Provided is a hub unit bearing wherein a cover can be firmly fitted with an outer ring member, and it is difficult for foreign matter to enter inside through a water drainage hole formed in the cover. The cover that covers the inside end section in the axial direction of the hub unit bearing includes a disk section, a small-diameter cylindrical section bent in the axial direction from the outer perimeter edge section of the disk section and a large-diameter cylindrical section. A cut and raised section that is cut and raised toward the inside in the radial direction is formed in the small-diameter cylindrical section, and a water drainage hole that passes through from inside to outside the cover is provided in the portion that is cut and separated from the small-diameter cylindrical section.

An axle assembly of a vehicle including a differential assembly, an axle tube extending outwardly from a first side of the differential assembly and defining an axle bore, an axle shaft rotatably received in the first axle tube and defining an annular groove extending radially inwardly from its outer surface, a retaining nut axially fixed to the distal end of the first axle tube, and a snap ring received in the annular groove of the first axle shaft, wherein the snap ring abuts the retaining nut, thereby preventing outward motion of the first axle shaft with respect to the first axle tube.

Provided is a hub unit bearing wherein a cover can be firmly fitted with an outer ring member, and it is difficult for foreign matter to enter inside through a water drainage hole formed in the cover. The cover that covers the inside end section in the axial direction of the hub unit bearing includes a disk section, a small-diameter cylindrical section bent in the axial direction from the outer perimeter edge section of the disk section and a large-diameter cylindrical section. A cut and raised section that is cut and raised toward the inside in the radial direction is formed in the small-diameter cylindrical section, and a water drainage hole that passes through from inside to outside the cover is provided in the portion that is cut and separated from the small-diameter cylindrical section.

An axle assembly of a vehicle including a differential assembly, an axle tube extending outwardly from a first side of the differential assembly and defining an axle bore, an axle shaft rotatably received in the first axle tube and defining an annular groove extending radially inwardly from its outer surface, a retaining nut axially fixed to the distal end of the first axle tube, and a snap ring received in the annular groove of the first axle shaft, wherein the snap ring abuts the retaining nut, thereby preventing out ward motion of the first axle shaft with respect to the first axle tube.