| 摘要 |
PROBLEM TO BE SOLVED: To improve fastening fixing performance when a bolt and a nut are fastened to a hub to press-contact fix a wheel.SOLUTION: On an installation surface 15c by a nut 12 of a wheel 15, an annular groove 16 including an installation hole 15a is provided at an asymmetrical position where a center of groove width does not match with a center of the installation hole 15a. A distance from the center of the installation hole 15a to a side wall portion 16a on the outer side of the groove portion 16 is shorter than a distance from the center of the installation hole 15a to a side wall portion 16b on the inner side of the groove portion 16. Therefore, a contact surface 15b of the wheel 15 is made to be an inner and outer double ring-shaped contact area, and much more bolt axial force can be distributed in the contact area on the outer side. By preventing the contact surface pressure of the contact area on the inner side from relatively becoming high, fastening fixing performance can be improved. |
