ANALYSIS OF RAIL-WHEEL INTERACTION IN CURVES WITH SMALL RADII

Purpose. The authors goal is to point out that the new geometric design of the curves of tramways is recommended, furthermore the introduction of a new parameter too. This new parameter is the Creepage Index (CI), which takes into consideration the values of wheel creep from the optimal rolling radii difference on every wheelset in the bogie. Methodology. The several types of railprofiles and railway wheel tread profile geometres have been analised with a special softver and compared with standards, TSIs and BOStrab. Findings. The result of the analisys is that the mechanical conformity of rail/wheel interaction (running characteristic) in tramway tracks are unfavourable and new regulations are necessary to reduce the rail/wheel wear and corrugation especially in curves with small radii. Originality. In the EU the Technical Specifications for Interoperability (TSI) are in force, which regulate the parameters of running behaviour for the international and national public railways. However, the regulation does not apply to domestic tramways. In the course of the analysis, the author propose to introduce a system of regulation, which based on the mechanical suitability of the rail/wheel interaction. This is especially justified, because for example the regulation of German light rails (BOStrab) only requires the geometric dimensions of the wheel and the groove of the rail and their limits. Practical value. The author developed new geometric design and limit systems of narrow curves and straight tracks and a new test parameter, which shows degree of coherence for running characteristic of the given curve and vehicle, from the aspect of infrastructure, in case of all wheelsets of bogie. This CI (Creepage Index) parameter takes into account all wheel creep values resulting from the variations (+, –) of the optimum rolling radius difference. This results the tightening of bogie design principles and for running characteristic reasons, it requires the continous flange running of the outer wheel in narrow curves.