Gauge widening of passenger coach wheel sets in Indian Railways: Observed statistics and failure analysis

Abstract Several hundreds of gauge widening cases have been reported in coaching stock wheel sets of Indian Railways over the last two years. This work investigates the effect of non-uniformity in braking, brake load, braking frequency, wheel profile, and braking cycles on wheel gauge evolution in coach wheel sets with an aim to identify root cause of the problem. A validated finite element model considering heat generation at brake-wheel interface, heat partitioning at wheel-brake block and wheel-rail interfaces, and convective, radiative heat loss to ambient air is used to estimate wheel temperatures, stresses, and gauge change. Residual stresses generated during wheel manufacturing and fitment of wheel onto axle are considered in the study. It is found that wheel gauge reduces during braking and increases as wheels subsequently cool down. Magnitude of temporary gauge reduction and permanent gauge widening increases with increasing heat input. Thus, higher non-uniformity in braking – leading to overheating of some wheels – can cause wheel gauge widening. Interestingly, reduction in brake load reduces permanent gauge widening but increases temporary gauge reduction during braking. Nature of gauge change and effect of wheel profile, seen from gauge widening statistics, correlate well with findings from simulations.