SEEDING MACHINE

Description

[0001] The invention relates to a seed drill which is movable for sowing seed on an agricultural area along a direction of travel, with a storage container for receiving the seed, several metering units arranged next to each other, each of which has at least one rotatably mounted metering wheel for metering the seed and a metering shaft for driving the metering wheel, and a drive shaft for driving the metering shafts.

[0002] US patent 2020 / 081457 A1 discloses a seed drill with the features of the preamble of claim 1.

[0003] Such seed drills usually have a storage container for receiving the seed to be sown, which is often granular or grainy and is frequently designed in the form of a large-volume, tank-like vessel for transporting the seed to the field and / or for storing the seed during sowing.

[0004] In this context, the term "seed" encompasses all granular or granular materials usable in agriculture, including fertilizers, etc. "Sowing" will be used to refer to the spreading of all such materials on cultivated land.

[0005] To sow the seeds, appropriate seed drills are usually driven across the field in a grid pattern along a direction of travel, for example by being pulled by an agricultural tractor.

[0006] To ensure consistent seed metering during application and thus a uniform seed pattern along the direction of travel, these seed drills typically have several metering units arranged side by side, positioned downstream of the hopper along the seed flow. The seed is metered in each unit by means of at least one rotatable metering wheel. Such a metering wheel often has metering chambers distributed around its circumference to collect the seed from the hopper, with the amount of seed dispensed being adjustable via the wheel's rotational speed. For broadcast sowing, each of the adjacent metering units dispenses the seed, which can then be sown into one of the rows running parallel to each other in the direction of travel of the seed drill.

[0007] In such seed drills, several metering wheels are typically arranged on a common pivot, forming a metering roller driven by a central metering drive. These machines have generally proven effective. However, in practice, to create a tramline usable in the subsequent crop stand or to avoid double sowing, it may be necessary to deactivate certain metering units individually or in groups during sowing. This is not easily accomplished with a seed drill where the metering wheels are arranged on a common pivot and driven collectively. While switching off the metering drive can deactivate all metering wheels on the common pivot of a metering roller, thus stopping the metering in all corresponding units and interrupting the sowing process, this is not always feasible.However, it is not possible to selectively switch off individual dosing units.

[0008] Against this background, it is known from EP 3 918 897 A1 that metering units have their own metering shafts for driving the metering wheel. The metering shafts of the individual metering units are driven via a drive shaft of the seed drill, through which all metering wheels can be driven by a central drive. The drive shaft is arranged behind the metering wheels in the direction of travel, so that it is accessible from the outside when the seed drill is coupled to the tractor. The metering shafts can be disconnected from the drive shaft, so that metering units can be switched off individually or in groups during sowing.

[0009] As the rotating metering wheel picks up seed on one side of the metering unit during metering, carries it along its direction of rotation, and releases it in metered form on the other side, the seed exerts a force on the metering wheel and the metering shaft as it passes through the area beneath it. The metering wheel is driven by the drive shaft, which transmits a torque driving the metering wheel to the metering shaft and the metering wheels. During this torque transmission, a force is exerted from the drive shaft to the metering shaft. Because the directions of rotation of the metering shaft and the drive shaft are opposite due to the direct coupling of both shafts, this force has a non-zero component parallel to the force exerted by the seed on the metering shaft.In such known arrangements, the force exerted by the drive shaft on the metering shaft is therefore structurally superimposed on the force exerted by the seed on the metering shaft, so that a higher overall force is exerted on the metering shaft.

[0010] The metering shafts and units are subjected to greater stress due to the increased overall force, leading to accelerated wear. Particularly with metering shafts that are detachably mounted within the metering unit, this overall force can cause the shafts to pop out. In this case, sowing must be interrupted, the fault diagnosed, and the problem rectified manually before sowing can resume. This results in significant interruptions and increased effort.

[0011] Therefore, the present invention presents itself as Task, to specify a seed drill in which wear and tear and the occurrence of interruptions during sowing are reduced.

[0012] This task is accomplished in a machine of the type mentioned above by the features of claim 1. solved . Advantageous further training opportunities are listed in the dependent sub-claims.

[0013] Positioning the drive shaft in the direction of travel in front of the metering wheels allows the direction of force during torque transmission from the drive shaft to the individual metering shafts and wheels of the metering units to be inverted without changing the direction of rotation of the metering wheels. In this way, the force exerted on the metering shaft by the drive shaft can be superimposed destructively on the force exerted on the metering shaft by the seed, resulting in a lower overall force on the metering shaft. This reduces wear on the metering shaft. Particularly with metering shafts that are detachably mounted in the metering unit, the likelihood of the metering shafts popping out can be reduced.

