Experimental Investigation of the Parameters Affecting the Castor Stability of Road Wheels

Abstract

The experimental testing of a model castoring wheel on a moving road surface is described. The stability of this steerable wheel was investigated as a function of various geometrical and physical parameters. A most important parameter was found to be the lateral stiffness of the system relative to the steering axis. Previous work has explained instability in terms of tyre behaviour, notably for aircraft landing gear, but in these tests a tyre-less wheel was used in an attempt to find a more fundamental cause. It was concluded that the overall lateral stiffness of the wheel system, of which tyre stiffness is one component, is important. The graphical results form a basis for improving the design of motorcycle and motor car front wheel assemblies.