Development of a Mechanical Harvester for Crisphead Vegetables

Development of a Harvesting Mechanism

Abstract

In this paper we describe the developments of a harvesting mechanism and an experimental harvester including the results of field tests from 1973 to 1977.
1) The developed harvesting unit was constructed with main parts as follows; two vertical rubber rolls and V-belts stuck rubber tubes which made the control of the posture and the feeding of heads, a disk-type rotary cutter, a floor conveyer, and a lifting conveyer which was constructed with two upper rubber tubes and two under V-belts stuck rubber tubes. This unit was for harvesting crisphead lettuce, and Chinese cabbage was harvested by attaching a free roll in front of the lifting conveyer to fall before coming in the conveyer. Also, cabbage and cauliflower were harvested by attaching an unit to hold stems between two augers and feed them to the cutter, (see Fig. 1).
2) An experimental harvester was made for the purpose of field tests mainly for the harvesting unit. This harvester had a crawler traveling unit and a 8 P. S. engine, and the above harvesting unit was suspended in front of the left side track. Also, a belt conveyer for cutting heads again with stem parts and for separating heads, three boxes for collecting graded heads, a floor for packing heads, a shelf for loading cartons and the others were mounted on the frame of the tracks (See Fig. 2).
3) In harvesting lettuce the percentages of good harvested heads, of which the cutting stem parts again were almost unnecessary, were 60-70%, and in this case the percentages of deep cut heads were 6-7%. Under the above conditions and the plant condition of the harvesting rate of about 60% harvesting was able to be performed in the working speed of 2.0 seconds per space between plants with the crew of 3 men including an operator.
4) In the harvesting of cabbage of many varieties the percentage of deep cut heads was less than 5% when the percentage of good harvested heads was less than 50%. However, important problems have been left. Those are the problems of the harvesting unit of which raising action is inferior to lodging plants and leaves are accumulated inside the unit and that the reducing of crew on the harvester is most necessary in comparison with the field efficiency of actual once-over harvests by hand-crew.
5) It was recognized that there was a possibility of using the harvesting unit for Chinese cabbage and cauliflower.