Introduction. The article is devoted to the study of the waves propagation of lightning overvoltage impulse in the catenary system of electrified railways. The purpose of the work is to determine the zone of waves propagation of lightning overvoltage impulse along the catenary system, the degree of attenuation and the influence of the soil condition on the mode of their propagation.
Materials and methods. The authors carried out tests on the waves propagation of lightning overvoltage impulse along the catenary system of the 1st (ring) track and the 15th (dead end) track of the Experimental Loop of the Railway Research Institute at the Shcherbinka station using a high-voltage impulse voltage generator.
Results. During the tests, the influence of the soil condition on the mode of waves propagation of lightning overvoltage impulse was determined. The degree of attenuation of the lightning overvoltage impulse wave in the catenary system in the looped and dead end sections is determined, considering the influence of the reverse (reflected) overvoltage wave, as well as changes in the voltage level during the wave process occurring in the catenary system. The data obtained during the tests enable to determine the propagation speed of the lightning impulse wave.
Discussion and conclusion. The obtained test results will be useful for improving the reliability of lightning protection devices of the catenary system against external overvoltages and can be used to improve insulating elements.

Introduction. One of the ways to increase the traffic-carrying capacity of railway lines is increasing the amount of cargo carried in cars, while taking into account the inevitable increase in the axial and linear load of the car. The decision to use cars with increased axial load should be based on an assessment of their technical and economic efficiency in comparison with the innovative and widely used open-box wagons with a load of 25 tonnes per axle. When assessing the economic efficiency of such cars, it is required to consider their impact on changes in the parameters of the organisation of the transportation process.
Materials and methods. Based on the presented initial data on the estimated predicted freight flow, the numerical values of the parameters of the transportation process were determined when introducing 8- and 4-axle (27 t/axle) open-box wagons. When determining the increase in the traffic-carrying capacity, its change due to an increase in the net mass of the train and a change in the total number of trains is taken into account. The calculation was made accounting for the increase in traction in proportion to the increase in the gross mass of the 8- and 4-axle (27 t/axle) open-box wagon trains on the existing infrastructure.
Results. The authors have developed methodological provisions to determine the numerical values: an increase in the traffic- carrying capacity, the required inventory fleet of cars and the available locomotive fleet in the context of the introduction of new 8- and 4-axle (27 t/axle) open-box wagons.
Discussion and conclusion. The article is theoretical and is devoted to calculation mechanisms and methodological issues. The results of the study may be applied to the ranges of the Russian Railways network, in particular, to solve complex issues of increasing the traffic-carrying capacity of the Eastern range.

Introduction. On-board fuel metering systems for diesel locomotives created by different manufacturers differ both in the composition of the sensors used and in the software for processing the registration data. This indicates that the pursuit of better efficiency for these systems is still ongoing and is an urgent problem.
Materials and methods. The article discusses the problems of determining the fuel consumption according to the data of on-board fuel metering systems for diesel locomotives, associated with various methods for determining the moments of measuring the fuel amount in the tank. The possibility of estimating the influence of the number of position switches of the locomotive throttle on the indicators of absolute and specific fuel consumption has been studied.
Results. In the absence of distance and speed sensors in the on-board system, it is proposed to determine the moments of measurement of the fuel amount based on the analysis of changes in the signals of the fuel level sensors over time. The authors present an example of the practical implementation of this solution. The results of on-board systems data processing are also presented, showing that the effect of the spread in the number of throttle position switches observed in ordinary operation of diesel shunter on fuel consumption is comparable to the error in determining this value according to the on-board systems data. The implementation of algorithms in specialised software designed to process data from onboard systems that allow identifying the indicated influence is relevant only for cases of extreme (by an order of magnitude) difference in the number of switching throttle positions in work shifts.
Discussion and conclusion. The efficiency of the practical use of information from the on-board systems for metering fuel consumption of a diesel locomotive is largely determined by the quality of specialised software. When developing and improving software, it is recommended to use the approaches discussed in the article.

Introduction. Until now, the requirements for manual and automatic couplers for locomotive-hauled passenger carriages and electric trains have been completely identical, despite the significantly lower level of longitudinal forces during the movement of multi-unit rolling stock with distributed traction. The introduction of specialised designs of coupling devices for electric trains led to the development of strength requirements that enable the creation of new models with smaller dimensions and weight. Operating experience has shown that parts of couplings may be destroyed, leading to the uncoupling of trains. Fatigue damage may cause accidents. However, there were studies of the draft loads of electric trains couplers in operation, on the basis of which it was possible to develop regulatory requirements for specialised coupling devices.
Materials and methods. The authors measured the forces acting in the couplings of electric trains of various categories and types during normal operation, as well as the frequencies of the occurrence of forces of various levels. The article includes histograms based on the results of processing the received data showing the distribution of longitudinal forces acting on the inter-car couplers and the parameter characterising the accumulation of fatigue damage per 100,000 km. 
Results. According to the results of processing of the experimental data, the calculation of the accumulation of fatigue damage to the couplers was carried out and the requirements for their expected service life were established. Test procedures have also been developed to evaluate strength and fatigue resistance under high-cycle and low-cycle loading conditions. The article provides ground for introducing a correction factor into the procedure for processing test results, which makes it possible to perform life tests on equipment with different values of the load cycle asymmetry factor.
Discussion and conclusion. The authors have evaluated the draft loads in coupling devices during the operation of electric trains, on the basis of which technical requirements and test methods were developed and approved by JSC Russian Railways. Development and acceptance of all new models of coupling devices for electric trains will be carried out in accordance with these regulatory documents.

