ABSTRACT Agricultural machinery plays a key role in optimizing crop yields. In tillage operations, it is essential to analyze both operational and energy performance variables. Continuous research is needed to quantify performance without compromising soil conservation, particularly with modern agricultural tractors, to update strategies, increase productivity and ensure the sustainability of mechanized operations. This study aimed to assess the energy and operational efficiency of an agricultural tractor (John Deere®, model 8400R), during subsoiling at different speeds, using five gear settings (A, B, C, D and E, corresponding to gears F5, F6, F7, F8 and F9), with a nominal engine speed of 2,100 rpm. The parameters evaluated were operating speed, wheel slip, engine speed, drawbar force, drawbar efficiency, hourly fuel consumption, fuel consumption per unit area, brake specific fuel consumption, brake thermal efficiency, and field capacity. The experiment followed a randomized block design. Analysis of variance indicated significant improvements in operating speed, wheel slippage, engine speed, drawbar force and drawbar efficiency as the gears shifted from A to E. Correlation analysis showed strong relationships between operating speed and parameters such as wheel slippage, drawback force and drawback efficiency, hourly fuel consumption and operational field capacity. Gear D was the most efficient for tillage. Although gear E improved operational performance, it reduced energy efficiency, indicating a trade-off between speed and fuel economy.
Jung et al. (Wed,) studied this question.