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The article presents the results of a study of the effect of the functional relationship between the parameters of the microgeometry of the brake disc surface and the level of the stress-strain state of the contact area on the thermal resistance coefficient. The results of an experimental study of the process of changing the step and altitude parameters of the microgeometry of the surface of the brake disc under the influence of normal and tangential forces realized during friction are obtained. It was found that under the influence of normal and tangential forces, the height parameters of the microgeometry tend to increase, and the step parameters tend to decrease. It is shown that when calculating the contact thermal resistance, it is necessary to take into account the functional relationship between the geometric parameters of the microroughness of the brake disc surface and the level of the stress-strain state of the contact area. The calculations performed without taking into account this connection lead to overestimated values of the contact thermal resistance and, accordingly, to errors in determining the values of heat fluxes passing through the contact area of the mating surfaces. The values of the constants, which depend on the design features of the friction unit of the disc brake and are used to determine the nature of the change in the geometric features of microroughnesses, have been specified. The correction of the input parameters of the microgeometry of the surface of the brake disc is performed, taking into account the dynamics of changes in their geometry under the influence of force loading. It is shown that it is advisable to take into account the dynamics of changes in the surface microgeometry in the analytical determination of the contact thermal resistance of a disc brake. The results obtained are recommended to be used in calculating the friction characteristics and assessing the heat fluxes passing through the area of mutual contact of the brake disc and brake pads of the disc brake.

Comparative bench tests of acoustic emission occurring during the interaction of the brake pad with a brake disc for the brake unit with a stationary brake pad and a brake unit with a floating brake pad are carried out. The floating brake pad, depending on the braking conditions, occupies an optimum position on the surface of the brake disc, while making movements of an oscillating nature around the turning axis that does not pass through its center of mass and parallel to the axis of rotation of the brake disc. The frequency range is determined in which there are noticeable differences in the acoustic emission of a brake unit with a floating brake pad and a stationary brake pad. The theory of fuzzy sets is used to analyze the acoustic emission perceived by the human hearing organs, which accompanies the interaction of the surfaces of a friction pair in the investigated frequency region. The results of a comparative analysis of the noise characteristics of the brake blocks under investigation are discussed. The spectra of the acoustic emission power are compared according to the obtained base of the expert evaluation of the noise power perceived by man.

Features of the methods of calculation of a braking distance of the train applied now are considered. The main shortcomings of the most widespread method of definition of a braking distance on speed intervals are shown. Authors offered the new method of calculation allowing to consider critical parameters of process of braking (speed of a brake wave; character of an indicator diagram of the brake cylinder and mode of a brake; the actual initial speed for calculation of a way of action of brakes of the train). For verification of the offered method computer modeling is executed and the analysis of results of the different methods of calculation of braking length received at application is carried out. The new method allows to make calculation of braking length of the rolling stock more precisely.

Traffic safety of trains is a priority task of JSC «Russian Railways». In article the reasons of spontaneous operation of brakes of freight trains are investigated and their statistics depending on density of brake network of the train is given. Calculation of pressure in the camera under the equalization piston of the crane of the driver is made. Inertial characteristics of the equalization piston and its static characteristics are defined. Process of spontaneous operation of autobrakes on the basis of fundamental laws of a hydraulic gas dynamics is simulated.

The results of mathematical modeling of the heating process of the wheel material during braking mode of the locomotive are presented in article. The results can be used to calculate the temperature change for any point of the wheel during the braking operation.

The subject of this article is the pressure in the main reservoir of the locomotive. The purpose of the study is to obtain and analyze unique data on pressure reduction in the main reservoir of the locomotive. When carrying out train tests developed by the author of the train brake diagnostic system, pressure changes in the main reservoir of the locomotive were obtained depending on the driver's control effects in real time. This was achieved by installing a sensor measuring the pressure in the nutrient line of the locomotive and processing data using the software and hardware complex diagnostics system for the brake network of the train. In work methods of the mathematical analysis, a method of experiment, an analytical method are applied. As a result of the work, pressure reduction curves are described in accordance with the processes occurring in the main tanks of the locomotive during train operation. An explanation of the flow of pneumatic processes in accordance with the specifics of the braking equipment of the rolling stock of railways. An experiment was carried out to measure the density of the brake network of a train by a machinist and a system for diagnosing the brake network of a train, and the convergence of results was presented. Also, quantitative indicators of the measurement rate by the standard and proposed method are determined. The research results were applied to improve the methods and means of diagnosing the brake network of a train, modeling pneumatic processes of the train's brake system. Pressure reduction curves have their own gas-dynamic nature, which allows to determine the mode of operation of the braking system, as well as diagnose faults in the brake network of the train, such as shutting off end valves, leaks along the way.

The article considers the existing methods for solving problems to improve the purification of compressed air in the brake system of the rolling stock. Presents the disadvantages of these methods and proposed a fundamentally new method of purification of compressed air, not previously used on rolling stock.

