ROLLING BEARING UNIT FOR WHEEL

摘要

PROBLEM TO BE SOLVED: To miniaturize and lighten by preventing the pitch circle diameter of a stud for fixing a wheel from becoming larger than needed. SOLUTION: A first inner raceway track 11 located outside out of first and second inner raceway tracks 11 and 12 is formed directly in the outer peripheral surface of the intermediate section of a hub 4a. In addition, an inner ring 6 having the second inner raceway track 12 is fitted around the hub 4a to prevent the inner ring 6 from axially shifting by the locating snap ring 16a locked in a locking recessed groove 15. The pitch circle diameters of rolling elements 13 and 13 relating this first inner raceway track 11 are made smaller than those of rolling elements 13 and 13 of the second inner raceway track 12 by the diameter of the first inner raceway track 11 formed in the outer peripheral surface of the hub 4a. By this constitution, a stud 8 can be installed inside the diameter direction of the hub 4a.