Estimativa do desempenho de tratores agrícolas em campo e pista a partir do ensaio dinamométrico

Abstract

The agricultural tractor allows to move and to pull machines and implements used during the execution of the activities to field. One of the largest problem refers to the acting of the tractor, the reason of a lot of questions between farmers and manufacturing companies. The perfomance determination is a much complex task, mainly when realized in field level, because the variables that should be analyzed are countless, inside of an extremely wide context. The solution found by a lot of researchers was the standardization through testings realized in concrete track, what shows unreliable results about the perfomance of the tractor in the field, besides they can be expensives. The aim of this work was to previse, through dynamometrics tests, the perfomance of an agricultural tractor of wheels in track and in the field, without appeal to the direct tests. The experiment was conducted in Federal University of Santa Maria, submitting a instrumented tractor to dynamic tests of traction in a paved surface and in the field, besides static tests, using an electric dynamometer with Foucault current. Through the use of equations, already conceptualized, was possible to create a interrelation between the following variables: torque and power of the engine, resistance to the rollover, wheel slipping, relation between the transmission relation and the tires dimensions, providing a way to estimate the power developed in the traction bar and the fuel consumption, with subsequent comparison with the dynamic tests. It was found by the correlation analysis, using obtained and estimated values, that there was a high correlation coefficient between the power traction observed in the track and in the field, relative to the estimated power (0.99 and 0.98) respectively.The equations estimating the fuel consumption presented a high adjustment for 90%, obtaining variation between the field treatments and the track in order to 1,19% and 2,09% respectively. Therefore, the estimate of the tractor performance can be made with high accuracy, just doing the dynamometric tests in laboratory, substituting the dynamic tests of field and track.