[0014] Preferably, the drive shaft is positioned above the metering shafts. This arrangement above the metering shafts provides better protection for the drive shaft from external influences during sowing.

[0015] According to one embodiment of the invention, the drive shaft extends transversely to the direction of travel. In this way, the drive shaft can be used to drive all metering shafts arranged side by side transversely to the direction of travel.

[0016] Advantageously, the seed drill has several seeding units that can be supplied with seed by the metering units. The seed can be dispersed via the individual seeding units to create a row of seeds extending in the direction of travel across the field. The required quantity of seed is supplied to the seeding units by the individual metering units. For broadcast sowing, numerous seeding units can be arranged parallel to one another, allowing the seed to be sown in numerous rows extending parallel to each other in the direction of travel. Preferably, each metering unit is assigned to one seeding unit.

[0017] Advantageously, the several metering units arranged side by side are identical in construction. In addition to the metering units arranged side by side, each of which has at least one rotatably mounted metering wheel and a metering shaft for driving the metering wheel, the seed drill can have further metering units which differ structurally from these several metering units arranged side by side and, in particular, may be driven in a different way.

[0018] According to one design, it is proposed that each of the several adjacent metering units has a drive element for driving the metering shafts. The drive element, which forms part of the metering unit, allows torque to be transmitted from the drive shaft to the metering shaft.

[0019] In this context, it has proven advantageous if the drive elements can be coupled to the drive shaft. The metering shafts assigned to each drive element can be selectively coupled to or disconnected from the drive shaft via these coupling elements. The coupling elements also allow for the selective activation and deactivation of individual metering units.

[0020] In an advantageous embodiment, each metering unit of the seed drill has its own metering shaft. This eliminates the need for metering units that share a single metering shaft to drive their metering wheels. Each individual metering unit of the seed drill can thus be driven independently, and in particular, switched on and off individually. In particular, all metering units of the seed drill can be of identical construction, thereby reducing the need for different components.

[0021] Preferably, the metering wheels of the metering units are mounted independently of the metering wheels of the other metering units. This prevents mutual interference between the metering wheels of different metering units. However, a metering unit can have several metering wheels, which can be mounted together and, in particular, driven by the same metering shaft.

[0022] According to the invention, the drive shaft is arranged to penetrate the storage container, in particular partially within the seed reservoir of the storage container. An arrangement of the drive shaft that penetrates the storage container, in which the drive shaft enters the storage container from the outside and exits it at a different point, makes it easy to position the drive shaft in the direction of travel in front of the metering wheels. Furthermore, the drive shaft penetrating the storage container can also be used within the storage container for additional functions during or in connection with sowing. In this way, the drive shaft can assume a multifunctional role.Furthermore, a drive shaft that is partially located in the seed reservoir of the storage container, which can be filled with seed, can allow the drive shaft to directly influence the seed, since such a drive shaft would not be shielded from the seed that can be received in the seed reservoir.

[0023] It is further advantageous if the drive shaft, particularly those located outside the hopper, has drive sections for driving the metering shafts and, particularly those located inside the hopper, stirring sections for mixing the seed. By dividing the drive shaft into drive sections and stirring sections, the drive function and the stirring function of a multifunctional drive shaft can be spatially separated. The drive sections of the drive shaft can be used to drive the metering shafts and thus the individual metering wheels. The stirring sections, on the other hand, can be used to stir the seed, thereby preventing clumping during sowing and ensuring uniform distribution.Spatially separating the drive area from the mixing area prevents seed in contact with the mixing area from entering the drive area and negatively affecting the drive of a metering unit. Similarly, a physical separation of the drive and mixing areas prevents contaminants, such as lubricants, from migrating from the drive area into the mixing area and thus into the seed reservoir.

[0024] In this context, it is particularly advantageous if the drive sections and the stirring sections are arranged alternately along the drive shaft. This alternating arrangement allows the drive shaft to be used at several points along the hopper to both drive the metering wheels and stir the seed. Furthermore, it has proven advantageous to assign a metering unit to each drive section. At the transition from the drive section to the stirring section, the drive shaft can penetrate the hopper from the outside, and at the transition from the stirring section to the drive section, it can penetrate from the inside.

[0025] According to one design, it is proposed that the drive shaft incorporates stirring elements arranged in the stirring areas to mix the seed. These stirring elements allow the drive shaft to mix the seed more effectively. The stirring elements can extend radially away from the drive shaft and further into the seed reservoir of the storage container. The stirring elements, which are fixed to the drive shaft, can thus increase their interaction with the seed and contribute to better mixing. This helps to break up clumps and sticking of the seed and prevent new clumping from occurring.

