RESUMO A eficiência em tração do trator agrícola pode ser maximizada ajustando a massa total e sua distribuição entre os eixos. O objetivo do experimento foi determinar a configuração de distribuição de massa entre eixos e velocidade de deslocamento que proporcione maior eficiência em tração na operação de gradagem. O experimento foi conduzido no delineamento em blocos casualizados no esquema fatorial 2 × 3, com cinco repetições, sendo o primeiro fator duas distribuições de massa entre eixos e o segundo fator três marchas. Os dados coletados foram submetidos à análise de variância e ao teste de Tukey. A condição que maximiza o desempenho do trator corresponde a 39% da massa total no eixo dianteiro e 61% no eixo traseiro, com marcha que proporcione velocidade próxima a 10 km h-1.

ABSTRACT The traction efficiency of the agricultural tractor can be maximized by adjusting the total mass and its distribution between the axles. The experiment’s objective was to determine the configuration of mass distribution between axles and the displacement speed that provides greater traction efficiency in the harrowing operation. A randomized block design in a 2 × 3 factorial scheme with five replications was used. The first factor was two mass distributions between axles, and the second factor was three gears. The collected data were submitted to analysis of variance and the Tukey test. The condition that maximizes the tractor’s performance corresponds to 39% of the total mass on the front axle and 61% on the rear axle, with a gear that provides speed close to 10 km h-1.

RESUMO A resistência à penetração do solo (RSP) é empregada como indicadora da compactação, por estar relacionada a importantes atributos do solo e das plantas, e por ser uma medida de fácil obtenção. Sua determinação com o uso do penetrômetro orienta para as melhores estratégias de manejo do solo, favorecendo assim o desenvolvimento das culturas. O objetivo deste estudo foi desenvolver e validar o penetrômetro eletrônico de acionamento hidráulico georreferenciado, facilitando a obtenção da RSP. Para tanto foram realizadas 36 leituras de 0 a 0,60 m de profundidade da RSP com os penetrômetros manual e hidráulico em duas áreas. Os resultados de RSP foram analisados estabelecendo-se os intervalos de confiança pelo teste t (p ≤ 0,10), a cada 0,05 m de profundidade, e o georreferenciamento através da raiz do erro quadrático médio (RSME). Constatou-se que ambos penetrômetros apresentaram similaridade na mensuração da RSP e do georreferenciamento dos pontos.

ABSTRACT Soil penetration resistance (SPR) is used as an indicator of compaction, as it is related to important soil and plant attributes and is an easily obtainable measure. Its determination with the use of the penetrometer guides to the best soil management strategies, thus favoring crop development. The objective of this study was to develop and validate the georeferenced hydraulic driven electronic penetrometer, making it easier to obtain SPR. For this, 36 SPR readings from 0 to 0.60 m depth were performed with the manual and hydraulic penetrometers in two areas. The SPR results were analyzed by establishing the confidence intervals by the t-test (p ≤ 0.10) at each 0.05 m depth and the georeferencing was analyzed through the root mean square error (RMSE). It was found that both penetrometers showed similarity in SPR measurement and in the georeferencing of the points.

ABSTRACT The operational performance of the agricultural tractor can be increased by adjusting parameters such as tire inflation pressure, axle mass distribution and gauge opening, which is a very divergent factor in controlled-traffic production. The objective of the experiment was to measure the energy performance of a 93 kW agricultural tractor in intermediate grading operation in two slopes (flat and sloping) and three gauge configurations (closed, intermediate and open) in mobilized soil. Energy performance was determined from the following parameters: slip, engine speed, actual effective speed, hourly and specific fuel consumption; strength, power and performance on the drawbar. Turbo pressure and temperature monitoring was also performed at six different engine points. The experiment was conducted in double factorial arrangement (2 slopes and 3 gauges), with four replications, totaling 24 plots. Data were analyzed for normality and homoscedasticity of the residues, after ANOVA and when significant, the means test. Tilts and tire gauges did not differ statistically, so it can be concluded that depending on the operation do not interfere with operating performance.