A researcher from the Civil Engineering Department at RWTH Aachen University in Aachen, Germany visually demonstrates scenarios in which different wheels are tested on a short, curvy metal track. The conclusion made is that train wheels require a rigid conical shape with a flange to keep the ride smooth.
The model explains the interaction between railway wheels and railway tracks. It is shown how design features such as a conical tread, a rigid axle, and a flange are necessary to impede jamming and override. Together they prevent the wheel, and consequently the train, from derailing.
via Boing Boing