Abstract
Conventional tractors are not equipped with a suspension system. Due to the potential of these systems to improve ride comfort and dynamic behavior however, modern agricultural vehicles are equipped with a variety of different suspension systems such as seat-, cabin- or chassis suspension. This paper will present the capability of a semi-active suspension for full spring mounted tractors.
Based on a tractor with conventional rigid axles, a new hydro-pneumatic chassis suspension for front and rear axle was developed, including a set of sensors, hydraulic actuators and an electronic controller. Different parameters such as rod side preload pressure, speed, number of sprung axis as well as passive and semi-active suspension were examined. The skyhook-algorithm was used for the semi-active suspension.
The results show a low influence of the rod side pressure on the seat acceleration while the influence of the driving speed was found to be high, showing twice the accelerations at 14 km/h compared to 7 km/h. An acceleration decrease of 35%, comparing the full suspension concept and a front axle suspension, could be measured. A reduction of 8% of the seat accelerations could be measured in the z-direction when a semi-active suspension was used instead of a passive suspension. Additional research has the potential to reduce accelerations further, using improved sensors and control strategies.
Keywords: driving safety, driving comfort, suspension, hydro-pneumatic, tractor