Currently, in the brake system of operated cars, there is a problem of lack of brake pressure on the wheel, which is necessary for the movement of the train at a set speed in accordance with the regulatory documentation. This is due to the tendency to increase the mass of trains and the maximum load of cars with a constant tare weight, which requires an extended range of pressure control in the brake cylinder by an air distributor or auto mode, depending on the load of the car. To solve this problem, calculations were made of the braking coefficient of cars equipped with air distributors № 483, which showed that the freight car was not equipped with brakes to run as part of a train at a set speed. In the course of engineering studies, it turned out that increasing the spring rate of loaded and medium modes can increase the adjusting range of the air distributor and partially solve the problem of lack of brake pressure. Thus, it is proposed to recalculate the stiffness of the adjusting spring. Calculations of the rigidity of regular and proposed springs were made. The braking coefficient has been recalculated, taking into account the increased spring constant. As a result, this coefficient has increased, which makes it possible to remove speed limits. The proposed method for upgrading the air distributor can be carried out on all types of repairs, which facilitates the implementation process.

The article discusses the thermal state of the disc brake elements during braking, taking into account the distribution of heat fluxes between the friction elements. The results of the study of the influence of the thermal resistance of the medium filling the microcontact gaps, caused by reversible deformations of the surface microgeometry, on the thermal state of the disc brake elements are presented. Method - the description of the thermal state of the disc brake elements during braking is made on the basis of the Fourier - Kirchhoff differential equation of thermal conductivity, taking into account the influence of the thermal resistance of the medium filling the microgaps between the surfaces of the brake pad and the brake disc. Results of the work: The calculation of the thermal state of a railway disc brake was carried out taking into account the reversible deformations of the microgeometry of the surfaces of the working elements of the disc brake. The exact dimensions and shape of the disc brake elements are specified in the CAD system (SolidWorks). The graphs of changes in the thermal energy generated and dissipated by the disc brake at different initial speed and duration of braking are given. The obtained dependences illustrate the process of heat energy dissipation into the environment. The inertia of the friction system of the disc brake in relation to the dissipation of the generated thermal energy during braking is shown. It has been shown that the distribution of heat fluxes between the working elements of a disc brake depends on the level of reversible deformations of the microgeometry of the brake disc surface, which directly determine the thermal resistance of the medium filling the microcontact gaps. Taking this circumstance into account makes it possible to increase the reliability of calculations of the generated and dissipated energy by the working elements of the disc brake during braking. The results of the study are recommended for use in calculating the thermal state of the working elements of the disc brake during braking.

In this article, with the help of software, the relationship between the structure of the material of the brake pad and the temperature distribution of thermal stress on it is established. Spatio-temporal distributions of thermal stresses were analytically determined for the surface layer of the friction element based on the model of a three-section brake pad with non-fixed edges. At present, shoe brake is widely used for freight trains. It converts dynamic energy into thermal energy using the friction between the pads and the wheel, and then dissipates the thermal energy through a heat exchanger. This process includes heat transfer, design features, mechanical characteristics, material properties and other. The article pays special attention to the brake pad pressure, braking mode, brake pad material and other factors. Modeling of thermal effects is the most important in the design of vehicle parts and assemblies. Thermal research is an important step in the study of braking systems namely railway vehicles, where it is necessary to breakе large masses, since the thermal load on the braked railway wheel prevails compared to other types of loads. In this paper, the thermal stress on the friction element of the shoe during braking is investigated. In frictional braking, the process of friction between the brake pad and the wheel occurs at the points of actual contact. The heat flow from the points of actual contact spreads over the entire geometric area of the block.

The article discusses a question, which is bonded with the traffic safety, namely the integrity’s verification of the braking highway’s of the freight train before the departure. There was given a range of reports in the absence of the braking highway’s integrity’s test by the locomotive crews. There was the verification’s order developed and his testing done. There were made the suggestions for improvement of the safety devices in terms of automation of the integrity’s verification of the braking highway.

In this article, the currently existing methods for determining such a technical parameter as the sliding friction coefficient were considered. The coefficient of friction is one of the main parameters characterizing the operation of tribological pairs of any engineering system. Stable and efficient operation of tribological pairs in such systems, along with high strength and fatigue characteristics, are not only the basis of safety, but also a promising direction in terms of economic benefits in the design and operation of various devices and systems. Accordingly, this area of research is very relevant for the railway industry, and for railway rolling stock in particular. This is caused by a large number of friction pairs in different nodes of passenger and freight cars, locomotives, ensuring safe and uninterrupted movement of rolling stock as a whole on iron drogs. Tribological processes are important both directly during movement and during braking processes. In this matter, the factor of determining and analyzing the sliding friction coefficient comes to the fore. One of these friction pairs is the «pad-wheel» system, which is the executive body of the braking system of a railway train. Optimization of contact in this system is one of the determining factors for the growth of braking efficiency during braking, increasing the working life of the elements of the friction pair, reducing the likelihood of defects. The search for new approaches to the study of friction issues is a direct catalyst for scientific and technological progress in the engineering industry.

In article the design of an automatic pneumatic brake of the car with the braking accelerator is offered. Use of the developed accelerator of braking of an automatic pneumatic brake by freight cars allows to reduce a brake way of the train and to reduce longitudinally dynamic forces in the train when braking.