Survey on the Stability of Tractor-Implement Combination on Increasing Slopes

Overturning of the tractor is the main factor in fatal accidents and/or serious disabilities in agriculture. For this reason, numerous studies have been carried out and regulations have been issued over time, to highlight the most critical conditions (e.g. the stability limit angles) related to overturning of agricultural machinery. However, often only the tractor alone is taken into account, but in all the field working conditions tractors are always coupled with one or more implements, thus changing (sometime greatly) the stability conditions, mainly due to the mass and the position of the implement centre of gravity. More in detail, the stability becomes worse when the implement is coupled at the 3-point linkage. The static stability of two combinations of tractor and implement coupled at the 3-point linkage was analysed on a rigid, flat tilting platform, varying the height from the ground and the cantilever of the implement, and the tyre pressure of the tractor. The goal has been the check of the Static Overturning Angle (SOA), simulating the main common machinery situations when working on slope, to ascertain those that most affect stability. As expected, coupling a tool to the 3-point rear coupling worsens the SOA, while the variation in tyre pressure has only a slight effect on the overall stability.