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The stability and smoothness of rolling stock running could be defined accurately by universal Sperling's comfort index. The divergences of variation of Sperling's comfort index of a passenger car under specific operating conditions of running gear are examining in this paper. Numerical simulations of a passenger car running with independently rotating wheels under various conditions have been performing. Gained results showed that divergences of the Sperling's comfort index variation are particularly significant due to running gear component oscillations in the horizontal plane (lateral direction). A field experiment of a passenger car with a solid (traditional) wheelset with a flat running surface proved this hypothesis. The obtained results of this experiment confirmed this assumption. Therefore, the study of the regularities of lateral oscillations of a passenger car is the logical direction of further research.

An improved method for spectral analysis of traction current of an Alternating Current (AC) electric locomotive is considered in the article. A new method of spectral analysis considers the change in voltage in the catenary system as a non-deterministic, non-ergodic and non-Gaussian process. It has been established that higher voltage harmonics in the catenary system have a significant negative effect on the operation of non-traction railway consumers of electricity. In addition, electric locomotives operating in the same feeder zone have a mutual influence on each other. Electric railway transport is a source of higher voltage harmonics and strongly distorts the shape of the sinusoidal voltage of the catenary system, which are caused by the higher spectral components of the current in the electric locomotive traction drive circuit. These spectral components of the traction current arise in the traction drive circuit due to the nonlinearity of the current-voltage characteristics of the electronic devices of an electric locomotive, for example, a contact rectifier, a capacitor circuit of traction motors. Reactive power compensators are used in electric locomotives to eliminate components of higher harmonic traction current in the catenary system. Traditionally, spectral analysis in such systems is performed using Fourier methods. However, the determination of the spectral components of the traction current by the Fourier method for constructing a control system for a reactive power compensator is possible only if the process of voltage variation is a deterministic or ergodic Gaussian process. Otherwise, the application of Fourier transform methods will be incorrect. An analysis of the factors that affect voltage changes in the catenary system showed that this process is significantly different from the ergodic Gaussian process. Such factors include the following: the operating mode of the electric locomotives; number and total capacity of electric locomotives in one feeder zone; electric locomotives passing through feeder zones; instability of collection current. Thus, in the case under consideration, the application of the Fourier methods is incorrect for the analysis of the spectral components of the traction current. This affects the quality of compensation of the higher harmonic components of the traction current, and in some cases, the unstable operation of the control system of the active part of the reactive power compensator. Proposed scientific approach is based on the Levinson–Durbin linear prediction algorithm. On the one hand, this allows adapting the control system of the compensator to the voltage parameters of the catenary system. On the other hand, this allows taking into account the operating modes of electric rail vehicle with reactive power compensation. The construction of a compensator control system using the Levinson–Durbin algorithm significantly simplifies thensynchronization scheme of the compensator and power circuits of the traction electric drive of AC electric locomotive. A comparison of the traditional method of spectral analysis, based on the Fast Fourier Transform (FFT), and the method, based on the Levinson–Durbin algorithm, proposed by the authors, showed the high efficiency of the latter. First published online 21 January 2021

The article observes problems of detection of rolling bearing damages in rail vehicles. Two methods of bearing damage detection are examined – according to heating of axleboxes and by vibro-diagnostic manner. The disadvantage of vibro-diagnostic method is that a contact vibration sensor is used for vibration diagnostics, intervention into rail vehicle structure is required. The method according to heating of axle-boxes also has drawbacks. The same temperature value of axle-box in various conditions may characterize different bearing technical state. The Authors studied a possibility to use temperature change intensity parameters as the diagnostics criteria. Based on the examples of axle-box temperature measurement data, Authors developed and proposed a methodology for detecting axle-box bearings defects. The Authors suggest the use the method according to heating of axle-boxes. The given example proofs that the fact of the presence of their damages can be unambiguously identified by the intensity of temperature change of the axle-boxes.

The article describes a method of increasing the adhesion of the wheel to the rail based on the preliminary electrification of the abrasive-air mixture before its feed into a contact. A simulation model of the movement of sand in the system “injecting nozzle of a sandbox - a rail” is presented. The effectiveness of the proposed method to improve adhesion is confirmed experimentally. The results of experiments carried out on a friction machine, which characterize the change in friction ratio depending on the temperature with different methods of sand supply, are presented. The reduction in the consumption of sand caused by its electrification and the supply of a rational amount of abrasive substance into the contact of the wheel with the rail is estimated.

