Purpose. To determine the basic dynamic characteristics of a standard Ukrainian boxcar with the Y25 bogie by means of the mathematic modelling of dynamic loads in the vertical plane and to compare them with the dynamic characteristics obtained for a boxcar with the 18100 bogie. It can be used for substantiation of application of the Y25 bogie as more promising, which can improve the operational efficiency of rail transportation and foster integration of the Ukrainian transport system into the European transportation complex. Methodology. The authors used the mathematical modelling of a boxcar with the Y25 bogie. The research was made in the vertical plane. It was taken into account that an empty car passed over a joint irregularity. The research was made for an 11217boxcar as a predominant type to be used. The authors studied the motion of a car on the 18100 and Y25 bogies. The basic dynamic characteristics were determined for a boxcar with the nominal (design) dimensions of the carrying elements and a boxcar with the actual dimensions (after a long service life) on the basis of the field tests. The differential equations were solved by theRungeKutta method in MathCad software suite. The initial displacements and the speeds were taken equal to zero. The following dynamic characteristics of a boxcar were obtained: acceleration of the body in the center of mass, acceleration of the body in the areas of support on the bogies, forces in the spring suspension of the bogie, and dynamic coefficients of the bogies. Findings. The theoretical research showed that the basic dynamic characteristics of a boxcar with the nominal dimensions were improved by 3851% in comparison to a similar one with the 18100 bogie, and for a boxcar with the actual dimensions the dynamic characteristics were improved by 4350%. Originality. The authors substantiated the application of the Y25 bogie for a standard Ukrainian boxcar with the nominal and actual dimensions of the carrying elements by means of the mathematical modelling of the dynamic loads in the vertical plane. Practical value. Due to lower dynamic loads on the carrying structures of freight cars with the Y25 bogie, it is possible to improve the dynamic characteristics of the structures under the operational modes, to increase the fatigue strength and the operational resource, to decrease the total repair and maintenance costs, to ensure better security and reliability of freight transportation through lower loads on both carrying structures and lashing devices, to increase the speed of freight delivery thanks to better dynamic characteristics of cars, to improve the traffic security, and so on.
Mathematical modelling of the interrelated electric and mechanical systems of continuous sub-group of the rolling mill stands. Part 2. Study of dynamic loads in the universal mill stands