Three combine harvesters at different service life (Fortschritt E514 {1} has been serving for 25 years – Class {2} has been serving for 15 years and John Deer {3} has been serving for 2 years) were tested and compared to another mechanical method mower than thresher (one thresher has free knives on the threshing drum {1} and the other has fixed knives on the drum {2}) compared to traditional method (sickle than thresher {1}). The mechanical harvesting methods were done at three different field speeds 1.9, 2.7 and 3.9 km/h for mower and combines. Also, three different moisture contents 12.1, 14.34 and 16.58 % were effected on harvesting, threshing unthreshing, damaged grain and total grain losses for the previous machines.
The experimental results showed that pre-harvesting losses for Sakha 93 was about 0.51 %. The highest total grain losses for combine 1, 2, 3 and mower were 10.36, 7.19. 3.14 and 3.98 % respectively at field speed 3.9 km/h and grain moisture content 12.1 %. Besides, the highest sickle loss is 2.01 % at moisture content 12.1 %. The highest un-threshing losses were 1.13 and 1.22 % for thresher 1 and 2 respectively at grain moisture content 16.58 %. The highest grain damage were 2.24 and 2.02 % at grain moisture content 12.1 % for thresher 1 and 2 respectively. Harvesting speed 2.7 km/h gave the lowest energy with combine 1, 2 and 3, which were 38.95, 34.76 and 43.61 kW.h/fed respectively. Mechanical method (mower then thresher) consumed about double energy consumed by combine; while, traditional method (sickle then thresher) consume about the same energy with combine. Thresher 2 consumed less energy than thresher 1 that because thresher 2 has free knives on the drum depend on the impact. The highest criterion cost with combine1, 2, 3 and mower are 355.9, 277.59, 177.56 and 158.06 LE/fed respectively at field speed 3.9 km/h, and grain moisture content 12.1 %.
* Senior Res ., Ag. Eng. Res. Inst . ( AEn.RI) , Egypt .
The highest criterion cost with sickle is 229.65 LE/fed at grain moisture content 12.1 %. The highest criterion cost with thresher 1 and 2 are 225.89 and 223.67 LE/fed respectively at grain moisture content 12.1 %.