Kuzyshyn A. The methods improvement for determining the main dynamic parameters of motor-vehicle rolling stock at the design stage

Due to the introduction of modern rolling stock in Ukraine, the speed of passenger trains on the railways of Ukraine increases considerably. At the same time, scientific studies of the stability of rolling stock during its movement, both on the straight and on the curvilinear sections of railway track become important. The study of the interaction of track and rolling stock in the course of operation will allow to establish the main dynamic parameters in order to improve safety traffic. In the work, special attention is paid to determining frame and guiding forces while rolling stock movement on rail track with tolerance deviation from the maintenance rules. According to the values of these forces, the most important dynamic parameters of rolling stock are determined, such as the coefficients of vertical and horizontal dynamics in the axlebox and central spring suspensions, the coefficient of stability against wheel derailment. As a result, the admissible speeds of rolling stock are determined, depending on the technical condition of rail track, with the purpose of ensuring safety traffic. Scientific novelty of the obtained results: - for the first time, with the use of the developed spatial mathematical model of a car of diesel train DPKr-2, the guiding force values have been determined that allow to estimate the force influence of rolling stock on railway track at the design stage; - for the first time, the comparison of dynamic parameters of diesel-train DPKr-2 has been conducted according to the requirements of normative documents, which are valid in Ukraine and the European Union countries. The comparison is carried out with the aim of harmonizing these normative documents; - the spatial analysis scheme and the mathematical model for the calculation of DPKr-2 diesel train car oscillation have been developed with the consideration of its design features, which allows to determine its main dynamic parameters and their dependence on the speed of train car movement and railway track condition; - the method of determining the guiding force is improved by simultaneous consideration of transverse forces of the creep, as well as the inclination angle of the guiding force to the vertical axis, which allows to approximate the mathematical model of the diesel train to real conditions of loading. The practical significance of the developed methodology lies in the possibility of its use in forensic railway-transport expertise in conducting expert investigations. A mathematical model of oscillations of the car of diesel-train has been developed which makes it quite easy to build a train accident mechanism in cases of rolling stock derailment from a track. Taking into account the design features of the diesel-train car DPKr-2 in the developed mathematical model also allows to determine the main dynamic indicators of traffic safety and the maximum allowable speeds at the design stage. The resulting technique has been introduced into the practice of conducting forensic railway-transport expertise of the Lviv Scientific Research Institute of Forensic Science of the Ministry of Justice of Ukraine (from 20.03.2019), while repairing and modernizing rolling stock of the Lviv Locomotive Repair Plant (from 12.03.2019), determining, at the design stage, the optimal parameters for suspending new types of rolling stock of the Kryukiv Railway Car Building Works (from 21.03.2019).