This article deals with computer analyses of output quantities of a railway vehicle depending on changing of parameters of suspension system. A passenger car was chosen for dynamic analyses. An analysed passenger railway vehicle uses two stage suspension system composed of coil springs and hydraulic dampers. Stiffness of coil springs of primary and secondary suspensions were defined for two states and its influence on output values in terms of quality and quantity was evaluated. As output variables, values of forces in a wheel/rail contact and accelerations in several locations on a wagon body floor were chosen. Values of forces in a wheel/rail contact indicate dynamic response of a railway vehicle running in terms of running safety and values of accelerations serve as important input for evaluation of passenger ride comfort.

The article deals with the design and use of the underground metro door, taking into account the operational and normative requirements for the underground metro’s outer door. The dimensions of door gained from its previous design will serve as input data for performing technical calculations which will be used to determine the load conditions for the numerical simulation. The aim is using this preparation to obtain all the necessary data entering the analytical calculations for the parametric model creation. This will be able to be used for other door systems of a similar design thanks to the use of variables. The designed door system will meet all imposed requirements on safety, reliability and comfort.

Harvesting of mechanical vibration energy recently is a popular idea, but its implementation is still limited due to real size of harvesters and efficiency of the systems. Here provided an idea and realization of smart shock absorber with smart liquid, able to generate electric energy from vehicle suspension excitation and thus damping vehicle vibrations. Linear types of electric generators are not very efficient due to limited stroke, therefore their efficiency of energy transformation is far from ideal. This paper provides experimental research of energy harvesting efficiency using smart liquid core, magnetic core and ferromagnetic core of shock absorber. Comparison of these materials in the shock absorber provides clear ability to use smart liquid as ferromagnetic core in the process of power generating. Such device proves possibility to be implemented in the vehicle suspension and allows power-damping control as well as data transmission energy request. Generated power and its dependency from excitation frequency provided in the result graphs.

A scientific method for estimating the effect of dynamic loads arising at the wheel and rail contacts during locomotive movement is proposed, which most accurately describes the behaviour of a real rolling stock and complies with existing standards on the criteria of vertical and horizontal dynamics, as well as indicators of the movement stability. The dependences allowing illustrating the influence of the coefficient of vertical dynamics and relative horizontal slip on the tractive qualities of a locomotive are obtained.

Research of mathematical model of movement of six-axial locomotive with controllable wheelsets installation. Based on the general system of nonlinear variable coefficient differential equations of the vehicle movement in a rail track with inequalities in plan, the mathematical model of movement dynamics of locomotive of improved design with the axial formula 30-30 as an object of automatic control of the wheelsets position in the rail track is considered. Movement simulation is performed on the example of a six-axle locomotive at the speeds of movement and parameters of the curvilinear track sections, which coincide with the conditions of the experiment presented in the thesis work of V. N. Yazykov. The article presents research results of the mathematical model of movement of the improved locomotive bogie with controllable wheelsets installation in the curvilinear track sections using the Matlab/Simulink software package. The results of experimental studies of the All-Russian Scientific-Research and Design Technological Institute of Rolling Stock and the performed theoretical studies show that the efficiency of the improved system for controlling the wheelset position is higher than that of the serial design, in all modes of movement. The improved system of automatic control of wheelsets position makes it possible to reduce guiding forces by 35%. The possibility of using the mathematical model of locomotive movement of the axial formula 30-30 of improved bogie design with axle-box links of adjustable length, taking into account the dynamics of the automatic control system of the wheelsets installation in the rail track, is theoretically substantiated. The theoretical research found out the reduction of lateral forces in the improved bogie design during the passage of curvilinear track sections. The use of the explored mathematical model of locomotive movement reduces the volume and complexity of research works, as well as increases the reliability of engineering calculations when designing new and improving existing designs of the locomotive underframe.

The paper contains main structural disadvantages of 18-100 bogies, namely large unsprung mass, instability of characteristics, low critical velocity, intense wear and others. The experience of domestic and foreign developments, devoted to improving the dynamics and energy efficiency indicators of freight wagon undercarriage, indicates the need for fundamentally new structures or deep modernization of existing bogies. To study the dynamics of freight wagon, the dynamic model in the licensed software complex “UM 6.0” was improved. As the first stage of verification of the model, a simple model of vertical vibration of a wagon with one degree of freedom was calculated. As the second stage of the verification of the computer model of the wagon dynamics, the data of measurements of accelerations of the elements of the wagon during the running dynamic tests performed in an empty and loaded state are used. According to the results of the simulation, the values of the dynamic coefficients of the spring-suspended and unsprung elements of the bogie are obtained. Technical solution and concept of new bogie are developed.

