Effect of Cant Deficiency on Rail Vehicle Performance

Abstract

Simplified train models are analyzed to assess the relationship of unbalance on carbody acceleration and wheel unloading during steady state curving motion. In this paper a half-car model appropriate for both power cars and tilting coach cars is theoretically analyzed. Models of this type are useful for examining static lean requirements as well as margins of safety at higher cant deficiencies in the Track Safety Standards of the Federal Railroad Administration (FRA). The suspension systems modeled and analyzed include the following types: rigid, flexible, tilting actuation, and combined flexible and tilting actuation suspension. Simplified formulas are derived which can be used as an analysis tool by railroad designers to assess vehicle performance. Parametric results are presented for vertical wheel unloading and lateral carbody acceleration as a function of cant deficiency. Results show that incorporation of tilting systems, better suspension designs and better track quality, are necessary in order to provide an equivalent level of margin of safety for operations at higher cant deficiency. The relationship of these results to limits in the Track Safety Standards is discussed.