According to the design requirements of a bus,the following items are accomplished in this paper: calculating the arc height with the spring in free state,selecting all the different pre-stressed forces of the films,calculating the films radius of curvature.Considering that the center bolt and spring and other factors could cause actual arc height changes,we calculate the actual arc height of the spring which is a small leaf and equal length but variable cross-section.Finally,the design parameters are vali...