At present, nearly all countries of the world develop and implement measures aimed to increase the competitiveness and efficiency of their railways. One of the priority lines is to increase the carrying capacity of freight trains. In Ukraine, 18-9817 trucks of axle load 25 tf were developed and adopted as basic ones for new-generation freight cars, and the ITM-73-03 wear-resistant wheel profile of flange thickness 32 mm was developed for them too. The aim of this paper is to study the effect of in-service variation in the wheel and rail profile shape on the spatial oscillations of a freight car with 18-9817 trucks and the ITM-73-03 wheel profile. The paper estimates the effect of in-service variation in the wheel and rail profile shape on the dynamic stability and ride performance of the car under consideration. The wear of wheels with the new profile is predicted by solving the geometrical problem of wheel–rail interaction with account for the mutual horizontal lateral displacements of the wheel and the rail, the wheelset angle of attack and angle of roll, the nonlinearity of the contacting surfaces, and the possibility of their conformal contact. The results of calculation of the spatial oscillations of the car in tangents and curves are presented. It is shown that wear-caused variation in the wheel and rail profile shape has little effect of the dynamic performance of a new-generation freight car with 18-9817 trucks with an increased axle load and the ITM-73-03 wear-resistant wheel profile, its dynamic stability and ride performance remaining at a high level. The use of the above car on the Ukrainian railways fully meets the objectives of home rolling stock renewal: vehicle ride performance improvement, running gear life extension, and vehicle and track wear reduction

At present, one of the global trends in railway transport development, which becomes clearer and clearer, is increasing the axle load of freight cars, which gives a considerable economic benefit. In this connection, of importance is not only the car design, but also the car capacity utilization factor: the higher this factor, the more economically efficient the car use. Because of this, one of the priority global lines in increasing the volume of fright traffic and the railway operation efficiency is increasing the carrying capacity of freight cars. Preparing the railways for cars with increased axle loads calls for the development of measures to decrease the track deformability, in particular by choosing appropriate wheel and rail profiles. The aim of this work was to develop recommendations on refining the wheel?rail contact pair to improve curve negotiation by railway vehicles with an increased axle loads on the Ukrainian railways. This paper presents the proprietary R-ITM wear-resistant railhead profile. The effect of the new profile on wheel?rail interaction in negotiating a curve of radius 300 m at a constant speed was studied for different cars. In doing so, emphasis was on wheel?rail interaction for a new-generation freight car on 18-9817 trucks with an axle load increased to 36 tf. The studies conducted made it possible to formulate the following recommendations: to improve curve negotiation by railway vehicles with increased axle loads, reduce the adverse effect on the track and improve traffic safety, new proprietary contact pair profiles are recommended: the ITM-73-03 wheel profile for cars, and the R-ITM railhead profile for outer rails together with the standard R65 railhead profile for inner rails.