On the Directional Response Characteristics of Heavy Trucks

The cornering performance of heavy trucks incorporating multiple, non-steering axles and dual tyres is examined in the linear regime to identify how this performance differs from that of the simple two-axle, four-wheel vehicle. Multiple, non-steering rear axles and dual tyre arrangements are seen to increase the steer angles required to negotiate a turn because these elements produce a moment resistant to turning. Vehicles which have these elements may be characterized by an "effective wheelbase" which is greater than the geometric wheelbase. Experimental data are shown which verify steer angle predictions made using this characterization. (TRRL)