Determination of the Metal Structure, Testing of Hardness of the Fastening Bolts of the Rubber-cord Coupling for Traction Gear of Electric Trains of the ER2 Series

In the presented article, we will focus on identifying the causes of the fracture of the M-24 bolts for fastening the rubber-cord coupling of the traction drive of the ER2 series electric multiple unit (EMU) trains. Broken M-24 bolts taken in June and October2020 from motor cars of the ER2 series No. 1342-02 and No. 3034-06 after unscheduled repairs due to the replacement of traction motors was investigated. Also, for comparison, a new M-24 bolt for fastening the rubber-cord coupling was taken. The purpose of writing this article was a large number of unscheduled repairs (failures) of the traction drive due to the fracture of the rubber-cord coupling bolts. The data on the number of unscheduled repairs was taken on the basis of reports (F-T22 template) of the railway company JSC "Pasažieru vilciens", which were summarized for the period from 2015 to 2020. The total number of unscheduled repairs for the breakage of the cord coupling bolts was 158 cases. In connection with a large number of unscheduled repairs, the question arises about the quality of the M-24 bolts for fastening the rubber-cord coupling of the traction drive and the compliance of the bolts with the specification requirements according to GOST 4543-71. Based on the data of the analysis of the metal structure and the results of determining the hardness the article analyses the reasons for the failure of the M-24 bolts of the rubber-cord coupling of traction drives and reveals that the samples do not comply with the specification data according to GOST-4543-71.