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Results of mathematical modeling of determination of character and the law of change of forces and tension arising in the field of contact of interacting bodies on the example of dynamic contact at impact of an elastic sphere about motionless, absolutely rigid plate are presented in article, at its flat movement. The received results can be used at calculations of contact forces and material tension in a metalwork at shock influences.

The article considers a suitability of mathematical model of stretched rod to determine the relationship of the parameters oscillations of the contact wires and their tension. This model allows you to determine the tension by the frequency oscillations of the contact wire obtained after the passage of the current collector. In this case, the speed of the electric rolling stock will not affect the frequency of the damped oscillations. Thanks to the proposed model, the labor intensity is reduced of determining the tension of wires without interruptions in the movement of trains is reduced and there is an opportunity of operational monitoring of the state of the contact suspension remotely.

The analysis of the influence of operating modes and the development of the residual life, expressed through thermal wear of the insulation of the asynchronous traction motor. The research subject is to obtain new patterns of change in the residual life of the stator winding insulation, which make it possible to determine the specific life of the winding for each mode of the asynchronous traction motor. The research aim is to create a system for determining and assessing the residual life by developing methods and technical means of monitoring and comprehensive diagnostics, as well as theoretical justification using the method for determining additional thermal wear of the stator winding insulation, taking into account the combined effect of the starting transient process, the long-term allowable load schedule and the maximum allowable temperature values. To determine and assess the possible residual life, the method of sequential influence of starting transients, maximum permissible load curves, as well as long-term overloads at the maximum permissible temperature, taking place under various operating factors during the movement of electric rolling stock, was used. The expediency of determining the function of uneven resource development, which has a monotonic character and is approximated by a linear double exponential and exponential functions, is shown. Specific proportionality coefficients are experimentally determined, which characterize the decrease in the dielectric strength of the insulation with sequential alternation of maximum and long-term permissible loads and maximum permissible temperature values, followed by obtaining an analytical relationship that predetermines the insulation resource. It is shown that the determination and assessment of the residual resource under typical modes practically makes it possible to clarify the timing of preventive measures and predict the expected duration of accident-free operation and forestall the premature failure of the asynchronous traction motor.

The article is devoted to the description of the requirements for the accuracy of control devices and the development of methods to ensure the claimed dimensional accuracy by methods of dimensional analysis. The conditions for ensuring the accuracy of the assembly scheme, the determination of the dimensional chain and dimensional analysis of the dimensional chain during the assembly of the control device, as well as the main causes of errors during assembly and ways to eliminate them are listed. In addition, the consequences of the influence of irregular gaps in the interfaces of the control device parts on the measurement accuracy are presented, various types of assembly dimensional chains are considered, tasks solved when calculating the dimensional chain. The paper presents a compiled dimensional chain of the technological process of assembling a measuring instrument for monitoring the alignment of the inserts of motor-axial bearings of traction electric motors of locomotives, which represents a dimensional chain of the first type and is a chain with linear dimensions and vertically parallel links. The purpose of the work is to substantiate the calculated tolerances and limit deviations of the links of the assembly dimensional chain, providing the required value of the closing link for the proper functioning of the assembled measuring instrument. The paper describes the selection of the closing link of the dimensional chain, the selection of the links that make up the dimensional chain, the calculation of the limiting deviations of the closing link that ensure the required measurement accuracy during operation of the control device and the calculation of the limiting deviations of the components of the links of the dimensional chain by the "maximum-minimum" method. Thus, the article presents a solution to the design problem of dimensional analysis, which consists in determining the accuracy of the component links of the dimensional chain when assembling the control device according to the known calculated tolerance of the closing link and its limit deviations.

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.

The traffic speed increasing on the railways makes strict requirements to the supporting and supporting structures of the contact network, as well as to the parameters and indicators of the contact suspension. The presence of dry friction in the cantilever attachment points indicates a negative effect on the accuracy of adjusting the wires of the contact suspension and on its parameters. The article presents the results of studies of the dry friction value in the console fastening points depending on the type of the contact suspension and suggests a method for reducing friction in the console attachment points. The results of calculations of the effect of friction in the console attachment points on the tension variation along the length of the anchor section are presented.

In this paper we consider an alternative method to solving problems of technical diagnostics of railway wheels, which consists in developing a system for monitoring critical states of near-surface layers of metal, which has the ability to detect incipient defects in the metal structure of the rolling surface of a wheel.