Introduction. The development of power electronics and information technology facilitates the development and implementation of variable frequency electric drives for both traction motors and auxiliary machines of an electric locomotive. This publication is a continuation of research into controlling asynchronous machines of AC locomotives auxiliary electric drives (“Russian Railway Science Journal”, 2021, No. 5; 2022, No. 1; 2023, No. 1).

Materials and methods. In order to simulate dynamic processes that occur in the modal controller of an asynchronous motor the authors used SimInTech software developed by 3V Service, a domestic vendor, that enables exploring the operation of an asynchronous drive using a simulation modeling technique.

Results. It is established that the applied modal control method enables setting the time and nature of transient processes during an asynchronous motor control. The results of modeling a simulation of an automatic control system confirmed that the application of this method features long-term benefits.

Discussion and conclusion. The presented outcomes of modeling an automatic control system for an asynchronous drive based on the modal control method revealed an opportunity to significantly reduce transient processes period. This is achieved through the use of delayless flux linkage and angular rotation speed feedback of the motor rotor in the modal controller.

Introduction. Electric locomotive wheel–rail adhesion is determined by various parameters (kinematic and energetic) that affect the mass and speed of the train, energy consumption, etc. Goods trains of increased weight and length considerably increase the urgency of the problem of electric locomotive wheel–rail adhesion, especially when using powerful electric traction motors, including commutatorless ones. Making reasonable decisions to increase the mass and speed of trains, reduce energy consumption for traction and generally reduce operating costs requires a clear understanding of the basic regularities of the processes in electric locomotive wheel–rail adhesion zones and their parameters.

Materials and methods. The paper uses a system approach, methods of mathematical analysis and energy balance to consider the main regularities of processes in the electric locomotive wheel–rail adhesion zone, their kinematic and energy parameters. Consideration of these processes takes some assumptions: diameters of electric locomotive wheels and pressure of all wheels on rails at any moment of time and at each point of the track is the same, oscillations of wheel pairs are absent, etc. These assumptions do not significantly affect the final results but greatly simplify the derivation of the necessary analytical expressions.

Results. The researcher obtained numerical values of the electric locomotive wheel–rail adhesion parameters, which agree with the experimental data.

Discussion and conclusion. The author proposed the principles of analysis and a system of logically justified and interrelated kinematic and energy parameters of electric locomotive wheel–rail adhesion, identified the main regularities of changes in these parameters. The research results can be used to make science based decisions on the practical application of the electric locomotive wheel–rail adhesion.

Introduction. Onboarding rolling stock that exerts increased axial loads makes assessing wheels force impact on railway tracks more acute and relevant. Specialist literature describes many techniques for measuring lateral forces and lateral wear with varying degrees of accuracy. However, the questions of the correct position of measuring devices along the circular segments of a curve, spacing and frequency of measuring force parameters during the service life of the track rails are still open. The article discusses the impact of 25 tf open-box cars on the load and wear of the trackways in curves that have different radii.

Materials and methods. In order to analyse and detail the total load exerted by each car wheel on track rails on the second main track of the Slyudyanskaya Division, East Siberian Infrastructure Directorate (descending segment), the authors selected two (R298 and R565 m) curved segments with almost identical slopes and comparable operating parameters. Tests were carried out to measure the load exerted on the rails along two trial segments of the track and also measurement trips of Sprinter-Integral, an infrastructure diagnostic complex (by Firma TVEMA JSC), were made along the trial curve.

Results. The researchers processed and analysed the data obtained for open-box cars with an axial load of 25 tf (245.3 kN). It has been established that of all the wheels that passed along the R298 m curve, 58% impacted the inner rail in an outward direction from the rail track with 42% having an inward impact. The inner rail is exposed to an average lateral force of 37.9 kN directed outward and 30.9 kN directed inward. Similar data is obtained for the R565 m curve. A comparison of the diagrams of lateral wear and lateral forces obtained for both curves showed that changes in them occurred synchronically.

Discussion and conclusion. In order to comprehensively analyse wheels impact, it is necessary to assess the impact from lateral forces which is especially important for curved track.

Introduction. Unsteady train movement causes abrupt changes in the traction magnitude with oscillating and sometimes shocking relative movements of the cars. Under these conditions, the automatic couplers are subjected to stress, which leads to their breakage. The research is intended to determine the magnitudes and nature of changes in longitudinal dynamic inter-car forces arising when the train pulls off and pulls off without holding the time of full brake release (with braking forces acting in the tail section).

Materials and methods. Calculation of the longitudinal forces occurring when the train pulls off applies numerical modelling. The digital multi-mass model of each train is a system of solid bodies connected by elastic ductile bonds. The author developed a simplified model of the automatic coupler that takes into account the stiffness and ductility of the draft gear as well as the clearances in the shock and traction devices.

Results. The researcher performed numerical experiments of the three operation modes: train pulling off; train pulling off without holding the time of full brake release of the last car (with the last car assumed stationary); train pulling off without full brake release in the last third of the train under variable braking forces. Modelling for each type of virtual experiment established the nature and magnitude of changes in the longitudinal inter-car forces: in the steady-state motion and in the transient, the most loaded mode of train operation.

Discussion and conclusion. The trains under consideration show that the maximum inter-car loading when pulling off with the last car stationary is, on average, twice as high as the maximum inter-car loading when a train pulls off after full brake release. The author determined that incomplete brake release in the last third of the train under selected conditions increases the maximum longitudinal loading by 2.22–6.23%.

