ANALYSIS OF EMERGENCY FAILURES IN THE UNDERCARRIAGE ANDPOWER TRANSMISSION OF TRAM MOTOR CARS IN THE CITY OF SOFIA

Emil Mihaylov Mihaylov

Scientific paper ID 2734 : 2025/3

ANALYSIS OF EMERGENCY FAILURES IN THE UNDERCARRIAGE ANDPOWER TRANSMISSION OF TRAM MOTOR CARS IN THE CITY OF SOFIA

Emil Mihaylov Mihaylov

The material concerns emergency failures in the undercarriage and power transmission of the tractors and cases of derailment in the tram system of the city of Sofia in 2023 and 2024. This analysis is part of a larger study of the operational parameters of the system. The data used for the two years, subject to the study, were taken from the ”Bulletin of Accidents”, kept in the ”Emergency Service” - a unit for emergency technical assistance and elimination of emergency situations of ”Stolichne Elektrotransport” EAD - Sofia. In addition to the number of emergency failures in the running gear and power transmission, the number of cases of derailment and entry of a tram car into two tracks were added. These emergency failures and emergencies represent about 10% of the total number of emergency failures in the tram system of Sofia. An analysis was made using the Pareto method of emergency failures in the running gear and power transmission of the tram rolling stock according to various criteria. The failures are grouped according to the following features: derailment and entry of the tram car into two tracks, damage to the running gear, noise, vibrations from the bogies, overheating of the nodes, damage to the wheel reducers, damage to the cardan shafts, mechanical damage to traction motors and problems with tram track elements. Dependencies in failures according to the studied criteria and their influence on the overall picture of failures have been established. The data show that cases of tram railcar derailments, damage to running gear elements and cardan shafts have the largest share in emergency failures and emergency situations.

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трамвайни мотриси аварийни откази ходова част силово предаванеtram railcars emergency failures running gear power transmission.Emil Mihaylov Mihaylov

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