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

266 M. Ruiz-Altisent et al.
etc.). The conventional cutting devices are applied for this function: rotating discs
with dented edge, flat or with some concavity; cutting bars, simple or double. In
some cases the objective may be to remove entire plants, even below the surface
(tomatoes, pickling cucumbers) to be subjected to further detachment of the fruits;
in others, to recover the tender edible green parts (spinach, cabbage) (Figure 2).
Frequently, a powered reel or rotating side cylinders are added to help feeding
and further conveying the product up the band or bar-chain conveyor. Functional
parameters of cutting devices are:
– cutting speed;
– advance speed;
– sharpness of the cutting edge;
– speed and position of the feeding reel or cylinders, with respect to the cutting
elements.
Combing is based on particular properties of the plants:
– the plant is firmly attached to the soil by its root system and grows erect;
– the portions to be detached and removed have different size, shape and/or rigidity
from the leaves and stalks (e.g. green-beans or pea pods);
– the portions to be detached possess a zone of abscission, susceptible of being
severed by traction or by flexural forces;
– the parts to be recovered (e.g. strawberry fruits, green bean pods) have to be
capable of resisting the action of the combing fingers.
Functional parameters of combing are:
– speed of the extreme of the combing fingers that has to be around 4 m/s for a
forward speed of approx. 0.5 m/s;
– speed and position of the conveying device situated behind the combing fingers,
to assure the removal of the product from further impacts;
– speed of the feeding reel, conveying band or brushes which are installed in
front of the combing fingers (Figure 3).
Figure 2. Cabbage harvester. (1) guiding discs, (2) guiding surfaces, (3) driving belt, (4) coulter bar,
(5, 6, 7) band conveyors (8, 9) separation devices.