Problems and Prospects of Improving the Design and Testing Methods of Three-Axle Trolleys for Freight Cars with Increased Axial Loads (Based on Industrial Transport)

Objective: to analyze the evolution of three-axle freight car bogie designs, summarize the experience of their operation in industrial transport, and critically evaluate the current regulatory framework to substantiate areas for improving testing methods for increased axle loads (up to 30 tf or more). Methods: methods of system analysis of scientific and technical literature and patent information, generalization of operational data, analytical modeling of bogie element loading, and a comparative analysis of regulatory requirements were used. Results: it was revealed that the main fleet of three-axle bogies is operated on industrial transport tracks under conditions significantly different from main roads (heavy profile (long slopes, small-radius curves, variable profile), cyclic impact loads during loading and unloading, aggravated by the absence or poor condition of the ballast layer on temporary tracks, which leads to the transfer of unabsorbed dynamic effects to the chassis). It was found that 77.8 % of failures are associated with design imperfections. It is shown that the current system of GOSTs is oriented primarily towards public tracks and does not take into account the specifics of industrial conditions. Analytical relationships are proposed for estimating additional frame forces in small-radius curves and for adjusting equivalent loads during fatigue testing, taking into account actual loading spectra. Specific areas for improving the regulatory framework are identified (introduction of correction factors, mandatory use of wear-resistant center plate components, requirements for test rigs, and development of load spectra). Practical importance: the need to adjust the regulatory framework and certification test methods for three-axle bogies for industrial transport conditions is substantiated. The goals and objectivesof further research aimed at developing scientifically sound calculation and test rig methods are formulated,thereby improving the reliability and safety of heavy-duty rolling stock.