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The article examines curves controlling asynchronous traction motors increasingly used in locomotive electric drives the main task of which is to create a tractive effort-speed curve of an ideal locomotive Fk = f(v), including a hyperbolic area the curve of which will create conditions showing that energy created by the diesel engine of diesel locomotives (electric locomotives and in case of electric trains, electricity taken from the contact network) over the entire range of locomotive speed is turned into efficient work. Mechanical power on wheel sets is constant Pk = Fkv = const, the power of the diesel engine is fully used over the entire range of locomotive speed. Tractive effort-speed curve Fk(v) shows the dependency of locomotive traction power Fk on movement speed v. The article presents theoretical and practical aspects relevant to creating the structure of locomotive electric drive and selecting optimal control that is especially relevant to creating the structure of locomotive electric drive using ATM (asynchronous traction motor) that gains special popularity in traction rolling stock replacing DC traction motors having low reliability. The frequency modes of asynchronous motor speed regulation are examined. To control ATM, the authors suggest the method of vector control presenting the structural schemes of a locomotive with ATM and control algorithm.

The tests performed by the authors have shown that diesel locomotive engines efficiently operate using a mixture of diesel oil and about 40% of rapeseed oil methyl ester (RME) while their ecological and economical parameters do not differ much from those of the locomotives operating on pure diesel oil. When biodiesel is used, the pollutants released into the atmosphere by an engine are less harmful. Therefore, the respective laws of the Republic of Lithuania provide for some financial incentives and allowances to transport enterprises using biological diesel oil. The paper presents a mathematical model for determining the expenses associated with the use of biological diesel oil.

The article presents a mathematical model for assessing the real operating conditions of railway rolling stock, taking into account the situations when the wheel loses contact with rail. The obtained amplitudinal fluctuation characteristics depend on the set roughness function and the running speed of the wheel. When calculating dynamic processes, the contact between wheel and rail should be considered unstable. With the increase of speed, the impact of this instability increases.

The number of various transport facilities used in Europe is rapidly growing. They release a big amount of pollutants into the atmosphere. Therefore, environment protection from these pollutants ejected by internal combustion engines is a key problem facing us today and which will be acute in the future. Biofuel is the only effective and widely used alternative fuel which can reduce pollution of the environment. The main aim of the present paper is to perform a comparative analysis of burnt gases of engines using rapeseed oil methyl ester and petroleum diesel oil and to determine ecological effectiveness of biofuel used in diesel locomotive engines in railway transport.

One of the major economic criteria is associated with the growth of maintenance costs of old rail vehicles. The research aims to determine the ageing criteria of passenger rolling stock, which could take into account fuel, diesel oil and repair costs. Therefore, economic criteria based on the above costs are generated and their comparative analysis is made. The research object is Vilnius locomotive depot.

The paper considers electrodynamic braking of trains, which is of particular importance for high-speed railway transport from theoretical and technical perspectives. Braking methods used for high-speed trains should ensure compatibility and redundancy of braking systems. They include a mechanical method (based on adding frictional disks to wheelsets), as well as magnetic braking, which is being currently implemented and based on eddy currents, etc. High-speed trains have AC/DC engines, for which the principles of electric braking can be applied. Electrodynamic braking is of particular importance for high-speed transport using linear motors and developing the speed of 400–500 km/h. These traction rolling stocks will not have commonly used trucks. The tests in this area are being conducted in Japan and Germany now. The paper suggests some theoretical and practical solutions to these problems. Schematic diagrams of the locomotive braking and ways of controlling the braking force by varying electric circuit parameters are presented. The authors suggested contact-free regulation of braking rheostat resistor for controlling braking force in rheostatic braking. A schematic diagram of harmonizing electrified railways and power system’s upgrading aimed at ensuring power regeneration is also presented.

