Effects of slip ratio on wear performance of class B wheel steels against softer R260 rail steels using the twin disc setup

Abstract

A train experiences different slip ratios at the wheel/rail contact point as it moves along the rail track, which influences the rolling contact fatigue (RCF) and wear properties of wheel and rail materials. This variation in slip ratios is caused by a change in contact area between the wheel and rail head at curves, as the slip ratio increases compared with when a train is moving on a straight track. When the train is moving on a straight track, the wheel is found to be in contact with the rail head; but that changes when moving around curves, as the wheel flange will now be in contact with the gauge corner of the rail, affecting the severity of wear. Therefore, more research needs to be done to understand the role that slip ratio plays in the wear performance of wheel and rail materials in order to be able to develop models or systems that could be used to predict preventive maintenance. The aim of this work was to investigate the effect of the slip ratio on the wear performance of class B wheels against softer R260 rail steels under rolling and sliding conditions, using a twin-disc setup developed at the University of Pretoria. The results showed that the severity of wear was heavily dependent on the slip ratio – i.e., it increased with the slip ratio, with class B wheels performing better than the softer R260 rail.

’n Trein ervaar verskillende glipverhoudings by die wiel/spoorkontakpunt soos dit langs die spoorlyn beweeg, wat die rolkontakmoegheid (RCF) en slytasie-eienskappe van wiel- en spoormateriaal beïnvloed. Hierdie variasie in glipverhoudings word veroorsaak deur 'n verandering in kontakarea tussen die wiel en spoorkop by kurwes, aangesien die glipverhouding toeneem in vergelyking met wanneer 'n trein op 'n reguit spoor beweeg. Wanneer die trein op 'n reguit spoor beweeg, word gevind dat die wiel in kontak is met die spoorkop; maar dit verander wanneer om die trein om kurwes beweeg, aangesien die wielflens nou in kontak sal wees met die spoorhoek van die spoorstaaf, wat die hoeveelheid slytasie beïnvloed. Daarom moet meer navorsing gedoen word om die rol wat glipverhouding speel in die slytasieprestasie van wiel- en spoormateriaal te verstaan, ten einde modelle of stelsels te kan ontwikkel wat gebruik kan word vir die voorspelling van voorkomende instandhouding. Die doel van hierdie werk was om die effek van die glyverhouding op die slytasieprestasie van klas B-wiele teen sagter R260 spoorstaal onder rol- en glytoestande te ondersoek, met behulp van 'n tweeskyf-opstelling wat by die Universiteit van Pretoria ontwikkel is. Die resultate het getoon dat die erns van slytasie baie afhanklik was van die glipverhouding - dit wil sê, dit het toegeneem met die glipverhouding, met klas B-wiele wat beter presteer as die sagter R260-reling.