摘要: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 ”.