BEARING DEVICE FOR WHEEL

摘要

Provided is a bearing device for a wheel, which increases a sealing effect by preventing intrusion of rain water and dust etc. and leakage of differential oil, and which ensures reliability for a long time. A bearing device which is a semi-floating type bearing device, wherein the bearing device comprises: an outer member (20) including a pilot section (21) constituted by a cylindrical section (21a) extending axially from a vehicle-body attachment flange (4b), and a taper section (21b) gradually reducing in diameter from the cylindrical section (21a) toward an inner-side end surface; a vehicle shaft tube (14) including a fitting section (16) formed in a shape corresponding to the shape of the pilot section (21) of the outer member (20); a ring-shaped groove (22) having an substantially rectangular cross-sectional shape and formed in the taper section (21b) of the pilot section (21); and a seal ring (23) formed of synthetic rubber and mounted in the ring-shaped groove (22). An outer diameter (d3) of the seal ring (23) measured after the seal ring (23) is mounted is smaller than an inner diameter (d4) of a cylindrical section (16a) of the vehicle shaft tube (14), and the seal ring (23) is elastically brought into contact with the vehicle shaft tube (14). Small gaps formed in the fitting section between the outer member (20) and the vehicle shaft tube (14) can therefore be blocked.