Car—caravan snaking: Part 1: The influence of pintle pin friction

Abstract

A brief review of knowledge of car-caravan snaking is carried out. Against the background described, a fairly detailed mathematical model of a contemporary car-trailer system is constructed and a baseline set of parameter values is given. In reduced form, the model is shown to give results in accordance with literature. The properties of the baseline combination are explored using both linear and non-linear versions of the model. The influences of damping at the pintle joint and of several other design parameters on the stability of the linear system in the neighbourhood of the critical snaking speed are calculated and discussed. Coulomb friction damping at the pintle pin is then included and simulations are used to indicate the consequent amplitude-dependent behaviour. The friction damping, especially when its level has to be chosen by the user, is shown to give dangerous characteristics, despite having some capacity for stabilization of the snaking motions. It is concluded that pintle pin friction damping does not represent a satisfactory solution to the snaking problem. The paper sets the scene for the development of an improved solution. This involves actively braking the caravan wheels, which is treated in Part 2 of the paper.