Scientific paper ID 1950 : 2020/3

Emil M. Mihaylov, M.Sc.Eng.

This material presents a study of the derailment of trams as a result of successive abrupt jumping or falling of the wheels on one side when driving on a built-in track built with grooved rails. The following cases are considered: Consecutive jumping of the left or right wheels of the bogie due to the presence of a foreign body in the groove of the rail, the dimensions of which are comparable to the size of the groove. Consecutive abrupt failure of the left or right wheels of the bogie when there is a torn rail, the failure of which is comparable to the size of the rail head. Statistics show that these defects on the track do not always cause derailment. At the same time, when derailed, the traces left on the road surface show a special behavior of the bogie during derailment. To establish the reasons, a study of the behavior of the tram bogie was carried out when consecutive jumping of the wheels occurred on one of its sides. With the use of a ”wedge for controlled derailment” a jump of the right wheel has been caused, as a result of which the accelerations above the first right wheel of the T 81 tram bogie were measured. The results show that when the second wheel jumps in the bogie frame above the first wheel, the values of the accelerations along the vertical and transverse axes are 2 to 3 times higher. Also, the measured values of the angular velocity along the transverse axis follow the same trend. This gives grounds to conclude that derailment occurs when the maximum values of accelerations and the transverse angular velocity coincide.

трамвайна мотриса коловоз трамваен релсов път улейни релси талиги колооси дерайлиране tram track tram railway grooved rails bogies wheelsets derailmentEmil M. Mihaylov M.Sc.Eng.


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