Experimental modelling of lipping in insulated rail joints and investigation of rail head material improvements

An insulated rail joint is a component used to join two abutting rails while keeping them electrically separated from one another. This allows for the construction of track circuits and train detection within signalling systems. Electrical failure of the joints can be caused by plastic flow of the rail steel over the insulating gap, known as lipping. In this paper, this failure mode has been experimentally modelled using twin-disc testing and indicative conclusions have been formed. It has been found in this testing that the thickness of the endpost does not have an effect on the rate of lipping, however, the endpost and rail material do have an effect. An endpost with a higher compressive strength will perform better and tougher/harder rail steel will also improve performance. The application of a laser clad layer of tougher material on the running surface, however, gave the greatest resistance to lipping.