No abstract

Extensive field experiments (the ‘Silinge wheel flat experiments’) with a moving train have been designed, performed (at Silinge) and evaluated. More than 200 wheel flats were formed under controlled conditions involving different wheel loads, train speeds and sliding durations, and the friction coefficient between the wheel and the rail was also varied (and indirectly measured). Samples extracted from flats of the tested wheels have been metallographically examined with respect to phase transformations and cracks. A numerical model for wheel flat prediction has been qualitatively verified and quantitatively calibrated. In the experiments, martensite was found beneath all flats and cracks were observed in most cases. It is concluded that the risk for future spalling should be considered for all wheelsets with flats. A damaged wheelset should be taken out of service as quickly as possible. When reprofiling the wheels, all martensite and an additional layer of several millimetres should be machined off.

Vertical wheel-rail contact forces with high magnitudes are generated in vehicle operation on track sections with periodic (rail corrugation) or discrete (rail joints, crossings) surface defects and/or in operations with out-of-round wheels. This may result in severe wheel damage, such as subsurface rolling contact fatigue and deep shelling. Based on input data in the form of contact forces measured by an instrumented wheelset, including contributions with frequencies up to about 2 kHz, a track condition analyser (TCA) has been developed. The dominating and most frequently occurring types of rail rolling surface defects can be detected, their location along the line can be determined, and their detrimental effect on the fatigue life of wheels can be estimated. This means that the TCA can be used as a tool to assess the current track quality and determine the need for immediate and planned track maintenance. Using the instrumented wheelset on a Swedish passenger train, the 450 km line Stockholm-Gothenburg can be measured in both directions during an 8 h test campaign.