A new method on the detailed examination about vertical buckling phenomenon of railway train sets is studied in this paper. One cause of this phenomenon is an excessive coupler force that acts on a decelerating vehicle, which is being supported by soft bellows. The coupler force has already been analyzed dynamically using the model composed of a draft gear and a mass equivalent to the vehicle and coupler. The buckling phenomenon, on the other hand, has been analyzed statically and the upper limit of stationary compressive coupler force has only be made clear. The present study is technological importance on relief of Shinkansen electric-car which has been broken down. Especially, some kind of car and train set form is diversifying. Thus, it is important to examine the relief method which can be applied to various accidental situations.