Stability of Freight Cars Under the Action of Compressive Longitudinal Forces

Abstract

Purpose. The aim of the work is: a theoretical study of the car movement stability when exposed to longitudinal forces of a quasistatic nature; determination of analytical for estimating the longitudinal loading of cars in trains; the influence analysis of simultaneous action of certain factors on the value of longitudinal forces, at which the car movement stability is still preserved. Methodology. Assessment of the freight car stability when moving at different speeds along curved track sections was investigated using the analytical method. The most unfavorable schemes for applying compressive longitudinal forces in a vertical and horizontal plane are considered. Findings. Expressions are obtained for calculating the value of the car lift resistance coefficient by the longitudinal compressive force acting on the car as part of a freight train. The calculations were carried out in an empty and loaded state with a transverse run-up of the car body frame relative to the track axis in a guiding section of 50 mm in a curve of small radius taking into account the inertia forces from the unbalanced acceleration. Originality. In a theoretical study, the effect on the movement stability of quasistatic longitudinal compressive forces depending on the change in speed and the force value, as well as the effect of friction forces at the contact point of the wheel flange and rail and the eccentricity of fastening the tail of the automatic coupler, are considered. The influence of longitudinal compressive forces on the stability of freight rolling stock when moving in a curve of small radius with speeds up to a design value of 120 km/h is investigated. Practical value. The application of the results obtained by the above method will help to increase the stability of the freight rolling stock, which in turn will allow increasing the technical speed of train movement by removing some existing limits of permissible speeds. Using the described methodology for determining the car lift resistance coefficient will allow justifying the cause of wheel derailment, as well as to develop and put into practice the technical measures to prevent the lift of carriages, thrusts and shears of the track.

Dynamic indicators influencing design solution for modernization of the freight rolling stock

“…Moving along the curve, a wagon under the action of longitudinal forces in auto-couplings may take different positions relative to the track axis, which greatly affects the values of lateral horizontal forces of interaction and the force of friction of wheels and the rails. In the mode of braking, the compressive forces can contribute to the herringbone positioning of wagon s in the track, which leads to an increase in the angles of wheel climbing on the rails [20,21].…”

“…It is known that increasing train mass is one of the most effective ways to increase rail traffic. Therefore, sufficient strength of automatic couplers is required, corresponding to the large longitudinal forces that develop in trains of large mass [19][20][21]. In work [22], the body of the automatic coupler was calculated for the strength under the action of both tensile and compressive quasi-static and shock loads (Fig.…”

“…2), the nature of the interaction changes significantly. For a more accurate determination of the dynamic loading and stability of the rolling stock, when determining the components of the longitudinal forces, it is necessary to take into account the action of neighboring wagons on each other [20,21].…”

Investigation of Coupling Strength at Non-Central Interaction of Railcars

“…The magnitude of forces, which are transmitted to the frame and other parts of the car by the shock-traction devices, depends on the effectiveness of the absorption devices and misalignment of the axles of the couplers of the neighboring cars. The correct positioning of the coupling device on the car frame is of great importance (prevention of the damping device misalignment and ensuring the central loading of the ridge beam) [14][15][16][17].…”

“…In works [18,22], the coupler body was calculated for the strength under the action on it of both tensile and compressive quasi-static and impact loads. The calculation scheme envisages the action of longitudinal forces on the stops at both ends of the car in the presence of a 100 mm difference in the height of coupling devices of interacting cars [14,15,17].…”