Patent Description:
The importance of crop yields in modern agriculture is the result of a joint evolution of soil management practices. The high production costs that exist today lead producers to seek to optimize the use of inputs. In this, the sowing operation has a transcendental role that not only implies the optimization of the seed as a high cost input, but also leads to the achievement of a planned plant location, a uniform distribution and with a homogeneous development that will have a decisive influence on the expression of the yield potential, the optimization of the gap available for each plant, which increases the yield of the crop by minimizing the intraspecific competition for light, water and nutrients, and these are directly dependent on the seed dosing system.

A coarse grain-sowing machine, including a horizontal tool bar attached to a hitch set to be towed by a tractor, has a set of wheels that allow its offset. It is also made up of a chassis that provides structure to all the components. Above it, there is a container hopper, which can be centrally loaded, and from there, by means of an air current, the seeds are transferred to each sowing line.

Another version of the sowing machine called mono-hopper with seed exhaust by gravity has individual drops for each sowing line. In addition, in less demand of use, the individual hoppers are located on each body of sowing. In the chassis, it has a main horizontal tube or tool bar, wherein the sowing bodies are located along the length, distanced from each other according to the desired sowing distance. This position can be fixed for each seeder model or can be transformed at a different distance. The "seed dispenser" is located on top of the sowing bodies. These bodies can move vertically through parallel bars, they have two basic elements that are smooth discs with sharp edges, located on an inclined shaft that allows the rotation, maintaining the contact of both edges in the front and its angular opening is open backwards. This allows generating a sowing furrow in the soil to receive the seeds. In the center of these elements is located a seed conductor tube, this is the part that receives the seeds coming from the dispenser.

In general, more particularly in accordance with <FIG> related to the prior art, wherein a scheme of a sowing set with seed feeding by gravity fall is illustrated, the constituent elements are: main hopper <NUM>, turbine suction <NUM>, air conductive suction tube <NUM>, seed exhaust hose <NUM>, pneumatic grain dispenser <NUM>, cross beam <NUM>, sowing body <NUM>, discharge tube <NUM> and planting discs <NUM>.

In <FIG>, also related to the prior art, a general scheme of an air stream seed feeding sowing set is presented. Wherein said set comprises a pressurized hopper <NUM>, a blower turbine <NUM>, a seed conducting hose <NUM>, a cross tube <NUM>, a pneumatic seed dispenser <NUM>, a sowing body <NUM>, an exhaust tube <NUM> and the seed planting discs <NUM>. Further relevant prior art is <CIT>, <CIT> and <CIT>.

Possibly the seed drill metering unit is the most important element of the seed drill. Coarse grain seed drills are characterized by the use of single grain dispensers, which are capable of distributing the seeds individually.

The furrow seeders are designed to place the seeds in spacings determined according to each type of seed.

The mechanical dosing units with horizontal or inclined plate are known wherein the collection of the seeds is done by means of a plate with bores. Both the thickness of the plate and the size of the bores are limited by the shape and dimensions of the seed to be sown (width, length, thickness), in order to capture one per bore, which determines a limitation in the versatility of the mechanism depending on the seed used and the uniformity of the same. In the horizontal models, the flush triggers or brushes are used to regulate the entry of seed into the seed catchment area, and the driving triggers drop the seed onto the exhaust area of the counter plate and from here the seed is lowered by the action of gravity through the exhaust tube into the furrow.

Other known mechanical meters are finger meters, which are constructed so that radially positioned fingers (metal tabs) are held in contact with the face of a smooth plate and grasp the seeds as they pass through the seed reservoir, subsequently releasing those seeds as they pass through an empty area in the plate and from there fall by gravity into the seed exhaust conduit. Although these mechanical seed meters are effective, they have limited capacity to ensure uniformity of individualized seed delivery.

Unlike mechanical seed meters, in pneumatic seed meters the plate has smaller diameter bores than the seeds and the seeds are captured over said bore (they do not pass through it) by means of a stream of air that can be either suction or pressure. This defines a first categorization of pneumatic systems, i.e. those that work by negative pressure (suction or vacuum) or by positive pressure (blowing).

In its most basic form, the seed dispenser includes a container and inside it a seed receiving plate (sowing plate). We can differentiate the housing as a fixed element with a configuration in such a way that it sectorizes the areas and generates a reservoir to contain the seeds. The sowing plate resides inside the housing and rotates around a central axis that is generally horizontal. As the sowing plate passes through the seed reservoir it collects seeds individually. The seeds are then distributed in a seed conduit wherein they fall into the sowing furrow.

