Optimizing the performance of tractors in disc harrow systems

This paper discusses the dynamics of the tractor-implement combination in traction works, in the specific soil conditions present in Southern Portuguese agriculture. The tillage operations are very power demanding and are therefore responsible for significant energy inputs. The inappropriate operation of the tractor, in regarding to engine and gearbox speeds and poor management of ballast and tire inflation pressure, combined with poor regulation of tillage implements can result in significant energetic efficiency losses with impact on the economic returns that can be provided by agriculture to farmers and the viability of agricultural enterprises. The purpose of this project was to study tractor-implement dynamics in tillage operations. A portable computer- based recording system (data acquisition system) was developed and installed on tractors to monitor engine speed, fuel consumption, actual forward speed, wheel slip and draught force required for trailed implements. The field tests were performed under real working conditions. Field trials carried out under different working conditions allowed, firstly, to establish predictive models for traction effort and fuel consumption per unit of area that can be used by farmers as a reference when working with trailed offset disc harrows, and secondly, to quantify the actual fuel savings that can be obtained by selecting an engine speed of about 80% of rated speed, using the highest allowed gear ratio, by adjusting the tire inflation pressure and liquid ballast for each work situation (according to the coefficient of traction and traction-wheel slip) and adjusting the gang angle of the trailed disc harrow (and the working width and depth) to the soil conditions (soil type and moisture content)