@conference{
author = "Tanasković, Jovan and Stojanović, Jagoš and Vukšić Popović, Marija and Rusov, Srđan",
year = "2024",
abstract = "The passenger diesel-hydraulic train series DMU 711 is one of the newer trains in Serbia, owned by “Srbija voz”. The train consists of two coaches. Each coach is equipped with one driving bogie powered by a diesel engine coupled with a hydraulic transmission and one free bogie. Diesel engines, hydraulic transmissions, cooling and heating systems, and many other pieces of equipment and devices were placed in one assembly - a power pack. During operation, the owner noticed that the train was often out of service because of failures in the power pack. The main reason for the failure of the power pack is overheating. Radiators, as a part of the cooling and heating system, were placed along one side of the power packs. During the inspection, it was observed that the radiators are heavily contaminated with vegetation, dust, and debris picked up during operation. The maximum designed speed of the train is 120 kilometres per hour, but most often running speed is significantly lower. The owner informed the producer that DMU has had problems with overheating from the start of service. Analysis of the train behaviour in different weather conditions and seasons, over the years, gave a clearer image of the overheating problem. The most common problem caused is the low running speed in combination with dust, grass, and other dirt that trains collect in the cooling radiators. This leads to radiator clogging, decreasing cooling capacity, and therefore overheating. When the operating temperature of the diesel motor exceeds the limit value, the safety system of the power pack is activated, causing it to shut down. Next to the mentioned problem, one more is directed to the common cooling-heating system for the power pack and passenger area, which is obvious under-dimension, especially for the summer days. Considering the reasons for the power pack frequently malfunctioning, one of the solutions for resolving the problem is the separation of a cooling-heating system for the power pack and passenger area. Additionally, analyses showed that displacement of the cooling system on the roof is an even better solution, to exclude dirt impact and improve airflow and cooling. Both solutions can be implemented during regular repair or modernization of DMU. Additional analyses will be conducted after the owner provides source documentation from the producer. Finally, the possibility of replacing the power pack with one of the improved generations installed in the newer DMU 711 should be explored for efficiency, although it may not necessarily be the most cost-effective solution.",
journal = "International Conference of Experimental and Numerical Investigations and New Technologies, The book of Abstract, 24.06. – 27.06.2024. Belgrade",
title = "Analysis of failures of power pack of diesel hydraulic multiple unit series 711",
pages = "9",
url = "https://hdl.handle.net/21.15107/rcub_machinery_7866"
}