Introduction. The authors examine the development of new, updated mathematics in the automated control of the geometry of rolling stock wheel pairs for the CONLOC measuring system. The system uses non-contact 2D laser profile gauges to measure the parameters of locomotive wheels when they are placed in a depot and cars during their operation on the railway.

Materials and methods. The researchers apply mathematical models with algorithms for describing and assessing the wheel profile given additional requirements to the smoothness and continuity of the functions in use. The paper analyses actual data on the state of the tread profiles of wheel pairs of wagons, and compared the results with the reference state of the tread surface profile under GOST 10791-2011.

Results. The authors develop a new promising algorithm for describing and assessing the wheel rolling profile and improved the measurement accuracy by reducing the human factor, digitalising processes and automating the monitoring of the health of rolling stock along the route. The research determine the parameters of the tread surface profile of a wagon wheel with an operating time of 450 thousand kilometers.

Discussion and conclusion. This data processing algorithm provides for non-contact and automated measurement of the geometry of wheel pairs of locomotives and multi-unit rolling stock, as well as passenger carriages and wagons in motion based on laser profile gauge data, as well as automated measurement reporting process, including information on the object under examination, and repair recommendations. The new algorithms and modern hardware provide accurate and reliable data on wheel pair geometry, predict the operating wear of the wheel pair without the need for manual measurements.

Introduction. This article examines the temperature of separation of a cylindrical part from the axis and its dependence on the interference and induction heating power based on theoretical calculations and experiments.

Materials and methods. The calculations show the temperature of the outer surface of a cylindrical part, where the interference vanish and the part comes off without force. The authors numerically solved the heat conduction and deformation equations and determined these separation temperatures. The researchers also calculated the temperature profile over the cross-section of a cylindrical part.

Results. The authors identified the dependence of the separation temperature of a cylindrical part (the inner ring of a bearing) on the power of the induction heater. The article considers the dependence of the thermal diffusivity coefficient on temperature and examined the features of fitting cylindrical parts on axes and shafts.

Discussion and conclusion. The research shows that the dependence of the separation temperature of a cylindrical part (the inner ring of a bearing) on power has two regions: the separation temperature is almost constant for relatively small values (up to 5-6 kW); and the separation temperature is proportional to the power for higher values, above 6 kW. In this case, the induction heater requires a controller for induction heating power and heating time. This would technically prohibit operations with parameters outside the test procedure. The research results are applicable to a wide range of axis associated parts, for example, for bands of cold pipe drawing mills, bands for the centres of locomotive wheel pairs.

Introduction. This is a description of a technology for assessing the quality of thermal insulation of passenger carriages bodies using the portable tool developed. The research focuses on  the thermal insulation characteristics of the walls  of passenger carriages bodies. Heat insulation is assessed by the reduced heat transfer coefficient which  increases during the service life driving up the costs of heating and air-conditioning the car interior. The thermal camera helps create a heat enginering data sheet of the car with  photos of the body parts with  poor thermal insulation. However, the overhaul of the car requires pinpointing these places by measuring locally the specific thermal resistance of the body walls. The research is intended to develop a method for determining the specific  thermal resistance of the walls of passenger carriages bodies in minimal time  using a portable tool.

Materials and methods. The research methods are  a combination of a physical  experiment on  a section of the wall of a passenger carriage body and on a model of such wall using the developed tool, as well as a digital experiment on their 3D-models. In particular, the tool calibration involved a finite element analysis  of an unsteady thermal process in a digital model of the tool and a 3D-model of the passenger carriage body using SolidWorks Simulation software.

Results. The authors prove that the portable tool can determine the local specific  heat resistance in a passenger carriage body wall in minimal time  of 40 minutes.

Discussion and conclusion. The  portable passenger carriage heat insulation tool can  be  used for  input and output control of thermal insulation of a passenger carriage during a major overhaul.

Introduction. Railroad switches velocities significantly affect line throughput capacity. The article examines approaches to establishing railroad switches velocities in connection with intensified traffic, new designs of rolling stock, organisation of fast, high-speed and heavy traffic.

Materials and methods. Railroad switches velocities are determined by safety criteria and traffic intensity. The researcher analysed the criteria for railroad switches velocities design, railroad switches velocities for particular types of the rolling stock, velocities along railroad switches combinations. The author examined methods for establishing velocities along rail-road switches in curved sections of the track.

Results. The article provided data on speed limits on railroad switches considering their actual condition and presented railroad switches test results substantiating the speed criteria in use.

Discussion and conclusion. These criteria, requirements and methods for establishing rolling stock railroad switches velocities constitute a unified system for developing railroad switches, establishing and limiting the rolling stock railroad switches velocities under operating conditions.

