| 摘要 |
PROBLEM TO BE SOLVED: To provide a wheel supporting bearing unit for suppressing an abrupt reduction of a bearing life by preventing the fall-off of a cap which closes an axial inner end opening of an outer ring.SOLUTION: A cap 5a having a through-hole 22 passing through a cylindrical part 20 in the radial direction is fitted and fixed into the inner-end inner peripheral face of an outer ring 1. During assembly, the outer-diameter-side opening of the through-hole 22 is sealed by the inner peripheral face of the outer ring 1. When a temperature in an internal space 11 rises and an inner pressure rises, the cap 5a receiving the pressure is moved to the axial inside. Then, when the outer-diameter-side opening of the through-hole 22 arrives at the further axial inside than the inner-end end face of the outer ring 1, the sealing state that the inner peripheral face (a sealing member) of the outer ring 1 seals the outer-diameter-side opening of the through-hole 22 is released into the state that the internal space 11 and an external space are communicated with each other by the through-hole 22. |
