The Effect of Kingpin Inclination Angle and Wheel Offset on Medium-Duty Truck Handling

The effect of kingpin inclination angle and wheel offset on various vehicle performance metrics such as steering effort, vehicle handling, and steering system vibration is described in this paper. A simple ADAMS model of a medium-duty truck has been developed for this study. The front axle consists of an idealized solid axle suspension with suspension system components represented by rigid bodies. The tire model used in this study is a linear tire model, and estimates of tire force coefficients were obtained as an average of several published estimates of medium-duty truck tires. Experimental design procedures (DOE) have been conducted to determine the effects of kingpin inclination angle and wheel offset on various steering system performance measures. For each performance metric, a 2-variable (KPIA and wheel offset), 5-level DOE was performed using the full factorial matrix for a total of 25 tests for each performance metric. The KPIA was allowed to take on values of 6.25°, 7.0°, 7.75°, 8.5°, and 9.25°. The wheel offset was allowed to take on values of 2.5, 3.0, 3.5, 4.0, and 4.5 inches. The results of each DOE study provide a measure of the sensitivity of each performance metric to the individual and combined effects kingpin inclination angle and wheel offset.