HIGHLIGHTS:
Automatic mode presents less wheel slippage than manual mode at 4, 6, 8, and 10 km h-1.
At 4 km h-1, manual mode shows greater drawbar power and yield.
At lower speeds, automatic mode consumes less fuel per hour.
ABSTRACT
Automatic production management (APM) is a tool that assists in the operations of agricultural tractors, increasing yield and energy efficiency. The objective of the experiment was to compare the energy and operational performance of a 373-kW articulated tractor equipped with APM and manual mode of engine transmission and rotation, across different real-world speeds. The experiment was conducted in a randomized block design with five replicates, using a split-plot arrangement with two system modes (manual and automatic) in the plots and four real-world speeds (4, 6, 8, and 10 km h-1) in the subplots, totaling 40 experimental units. The evaluated variables were: wheel slippage; engine rotation; hourly and specific fuel consumptions; drawbar force, power, and yield; operating speed; and engine thermal efficiency. The variance of the data was analyzed using Tukey’s test for the first factor, and regression analysis for the second factor and interactions. The automatic mode showed lower engine rotation and wheel slippage without compromising the other variables. The use of this mode showed energy advantages at 4 and 6 km h-1 by resulting in less fuel consumption per hour. In addition, the manual mode presented higher thermal efficiency at lower speeds than the automatic mode, which showed a linear increase.
Key words:
engine rotation; fuel consumption; engine thermal efficiency
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* - Significant at p ≤ 0.05 and ** - significant at p ≤ 0.01 by the F test; Vertical bar - Minimum significant difference (MSD). Symbols followed by the same lowercase letter do not differ from each other by the Tukey’s test (p ≤ 0.05)