and a plurality of rows of rolling elements interposed between the inner ring fitted around the hub wheel and the outer ring, wherein the hub mounting portion of the axle is inserted into the shaft hole in the hub wheel from a vehicle inner side so that the hub unit is fixed to the vehicle body, wherein a lubricating ring member is held between a hub receiving surface on the step portion of the axle and a vehicle inner side end face of the inner ring, and the lubricating ring member includes a lubricant holding surface which holds a lubricant on at least one of an abutment surface thereof to the hub receiving surface and an abutment surface thereof to the vehicle inner end face of the inner ring.