Pneumatic seed dispensers with honeycombed plates, by "pressure", are made up of a plate that has a plurality of small cavities with a certain shape. These cavities, with a drilling smaller than the size of each seed, allow the seeds to be lodged in these cavities, driven and supported by the air pressure generated by a hydraulically driven turbine. The plate rotates, until each drilling reaches a point wherein the pressure is canceled and the seed is released. In some cases they have a series of brushes that act as flushes, i.e. seed orientators on the drilling. The pressure must be regulated, according to the type of seed and its weight.

The pneumatic dispensers, by "suction", are constituted by a flat plate in vertical position and there are variants of plates with cavities in low relief. The bores in the plate are smaller than the seed and in communication with the suction channel produced by a vacuum turbine, each seed is captured by the plate and remains there until, by the rotation of the plate, it reaches the point of detachment wherein the suction cut for release occurs, and falls by gravity. In order to prevent duplication of seeds in the same bore, a flush is used, which can be fixed or mobile, to orient and leave only one seed. When soybeans are sown, the plate usually has two rows of drilling for high planting density, or a single row for lower densities. A hydraulically driven turbine must have sufficient capacity to produce the required suction. Under certain conditions it may be necessary to regulate the suction according to the size and weight of the seed. Once the seeds have adhered to the bores in the plate in the feeding phase, they are transported during the rotation of the plate until they reach the point of fall wherein they are released, and from there they fall by gravity. The suction area is the one that limits the beginning of the seed collection and the end wherein the seed is released through the conductor tube into the furrow.

Pneumatic metering units can be driven by mechanical transmission connected in all the seeding lines to a shaft which is commanded by a transmission box, driven by a driving wheel which is kept in contact with the soil. In recent times the demand for electric motor drive systems is growing.

To obtain the best conditions in the agricultural crops and harvest, it is important that the seeds are placed at a constant and equal distance from each other, maintaining the uniformity in the depth wherein the seed is housed in the furrow formed in the soil. This improves crop yields and thus increases the profitability of the sowing.

In accordance with <FIG> related to the prior art, a pneumatic dispenser fed with seeds through a positive air stream <NUM> is shown. And in <FIG> a gravity fed seed dispenser <NUM> is shown.

Currently, pneumatic dispensers have seed receptacles with a low volume of content and cannot dose large seeds such as beans and peanuts. This makes it difficult for the seeds to circulate correctly to the sowing plate, causing an obstruction in the entrance.

With respect to the reduced diameters of the sowing plates in situations of high seed dosages, it causes that the plate must have higher revolutions to deliver the desired doses and this causes that the seeds are detached from the plate with high rotational speed generating impacts on the exhaust tube, causing that the seed is delivered to the furrow with delay. Or double bore row seeding plates are used, but these devices lose dosing accuracy.

Pneumatic seed fed metering devices through a positive airflow, usually present problems of overflow inside, delivering seeds without metering through the exhaust tube due to failures in the design of a system to regulate the volume contained.

Pneumatic dispensers are prepared to work in vertical position, the volume of seeds contained inside can spill if the dispenser changes to horizontal position. This situation occurs when the machine performs chassis folding manoeuvres by rotating the tool bar to change from the sowing position to the sowing machine's transfer position.

The setting and changing of the sowing plates in the pneumatic seed drills involves time losses that can be reduced with anchoring and quick release mechanisms, without the need for tools.

The systems that generate the suction area and the seed flushes, according to their shape and material used, come to perform too much friction on the moving parts causing an increase in the torque required for the performance of the dispenser. This fact, when using electric drive, increases the consumption of electric energy. And, when this happens, more elements must be added such as an electric generator and additional batteries to cover the consumption demand that the tractor cannot supply.

The access of the suction hose that is connected to the dispenser requires integrated or coupled nozzles in the dispenser cap, being defined whether the hose connection is to the front of the seeding machine or to the rear, which implies lack of adaptability to different machine models. Some dispenser brands offer different nozzles to suit the location of the hose.

The present invention is defined by the claims and relates to a pneumatic seed dispenser which permits the delivery of the seeds into the soil with the desired density and uniformity of spacing.

