Development of an easily adaptable three-point hitch dynamometer for agricultural tractors. Analysis of the disruptive effects on the measurements

Abstract

Abstract The quantification of all the forces and moments between a tractor and an implement, when linked through the three-point hitch, is interesting for different purposes, including the optimization of the implement design, the evaluation of the tractor settings or the application in precision agriculture. This work presents the development of a new double frame dynamometer to measure them. The design has been focused in the mechanical optimisation of it while making it easily adaptable to a wide range of tractors and implements. A mathematical model has been developed to determine the forces and the moments at the different couplers between bodies of the tractor-dynamometer-implement system, taking into account the mechanical characteristics of the dynamometer and the inclination of the terrain where the tractor is working. Then the disruptive effect of the dynamometer on the forces acting on the tractor can be evaluated. Resultant longitudinal force between implement and soil is also determined, taking into consideration the inclination of the terrain and the mass of the implement. A prototype of the dynamometer has been built up and some initial field tests have been carried out to validate the design and the functionality of the dynamometer.