| 摘要 |
PROBLEM TO BE SOLVED: To provide a wheel supporting rolling bearing unit having a longer life even when used under an environment where water is mixed in lubricating oil. SOLUTION: An outer ring 3 of the wheel supporting rolling bearing unit is formed of a steel. An old austenite crystal of each of its outer ring raceway surface 3a, 3b has an average particle size of 30μm or less and the ratio (D<SB>max</SB>/D<SB>min</SB>) of the maximum particle size to the minimum particle size being 2.0 or less. COPYRIGHT: (C)2006,JPO&NCIPI
|
