Purpose. The railway transport plays an important role in social and economic life of the country and carries out the large containment of transportation activities. The transport industry should migrate towards innovation changes and increase its significance as an important transit subsystem on the way of renovation of both the infrastructure and the strategy of all transportation process components including the interaction with other transport modes. At present the life sets strategic challenges for the railway branch, and the basic goals among them are as follows: high-speed train traffic development, increase of the weight of freight trains, new rolling stock development etc. Due to the urgency of this subject, the researchers should cope with the task devoted to one of aspects of improving the freight transportation efficiency, namely to the study of effects of various factors and characteristics of technical conditions of the freight cars running gears (which are unavoidable to arise during operation) on their basic dynamic indices. The deviations of technical conditions of running gears from the normal state of the wedge system of bogie swing suspension also play an important role among them. The purpose of the paper is to investigate the influence of different factors of the technical conditions of freight car running gears (size deviation in both the bearers and the wedge system during operation) on their basic indices – coefficients of horizontal and vertical dynamics, vehicle body acceleration, frame strength, and derailment stability coefficient. Methodology. The study was conducted by numerical integration and mathematical modeling of the freight car dynamic loading using the software package “Dynamics of Rail Vehicles” (“DYNRAIL”). Findings. As a result of the research for freight car dynamic coefficients determination taking into account technical conditions of the side bearers, the dependencies of the basic freight cars dynamic coefficients on the parameters of side bearers (the clearances in the side bearers and the wedge system conditions of the bogie swing suspension) considering running speed in the tangent and curved track sections of minor and mean radii were obtained. Originality. The impact of the technical condition of the car running gears on the traffic safety factors is determined.Practical value. The theoretical research results in determination of freight car dynamic indices taking into consideration the technical conditions of the side bearers of freight cars allow for an adequate assessment of effect of the freight car bogies’ technical conditions, namely the bearers parameters, on the railway traffic safety factors (coefficients of horizontal and vertical dynamics, vehicle body acceleration, frame strength and derailment stability coefficient).