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The agricultural tractor is the main mobile energy source in rural companies, with power take-off being one of the most important uses of the energy produced by the engine. This study evaluates the torque and power demand required to activate active parts of agricultural equipment through tractor power take-off in different working condi­tions. For this, a boom sprayer, an atomizer, a rotary hoe, and a rotary ditcher were used. The experimental de­sign for the sprayers was completely randomized, with working pressures of 150, 240, and 310 kPa for the boom sprayer and flow rates of 11.5, 13.0, and 22.0 L min h -1 for the atomizer. The randomized block experimental design, in a bi-factorial design (3 x 2), was used for the rotary hoe and rotary ditcher, with three speeds (2.10; 2.60 and 3.10 km h -1 ) and two soil conditions for the rotary hoe (one harrowing and two harrowings) and two working depths for the rotary ditcher (0.10 m and 0.20 m). Torque and power values were obtained using a torque indicator installed between the power take-off and the universal joint shaft, which links the tractor to the equip­ment. From the data obtained, it was concluded that the boom sprayer demanded the highest torque and power at the highest working pressure. The rotary ditcher increased torque and power demand as speed and working depth increased.

This study evaluates the performance of an agricultural tractor with a maximum power of 92.4 kW (125.6 hp), equipped with different wheel and tire configurations. The experiment was carried out in the field, with a random­ized block design in a trifactorial scheme, with two wheel and tire configurations (double wheel and diagonal tire; single wheel and radial tire), three mass-power ratios (61, 67, and 74 kg kW -1 ), and three levels of partial loads imposed on the drawbar (24, 27, and 36 kN), on firm soil covered with vegetation. The data were recorded by means of electronic instrumentation installed in the tractor. The results indicate that the double wheel and diago­nal tire configuration showed better performance regarding traction force, traction power, and traction efficiency, as well as lower specific fuel consumption. In turn, the simple wheel and radial tire configuration showed the low­est values of driving wheel slipping. The best traction performance was obtained with the mass-power ratio of 67 kg kW -1 for the double wheel and diagonal tire configuration, and 61 kg kW -1 for the single wheel and radial tire configuration.

Pollutant gases emitted by engines depend mainly on the applied load and engine speed. This study quantifies the emissions of pollutant gases from a diesel-cycle engine, while changing the configuration of the air and fuel supply system. We analyzed the variables particulate matter (g kWh -1 ), carbon monoxide (g kWh -1 ), nitrogen oxides (g kWh -1 ), oxygen (%vol.) and hydrocarbons (g kWh -1 ), in different engine configurations (aspirated; aspirated + service; turbocharged + service; and turbocharged). Dynamometric experiments were carried out by means of the power take-off of an agricultural tractor. The experimental design was completely randomized, in a two-factorial scheme with three replicates. The results indicate that engine supercharging, compared to the original configuration, significantly reduces the particulate matter of gases and carbon monoxide, but increases the levels of nitrogen oxides emitted. The load applied to the engine was directly related to the emissions, except for oxygen.

The objective of this study is to evaluate the energy efficiency of an agricultural tractor according to driving modes (full throttle and shift up and throttle back) and working speeds (3.50 km h -1 , 6.70 km h -1 and 9.80 km h -1 ) during a disc harrow operation. The experimental design was randomized blocks in a bi-factorial design (2x3) with three replications, totaling 18 experimental units. An agricultural tractor was used with a nominal power of 55 kW (75 hp) pulling a disc harrow. The evaluated variables were hourly, specific and operational fuel consumption, all recorded by electronic instrumentation installed in the tractor. The results indicate that the shift up and throttle back mode may be used as a rational driving strategy for agricultural tractors. Savings of up to 22.43% of fuel have been obtained in face of the full throttle mode normally used by farmers.