Surface morphology of wheels in rail vehicles in urban transport

Purpose: The general purpose of presented research was evaluation of surface morphology of chosen tram wheels: LUCCHINI (of Siemens Combino tram), PST (of Moderus Beta tram), and GT no 1 (of Duewag tram) operating in Poznan agglomeration. Design/methodology/approach: 3D surface profile study, macro and microscopic research with light and scanning electron microscopes, and Vickers hardness measurements were done. Findings: Wear effects were observed on the rolling surface, as well on the surface of the top of the wheel flange. Rolling contact fatigue was dominant type of wear. Abrasion was also noticed, especially on the top of the wheel flange. Changes in the surface layer were also noticed, like sever plastic deformation as: overhangs, flattened grains and delamination. Plastic deformation was the reason of hardness increase. Though the rolling surface is the surface responsible for the load transfer, more plastically deformed was the surface layer of the top of the wheel flange. Although investigated wheels was operated in different trams wear effects were similar. Research limitations/implications: The research represents part of a project considering identification of phenomena occurring in the contact zone between tram wheel and the rail funded by the National Centre for Research and Development of the LIDER program. Further research should concentrate on designing of the new wheel (new profile and modified material). Practical implications: On the base of performed research it also was possible to determine some suggestions in the order to extend tram wheel life. Originality/value: The surface morphology of tram wheels has been describe quantitatively on the base of 3D roughness parameters. Main type of wear that dominate in case of chosen tram wheels in Poznan agglomeration was identified. Main material changes in the surface layer were described in those wheels.