Introduction. The author examines the problem of improving the accuracy of computer simulation of electromagnetic processes of an auxiliary asynchronous motor of an electric locomotive with the frequency adjusted by an autonomous voltage inverter. The calculations of instantaneous motor phase currents were improved. The research justified the proposed adjustments to the computer model of a three-phase asynchronous motor to consider the skin effect in the stator and rotor windings, and the effect of the magnetic circuit saturation from leakage fluxes on the leakage inductance of the phases and, thereby, on the instantaneous phase currents. The model is necessary to enhance the reliability of the auxiliary electric drive of an electric locomotive through the correct selection of semiconductor switches for the electric motor inverter. Materials and methods. The researcher chose computer simulation using OrCAD as our research method, and the input data include experimental instantaneous phase voltages of the auxiliary asynchronous motor.

Results. The article presents the results of adjusted computer simulations of instantaneous variables for steady-state engine operation and compares them with experimental data.

Discussion and conclusion. The author compared the experimental and calculated data (phase current, torque, rotation speed of the auxiliary asynchronous motor of an electric locomotive) and substantiated the adjusted computer model to reduce errors in the calculation of electromagnetic processes of the electric motor. The adjusted computer model improves the accuracy of calculating the instantaneous phase currents of the motor. The calculations were performed for the steady-state operation of an asynchronous motor of the AZhV250M2RUHL2 type. The results show that the skin effect has the greatest influence on the leakage inductance of the stator winding.

Introduction. Dynamic loads cause high contact stresses in the materials of wheels and rails, which leads to their wear and accumulation of contact fatigue damage. A number of approaches were proposed for calculations of contact fatigue and prediction of damage accumulation processes. One of them uses the Dang Van criterion. It involves time-consuming iterative procedures, so it is used to assess contact fatigue at individual points of wheel and rail. In order to simplify calculations and obtain more extensive information, the authors proposed an engineering method that allows determining the risk of contact fatigue damage for sub-contact layer nodes represented by a finite element model, with an unlimited number of wheel — rail contact implementations.

Materials and methods. The approach is based on the use of the Dang Van criterion with the introduction of some assumptions. The amplitude of the largest shear stresses is taken as the amplitude of the shear stresses. The components of technological and operational residual stresses are set using the results of experimental studies or those obtained by calculation methods. Information about wheel — rail contact conditions was obtained by modeling of the vehicle movement. Calculations were performed considering changes in wheel and rail profiles during the modeling process caused by wear. Results. The test results were obtained for some cases of wheel — rail contact, as well as for determining the contact fatigue damage risk indicator for the wheel and rail with a sufficiently large number of contact implementations. The calculation results are presented in the form of isolines of the value of indicator for the points of the layer adjacent to the tread surfaces.

Discussion and conclusion. The proposed approach can be used to determine the risks of contact fatigue damage in railway wheels and rails, in particular, to optimise wheel and rail profiles according to wear and contact fatigue criteria.

Introduction. Seasons with dominant negative ambient temperatures increase the possibility of insulation failure of electric locomotive traction motors with the service reliability of electric locomotive inevitably plummeting as a whole. Wet commutator and windings result from approximately 70% of insulation failures. The paper examines ways of improving the service reliability of electric locomotives by reducing the moisture content in the insulation of DC commutator traction motors based on electrokinetic phenomena (electroosmosis) with testing the actual parameters of the electroosmotic drying.

Materials and methods. We obtained experimental data from tests on real electric traction motors in a locomotive service depot. The electroosmotic drying technology involved a device for moistening the electric motor commutator and windings developed by the authors, and standard tools for measuring the insulation resistance of electric traction motors.

Results. The research shows that electroosmotic drying is feasible at a voltage of 3000 V; drying is effective with electric heater blowing; electroosmotic and electric heat drying system together increase insulation resistance by 20-40 % in the first two to three hours; electroosmotic drying shows the highest rate of increase in insulation resistance when connected to windings with a resistance below 500 kΩ; electroosmotic and electric heat drying system together use 60% less electricity and 20% less time.

Discussion and conclusion. The drying technology is useful in locomotive service depots, in workshops during TR-1 maintenance and when operating traction electric rolling stock in low ambient temperatures. The drying technology is applicable in hot storage of electric locomotives; the effectiveness of this method requires experimental confirmation. This technology for increasing the resistance of wet insulation would reduce electric traction motor failures using electrokinetic phenomena, increasing reliability of electric locomotives.

Introduction. Improving the management system of industrial and consumption waste of the Russian Railways, waste processing and recycling are some of the main focuses of the company's environmental strategy.

Materials and methods. The paper statistically analyses official data on the generation of industrial and consumption waste for 2015-2021, examines waste generation trends by hazard classes and volumes of annual waste dumping.

Results. The statistical analysis shows that the process of generation of industrial and consumption waste and the annual amount of waste over the past seven years slightly decreases. The share of hazardous waste is approximately 25% of the total waste mass. This period sees total landfill volumes tend to decrease, likely due to less use of highly hazardous goods, more installations for the safe processing of industrial waste, and measures to increase waste recycling.

Discussion and conclusion. New approaches help decrease waste generation: recycling of worn sleepers, waste oil, ferrous and non-ferrous scrap and other waste; electronic document management to save paper and cardboard.