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Handling Comparison of Vehicles with Steerable Auxiliary Axles

Journal Article
ISSN: 1946-391X, e-ISSN: 1946-3928
Published September 24, 2013 by SAE International in United States
Handling Comparison of Vehicles with Steerable Auxiliary Axles
Citation: Williams, D. and Nhila, A., "Handling Comparison of Vehicles with Steerable Auxiliary Axles," SAE Int. J. Commer. Veh. 6(2):281-287, 2013,
Language: English


Self-steered or caster steered axles are commonly used to support load on multi-axle commercial vehicles. Such axles can allow more payload to be hauled in some vehicle configurations under the existing bridge formulas. These self-steered axles cannot generate a side load, and serve to unload surrounding fixed axles that do generate lateral forces to turn the vehicle with payload. Since the tire's ability to generate a side load is dependent upon its load, the use of caster-steered auxiliary axles can upset the balance (or the understeering) properties of the vehicle. This work will define the effect of adding a caster steered auxiliary axle and compare it with a steerable axle that positively controls the steer angle and thereby generates a lateral force. This work assumes the reader has a basic knowledge of the well publicized “bicycle” model, and particularly its extension to multi-axle vehicles.