Combines possess the complex mechanisms and characteristics of the power requirements. We measured grain losses, torques and revolutions at each element of rice-combine, and in this paper the fluctuations of the torques and the distributions of power requirements were discussed. As a result of these experiments and discussions the following were obtained.
1) The grain loss was 4.5 per cent when a operating condition was good, but in the case of harvesting the lodging rice the grain loss amounted to 20 per cent. The greater part of this grain loss was the cylinder and straw rack loss, especially the most part of the cylinder loss was due to unripe grains.
2) power requirements of combine were closely related with the feed rate of the rice to be threshed, that is, power requirement was 26.5 PS when feed rate was 85.1kg/min and 13.5 PS when 40kg/min.
3) The characteristics of the load at each element were different. That is
a) The power at threshing cylinder was most closely related with the feed rate. It was 11.6 PS on the average when the feed rate was 85.1kg/min and 4.7 PS on the average when 49kg/min.
b) The cutter-bar power did not vary widely depending on the test conditions, and its value through the tests was small, about 1 PS.
c) Because of the low travelling speeds through the experiments, its maximum value was 0.32m/sec, the travelling power were small, that is from 4 PS to 8 PS.
4) The forces acted to the concave through straws by the threshing cylinder increased at intervals of 1.2 sec to 2.5 sec.
This seems to occur because the flow of the rice fed to the cylinder was not uniform. Hence, torques at the cylinder shaft also showed wide fluctuations. However, the torques at the engine and travelling counter shaft did not show such wide fluctuations as the cylinder shaft.
This fact seems to show that because of the great mass moments of inertia of the main rotating parts, especially of the cylinder, the kinetic energies of these parts compensate the momentary increase of the loads at the cylinder.
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