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Conventional railway vehicle systems exhibit hunting phenomenon which increases component wear and imposes operating speed limits. There is also a conflict between dynamic stability and the ability of the vehicle to steer around curves. Alternatively, independently rotating wheels (IRW) in a wheelset eliminate hunting but the wheelset guidance capability is lost. A compromise solution is made possible by a modified design that exploits a lack of fore-and-aft symmetry in the suspension design. A comparative study on steady state curving performance and dynamic stability of some unconventional truck designs is carried out. The effects of suspension and conicity are considered to evaluate the trade-off between dynamic stability and curving performance.

Modified railway passenger truck designs are considered to improve the compatibility between dynamic stability and the ability of the vehicle to steer around curves. A comparative study on the non-linear steady state curving behaviour of some unconventional truck designs is carried out. The study reveals that modified truck designs with primary yaw dampers improve the performance. A particular design of railway truck in which the rear axle is an independently rotating wheelset and in which the primary suspension in the leading axle is different from the trailing axle—known as the unsymmetric wheelset and suspension truck—has the potential to achieve overall superior performance compared to other truck models considered in this paper, for design speeds of around 80 m/s. For the lower design speed of around 60 m/s, a conventional truck provided with primary yaw damper achieves adequate performance and is recommended for its simpler design features.