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In article there are fluid flow mathematical models at the UV-sterilizer with concentric pipes installed in modernized water supply system of passenger car allowing to determine the velocity field of the rotational velocity component and assess the degree of attenuation depending on the chamber disinfection geometry, the inlet pressure in the water system, and fluid properties. There are exact solutions of the Navier-Stokes equations for a rotating fluid between fixed cylinder of infinite length and limited fictitious determined rotating lids provided Poiseuille axisymmetric flow. The decision explicitly contains the product of cylindrical Bessel functions and hyperbolic functions.

In the article there is the method of calculating the loss of water pressure in the water system of passenger cars, equipped with a cleaning system as a series of two filters installed and the flow of ultraviolet sterilizer screw design. There is the results of calculation of losses in the various water systems of cars with the maximum and minimum charging time and the water pressure in the water system station. The rational geometric parameters of the decontamination chamber flow ultraviolet sterilizer of the conditions to ensure complete filling of the tank car parking in the minimum time with minimum pressure of the water supply system of the station. The value of head loss does not exceed the nameplate values typical designs. The geometry of the sterilizer allows you to integrate the device into the car. Its design values are taken to develop the prototype of a UV sterilizer successfully tested. To be able to determine the loss of water pressure chamber decontamination sterilizer screw coil design is presented with a rectangular cross section, «wound» on the cylinder. Local loss of one turn calculated using the reference formula proposed by G.N. Abramovich.

The article discusses the possibility of extending the service life of passenger cars. The analysis of the state of the passenger car fleet has established that the rate of replenishment of reserved cars has been reduced by more than 40 % over the past 10 years, therefore, it is possible to ensure coverage and replenishment of the retirement of rolling stock of this type after the expiration of the standard service life only by extending the service life of existing cars by carrying out capital repairs with the establishment of a new standard service life. When analyzing the power frame of a reserved seat passenger car, it was found that the greatest static and dynamic loads are perceived by its center beam. It is precisely because of the stresses arising in it that an assessment is formed of the further possibility of operating a car both during its life cycle and further use in diagnostics for the possibility of assigning a new service life to it during overhaul repairs. Studies of a number of elements of center beams cut from passenger cars that have expired the standard period have established that the main characteristics of the metal meet the requirements of safety standards, this indicates that the safety margin and resource inherent in them has not been fully depleted. In the study of the presence of residual stresses that have arisen in the elements cut from the ridge beams, depending on the depth of etching carried out according to the method of N. N. Davidenkov in accordance with the TSNIITmash methodology, the most vulnerable and dangerous places of corrosion that require more careful control during the car maintenance and scheduled preventive repairs were identified. In order to reduce the development of residual stresses and the corrosive effect on the load-bearing frame of a second-class car, recommendations and technological operations have been developed for strengthening the ridge beam by the method of shot-blasting with the formation of a uniform fine-pored structure, which ensures uniform application of paint and varnish coating.