Ride Comfort Aspects of Heavy Truck Design

Abstract

The use of mathematical models to analyze articulated vehicles and their vibration-isolating system is reported. Damping, cab suspensions, and frame vibration are examined in terms of comfort. The application of the analytical results and those from impedance and road tests to the development of a cab-over-engine heavy truck family is discussed. The qualitative evaluation of the new design in terms of comfort is described. This study has demonstrated that a soft cab suspension improves comfort in the vertical as well as the longitudinal direction, although it does not eliminate the comfort problem associated with articulated vehicles. This type of suspension, however, eliminates the jumping ride problem caused by elastic vibrations of the frame. It has been shown that damping is very important for comfort, and that friction has a negative influence. The need is expressed for a numerical method to optimize the damping and to calculate the quality index (rms (root mean square) output/input) for a system with many degrees of freedom. The rms values represent accelerations on the driver's seat.