Introduction. Air conditioning systems installed in passenger carriages are currently powered using a gear-cardan drive connected to the middle part of the axis of a WBA-32/2 wheel pair designed by Flender (Germany) or its domestically manufactured analogues. Such drive dates back to the mid 1960s in terms of development and implementation. The article is devoted to the development and testing of a new generator-drive set for passenger carriages.

Materials and methods. The authors analysed the long-standing operation of the drive according to railway services involved in the maintenance and repair of passenger carriages equipped with air conditioning systems. Bench tests were carried out to test a pilot batch of the main units of the generator-drive set, such as gearbox, couplings and generator.

Results. A single-piece generator-drive set was developed and included a gearbox, generator, safety coupling and a elastic coupling. The entire structure of the set is installed on a bogie frame using three supporting elements of the suspension system.

Discussion and conclusion. The completed calculations and experimental studies show that the single-piece generatordrive set features parameters that significantly exceed those of series-produced peers. The design of 68-4066 and 68-4096 bogies was modified in order to enable the installation of a new generator-drive set on passenger carriages series-produced bogies. The completed calculation and graphical analyses demonstrates that the new generator-drive set could be installed on 18-6960 high-speed bogies frame.

Introduction. Long-term locomotive operation and safety considerations require new approaches to extending the life of its basic components operating under variable loads.

Materials and methods. The authors conducted bench life tests of frames under cyclic loading with vertical and horizontal transverse forces and calculated the bogie frame and intermediate frame life for the most stressed areas of their structures, where local fatigue damage can accumulate under cyclic loading leading to fatigue caused destruction. The calculation uses the results of bench fatigue tests.

Results. The research shows that the presented frames comply with GOST R 55513–2013 in terms of minimum reserve strength coefficient for fatigue resistance. The researchers proposed a methodology for estimating the residual life of bogie frames and intermediate frames.

Discussion and conclusion. The research indicates that the estimated safe service life of bogie frames and intermediate frames of an eight-axle diesel locomotive does not exceed 56 years from the date of construction. The expiry of this period allows for a repeat research and development work to determine the residual life of its basic parts. The above test methodology could be applied to assess the residual life of bogie frames and intermediate frames whose structure has localised zones of fatigue damage appearance and accumulation from cyclic loading, which may cause fatigue destruction.

Introduction. The paper analyses the causes of appearance and development of defects of the solid block with wing rails and welded rail ends (monoblock crossing) operating under heavy and intensive traffic conditions. Failure of such crossings is caused by crack initiation and development processes, as well as by metal pitting on the tread surface. One of the effective methods to increase the life of crossings is to harden their tread surface with blast wave energy.

Materials and methods. The metal microstructure of the prototype crossings was investigated using metallographic equipment based on Zeiss Axiovert 25 microscope with Thixomet Pro software. Chemical etching of the surface of the samples used a reagent of 4% nitric acid solution in distilled water. Hardness of the hardened layer was determined by the Brinell method as per GOST 9012–59 on a TSh-2M hardness tester.

Results. The author found that DS.30G.2 defects (Classifier of Defects and Damages of Turnout Elements) could be caused not only by oxide spots and cast seams in the metal but also by insufficient strength characteristics of the crossing structure, which should be eliminated when putting the product into production; increased dynamic loads not foreseen for the respective product. Microcracks formed in further operation in the overmoulded metal layer at the tread surface (without removing the defective layer) result in metal delamination and pitting. Thus, the turning of crossings should include the removal of the entire defective layer in addition to the removal of the swells. The research has shown that the most effective technology is explosive hardening of the crossing tread surface.

Discussion and conclusion. The results show that crossing life could be improved by pre-hardening of the tread surface.

Introduction. The research is intended to assess the line capacity of the Severomuisky Section of the Baikal-Amur Mainline (BAM). The selected section is typical for the BAM and consists mainly of single-track sections. One of the stations is a sectional station (where the type of locomotive traction is changed), the section has tracks through a mountain pass and a tunnel, which enables several train traffic routes. Separate stations generally perform uniform operations, such as stop and non-stop make way, technical inspection, change of crews, as well as make way on sections. At the same time, their duration is affected by random external influences, such as weather, breakdowns, and human factor.

Materials and methods. The authors use methods of mathematical and computer modelling and apply the mass service theory to build a mathematical model of traffic working along the section. It studies objects where uniform operations are regularly performed and their duration is not deterministic. Such objects include railway systems. Simulation modelling was used to analyze the resulting models.

Results. The researchers built a mathematical model of train traffic along the Severomuisky section in the form of a mass service network with two request inflows. It is used to conduct a number of computational experiments. Their results identified bottlenecks in the section infrastructure and assessed the effectiveness of the partial batch train time-table on the section.

Discussion and conclusion. The authors found that the Severomuisky Section now has a line capacity reserve, and its train traffic may be increased from the current 23 to 27 pairs of trains per day. The studies show that partial batch timetable reduces train delays on the section but requires upgrades to some stations and does not allow for an increase in train traffic above the designated level. Thus, it is concluded that partial batch time-table on this section is inexpedient, and a significant (by times) increase in its line and traffic-carrying capacity requires the creation of a double-track service.