The Nonlinear Lateral Stability of a Four-Axle Freight Car with Y25 Bogies and Measures to Improve Its Faults

Abstract

This paper presents investigations of rail vehicle bogies of the Y25 type. The Y25 bogie family is one of the most commonly used freight car bogie designs. In addition to several significant advantages characterising this design, several disadvantages have also been observed since the beginning of more than fifty years of its operation in several types of cargo vehicles. One of these defects observed in real systems is its “unsatisfactory running stability”, particularly for long straight tracks. This paper used the commercial engineering software VI-Rail (2010.13.0) to create a model of a gondola car (type 412W Eaos) with two Y25 bogies. The car model was tested in empty and loaded (maximum permissible load) modes. Its motion along straight and curved tracks with different radii values was analysed. The vehicle velocity was changed from a few m/s to the maximum values for which stable solutions of the model existed. For each route, the nonlinear critical velocity was determined, defining the maximum operating velocity of the modelled car. The model solutions were recorded, while just one was selected to present the results—the first wheelset’s lateral displacement ylw. Conjecture about its “imperfect running quality” on curved tracks was confirmed. The possible appearance of self-exciting wheelset vibrations in the modelled car’s operating velocity range in a laden state was also observed. The research results on the impact of changes in the bogie suspension parameters on the vehicle model’s stability are presented. The crucial parameter in the bogie suspension was indicated. Reducing its value by several percent about the nominal value increases the critical velocity of the car to values higher than the maximum operating velocity of the modelled vehicle.