Testing of the condition and performance of coupling links from screw couplings of train.

• Investigation focuses on coupling link inspection, integral safety components to train screw coupling systems. • Plastic deformation increase, during operational use, did not affect yield stress or ultimate tensile strength. • Fractured links showed ductile fractures with distinctive surface structures. • 83 % of links, tested after 30 years in operation, exceeded the minimum breaking force. • Train brake analysis suggests a decrease in link failures due to other component issues. This paper presents an analysis of train screw coupling used mainly in Europe as mechanical connection of wagons in train. An analysis of train breaks apart incidents revealed that less than 30 % of the cases were caused by elements of the screw coupling, with coupling links accounting for only 5 % of the failures. Therefore, the investigation focused on testing the coupling links, which are safety elements of the screw coupling. The coupling links underwent various inspections, including visual inspection, dimensional control, non-destructive testing, examination of chemical composition, and mechanical tests. Dimensional control found longitudinal plastic deformations of the links. Chemical examination revealed that the links were made of different material than recommended, but their mechanical properties generally met the recommended values. However, variations were observed among different links, likely due to different rates of deformation during testing and operational conditions. Overall, the analysis and inspections provided insights into the condition and performance of coupling links in the screw coupling system, highlighting the importance of monitoring and maintaining these elements to ensure safe and efficient railway operations. [ABSTRACT FROM AUTHOR]