Evaluation of a Tractor's Driving Performance on the Road

In recent years, tractor use on the road has increased, in part due to a higher maximum velocity allowed. An increase in velocity highlights certain limits of the vehicle in terms of driveability and comfort. Numerous studies regarding the standards of on-the-road behavior exist in the automotive sector. On the contrary, there are no studies concerning the on-the-road behavior of tractors but, rather, only off-the-road studies with the objective of developing steering systems that facilitate the driveability of the vehicle. The objective of this article is to discuss tests that allow the characterization of a tractor's steering system and its behavior on the road. The tests were performed on two tractors with the same power rating but different steering systems. The tests were carried out using the standards of the automotive sector but with some changes: a decrease of the traveling velocity, the lateral acceleration, and the maximum frequency of the steering action. Different parameters characteristic of the steering system were analyzed under lateral acceleration of the tractor while steering to make a turn with a constant velocity and when the system was excited in a transient manner. The global behavior of the tractor on the road and, in particular, the characterization of steering system quality are presented.