RESUMO: A assertiva adequação do trator agrícola é necessária para atingir máxima eficiência energética, podendo ser feita através da correta distribuição de massa entre eixos para cada superfície de operação. O objetivo deste trabalho foi avaliar diferentes distribuições de massa entre eixos em um trator de 93 kW equipado com tração dianteira auxiliar, em duas superfícies de solo. O experimento foi realizado em delineamento de faixas, com esquema fatorial duplo (2 x 3), sendo duas superfícies de solo (mobilizado e firme) e três distribuições de massa entre eixos (35/65%, 40/60% e 45/55%), com cinco repetições, totalizando 30 parcelas. Foram determinados os parâmetros de patinamento dos rodados dianteiros e traseiros, rotação do motor, consumo horário e específico de combustível, força, potência e rendimento na barra de tração, velocidade de deslocamento, eficiência térmica do motor, coeficiente de tração, resistência ao rolamento e rendimento em tração. Em solo firme, o desempenho energético do trator foi superior em relação ao mobilizado, o qual possibilitou maior rendimento tratoreo e na barra de tração com menor consumo específico de combustível. O uso da distribuição de massa entre eixo de 35/65% proporcionou a maximização na tração do conjunto motomecanizado, decorrente da redução do dispêndio energético gerado pelo patinamento e consequentemente o máximo aproveitamento da energia disponibilizada pelo conjunto mecanizado. Entretanto, a máxima conversão da energia contida no combustível em trabalho é obtida com a configuração 45/55%.

ABSTRACT: An adjustment of the agricultural tractor is necessary to achieve energy efficiency, which can be done through the correct distribution of mass between the axles for each operating surface. This research evaluated different distributions of mass between axles in a 93 kW tractor equipped with auxiliary front-wheel drive, on two soil surfaces. The experiment was carried out in strip design, with a double factorial scheme (2 x 3), with two soil surfaces (mobilized and firm) and three mass distributions between axes (35/65%, 40/60% and 45/55%), with five repetitions, totaling 30 parcels. The slippage parameters of the front and rear wheelset, engine rotation, hourly and specific fuel consumption, force, power and yield on the drawbar, displacement speed, engine thermal efficiency, traction coefficient, rolling resistance, and yield in traction. On firm soil, the energy performance of the tractor was superior in relation to the mobilized one, which allowed greater tractor and drawbar performance with lower specific fuel consumption. The use of a 35/65% between-axle mass distribution provided maximum traction for the mechanized set, resulting from the reduction in energy expenditure generated by skating and; consequently, the maximum use of the energy made available by the mechanized set. However, the maximum conversion of energy contained in the working fuel is obtained with the 45/55% setting.

ABSTRACT. The use of powdered graphite as a solid lubricant to reduce friction among soybean seeds during mechanical sowing aims to facilitate the seed flow into the seed reservoir, while reducing mechanical damage to the seed. The objective of this study was to evaluate the influence of graphite on the longitudinal deposition of soybean seeds using mechanical and pneumatic feeders at different distribution velocities. The experiment was performed on a static simulation-test bench, with a completely randomized design with two varying factors: graphite dose (0, 1, 2, 4, and 8 g kg-1 seed) and distribution velocity (5, 7, 9, and 11 km h-1 for the pneumatic feeder; and 3, 5, 7, and 9 km h-1 for the mechanical feeder). To assess the homogeneity of seed distribution, the frequency of parameters such as double, flawed, and acceptable spacings, coefficient of variation, and precision index were evaluated from five repetitions of 250 spacing each. For the pneumatic feeder, the optimal values to maximize precision of seed deposition were 4.6 g kg-1 and 6.7 km h-1 of graphite dose and distribution velocity, respectively. In turn, the optimal values to minimize undesirable spacing while maximizing accuracy with the mechanical feeder were 4.9±0.6 g kg-1 and 4.9±0.3 km h-1. Overall, regardless of feeding mechanism, the use of graphite promoted greater efficiency in the distribution of seeds owing to the higher level of fluidity inside the reservoir; however, high doses can cause the opposite effect. In addition, an excessive increase in speed influenced seed distribution negatively.

Abstract The need for energy rationalizing in farming operations require research that optimize grain crop conduction. The operations used in the processing and production of silage have limitations in energy optimization due to the lack of studies. This paper evaluated energy efficiency of whole-plant silage operations with the objective of favor the decision making. The adopted design of the experiment was in parcels (with seven replications), consisting of three harvesting modalities: single-line forage harvester, total area forage harvester, and total area forage harvester with support transshipment. The tractors were instrumented with sensors that measured engine rotation, travel speed, and hourly fuel consumption which were used to calculate field capacity, fuel consumption per area and per harvested mass, and production capacity of the harvester-tractor set. The results went to analysis of variance and subsequently to Tukey’s test. The single had a faster speed and lower hourly fuel consumption, but smaller field capacity and greater energy expenditure for the mass. The use of support transshipment set with the front harvester allowed an improvement in the operation, with an increase in the worked area, and material processing (18%), and speed (13%), without differing in fuel expenditure. The total-area forage harvester modality showed smaller costs (USD 6.7), followed by the total-area forage harvester with support transshipment set (USD 7.7) and the single-line forage harvester (USD 9.38), respectively. The use of forage harvesters with a wider working width proved to be more efficient in terms of production costs per harvested hectare, validating it’s reccomendation.