At present, a topical problem for the Ukrainian railways is a reduction of freight car and track structure maintenance and repair cost. An increase in train mass and speed significantly increases vehicle and track wear due to increased wheel-rail interaction forces. A way to reduce wheel-rail wear and interaction forces in curves is to use devices that align the wheelsets in a radial orientation. The aim of this work was to analyze the effect of the design features of freight-car trucks associated with the use of devices that align the wheelsets in a radial orientation on the indices of wheel-rail dynamic interaction and to choose their advisable parameters that would allow one to improve the running gear of different vehicles. To accomplish these objectives, mathematical simulation, oscillation theory, and elasticity theory methods were used. The motion of cars with variously designed trucks in curves was simulated. The analysis of the results showed that devices that align the wheelsets in a radial orientation have a favorable effect on wheel-rail interaction processes: they improve the car riding qualities and the wheel-rail interaction indices by (15-25) % and (20-45) %, respectively. Advisable parameters of these devices were chosen in such a way as to provide both a far lower level of wheel-rail dynamic interaction for vehicles of different types in curves and their high riding qualities in tangents at speeds up to 120 km/h.

A brief description is given of the comprehensive modernization of standard freight car trucks through the use of devices of American companies adapted for railways with a 1520 mm gauge and wheels with ITM-73 specially developed wear-resistant profile, which allows several times to increase the resource of problematic running gears. An approximate method is proposed for solving the wheel–rail interaction problem with determining the position and size of non-elliptic contact patches, including with conformal contact. Using this method, new profiles have been developed for turning worn wheels (ITM-73-01), as well as new wheels for cars with an axial load on rails of 23.5 tf (ITM-73-02) and 25 tf (ITM-73-03). The data of experimental studies showed that the average wear rate of the wheel flanges of freight cars with complex modernized trucks equipped with wheels with ITM-73-01 profile is 3.5-5 times lower than that of a standard car with a standard wheel profile. According to forecast estimates, the use of wheels with profiles ITM-73-02, ITM-73-03 will allow to achieve even greater increase in the resource indicators of wheelsets for wear of the flanges.

Although a large number of truck models have been put into service on the 1520 mm gage railways over the past ten years, the problem of an insufficient shear stiffness of a freight car truck still remains topical. This problem is a consequence of attempts to keep a sufficient degree of unification of new truck models with the 18-100 truck because this greatly simplifies the introduction of new trucks and allows one to make the best use of the existing maintenance and repair infrastructure. However, this also results in that new designs inherit many drawbacks of the 18-100 truck. One of its critical drawbacks is a low connectedness in a horizontal plane, which reduces the critical speed and increases truck component wear. A solution to this problem may be an auxiliary stiffening frame. This paper presents a new design of an auxiliary stiffening frame for the 18-100 truck. The design increases the truck shear stiffness, thus improving freight car dynamic performance and service life. Mathematical simulation, oscillation theory, and elasticity theory methods were used to design an auxiliary stiffening frame installable between the 18-100 truck side frames without any significant changes in the freight car basic design. The physical and mechanical properties of the auxiliary stiffening frame’s structural materials were selected. Loads on the auxiliary stiffening frame were determined and then used in the calculation of the stresses that develop therein in motion. It was found that the proposed auxiliary stiffening frame with resilient polyurethane inserts increases the truck shear stiffness by 0.5 MN/m. The proposed improved design of the 18-100 truck increases its shear stiffness, improves freight car dynamic and operational performance, and reduces truck component wear. Besides, the auxiliary stiffening frame is simple in design. Because of this, its introduction will bring considerable economic benefits.

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