Parameter sensitivity for tractor lateral stability against Phase I overturn on random road surfaces

Statistics show that lateral overturns are the most frequent fatal accidents involving tractors. There is thus much research interest in improving tractor lateral stability. Previous research has discovered the effects of various factors on tractor dynamic responses. While these factors have been analysed separately, their relative significance with respect to other factors remain uncertain. Furthermore, the practical limits of what operators can do have not been considered. The present study assumed a possible case that a tractor operator has several spare tyres of different types and service condition. Additionally, the ballast weight, track width, and implement position can usually be controlled before operation. A scale model tractor was thus developed allowing changes to these factors. The model tractor was designated to pass over typical farming road surfaces. Moreover, the tractor lateral stability was evaluated in terms of the roll angle, lateral-load transfer ratio, and Phase I overturn index. Employing the Taguchi method, we arranged experiments and assessed the applicability of the three kinds of indexes regarding tractor Phase I overturn. Results revealed that the roll angle did not well reflect the initiations of overturns. Compared with the lateral-load transfer ratio, the Phase I overturn index had more convincing factorial effects on tractor stability. Further investigation of the suggested tractor configuration supported this conclusion by comparing predicted and experimental results. In practical cases, this approach may provide a reference for engineers to help operators improve driving safety with limited spare parts.