This dispenser is designed to be placed on the sowing body of a coarse grain sowing machine or fine grain sowing machine with coarse grain kit, receives the seeds from a hopper, doses them and releases them through a seed exhaust tube. The seeds can reach the receptacle of the dispenser falling by gravity or by a current of blown air and, once entered, are captured by a negative air current which, by suction, leaves the seeds retained against the bores of the sowing plate. These voids called alveoli have a size determined by the type of seed to be implanted and are smaller than the seed.

The use of the pneumatic dispensers was conceived from the beginning to be used by means of a feeding of seeds that fall by gravity. In today's use with air stream seed feeding, a new functional concept is required. Since air stream systems move the seeds to a receptacle and do not stop carrying seeds until the end is blocked with them, the dispenser should have an area that allows the entrance of seeds to be regulated, allowing the entrance of the necessary amount to dose, and it should also have an air outlet that reaches the interior of the dispenser's receptacle to depressurize the circuit.

The dispenser according to the present invention solves the problem of being able to dose all types of seeds and of different calibers, achieving a correct uniformity of delivery of seeds to the furrow in the soil. Through its internal elements which allow regulating in a quick and simple way the leveling of the seeds, which enables always dosing one seed per alveolus, not allowing more quantity of seeds to go in order to avoid intra-specific competition. For each type of seed to be implanted, a specific perforated plate is used, which is changed in the dispenser quickly and easily.

It is the subject matter of the present invention, a pneumatic dispenser having a receptacle of suitable size for receiving, containing and dispensing seeds of various sizes.

It is the subject matter of the present invention, a pneumatic dispenser having a guillotine regulating the flow of seeds into the receptacle, with external regulation and with a numbered step graduation. Said guillotine has a substantially triangular shape and is vertically mounted in a movable form commanded by an external knob to regulate the flow of seeds in both dispensers with seed feeding by gravity and in dispensers with seed feeding by air current.

It is the subject matter of the present invention, it is then a pneumatic dispenser having external regulation of the flushes on the seed plate and of the position of a seed intake flow guillotine.

It is the subject matter of the present invention, a pneumatic dispenser which allows low and high seed rates with low rotational speed, while maintaining a high seed rate.

It is subject matter of the present invention, a pneumatic dispenser of low torque and with minimum friction of elements on the seeding plate, being the whole rotation system mounted on two ball bearings.

It is the subject matter of the present invention, a pneumatic dispenser of a honeycombed plate with low relief depressions which improve the seed collection and function as seed removers during the loading of the seed on the sowing plate.

It is, furthermore, another subject matter of the present invention to provide a pneumatic dispenser, which allows quick access to the area of the seeding plate, by removing the cap of the dispenser by means of <NUM>/<NUM> turn of two locks without the need to remove these parts.

It is also another subject matter of the present invention to provide a pneumatic seed dispenser having a quick change of seeding plates, carried out by a simple turn of a locking part and without the need for tools.

It is, furthermore, another subject matter of the present invention to provide a pneumatic dispenser with a floating seed flush set of permanent contact against the surface of the sowing plate and with external regulation of its position.

It is still another subject matter of the present invention to provide a pneumatic seed dispenser having a suction inlet nozzle to the metering unit which allows the hose to be positioned vertically. Allowing a versatile connection which can come from the rear of the machine or from the front.

It is furthermore another subject matter of the present invention to provide a pneumatic dispenser, with a system of mounting to the planting body with a quick anchorage, which allows it to be placed and removed quickly without requiring hand tools.

It is furthermore another subject matter of the present invention to provide a pneumatic dispenser having a support structure with attachment to the planting body with integrated feeding nozzle.

It is furthermore another subject matter of the present invention to provide a dispenser which can keep the seeds in the catchment receptacle, even if the metering device is placed in a horizontal position.

For greater clarity and understanding of the subject matter of the present invention, it has been illustrated in several figures, in which the invention has been depicted in one of the preferred forms of embodiment, all by way of example, wherein:.

With the subject matter, then, of showing and describing the advantages and advances of the dispenser subject matter of the present invention, different forms of embodiment will be described below by means of the accompanying Figures.

<FIG> is used to illustrate the details of a preferred form of embodiment of a dispenser according to the present invention with positive air pressure feed, such as a conductor tube <NUM> linked to the seed reservoir <NUM>, with air outlet slots to depressurize the circuit <NUM> and a translucent display to observe the normal operation of the entered seeds <NUM>. A cylindrical bar for attachment to a support <NUM>, centering device and support positioner <NUM>, quick leverage attachment system <NUM>, centering device and female locking area in housing <NUM>. A cap of cleaning mouth <NUM> and the elastic bands of locking <NUM>.

