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The use of twelve-pulse rectifiers instead of six-pulse rectifiers leads to increased efficiency and efficiency of traction substations of the underground. On the basis of experimental research and analysis of circuit solutions, the conclusion is made about the advantage of a twelve-pulse rectifier circuit of a serial type over parallel-type circuits. The use of rectifiers with a parallel type circuit is possible only if there is an equalization reactor, without which technical and economic indicators are reduced. The introduction of the most rational twelve-pulse bridge rectifier schemes of the sequential type can be carried out by upgrading the installed equipment, or by industrial development by manufacturers of dry transformers with different typical power and rectifiers with tablet avalanche valves with coolers based on heat pipes.

The method of determining the durability indicators of wheel pairs of locomotives is considered on the example of diesel locomotives of the 2TE25KM series operated on the Volga railway. For this purpose, the 90% resource of the wheel pairs of the studied series of locomotives was determined, and it was compared with the accepted standard indicator. In addition, a controlled parameter of the wheelset is selected, limiting the reliability of this node. To conduct the study, methods of mathematical statistics and probability theory were used, in particular, the Laplace distribution function, the Student's criterion, as well as the results of calculations of the dependencies of the mean value and the standard deviation of the controlled parameters, the initial values of developments and operating time corresponding to the probability of failure 0.5. In this study, a mathematical model for assessing the durability of wheelsets from the point of view of reliability theory was developed. The evaluation of the durability indicators of the wheelset elements was carried out on the basis of the type of random variable distribution law with its parameters obtained on a computer and adopted according to the Pearson criterion. As a result of the calculations, 90% of the life of the wheelset was obtained according to two controlled parameters, which amounted to 476.6 thousand km for the thickness of the bandage, and 282.6 thousand km for the thickness of the ridge. The results obtained were compared with the values adopted in the Technical Specifications for this series of locomotives (800 thousand km). km), as well as with statistical data on the values of controlled parameters obtained during processing and analysis - 240 thousand km. Due to the fact that in operation the average life of the wheelset is determined by a larger number of controlled parameters, taking into account unscheduled repairs, and in this study - only on the basis of the thickness of the bandage and the ridge, it is not possible to talk about full compliance with the calculated and actual data. According to the results of calculations, the limiting reliability of the wheelset is such a controlled parameter as the thickness of the ridge. For a more accurate assessment of the durability of wheelsets, it should also be taken into account that the intensity of wear of rolling stock equipment is affected by specific operating conditions, in this regard, inter-repair runs should be adjusted taking into account the influence of external factors during operation. In order to fully assess the durability of wheelsets in the future, it is necessary to take into account additional factors, in addition to those that affect the parametric change of random variables, as well as the fact that takes into account the monitoring and analysis of all controlled parameters of this node during the operation of locomotives.

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.

In this article, the process of wear of the material of the ridge of the wheel brace during the movement of the locomotive in a curve of a given radius is considered. The methodology of the study considered in this article was that, based on the expression for the depth of penetration of the rail head into the material of the bandage ridge, the movement of the wheel along the inner rail in the curve was considered. It was taken into account that the contact point on the ridge of the bandage will move along the edge of the rail with slippage and that the contact area is a fairly narrow surface with a border close to an ellipse. Formulas for calculating the speed and the slip path of the contact point of the ridge of the locomotive wheel brace with the rail are obtained. As a result of the study, equations were derived to estimate such quantities as the volume, intensity and wear rate of the bandage (per revolution of the wheel). It is shown that the expressions obtained as a result of the work carried out can be used to calculate the intensity of wear of the brace ridge when the locomotive is moving in a curve of a given radius. The amount of the ridges material wear of the wheelset bandages can be determined on the basis of the equations obtained individually for a specific locomotive series and a given range of its operation.

The increased influenceof cable-stayed - suspension bridges for crossing of sea passages is shown. The retrospective show of their development is given. The prospect of the big beam - combined bridges is resulted. Various schemes of vantovo-suspension bridges with rectilinear cables are considered. Two new schemes of cable-stayed suspension bridges with curvilinear cables are offered.

The article discusses the design features of the mechanical and crew parts of the passenger electric locomotive DC EP2K, which directly have or causes an impact on the rail track. The purpose of the work is to consider the features of the interaction of the crew and the track when moving this electric locomotive in small radius curves by evaluating the forces arising in the "wheel-rail" contact of the three-axle bogies of the EP2K electric locomotive under these conditions. The need to solve such a problem is caused by the results of the analysis of statistical data on the wear of the ridges of the wheels of EP2K electric locomotives. These electric locomotives are operated at the united railway landfill, where there are a large number of curved sections, including curves of small radius. To achieve this goal, a design scheme of a three-axle trolley of an EP2K electric locomotive has been compiled, which allows a quantitative assessment of the forces acting in contact with the wheel ridges with the relay heads. According to the calculation scheme, a system of equations has been compiled, the solution of which makes it possible to estimate the forces between the ridge and the inner face of the rail head. Based on the results of the calculation of the guiding forces of the wheel pairs of the three-axle bogie of the EP2K electric locomotive, it is concluded that the values of the guiding force acting on the second wheel pair are comparable to the forces acting on the first and third wheel pairs, and in some variants even exceed the values of these forces. The obtained results can be used for further research on the development of measures aimed at reducing the wear of the ridges of the wheels of electric locomotives of the EP2K series under operating conditions.