This paper aims to present the difficulties on designing and tuning a tractor suspension, specially due to its particular mass distribution and the trailer influence on its dynamic behavior. It also presents the development of a primary suspension for the new VW 18.310 Tractor.
The drivers for the development of this new primary suspension were: improve comfort level; achieve a better condition on fragile load transportation; and allow different fifth wheel positions and heights (to take the most advantages of legal limitations on GAWRs - Gross Axle Weight Rating - composition height and length). This should be accomplished without affecting other vehicle dynamic characteristics such as handling.
Due to its benefits to the pavement, the additional facility on tractor-trailer coupling operation and some package limitation, a mixed suspension (parabolic springs on the front axle and pneumatic foils on the rear) is chosen on the cost vs. functional attributes trade off process.
The experimental approach to the ride & handling tuning process is discussed, the subjective methods and objective metrics utilized to guide the development process are presented. Finally, the results obtained are compared to multi-body computer simulation, considering cost, time and precision.