The paper considers the variation of circuit design of the electric drives in traction rolling stocks when traditional DC electric machines are replaced with AC electric machines. Simplified circuit diagrams of the electric drives using electric machines of non-commutator type are offered. Operational defects of DC traction engines are weighed against some positive characteristics of direct current series excitation in traction engines, determining their extensive use in the electric drives of traction rolling stocks. However, the rapid development of semiconductor devices, e.g. thyristors and IGBT transistors, led to the creation of a great variety of semiconductor inverters. This made it possible to develop an autonomous three-phase power supply system for diesel locomotives and algorithms for the AC traction motors and to obtain engine characteristics matching the tractive force by using voltage frequency and current inverters. A mathematical justification of the engine torque and tractive force control as well as its particular characteristics is provided. The graphs demonstrating the particular ways of changing the electrical parameters of an asynchronous motor with a squirrel-cage rotor are also presented.

The planning of the optimal rolling stock for passenger carriage should be based on passenger flow forecasts, close examination of the available locomotives and cars and properly chosen methods of their writing off and plans for rolling stock renewal. The strategy of renewing the existing rolling stock for passenger transportation (including plans for writing off, modernization and purchasing of cars and locomotives) is offered by the authors which is based on forecasts of passenger flow variation and expenses.

For assessing the quality of rolling stocks, the research was made into the operational expenses aimed to derive their relation with the time of rolling stock operation which could be used as a basis of the above generalized complex criterion. In this way a dimensionless composite index with the value not exceeding one was obtained for assessing the locomotive performance. If this index is more than one, the rolling stock should be written off as inefficient and obsolete equipment.

The wear dynamics of wheel - set tyres of diesel locomotives was investigated. Basing on research results it is possible to predict wheel-tyre safety margin, to improve maintenance and to state the periodicity of repair, as well as most efficiently to use traction rolling-stock repair funds.

The article deals with the modelling of independently rotating wheels (IRW) systems for wagons. The research work of the intensity of rolling stock wheels rims and flanges is observed. The main performance objectives of IRW are to reduce winding of wheel-sets, to enable railway rolling stocks to achieve higher speeds, to decrease wear of rail and wheel rolling surface, to improve the performance on railway curves and to reduce lateral displacement on rails. IRW with profiled tread are examined and the mathematical model of these IRW is created. Finally, the peculiarities of the stability and wearing characteristics of such IRW systems are presented.

The system of transportation of schoolchildren should also be transformed with the aim of more rational use of resources and vehicles taking children in and out of schools. Rational structure of school network and a system of children transportation will help to save the money allocated on education as well as to ensure various educational services, taking into account social, economic, cultural and demographic changes. The research revealed considerable differences in operational costs of school buses in Lithuania. To account for this spread of values (up to 5 times), a more detailed analysis is needed. Considerable spread of operational costs of buses is questionable because they are in a good (or perfect) technical state. The repay time of the bus depends on the difference between the cost of carrying students by private and public transport covered by local government institutions and the relative expenses of busing a student per one kilometer by buses.

Wearing dynamics of traction rolling-stock wheel tyres of diesel locomotives was investigated. Based on research results it is possible to predict wheel-tyre safety margin, to improve maintenance and state periodicity of repair, as well as to use traction rolling-stock repair funds most efficiently.

Major constituent parts of the railway system are rolling stock and various objects making its infrastructure. Their maintenance is rather expensive, while renovation requires large investments. The researchers all over the world are working hard to make these investments effective. To make a decision in economics its economic effect should be established first. Generally, the latter is expressed as the repay time of investment or the economic effect in the particular period of time specified according to the particular technical requirements. The repay time is usually calculated optimizing the choice of the particular elements (i.e. an engine, gear-box, transmission, etc.) of the train. The optimization of the selection of the trains would require a comparative analysis of economic effects (expressed in monetary units at the particular time interval) of the alternative solutions available. If the target objects of the investments are well - known, the first approach described in the present paper may be used to determine the repay time of investment thus enabling us to check the effectiveness of a potential investment. If an object for the potential investment should be determined, implying that its major characteristics should be described, the second method based on increasing the economic effect may be applied.