Production Practices and Quality Assessment of Food Crops. Vol. 1

Fruit and Vegetables Harvesting Systems 267
Figure 3. Cylindrical reel-type snap-bean harvester. Pods are removed by contact of fingers with the
pedicle. Detachment originated by the cylindrical reel and the concave sheet in the plant.
As mentioned above, harvesters for strawberries (fruits which must be classified
in this group, as aerial herbaceous commodities) may be provided with combing
fingers attached to slow-moving elevating bands, and the operation is aided by
air currents which elevate fruits and leaves to the fingers for easier combing
(Figure 4). Instead of combing, some strawberry harvesters use a cutterbar-reel
principle, which cut the entire plant and separate the fruits in the machine by again
air-lifting and cutting, or by stripping The combing effect attained by two counterrotating
brushes is used in harvesters for some varieties of paprika-pepper for
the detachment of the fruits (the concept derives from the combers/strippers for
harvesting cotton capsules).
Stripping by the action of counterrotating rollers pulling the plant down is a
procedure by which the commodity (fruit) is separated from the plant, based on
the differential properties between fruit and plant: size, shape and attachment
strength. This principle is used to detach cucumbers (pickling) from their (already
cut) supporting plants; in pepper harvesters, and in combination with other functions
in selected harvesters: destemming of onions, strawberries, olives, cherries, . . . ;
detachment and deleafing of (sweet) corn cobs. The principle consists of the pulling
action of two counterrotating rollers, provided with some roughness condition: it
can be the surface itself (rough rubber rollers), or helix-shaped structures attached
to the rollers. The rollers trap the long and thin plant parts (stalks, with leaves),
and severe them from the commodity by a pulling action (Figure 5, see also 4).
The product is conveyed by different ways like: inclination of the rollers, or conveying
by the helicoidal attachments on them; or also by falling onto separate
conveyors (like in some onion harvesters). Functional parameters of this system
are:
– turning speed of the rollers;
– separation between the rollers;
– engagement speed (forward speed) to the plant.