Experimental evaluation of power losses in a power-shift agricultural tractor transmission

The results of tests on a full power-shift transmission, suitable for use on a 140 kW, agricultural tractor are reported. The aims of the research were to evaluate the working conditions where there are higher power losses, and to identify the causes of energy dissipation. The tests were carried out with the transmission set in motion and the power absorbed in each gear was evaluated. Following identification of the gears in which the higher losses were measured, the components were separated, one at a time, from the transmission and the influence on the losses measured. The results showed that higher losses occur in higher gears. The tests indicated that 52% of the total losses are caused by passive resistance and friction in the transmission together with the power absorbed by the hydraulic circuit in the neutral position, 40% by oil splashes in the transmission, 4% by the brakes, and 4% by the final reducers and corresponding sun wheels.