To provide a roller bearing unit for a wheel support with a long life.
The roller bearing unit 1 for a wheel support comprises a hub wheel 2 having a flange 10 for mounting wheels and a first inner ring raceway 20a on its outer periphery, an inner ring 3 integrally fixed on the hub wheel 2 and having a second inner ring raceway 20b on its outer periphery, an outer ring 4 having a first outer ring raceway 21a corresponding to the first inner ring raceway 20a and a second outer ring 21b corresponding to the second inner ring raceway 20b, and two rows of rolling bodies 5 rotatably arranged. The inner ring 3 is comprised of an alloy in which a former austenite crystal grain size is 10 or more at a grain size number specified in JIS G0551 standard, and surface hardness of the second inner ring raceway 20b is set to be HRC58 to 63.
MIYAMOTO YUJI
OKITA SHIGERU
Yoshiaki Naito
Cui Shu Tetsu