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From the field to the sugar factory: the beet harvest

Harvesting is the most complex phase of the sugar beets production. Technological progress and the implementation of more specific software, allow an improvement in harvest times and a better working environment for the operator

by Lavinia Eleonora Galli
January - February 2020 | Back

The self-propelled models, by far the most popular, are particularly powerful, able to reach up to 14 m in length and 4 m in width, with a storage capacity of up to 25-30 t. Consequently, these machines are characterized by high power, up to 4-500 kW, also because the traction is hydrostatic, ensured by two or sometimes three driving axles, often managed in order to distribute the weight evenly on the ground and contain in this way the compaction due to an uneven distribution of the load, also due to the uneven profile of the ground.
The self-propelled beet harvesters consist of a load-bearing frame, on which three different working groups are housed, for picking the tubers, defoliating and cleaning them from foreign material, and conveying to the storage hopper.

 

The harvesting group

The beets are uprooted from the ground by means of front scarifying head with 6-12 rows, preceded by a group of defoliation and root removal which eliminates the epigean part of the crop. The group is completed by a first cleaning group, usually consisting of a pair of star wheels (or rollers), which perform an initial coarse separation of the tubers from the soil and convey the product to the next steps.

The movement of the harvesting group devices is hydraulic: the German company Holmer offers various harvesting heads, with various parts for cutting the epigean part. Moreover, thanks to the device for managing the working depth and the width of the row, the tubers can be uprooted at varying depths, depending on the position of the beet in the ground. The position of the driving position on the machine, with front overhang, allows easy control of the working parts of the head, and therefore enables prompt intervention in case of problems.

 

The sorting system

It is one of the central bodies of the machine, which separates the product from foreign elements, such as vegetable residues, fine soil and small clods. The cleaning is performed by a series of “star wheels” with a more or less dense mesh, which remove the unwanted material through the effect of gravity and centrifugal for­ce. The Dutch company Vervaet adds coupled augers with the “star wheels”, which contribute to the conveyance of the product towards the storage hopper.

 

The transport and storage system

Given the large size of the beet harvesters and above all the considerable load capacity of the hopper and tanks, it is important to keep the centre of gravity as close as possible to the ground to ensure the best stability of the machine in different operating conditions. Moreover, for a correct weight balancing, in addition to placing the hopper near the wheels, it is necessary to carefully study the position of the transport unit, consisting of a vertical bucket conveyor belt. Since the hopper usually has a considerable capacity (up to 30-40 m3), to optimize its filling it is necessary to distribute the load evenly inside. The issue is usually resolved by applying a screw - directly under the conveyor belt unloading point - which distributes the tubers evenly throughout the entire volume. The high working capacity of the harvesters involves quickly filling the storage hopper, for which a bucket arm has been installed for external transport, which unloads the tubers in trailers waiting on the sidelines, or - more efficiently - which stands next to the machine as it operates.

 

Technological innovation

Beet harvesters have also benefited from the computerized solutions for optimizing the process and facilitating driving the machine.

The primary purpose is obviously to minimize losses and damage to the product, keeping the working capacity unchanged. To limit any damage to the tubers with the dislodging parts, some manufacturers, including Holmer on the Terra Dos T4 models, have adopted sensors that allow the adjustment of the grubbing up depth of the tubers, thanks to the dialogue with the hydraulic system control unit. This facilitates the operator's work, as well as reducing fuel costs and product waste.

To facilitate transfers, on larger models with 8-10-12 row heads it is possible to place the harvesting head on a trolley, hooked on the back of the machine, also to the benefit of transit safety. Holmer has developed the EasyConnect, a solution for quick coupling between the harvesting head and the machine body, which the manufacturer claims takes less than 2 minutes.

To reduce compaction and improve machine manoeuvrability at the headland, the load-bearing frame is articulated, upstream of the loading hopper. In addition, for working in the field (and up to a maximum of 10-15 km/h), the twin steering-type rear axles make it possible to keep the machine body misaligned with the harvesting head, thus avoiding the overlap of tyre tracks.

To optimize the headland turns and realign the head after the change of direction, Reichardt and Holmer have developed SmartTurn, a system awarded with the silver medal at Agrithecnica 2017. This option identifies the end of the row by means of foliar probes and warns the operator when it is time to start the turn by means of an acoustic signal. SmartTurn is associated with SmartControl, which allows the lifting of the grubbing head it it doesn't detect the leaf mass and during turns. The signal detected by the probes and combined with the use of a GPS enables the mapping of the field, and the resulting realignment of the harvesting head at the end of the reversal. Another innovation, always awarded the silver medal at Agrithecnica 2019, is the SmartView "See what and how you want" offered by Grimme, i.e. a set of video cameras that continuously monitor the flow of product outside and inside the machine. Thanks to a Wi-Fi or bluetooth connection, it is possible to view in the cabin, with the capability for zoom, slow motion and video recording, every processing moment inside the various points of the harvesting, cleaning and conveyance system, so as to be able to guarantee a better and more timely intervention in case of failure.


The cultivation of sugar beet

Sugar beet is the main sugar crop in the European area. The sowing is in rows, to ensure a suitable expansion of the aerial part of the plant, and consequently the best development of the tuber and effective mana­gement of the harvest, which is carried out from August onwards (practically at the end of the second growing season), so that the transfer of the sugars from the plant to the tuber is complete. Harvesting the tubers requires machines capable of defoliating the plant, and then grubbing up and conveying the tubers in special storage tanks on board the machine, which can be performed both with towed models coupled to the tractor and self-propelled tractors. The most common are self-propelled machines, suitable for high production.


The "V" or inclined wheels harvesting heads

The harvesting heads are composed of rollers, blades and/or knives for cutting the epigean part of the plants, followed by devices for the excavation of the tubers from the ground, usually opposing ploughshares or pairs of converging perforated wheels. As the machine advances, the bodies of the ploughshares, or the two wheels, surround the lower part of the tuber and lift it, dislodging it and pushing it towards the rear of the harvesting head.

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