Introduction. The aim of the study is to develop a basic configuration of the on-board system for diagnosing the technical condition of the wheels tread surface of a wagon while the train is running and to model its operation.
Materials and methods. The theoretical studies are based on the methods of Lagrange's analytical mechanics, the theory of oscillations and classical electrodynamics. The simulation was carried out for a flat design scheme using numerical methods. The results were processed using the developed algorithm implemented in the programming language of the Mathcad system.
Results. This article studies the problem of the negative impact of local wear of the wheel tread surface on the state of the carriage chassis of the car and the rail track, as well as on the safety of train traffic. The authors propose a basic configuration of an on-board system for diagnosing wheel pairs of a wagon with an autonomous power supply with a power of up to 10 W, which simultaneously acts as a sensor. A mathematical model of diagnostic signals for local wheel wear has been constructed, and an algorithm for their detection has been developed based on the results. A criterion for estimating the geometric parameters of wear is formulated and its threshold values for slots of various depths are calculated. Alarms have been identified that suggest a reduction in the speed of the train.
Discussion and conclusion. The solution of the stated problem is important both in the operation of existing cars and in the development of new, innovative cars with an axle load of 27–30 tf and speeds of up to 140 km/h. Timely detection of local wear of the tread surface of wagon wheels will increase the level of traffic safety and reduce the cost of repairing cars and rail tracks.

Introduction. One of the consequences of the introduction of the Instructions for Assessing the Condition of the Rail Track (enacted on February 28, 2020 No. 436/r) was an increase in the number of newly detected deviations from the norm of track maintenance and their reassignment as malfunctions. As a result, the number of kilometres with limited train speeds has increased by up to 3 times, which may lead to significant losses in transportation and an increase in the cost of the immediate track maintenance.
Materials and methods. Data from a special thoroughfare of a diagnostic complex along the operating lines of Russian Railways were used to analyse the actual distribution of types and magnitudes of malfunctions, the number and causes of the speed limits. The authors used computer simulations to determine the dynamic indicators of cars in accordance with the algorithm of the deterministic method for calculating the movement of cars along the railway track.
Results. The consequences for assessing the state of the track from the standards specified in Instruction 436/r are analysed. The authors present the results of mathematical modelling of the rolling stock interaction with the track, confirming the feasibility of the proposed changes in the standards: increasing the permissible speeds of passenger trains, assessing the gauge widening in curved sections, clarifying the estimates of unbalanced acceleration.
Discussion and conclusion. It is proposed to change a number of standards for assessing deviations from the norms of track maintenance in order to reduce the number of speed limits.

Introduction. Replacing the material of monometallic motor-axial bearings currently manufactured from bronze to aluminium alloy is advisable to improve traffic safety due to the higher reliability and efficiency of such bearings.
Materials and methods. This article studies the materials of monometallic motor-axial bearings, bronze and the proposed complex aluminium-tin alloys. Mechanical properties are determined by standard methods: tensile strength, relative elongation (ductility), Brinell hardness, impact strength. Antifriction properties (abradability, score resistance, wear resistance of the antifriction alloy and the steel associated with it, the heating temperature of the steel surface and the coefficient of friction) were determined according to the methods of the Railway Research Institute approved by JSC Russian Railways on the SMTs-2 friction machine. Bronze and three grades of aluminium alloys were tested with M-14V2 diesel oil, and bronze, B16 babbitt and one grade of aluminium alloy were tested with axial oil.
Results. This research shows the possibility of replacing bronze with complex-alloyed aluminium alloys both in terms of economic indicators and antifriction properties. A comparison of mechanical properties is carried out, in most of which aluminium alloys are found superior or not inferior to bronze. The exception is ductility, in terms of which bronze surpasses the proposed alloys.
Discussion and conclusion. According to the complex of service characteristics obtained in laboratory studies, it seems expedient to replace bronze with complex aluminium antifriction alloy. The final decision on such a replacement could be made after bench and operational tests of motor-axial bearings on diesel locomotives.

Introduction. In the conditions of an annual increase in load stress on the roads of the Eastern Polygon, an effective technical solution to the problem of an increased number of rolling stock derailments due to rail breakage is the creation of rails for cold climate conditions with increased hardness to increase wear resistance and contact endurance with simultaneously high values of impact strength. Such a set of properties can be achieved by using separate heating for quenching and cooling with a quenching medium with a high cooling capacity. Rails manufactured using this technology will belong to a new category. In this regard, the purpose of this work was to create a new category of rails for their use in particularly harsh operating conditions.

Materials and methods. In this paper the effect of separate induction heating before differentiated quenching with compressed air of controlled humidity on the microstructure and mechanical properties (hardness, mechanical properties during tensile and impact tests, endurance limit, cyclic crack resistance) of rails of type R65 was investigated.

The results of the study. A comparative analysis of the results obtained with similar indicators for rails of the DT350, DT350NN and DT370IK categories according to GOST R 51685-2013 was carried out. Studies of the chemical composition, mechanical properties, hardness on the rolling surface of the rail head and cross-section, as well as the microstructure of the rails of the experimental batch showed compliance with the requirements of GOST R 51685-2013 for rails of categories DT350, DT370IK, DT350NN.

Discussion and conclusion. It is shown that as a result of the application of differentiated thermal hardening of the rail using compressed air of controlled humidity as a quenching medium, a new category of DTO350NN rails was obtained, characterized by a favorable combination of strength properties, plasticity characteristics and brittle fracture resistance indicators. Rails of the new category can be recommended for use in particularly severe operating conditions (in curved sections of the track of a small radius at low temperatures), including on the roads of the Eastern Polygon.