Maintenance and repair specialists of rolling stock face the problem related to accurate and reliable assessment of the vibrations of the car body of passenger rail vehicle, caused by wheel damage, and its impact on passengers. Another important aspect is to deter-mine the permissible speed at which the passenger car with wheel damage could move to the nearest station or depot without badly damaging the rails. The purpose of this research is to examine the dynamic processes of the interaction of the passenger car chassis with the railway track using a newly developed mathematical models called the “Passenger Car - Track” system. During the simulation, the dynamic characteristics of the track, bogies and car body in different season temperature were estimated. The validation of theoretical results was obtained based on the field tests of the test train as well as the results of measurements of changes in track stiffness temperatures. Finally, conclusions and suggestions are presented.

The railway transport network is currently in a quite big expansion. Therefore, railway tracks are modernized and the attention is given also on the technical state of rail vehicles, which operate on them. However, it may happen that the wheel surface is damaged. One of the most common reasons of wheel damage is too much braking, which results to the wheel-flat formation. This article is focused on the evaluation of the influence of a rail vehicle running on the railway track, which a wheel is damaged by the wheel-flat. Investigation of these negative effects was performed by means of simulation computations. As evaluating parameters, values of the wheel force in the contact of the rail and wheel with a flat where observed.

In thisarticle,we compare the dynamic characteristics of cars with integral wheelsets and wheelsets with independently rotating wheels.We use Sperling’s comfort indexto assess the riding comfort. We compare the riding comfort of passenger cars with integral wheelsets and wheelsets with independently rotating wheels based onSperling’s comfort index.

Issues of the significance of Rail Baltica and its distribution for respective countries have been sufficiently investigated in literature sources. Some of literature references on this topic have been overviewed in this article. The article provides the methodology developed by the author used to assess the significance of extension of the passenger railway route in one or another direction. To this effect, the author suggests using a geometric mean method as a basis. The methodology was realized on the example of Rail Baltica line by investigating the significance of extension of the passenger railway route from Warsaw in the West and South directions.

The publication reflects the research results of the rationalization of the rolling stock use of JSC LG Lithuanian railways to increase the reliability indicators of the freight diesel locomotive exploitation reliability. The comparative evaluation of the exploited freight diesel locomotive work duration, according to the technical documentation, by using comparative test results and indirect diesel reliability criteria approved in practice. An algorithm of work duration forecasting methodology has been created, as well as a programme complex of mathematic modelling. The differences of the results indicated in the experiment and modelled by computer do not exceed 5 ÷ 7%. The proposed and described methodology of the diesel locomotive exploitation load cycle dynamic indicator reduction, by the use of which the following is achieved: increase of the diesel work duration by 7÷10%, reduction of fuel consumption up to 10%, reduction of the load cycle dynamic indicators (increasing the fatigue stress of parts and units of the diesel) by 15÷20%.

The traffic flow problem is spread analyzed by many authors like Liu et al., Nagatani and Kaur et al. This paper investigates the traffic flow problem that occurs due to the incorrect traffic lights control. Traffic lights should be match with the traffic flow and must to optimize it. The rational traffic lights period is set by the analysis of the situation on city’s street. A discrete model of traffic flow is used to obtain the results of traffic flow simulation. The results of modelling allow to analyze the dynamics of transport flows in the context of analyzed road and due to the studied boundary conditions. In this article the discrete model of traffic flow is complemented by new parameters (coefficients), which allows to fit the modelling results with real conditions of traffic flows. Authors argued that the last point of all traffic flows is the main aspect of the investigation of the effect of the changed concentration on the modelling street. Also an amplitude spectrum of traffic flow parameters has been created. This amplitude spectrum helps to determine the frequencies of the road network. DOI: http://dx.doi.org/10.5755/j01.mech.24.6.22477

The level of technical development and the diversification of energy sector of Lithuanian Railways, the scale of using of renewable energy sources have been defined in this article. The necessity and expediency of implementation of solar and wind hybrid power-plant in railway infrastructure objects have been reasoned. The methodology for calculation of rational proportion between solar and wind hybrid power-plant potential and electric energy demand, which notable varies during the year, have been proposed by authors. Based on suggested formula have been demonstrated that the wind potential part of solar and wind hybrid power-plant of Lithuanian rolling-stock depots and stations should be about 75%, and the solar – 25%. The procedure applied by authors for determination of proportions of hybrid plant shared power is universal. Finally, basic conclusions and recommendations are given.

