汽车起重机的底架在前后支腿之间,一般是设计成等截面的。本文认为底架在回转中心前后两段可以采用不相同的截面,即可以具有不相等的扭转刚度和弯曲刚度。文章具体分析了底架前后段刚度比对支腿反力的影响。分析表明,当大梁前段的刚度大于后段的刚度时,可以减小后支腿的起翘,改善底架的受力性能。本文还提供了计算支腿反力的公式。 The chassis of the truck crane is between the front and rear legs and is generally designed to have an equal section. In this paper, it is considered that the chassis can adopt different sections in the front and rear sections of the center of rotation, that is, it can have unequal torsional rigidity and bending stiffness. This article specifically analyzes the influence of the stiffness ratio of the front and rear sections of the chassis on the leg counterforce. The analysis shows that when the stiffness of the front section of the girder is greater than the stiffness of the rear section, the warping of the rear leg can be reduced and the performance of the undercarriage can be improved. This article also provides a formula for calculating the leg reaction force.