Technical and Economical Assessment of Tractor Mounted Topper

About one third of the onion harvesting time and cost is consumed for removing of leaves from onion bulbs. Accordingly, the use of appropriate topping technologies is one of the main objectives for development of onion harvesting mechanization. In this study, a rolling onion topper was modified in such a way that to be mounted on a tractor. Then, the effect of two rotational speeds of leaf remover blades namely, 2950 and 1800 rpm on remaining leaves of onion bulb after cutting, and also, the percentage of topped onions and percentage of damaged bulbs were measured to determine the suitable speed. Necessary modifications were made on the machine to enable it to be run and transported by a tractor. In the next step, the machine's field capacity was calculated and economical comparison between conventional topping method by labor and the device was carried out. The results showed that both 2950 and 1800 rpm rotational speeds of the topping blades do not have significant effect on remaining leaves after cutting, percentage of topped onions and percentage of damaged bulbs. According to the design requirements and energy reduction of leaves removing, the rotational speed of 1800 rpm was proved to be the appropriate speed. Economic evaluations showed that replacing of conventional topping method by topping machine reduces work force by 43 workers and saves 53% of the costs per hectare.