The article overviews scientific research studies that examine the interaction between railway vehicle wheel and rail, and the phenomena of wear on wheel rolling surface. Unique experimental research has been conducted, in which regularity of weariness on rolling surface of exploitable locomotive wheel and phenomena of metal fatigue on wheel were researched. A hypothesis is made, that according to the differences in weariness intensity of wheel rolling surface it is possible to determine the start of metal fatigue. The inequality of wear intensity of different locomotive wheels is assessed by the Sharpe ratio, adapting it to describe the wheel wear intensity criteria. Based on the results of research, the authors propose a simplified and reliable methodology for determining metal fatigue on locomotive wheels at initial stages. The uneven wear on rolling surface of different wheels of wheelset inevitably changes the values of Sharpe ratio, which can accurately describe the conditions in which the critical metal fatigue on wheels begins to emerge.

In most cases, dynamic characteristics determine the wagon maintenance cycle, traffic safety, reliability and durability performance. The main dynamic indicators include the vertical Kvd and horizontal Khd dynamic coefficients as well as the stability coefficient Ks, which determines the wheel flange resistance to derailment. The article compares dynamic indications for three different types of bogies. There were no tangible differences observed for all the three different types of bogies running at a speed of 40 to 120km/h on a direct tangent rail section. Nevertheless, there is a realistic potential to improve the dynamic indicators of a freight wagon by rationalising suspension unit parameters. First Published Online:27 Mar 2015

Graphical representation of laws governing the abrasion of locomotive wheelsets shows different distribution of values obtained for oiled and not oiled wheelset tyres. When wheelset tyres are oiled, the much higher deviation of abrasion values can be observed. This allows us to assume that oiling is more important for reducing the wear of not heavily loaded wheelset tyres.

While railway companies operate rolling-stock, a substantial part of its expenses goes to maintenance and repair. However, the amount of repair works is directly proportional to the average age of a rolling-stock fleet or its reliability. When renewal an existing fleet of a few dozen rolling-stocks, the installation of the new vehicles reduces the overall failure amount of the fleet proportionally to the number of acquired vehicles. This article provides a concept for creating the model of a passenger rollingstock's failure intensity according to the mileage. According to this model, a vehicle fleet renewal algorithm can be created and used in order to limit the fluctuation of the fleet's average failure intensity as much as possible and to achieve the most accurate correlation between the number of failures and the fleet's average mileage. Thus a railway company has an opportunity to avoid the unplanned expenses for repairing the vehicles during the unforeseen failure peaks. The SPLINE method is proposed in order to indicate the vehicle failure flow's dependency on the vehicle mileage. After using this method to indicate the variation of the fleet's constant interfailure according to the mileage, the fleet's failure intensity can be modelled according to the algorithm of installing the acquired vehicles for operation.

Metodiniame leidinyje „Lokomotyvai ir vagonai – 2“ nagrinėjama prekinių ir keleivinių vagonų paskirtis, jų konstrukcijos, apžvelgiami šių vagonų techniniai ir ekonominiai rodikliai. Taip pat supažindinama su dyzelinių traukinių, automotrisių, drezinų bei elektrovežių kai kuriais konstrukciniais ypatumais. Aprašyti pagrindiniai vagonų elementai. Pateikti kai kurie jų techniniai skaičiavimai. Leidinys skirtas VGTU Transporto inžinerijos bakalauro studijų programos Geležinkelių transporto inžinerijos specializacijos studen-tams kaip papildoma literatūra riedmenų konstrukcijoms nagrinėti, studijuoti modulius „Lokomotyvai ir vagonai – 2“ bei „Vagonai“.

After JSC ‘Lithuanian Railways’ (AB ‘Lietuvos geležinkeliai‘) bought new Siemens ER20 CF locomotives produced in Western Europe and brought them into service, some of them have already done about 170–200 thousand km that caused the appearance of indentations of an inadmissible size (the depth is more than 3 mm, the length – 10 mm) the elimination of which turning cutting results in up to 20 mm loss of a wheel. Having grounded off the metal layer of indentation depth, indentation reappears (metal ‘flakes off') and needs to be removed by returning cutting the wheel. The purpose of the current investigation is to determine whether there is a reason to claim that the cause of wheel surface crumbling could be a chemical composition of the wheel or wheel‐to‐rail hardness ratio. The carried out investigations have revealed that there is no reason to claim that the cause of wheel surface crumbling could be the chemical composition of the wheel or wheel‐to‐rail hardness ratio. First published online: 10 Feb 2011