Preliminary results of extensive tractor rollover stability tests using a tilting-rotating rig

Addressing safety issues in mountain agro-forestry operations, a critical focus is on the stability of machines to prevent rollovers. Despite advancements in technologies and techniques enhancing overall safety, fatalities remain a significant concern. Italy, for instance, witnesses over 120 fatal accidents annually due to tractor rollovers. Even in less serious cases, they still lead to considerable vehicle damage and financial losses. Consequently, investigating and characterising the tractor stability behaviour emerges as a crucial endeavour. This has led to consider in this work, also for certification purposes, the definition of mixed approaches typical of twin models, with predictive modelling assessments extended to a broad application context complemented by punctual measurements on full-scale machines. These measurements have been carried out by means of a novel rotating and tilting test-rig for tractor rollover evaluation available at the Agroforestry Innovation Laboratory (AFILab) of the Free University of Bozen-Bolzano. The study concentrates in particular on examining and comparing the (static) rollover stability results on three different types of tractors commonly employed in mountain operations: a conventional tractor, a narrow track tractor, and a mountain-specialist model. The output of this approach are the stability maps, graphical tools summarising stability limit conditions for diverse configurations. The preliminary results, despite some simplifications adopted in the first version of the digital model, show an excellent correlation between the modelling approach and real measurements. Aspects for future refinement may concern the inclusion of procedures capable of reproducing tyre deformation with greater fidelity under conditions of significant slope.