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.

This work is concerned with the resolution of the problem of Ukrainian freight car fleet upgrading with the aim to improve car ride quality, extend running gear service life, and increase train operation safety. The aim of this work is to develop recommendations on improvement of the running gear of prospective freight cars to increase their speed and ride quality and reduce wheel wear. Use is made of mathematical simulation, numerical integration, oscillation theory, and statistical dynamics methods. The paper presents the results of investigations into the efficiency of introduction of new elements into the design of 18-7020 trucks, such as cross links between the side frames, a resilient adapter in the journal box assembly, and the ITM-73-02 wheel profile developed at the Institute of Technical Mechanics. Their effect on car vibration and car-rail interaction is studied for a freight car moving at different speeds in tangent and curved track sections. Parameter values for the additional links are recommended. It is concluded that the proposed redesign makes it possible to develop prospective trucks for new generation cars with improved ride quality and low wheel wear.

The relevance of this work stems from the urgent need for the modern development of the Ukrainian railway transport and the acceleration of Ukraine's integration into the European railway transportation. Currently, the most effective way to travel across borders between countries with different track gauges is the use of gauge-changeable wheelsets, a system that can change from one gauge to another when moving through special gauge changing facilities. The use of cars with gauge-changeable wheelsets on the Ukrainian and European railways calls for assuring a good compatibility of the wheel-rail pair on tracks of both gauges. The goal of this work was to develop a unified wheel profile for the operation on the domestic and European railways and predict the safety of cars with that wheel profile, the ride quality, and processes of wheel-rail dynamic interaction for tracks with different parameters. Use was made of methods of deformable solid mechanics, statistical dynamics, and numerical integration. A family of wheel profiles was constructed, and the effectiveness of their use in passenger car wheelsets on the Ukrainian (1520 mm gauge) and European (1435 mm gauge) railways was evaluated. For each profile, the spatial problem of wheel?rail contact was solved, and the interaction parameters were analyzed, including the dimensions and location of the contact patches. Calculations were also made for a car negotiating a circular curve of a small radius (R = 300 m) and moving at different speeds on tangent track sections. The choice among the constructed profiles was made according to two criteria: wheel flange wear and car dynamic stability. Based on the studies conducted, a new wear-resistant wheel profile, ITM-73EP, was proposed. Its use in gauge-changeable wheelsets of passenger cars will provide reasonable indices of wheel–rail interaction both on the Ukrainian and on the European railways without sacrificing car dynamic performance.

The effect of preadaptation to non-damaging emotional stress on the synthesis of HSP70 (stress-limiting factor) in peripheral blood leukocytes was studied in experiments on August and Wistar rats characterized by different sensitivity of the gastric mucosa to stress-induced injury. It was found that preadaptation improves stress resistance of Wistar rats characterized by lower innate resistance to acute mental stress and activates HSP70 synthesis in blood leukocytes. In August rats characterized by higher resistance to acute stress, adaptation reduced the resistance to stress-induced injuries, which was accompanied by the absence of activation of HSP70 synthesis in leukocytes compared to the level observed in nonadapted rats during acute stress. Thus, the intensity of HSP70 synthesis in peripheral blood leukocytes can serve as a marker of changes in animal resistance to acute stress caused by adaptation to non-damaging stress exposures and probably to other environmental factors.