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The effect of the tailwind on the wagon when it is rolling down from the hump. Study of the movement of the wagon on the profile of the marshalling hump. To provide an incorrect formula for determining the relative velocity and air particles, taken as the absolute velocity of the particles. The article applies the theorem on the addition of velocities in complex motion in vector form. Mathematical substantiated errors in the determination of the specific resistance to movement of the wagon from the air medium and wind, derived from the empirical relationships given the aerodynamic performance of the wagons. The results of the research can be used in the processing of the normative-technical document on the design of hump devices on railways and making adjustments to the dynamics of rolling the wagon in textbooks for universities of railway transport. The results of this study prove the need to revise the practical significance of the formula for finding the specific resistance to the movement of the car from the air and wind in the in the normative-technical document “Rules and regulations for the design of sorting devices on the railways track gauge 1 520 mm ”.

The height of the high-speed section of the sorting slide. Design of high-speed section of the marshalling hump. To prove mathematically the absence of theoretical basis of the formula by which the height of the first profile section of the marshalling hump is calculated in current method of calculation of marshalling humps. The paper uses the theorem on the change of kinetic energy for a non-free material point in the final form, known from theoretical mechanics. The results of the research revealed that the formulas by which the height of the first profile section of the marshalling hump is calculated contradict the theorem on the change of kinetic energy for a non-free material point in the final form. The results of the research can be used in the processing of the normative-technical document on the design of hump devices on railways and making adjustments to the dynamics of rolling the car in textbooks for universities of railway transport. The results of the calculations proved the incorrectness of the derivation of the formula for calculating the height of the first profile section of the marshalling hump in the normative-technical document “Rules and standards for the design of sorting devices on the railways with gauge 1 520 mm”.

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The purpose of this paper is to calculate kinematic parameters of a railway car moving with a tailwind for designing a classification hump. The calculation of kinematic parameters is based on the d'Alembert principle, and the physical speed and distance formula for uniformly accelerated or uniformly decelerated motions of a body. By determining a difference between two components - gravitational force of a car and the resistance force of all kinds (frictional resistance, air and wind resistance, resistance from switches and curves, snow and frost resistance), which take place at different sections of a hump profile, the authors calculated the car acceleration at various types of car resistance, as well as time and speed of its movement. Acceleration, time and speed were plotted as a function of the length of a hump profile section. The research results suggest that permissible impact velocities of cars can be achieved by changing profiles of projected hump sections or by using additional hump retarders.