<FIG> shows a perspective view of the right side of the housing of a preferred form of embodiment of a dispenser according to the present invention with gravity feed of seeds. It shows the following parts: a gravity seed inlet nozzle <NUM>, reservoir <NUM> connected to the seed supply reservoir <NUM>, a seed passage shut-off guillotine <NUM>, dispenser housing <NUM> with air recirculation slots <NUM>, and a seed release sector <NUM> which is linked to the exhaust tube.

<FIG> shows a view of the left side of the dispenser cap. The following parts are identified: male cap lock link <NUM>, dispenser cap <NUM>, two snap shut knobs <NUM>, flush register lever <NUM>, register scale surface <NUM>, vertical air suction inlet nozzle <NUM>, and a drive cam <NUM>.

<FIG> shows the housing with details of the following parts: a guillotine position register knob <NUM> and the two areas with low relief to lock the cap lock <NUM>.

<FIG> is an interior view of the housing that identifies the cover plate for a seed discharge area <NUM>, a flow control guillotine <NUM>, a lock washer <NUM>, a compression spring for guillotine handle <NUM>, housing fixing nuts to the bracket <NUM>, seed content delimiting brushes <NUM>, guillotine fastening screws <NUM>, nut retention housing <NUM>, guillotine guide <NUM>, foreign particle drainage area <NUM> and foreign particle exhaust receptacle <NUM>. In particular, the regulating guillotine <NUM> of the flow of seeds into the receptacle comprises an external regulation with a numbered graduation. Said guillotine <NUM> has a substantially triangular shape and is vertically mounted in a movable form, commanded by an external knob <NUM> (see <FIG>) to regulate by means of a partial closure the flow of seed in both metering units with gravity or airflow seed feed.

<FIG> shows a main exploded view, namely: a seed flush set <NUM>, an eccentric shaft for flush adjustment <NUM>, a compression spring for permanent contact of the flush <NUM>, a plate drive plate <NUM>, a suction boundary seal <NUM>, a plate lock with triple contact spring <NUM>, a removable bracket for a cleaning wheel <NUM>, a plate pocket cleaning wheel <NUM>, a seed drill plate <NUM> and three seed drill shafts <NUM>.

<FIG> is a perspective view with an open section that allows the identification of the components in contact with the seeding plate, which are detailed in <FIG>.

<FIG> allows the identification of the assembly of the dispenser to the seed body, with the references indicated in <FIG> and the dispenser receiver bracket <NUM>.

<FIG> shows the housing <NUM> to receive the cleaning wheel <NUM> bracket <NUM>, a spring pin <NUM> from the locking pressure knobs <NUM> and other items already described in <FIG>.

<FIG> shows the sowing plate <NUM> with its main characteristics. The low relief remover zone is perimeter, wherein the right lateral sector of the low relief <NUM> is right angle to remove the seeds during rotation and the opposite side with inclination <NUM> to detach any foreign particles that are lodged in the low relief. The cylindrical drilling that cross the plate <NUM> are commonly called alveoli in the language of sowing. The center of the plate <NUM> has a cylindrical shape which allows to center the plate with the drag plate <NUM>, it has a ramp shaped surface <NUM> and works in conjunction with the plate lock <NUM>. The anchoring area comprises three rounded sectors <NUM>, which maintain contact with the three drive shafts of seed plate <NUM>.

<FIG> presents the flush register elements, the elongated slot <NUM> to allow the offset of the eccentric shaft <NUM> to regulate the movement of the flush set. The lower flush <NUM> moves in conjunction with the upper flush, because it is linked by a bridge <NUM>. The shaft <NUM> is the center of rotation of the flush set. The sector that links the cap to the housing has two cylindrical sections of the same cap material that serve as locators <NUM>, the cylindrical half rod <NUM> is to receive the elastic spine <NUM> of the cap lock.

Making reference to the figures detailed above, the present invention consists of a new pneumatic seed dispenser, which allows the dispensing of multiform seeds from fine grains such as "wheat" and large grains such as "beans or peanuts", individually and at the distance from each other required by the user. Having external regulations and in a very understandable way for its use.

