Linear and vibrating manual sorting table

Positioning in the grape harvest reception line

Linear manual sorting tables and vibrating tables operate on the same principles.
They can be positioned before or after the destemmer.

Before the destemmer

In the case of mechanical harvesting, the sorting table is used to eliminate any rotten or under-ripe grapes picked up by the machine, which are crushed and mixed with the healthy grapes after destemming.
Sorting before the destemmer also removes any leaves, petioles and other debris before they are torn off if not separated by the destemmer.

Sorting table positioned before the destemmer

After the destemmer

Manual sorting after the destemmer completes the cleaning of the harvest carried out mechanically by the destemmer, by eliminating some of the petioles, stalk fragments and leaves present in the destemmed harvest before vatting.

Manual sorting table positioned after the destemmer

Principle of sorting on a linear or vibrating table

The principle of manual sorting consists of passing the harvest in a thin layer on a moving support in front of the sorting personnel.
There are, however, static sorting tables available for sorting manual harvests in the vineyard.

Diagram of a linear belt sorting table

The main characteristics of manual sorting tables

Table dimensions

Table length
The length of table required depends on the number of sorters.
BCMEA recommendations (if n is the number of sorters):
Sorters on one side of the table: L = 0.80 m X n
Sorters on 2 sides of the table: L = 0.80 m X (n / 2 + 0.5) (in this case, a staggered layout is preferable).

Table width
The suggested widths depend on the distribution of the sorters.
Layout on one side only: 0.40 to 0.60 metre
Layout on both sides: 0.80 to 1 metre

Table height and inclination
It is preferable for the tables, which are generally mounted on castors with brakes, to be adjustable in height for the comfort of the sorters and to adapt them to the equipment located upstream and downstream.
The height can be adjusted either manually, using telescopic legs, or by means of a jack system.
By adjusting the height of the legs, the table can be tilted to ensure better juice recovery at the table entrance and to raise the harvest to the height of the equipment located downstream in the reception chain. Maximum gradients of 10-20% are possible.

The conveyor belt and vibrating plate

This is made of food-grade PVC (the vibrating tables are made of stainless steel), perforated or not.
It is tensioned by two rollers and the tension is generally adjustable.
Its colour should contrast well with the grapes. The mats on the tables offered are generally light-coloured.
Some tables are equipped with a belt scraper , which may be adjustable, to clean the belt continuously during work and facilitate cleaning at the end of the day.

Belt tension roller

Perforated belt

Belt scraper

Speed and motorisation

Linear sorting tables are generally fitted with a variable speed drive. Maximum belt speeds are generally around 10 m / minute, with some reaching around 40 m / minute.
Vibratory sorting tables are equipped with two centrifugal weights that vibrate the top plate. It is this vibration (wave effect) that carries the harvest to the end of the table. An electronic variable speed drive can be fitted as an option.
The forward speed required for effective sorting depends on the number of sorters - for a given table length - and the thickness of the layer of grapes.

This useful forward speed generally only allows low to very low throughputs of grapes, which determines the choice of equipment placed upstream or downstream.The correct operation of a reception chain requires the following rule:
Equipment placed upstream of the table: its flow rate must be 5% less than that of the table.
Device located downstream of the table: its flow rate must be 5% greater than that of the table.

A satisfactory compromise must therefore be found to ensure :

the correct flow rate to supply all the equipment (destemmers, pumps, etc.),
good coordination of the flow rates of the various devices,
sufficient sorting.

Systems for optimising sorting efficiency and quality

Juice recovery

To facilitate sorting, it is preferable for the harvest to be drained. Draining can be carried out at several levels:

Main draining: before the table, at reception (skip, conquet, vibrating draining table, etc.).
Additional draining: at the table, at different locations depending on the design:
Juice collection at the table entrance, in a collection tank topped by a draining hopper.
Juice collection and light sieving at the beginning of the manual sorting vibrating table.

Spreading device

For sorting to be effective, the table must be supplied regularly, at an adjustable rate, and the grapes must be spread evenly over the belt. In addition to the possibility of preceding the linear table with a vibrating draining and spreading table, some tables are equipped with devices for spreading the harvest.

Heat treatment and drying of the harvest

This option, which involves blowing hot or cold air over the harvest, is offered by some manufacturers on linear sorting tables

Selective berry sorting

On some models of vibrating table, a perforated plate slightly larger than the berries allows selective sorting by sieving the round berries detached from the stalks during mechanical harvesting. Bunches or portions of bunches, berries stuck to the plate and any particles larger than the perforation are deflected to either side of the table for passage through a destemmer.

Magnetic sorting

A magnetised bar, located above the passage of the harvest, retains the metallic elements. Some manufacturers offer this option on linear or vibrating sorting tables.

Cleaning, accessibility and safety

Cleaning and accessibility

Ease of cleaning is an important factor in the hygiene and lifespan of the table.
The components must be easy to dismantle and allow direct access to and under the table for thorough cleaning.
One manufacturer offers a quick-release belt system for easy access to all internal points (rollers, belt, etc.), while another offers a washing ramp.

Safety and protection

The equipment must comply with current legislation and, in particular, be fitted with :

emergency stop buttons on each side of the table for use from both sides,
protection of entry points.
protection of motors and control elements.

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