Improving the Reliability of the Pneumatic Elements in a Freight Car Braking System

Purpose: To perform a design justification of improving the braking system reliability (BS) of a freight car including the main air pipe, its mounting points, non-threaded connections, and the air distributor. Particular attention is paid to analyzing failures caused by loss of tightness of the air pipe non-threaded connections and brake equipment holes’ clogging. Methods: Calculation of the air pipe strength at internal pressure considering temperature effects and the corrosion resistance of steels; frequency analysis of the air pipe vibrations in SolidWorks Simulation to determine the optimal number of mounting points; modelling the stress-strain state of sealing rings made of rubber and Constaftor 200 composite material at various temperatures. Results: The strength margin of the main air pipeline to internal pressure (n = 67) has been found to exceed significantly the required minimum (n = 5). This allows reducing the structure mass by decreasing the pipe thickness without compromising reliability. A regression relationship between the natural vibration frequency of the air pipeline and the distance between the mounting points has been developed: f₁ = 215.04 ∙ exp(–0.95 ∙ Δl). To avoid resonance, it is recommended to have at least 5 mounting points at a pipe length of 12 m. It has been shown that replacing rubber seals with Constafor 200 reduces maximum deformation by 300 times (from 0.6 to 0.0022 mm) and improves the tightness of the joints at extreme temperatures (–60°C). Practical significance: Optimization methods such as reducing the pipe thickness, increasing the number of mounting points, and introducing an innovative sealing material have been proposed. The chemical treatment of the pipe inner surface has been recommended to prevent clogging of the brake equipment. The implementation of these methods will enhance the reliability of the freight car braking systems, reduce operating costs, and lower the risk of emergency situations.