As a highlight, the dispenser can be mounted on the seed body without the need of tools. <FIG> allows interpretation of the system, wherein the cylindrical hitch bar <NUM> is hung on the receiver bracket <NUM>, the centering shaft <NUM> must be inserted, and finally the quick lever hitch <NUM> is operated. Another highlight can be interpreted by looking at <FIG> and <FIG>, where you can see the centering device and female locking area in the housing <NUM> and the centering device and male locking area of the cap <NUM>, these elements are responsible for improving two functions, one is the guidance during the placement of the cap and the other is to provide a third point of blocking the cap. By operating two pressure/locking knobs <NUM>, the cap can be removed and there are no loose elements to be misplaced. When the cap is removed, the seed plate is accessible. To remove the seed plate, simply turn the triple contact spring plate lock <NUM> by <NUM> (<NUM>/<NUM>") and the seed plate can be removed. The necessary adjustments to set up the seed inlet flush and guillotine set are accessible from the outside.

<FIG> and <FIG> are used to show the two systems for feeding seeds into a dispenser according to the state of the art, showing the main components of the system. <FIG> identifies the parts of a positive air stream seed feeding nozzle, a metal tube <NUM> integrated into the top sheet seed reservoir <NUM>, this has slots in the reservoir <NUM> which carry out the depressurization of the system, the tube <NUM> is connected to a flexible hose <NUM> which carries the seeds from the centralized hopper <NUM>. Once the seeds are entered and when the level is completed until the mouth of the tube is covered, this generates the cut of entry of the seeds, until they are dosed with the sowing plate <NUM>, as illustrated in <FIG>. This dispenser, unlike others in the market, allows the dosage of multiform seeds, having a great capacity for feeding the seeds, comprises sowing plates designed for the main types of grains and alveolus cleaning wheels characterized for each plate. The system of adjustable seed flush allows the use of the same component with different types of grains and sizes, ensuring that only one seed is left in contact with the seedbed alveolus and that any surplus is removed, unlike other fixed flushes that do not have regulation, reducing their effectiveness with the variability of grain sizes. The simplicity of the system makes it easy to interpret the use of the flush register and its manipulation.

The sowing plate <NUM> in <FIG>, is a circular disc that is positioned on a central axis of the dispenser, each disc comprising a plurality of passing openings <NUM>, called alveoli, located radially and with equal spacing. It has an area under relief <NUM> that behaves as a seed agitator to improve the collection during the rotation of the plate. This bas-relief has the right side with a right angle <NUM> to perform the removal during the plate rotation, and the opposite side has an inclination to slide foreign particles that accumulate in this area to the outside through the exhaust tube or to the impurity receptacle <NUM>.

There is also a generic plate that comprises different amounts of bores or alveoli, and diameters to fit more types of seeds covering a greater variety of them.

The shaft that provides movement to the plate has a cam <NUM> from its external side, it is mounted on two spherical bearings or alternatively a polymer bushing with a high offset coefficient can be used, coupled to the shaft by means of a ratchet the rotation movement that can come from a mechanical transmission drive or from an electric motor is applied to it.

Behind the sowing plate as shown in <FIG>, there is a vacuum zone delimited by a flexible weatherstrip <NUM>, which allows a constant vacuum to be maintained against the plate, operating at low friction. On the housing there are two projections with cylindrical housing <NUM> to receive the bracket of the cleaning wheel <NUM>; this bracket has two wings that, when pressed inwards, are bent to be able to be mounted on the cylindrical housing.

As it has delimiting brushes in the seed storage sector, it allows that when the dispenser is in a horizontal position during supposed cases of machines that make rotation of the main bar of sowing bodies bracket, seeds are not spilled involuntarily towards the zone of the exhaust tube.

The dispenser housing <NUM> can be made of translucent plastic material to facilitate the visualization of the components inside the dispenser.

According to the description provided in <FIG> and <FIG>, the housing has an element called register handle <NUM>, having a low relief that allows positioning the height of the cutter point by point, as well as identifying its position and being able to repeat it in the other dispensers. The compression spring that operates on the knob, gives it security to maintain its position. The flow regulation guillotine <NUM> has a certain geometry to avoid that the positive pressure air that feeds the seeds to the dispenser can agitate the seeds and they overflow towards the exhaust tube in a direct way, without being dosed by the sowing plate. The arrangement of the boundary brushes of the seed collection chamber <NUM>, due to their location, allows to contain the seeds that have entered the collection area both in vertical and horizontal position. These brushes can be replaced without tools, they are held in place by wings made of the same material as the housing, and the recess is by the offset from one end. The housing is held closed by two locking knobs <NUM>, these knobs have a cylindrical shaft that links the grip area and at the opposite end is located transversely an elastic spine. <FIG> shows the two areas with low relief to block the cap lock <NUM>, where the lock is closed and opened. They have a chamfered shape that functions as the mouthpiece of the cylindrical section of the knobs, the vertical groove has a through draft to free the knob and the horizontal slot has a half-round shape to receive the lock.

