Rolling bearing unit with rotation speed detection instrument for use in cars and method for working outer race for use in this bearing unit

摘要

A rolling bearing unit with a rotation speed detection instrument having a hub with a plurality of inner race tracks, an outer race formed of steel material with a plurality of outer race tracks, rolling elements between the tracks, and encoder on the hub and a sensor supported in a mounting hole in the outer race. A hardened layer is formed on the inner surface of the outer race and each portion where the outer race tracks are formed. An area of the inner surface around the mounting hole is not hardened.