عنوان مقاله [English]
نویسندگان [English]چکیده [English]
Colza (Canola) is a crop with high rate of grain loss during harvesting. At harvest, semi-dried grains of canola’s pods are either opened or dropped due to mechanical impacts. Therefore, lots of grains drop before entering combine head. Another obstacle to successful harvest of canola is that ripe grain's pods are twisted together. This results in heavy grain loss at dividers of combine pickup head. The reason is that dividers tend to separate pods by imparting pressure on twisted pods causing heavy grain loss. In the present research, a mechanical attachment was designed, manufactured and mounted on the right hand side divider of a 955-John Deer combine common in local farms. The unit is aimed to separate pods which in turn reduce grain loss. The attachment is made up of two cylinders, each cylinder carrying 20 fingers. A mechanism is fitted to each cylinder to move the fingers in a reciprocating manner. The dual cylinders rotate about their main axes in opposite directions. Movement of adjacent fingers on each cylinder force twisted pods to separate. Field experiments were conducted to evaluate the performance of the unit in comparison with the control. A grain combine with no attachment on the divider was considered as control. The variables consisted of the rotational velocity of the cylinders in three levels (26.5, 53.0 and 79.5 rpm), and the number of fingers on each cylinder (10, 14 and 18). The treatments were arranged as a factorial experiment replicated three times. The forward speed of combine harvester was maintained at 1 km h-1. The weight of grain loss in each treatment was determined and used in subsequent analyses. Statistical analysis of data shows that variation of cylinder speed has significant effect on grain loss at p=0.01. Other results indicate that at rotational speed of 53.0 rpm, the grain loss is the lowest. Number of fingers also exerts a high significant effect on grain loss at p=0.01. Increasing the number of fingers on cylinders resulted in reducing grain loss. The grain loss of the combine harvester equipped with the separating unit was 51.1 kg ha-1 as compared to 61kg ha-1 for the control.