Valda Rondelli

Effects of rubber tracks on narrow-track tractors on the non-continuous rolling prediction model

Tractor rollover is one of the most hazardous events for the driver. The rollover protective structure (ROPS) was introduced to passively protect the driver. In the specific case of two-post protective structures fitted in front of the driver on narrow-track wheeled agricultural tractors, the ROPS has to avoid non-continuous rolling in the event of a lateral rollover. In order to check non-continuous rolling behavior in narrow-track wheeled agricultural tractors, a mathematical model is included in the preliminary ROPS tests of the standardized testing procedures issued by the Organization for Economic Co-operation and Development (OECD). A recent approach in the design of narrow-track tractors is the fitting of rubber tracks. A safety issue consequent to this new arrangement is that the standardized calculation does not cover narrow rubber-tracked tractors because it was originally developed assuming only the behavior of the tire in a lateral rollover. The aim of this study was to extend the field of application of the standardized calculation for non-continuous rolling behavior, allowing rubber-tracked tractors to be fitted with a front ROPS suitable for operation in narrow orchards and vineyards. The effect of track-ground interaction compared to tire-ground interaction was evaluated. The track shape and non-deformed behavior of the rubber track at a state of unstable equilibrium under full load caused the tractor to rotate around the outer edge of the track; therefore, the tipping axes and wheel characteristics in the original mathematical model were revised. The tracked tractor checked with the revised model required a higher ROPS with respect to the equivalent wheeled tractor to obtain non-rolling behavior. The ROPS needed to be increased by 0.28 m to meet the safety requirement.

Tractor ROPS and Stability Research: Introduction to this Special Issue

Agricultural production has clearly benefited from the development of the tractor. The tractor provides a traction device and mobile power source. However, operating large equipment with high clearance on uneven ground leads to stability and overturn issues. Around the world, tractor overturns are still a leading cause of agricultural production fatalities. This special issue of the Journal of Agricultural Safety and Health focuses on recent research on tractor ROPS (rollover protective structures) and stability. Engineers and scientists in both Italy and the U.S. have been working on these topics, attempting to solve old problems and address rising issues. Understanding the factors leading to tractor instability, investigating the structures protecting the operator, and examining the continuous roll potential will all lead to increased operator protection and reduced fatalities.