The negative air stream seed dispenser, according to the present invention, comprises a set of triple top contact and double bottom contact flushes, linked together by means of a bridge <NUM>. This set has an upper clamp with eccentric shaft <NUM> which gives it the movement and offset in contact with the groove <NUM>.

<FIG> shows the main zones of the dispenser corresponding to the dispensing stages, using two shafts perpendicular to each other that divide the quadrant into four zones.

In <FIG> the flush set has a second linkage point consisting of a fixed axis <NUM>, which acts as a center of rotation of the set.

On the bridge there is a projection to receive and centralize a compression spring, by which it gives a slight load to the flush set to maintain the necessary permanent contact of said flush on the seed plate.

The upper triple contact <NUM> acts on the circumference of the outer tangent of the seed plate pockets. These three elliptical projections with beveled edges are the ones that come into contact with the seeds. The three contacts generate interference on the plate's alveolus, reducing the capture area and favoring the positioning of a single seed per alveolus. With reference to the clockwise rotation of the plate, the plate rotates clockwise. These flushes, considering their position with respect to the dial of an analogical clock, act in the zone of the upper left quarter, which would be the hourly position between <NUM> a. and <NUM> p. of said clock taken as reference.

The contact is made in a progressive way against the seeds lodged in each alveolus, producing slight rubbing against them to leave only one seed per alveolus.

In this way, it is possible to generate a level that allows the removal of duplicated or tripled seeds for each alveolus of the sowing plate and the remaining seeds re-enter the catchment area, being the last superior contact the one in charge of ensuring that only one seed per alveolus is located and positioned.

The two lower contacts <NUM> work on the circumference of the inner tangent of the cells, being these circular contacts with beveled edges the ones in charge of leveling the seeds on the cell in combination with the upper leveler to leave only one seed positioned per cell.

This set of flushes adapts to different types of seeds without the need to replace parts when changing the sowing plate for different types of seed sizes of different crops.

This is a great difference from other sowing systems, which must replace the set of flushes together with the sowing plate.

It is also important to have a dispenser that can keep the seeds in the collection container, even when the dispenser is placed in a horizontal position (see <FIG>). This position is adopted during transport on those models of sowing machines, where the transport position requires turning the seed bodies to reduce the transport width.

Claim 1:
Pneumatic dispenser for sowing multiform seeds in low and high doses, comprising:
a housing (<NUM>) consisting of a first half and a second half with means of closure that fix both halves to each other, wherein the first half comprises a channel for the entry of seeds and having on the periphery a plurality of air recirculation slots (<NUM>), and the second right half comprises an air suction tube (<NUM>);
and, means of attachment to a seeder bracket and, underneath, a seed release sector (<NUM>) linked to an exhaust tube (<NUM>);
the pneumatic dispenser further internally houses a rotatable sowing plate (<NUM>) mounted on a three-segmented drive shaft whose center is substantially cylindrical, centering the sowing plate (<NUM>) with a drive plate (<NUM>), wherein the sowing plate comprises a plurality of cavities arranged perimetrically surrounded by depressions in low relief;
said dispenser also comprises a set of floating triple upper contact (<NUM>) and double lower contact flushes linked together by means of a bridge (<NUM>),
wherein, the set has an upper clamp with an eccentric shaft (<NUM>) that gives it movement and offset for a permanent contact against the surface of the sowing plate and with external regulation of its position, and a second point of connection consisting of a fixed shaft that constitutes a center of rotation of the set,
wherein, on said bridge (<NUM>), there is a ledge with for the assembly of a compression spring that regulates the permanent contact of said flushes on the sowing plate (<NUM>), and
wherein the triple upper contact is configured to act on the circumference of the outer tangent of the seed plate cavities and the double lower contact is configured to act on the circumference of the inner tangent of the seed plate cavities.