several phenomena. Generally, these phenomena are very complex and they can be divided into two main parts. To the first one belongs the electromechanical interaction between of the railway drive system including the: electric motor, gears, the driven part of disc clutch and driving parts of the gear clutch. To the second one belong torsional vibrations of the flexible wheels, and wheelsets caused by variation of adhesion forces in the wheel-rail contact zone. An interaction of the adhesion forces has nonlinear features which are related to the creep value and strongly depends on the wheel-rail zone condition and track geometry (when driving on a curve section of the track). In many modern mechanical systems torsional structural deformability plays an important role. Often the study of railway vehicle dynamics using the rigid multibody methods without torsionally deformable elements are used This approach does not allow to analyse self-excited vibrations which have an important influence on the wheel-rail longitudinal interaction. A dynamic modelling of the electrical drive systems coupled with elements of a driven machine or vehicle is particularly important when the purpose of such modelling is to obtain an information about the transient phenomena of system operation, like a run-up, run-down and loss of adhesion in the wheel-rail zone. The modelling of an electromechanical interaction between the electric driving motor and the machine as well as to an influence of the self-excited torsional vibrations in the drive system. Measuring torsional vibration on physical systems The most common way to measure torsional vibration is the approach of using equidistant pulses over one shaft revolution. Dedicated shaft encoders as well as gear tooth pickup transducers (induction, hall-effect, variable reluctance, etc.) can generate these pulses. The resulting encoder pulse train is converted into either a digital rpm reading or a voltage proportional to the rpm. The use of a dual-beam laser is another technique that is used to measure torsional vibrations. The operation of the dual-beam laser is based on the difference in reflection frequency of two perfectly aligned beams pointing at different points on a shaft. Despite its specific advantages, this method yields a limited frequency range, requires line-of-sight from the part to the laser, and represents multiple lasers in case several measurement points need to be measured in parallel. Torsional vibration software There are many software packages that are capable of solving the torsional vibration system of equations. Torsional vibration specific codes