Agriculture Reference
In-Depth Information
FIGURE 7.9
Mechanical harvester for sweet onions. (From Maw, B.W. et al.,
Trans. ASAE
,
41, 3, 517-524, 1998. With permission.)
foreign materials. Figure 7.8 illustrates the design of a mechanized potato harvester.
As this tractor-drawn harvester moves forward along the row, the soil mass contain-
ing the potatoes and the above-ground plant are excavated, lifted onto the conveyor,
separated from the soil, and finally topped, leaving the harvested potato to be con-
veyed to the transport vehicle.
Similar harvesting principles were incorporated in the self-propelled mechanical
harvester for sweet onions shown in Figure 7.9. The key features of this harvester
include a lifting head to raise the tops, an undercutter to separate roots from bulb, a
soil shaker, a topper to cut tops from the bulb, and a conveyor to move the onions to
transport vehicles (Maw et al., 1998).
7.3.3 S
URFACE
C
ROP
H
ARVESTING
In surface crop harvesting, the location of the harvestable portion is just above the
soil surface, as shown in Figure 7.7. However, the exact transition from surface
crop to bush crop is not well defined and left to interpretation. Cabbage, tomatoes,
strawberries, and lettuce are some examples of surface crops. The development of
mechanical harvesting of tomatoes, cabbage, celery, and strawberries began in the
1960s. Compared to root crops, surface crops require a higher level of technology
to mechanically harvest. Cutting, combing, stripping, vibration, and threshing are
some of the harvesting principles used for surface crops.
Figure 7.10 shows a mechanical harvester for cabbage (Chagnon et al., 2004). The
harvester is composed of a picker assembly, inclined conveyor, and horizontal con-
veyor. The picker pulls the cabbage up using two belts, which capture the head,
and then cuts the stalk using a rotating cutter belt. Both the inclined and horizontal
conveyors are used to move the cabbage to the human grader/sorters. This machine
is now available commercially.
