Axle spacing and vehicle dynamics for European tractor-semitrailer combinations

Abstract

European tractor-semitrailer combinations typically have a relatively short spacing  between the front and first rear axle for the tractor, motivated by the standardized  type of semitrailer together with an overall restricted combination length. These  combinations are notorious for their susceptibility to wintertime problems and incidents  with traction loss and jack-knifing in harsh road conditions common in Scandinavia. Transport  professionals have concurred that the main factor behind these accidents is the short  tractor axle spacing. Some vehicle dynamics modeling and simulation investigations,  however, assert that the role of tractor axle spacing is minor. One reason for these  differing inferences may be the role of overall combination length in the context.  Regulations in Scandinavia allow longer tractors than in Central Europe and most  simulation studies only consider spacings for fixed overall length 16.5 - 17 m.  We calculated effective yaw moments of inertia for these axle spacings as well as for a  longer, Scandinavian spacing to estimate its role for articulation dynamics of these  tractor-semitrailer combinations.