BEARING DEVICE FOE WHEEL

摘要

[PROBLEMS] A bearing device for a wheel, in which occurrence of stick-slip noise is prevented by realizing a smooth slip relative to a mating contact member. [MEANS FOR SOLVING PROBLEMS] In the bearing device for a wheel, a pair of inner rings (6) is press fitted on a small diameter step section (1b) of a hub ring (1), and an outer joint member (11), which is fitted in the hub ring (1) so that torque can be transmitted between the hub ring (1) and the outer joint member (11), is removably fastened to the hub ring (1) by a fixation nut (13). Serrations (10a) are formed on the outer periphery of a shaft (10) of the outer joint member (11), and the serrations have a twist angle tilted a predetermined angle relative to the axis of the shaft (10). A large end surface (6b) of the inner ring (6) is a ground surface, a shoulder (9) of the outer joint member (11) is a cut surface or a turned surface, and the surface roughness of the large end surface (6b) of the inner ring (6) is set within the range of Ra 0.1 - 0.3. As a result, friction coefficient is reduced to realize a smooth slip of the shoulder (9) relative to the large end section (6b), which prevents occurrence of stick-slip noise for a long period.