Failure analysis of rubber-cord couplings of ER2 series electric trains

The article analyses the statistics of rubber-cord coupling failures during 2015 till 2022. The analysis of failures shows that prevailing cases are rupture of the rubber-cord coupling side surface. It should be noted that the cost of eliminating the consequences of a rubber-cord coupling rupture is on average 575.21 EUR for one unscheduled repair. To study the possible reasons of the rubber-cord coupling rupture, the couplings removed from the motor cars after unscheduled repairs were taken. In the process of research, the warming temperature of the rubber-cord coupling, hardness at various temperatures and forces acting on the rubber-cord coupling during operation, i.e. the operational conditions of the rubber-cord coupling were determined. The purpose of these studies is to determine the possible causes of the rubber-cord coupling side surface. The research process of rubber-cord couplings consisted of four stages: 1. Determination of the geometric dimensions of the coupling and comparison of the obtained data with the data of ISO 14691:2008. 2. Theoretical determination (calculations) of: torque, centrifugal force, shear stress and radial load acting on the coupling. 3. Determination of hardness on the Shore A scale depending on the temperature of the rubber-cord coupling in three temperature ranges (t = −20 °C; 0 °C; + 22 °C; + 60 °C) in the RTU laboratory, and comparison of the obtained data with the data of ISO 14691:2008. 4. Drawing the main conclusions about the possible causes of rupture of the rubber-cord coupling. The purpose of these studies is to determine the possible causes of the rubber-cord coupling side surface. The forces and stresses acting in the zones of damage to rubber-cord couplings are determined. According to the results of calculations, the values of the forces Рс; Рс1 and stresses τk caused by the torque Ma acting on the rubber-cord coupling in the destruction zones and the values of forces and stresses capable of causing the destruction of rubber-cord couplings are determined. In the article hardness of the rubber-cord coupling was also studied at various temperature conditions.