摘要 |
PURPOSE:To increase the commodity value of a wheel with its increased rigidity without increasing its weight by forming a hollow part opened facing to the internal peripheral surface of a rim, in case of a cast hub unit in which its spoke part is united with the hub. CONSTITUTION:The spoke part 2b of a hub unit 2 is widened in its width W, and a hollow part 3 opened facing to the internal peripheral surface 1a of a rim 1 is provided. With such constitution, the spoke part 2b forms a pipe-shaped structure having an axis extending in the normal direction from a hub 2a acting as the center and it is possible to raise the cross sectional preformance and the rigidity of a wheel without increasing the weight. Further, it is possible to adopt a new design with a wider and flat side for the spoke part 2b, allowing commodity value to the raised. |