Theoretical Investigations of the Yaw Vibrations of Truck Trailers

Most studies of the yaw characteristics and the related stability of truck trailers are based on one or two mass models, and driving speed is considered as the critical criterion of stability. This study is based on a three mass, two axle trailer model which can better incorporate the influences of design parameters.

The three modeling masses are: the damped (suspension-supported) mass of the trailer (which forms the basis of the analysis' moving coordinate system), the undamped trailer mass, and the steering system's mass. Equations of motions are developed, based on forces and moments acting on the trailers. Much of the paper is dedicated to the mathematical treatment of these equations. Two coefficients are developed to quantify yaw in terms of other vehicle parameters. Finally, all vehicular input variables are classified into four priorities to indicate their respective scopes of effect on trailer yaw. The method allows simultaneous optimization of numerous design parameters