Calculation of actual examples show that when the bogie is in free position,the rear axle might be of loose contact or no contact to the rail,which indicates the flange force is not necessarily zero.

• 通过实例计算证实，当转向架处于自由位，后轮轴可能处于松贴靠钢轨位，也可能处于不贴靠钢轨位，故其轮缘力不一定为零。