Normal and longitudinal dynamics of vehicles interrelates via the normal and longitudinal tire reactions. The normal reactions are supposed to be formed by characteristics of the suspension system and tires, and the longitudinal forces in the tire patches are produced by the driveline system by supplying torques to the drive wheels. Usually, the normal and longitudinal reactions, independently generated by the two vehicle systems, are considered to interrelate, but not to impact each other.
An analytical study presented in this paper showed that the normal tire reactions are formed not only by the design of suspension but also by the longitudinal tire reactions (circumferential wheel forces), which follow from the wheel torques supplied by the driveline system. A 6×6 vehicle with A-type suspension systems at all three axles exhibits different normal tire reactions at the drive axles during motion even when the static weight distribution is equal. The paper presents this analytical study of the influence of the circumferential wheel forces on the normal reactions at the wheels.
At the same time, the difference in the normal reactions leads to the different rolling radii of the tires; this generates a kinematic discrepancy in the driveline system that impacts the power distribution between the drive axles and changes the circumferential wheel forces. Thus, the two systems, i.e., the driveline and suspension, impact each other. The paper presents this study in detail, illustrates it with practical examples, and provides recommendations for engineering design.