[0026] Another embodiment provides that the storage container has, in particular, roof-shaped cover elements to cover the drive areas, especially to protect the coupling elements of the drive shaft from the seed. The cover elements of the storage container can prevent seed from coming into contact with the drive areas of the drive shaft from above. In particular, the coupling elements of the drive shaft can be protected in this way from the seed and from damage caused by it. In addition to the cover elements, especially the roof-shaped ones, the storage container can have wall-like enclosures extending transversely to the drive shaft. These enclosures can connect to the cover elements and, in particular, extend between opposing side surfaces of the storage container.The drive areas of the drive shaft can be structurally separated from the interior of the storage container, in particular the seed reservoir, by the cover elements together with the housings.

[0027] It is further advantageous if the seed can be guided towards the stirring areas by adjacent cover elements, particularly those that interact in a funnel shape transversely to the direction of travel. Two adjacent cover elements interacting in a funnel shape can thus guide seed from the areas above the drive sections in the seed reservoir to the stirring sections of the drive shaft, where the seed can be stirred. Adjacent, interacting cover elements can be designed such that they only interact in a funnel shape transversely to the direction of travel, while they do not interact in a funnel shape along the direction of travel. Roof-shaped cover elements can simultaneously interact in a funnel shape with their adjacent cover elements to the left and right relative to the direction of travel, resulting in a more uniform distribution of the seed.

[0028] According to a further embodiment of the invention, the drive shaft, particularly in the drive areas, has coupling elements for the frictional coupling of the drive shaft with the metering shafts. In particular, each coupling element of the drive shaft can be assigned a metering shaft. For the frictional coupling of the drive shaft with the metering shafts, the coupling elements can interact with the drive elements of the metering shaft. The coupling elements and / or the drive elements can be designed as meshing gears.

[0029] In this context, it has proven advantageous to arrange the coupling elements outside the storage container, particularly outside the seed reservoir. By arranging the coupling elements outside the storage container, especially outside the seed reservoir, blockage of the coupling elements by seed can be easily prevented. Furthermore, by arranging the coupling elements outside the storage container, they can interact with the drive elements of the metering shafts in a structurally simple manner.

[0030] In an advantageous embodiment, couplings, in particular one coupling to each coupling element, are provided for the selective decoupling of the metering shafts associated with a coupling element from the drive shaft. The metering shaft associated with the coupling element can be de-energized via the coupling, thus disengaging the corresponding metering unit. The coupling can be designed such that the coupling element, which is otherwise rotationally fixed to the drive shaft, is freely rotatable on the drive shaft when the coupling is actuated. When the coupling is actuated, torque transmission from the drive shaft via the coupling element to the metering shaft can be prevented in this way. The metering shaft and the entire metering unit associated with it are therefore not driven when the coupling is actuated.The force transmission between the coupling element and its associated metering shaft can still exist despite this decoupling of the metering shaft from the drive shaft.

[0031] Preferably, the coupling is designed as an integral part of the coupling element to which it is assigned. The coupling, designed as an integral part of the coupling element, can be installed together with the coupling element in a simple manner. In particular, the coupling can be integrally formed with the coupling element.

[0032] In a further embodiment of the invention, the seed drill has a switching shaft for selectively disengaging the drive of individual metering shafts, in particular for actuating the clutches. The switching shaft allows individual metering shafts to be centrally controlled and disengaged from the drive, whereby this drive disengagement can be effected in particular by actuating a clutch, which may be assigned to the metering shaft and / or to a coupling element associated with the metering shaft.

[0033] In this context, it has proven advantageous if the switching shaft has at least one switching wheel, and in particular several switching wheels, which enable a rotation-position-dependent drive release of a metering shaft associated with the switching wheel. The switching shaft allows the switching wheel to be moved into different rotational positions. Depending on the rotational position, the switching wheel can either release the drive of the metering shaft or leave the metering shaft driven. In particular, with several switching wheels, each associated with a metering shaft, individual or groups of metering shafts can be disengaged, or the drive release of individual or multiple metering shafts can be removed.The rotational position of the control shaft, and thus the rotational position of the control wheels, allows the seeding pattern to be centrally adjusted. This enables, for example, the deactivation of multiple metering units to create a tramline, while allowing them to be centrally reactivated via the control shaft when driving over a different area of ​​the field, without requiring individual manual intervention at each metering unit. The control shaft, and therefore the control wheels, can be driven either manually or by a motor.

[0034] In this context, it has proven advantageous to assign a shift wheel to each metering shaft. This allows all metering shafts to be individually switched without drive engagement via the shift shaft. This avoids the need to limit the system to just a few metering shafts that can be switched without drive engagement, for example, those solely dedicated to tramline formation, and thus increases the operational flexibility of the seed drill.

[0035] Preferably, the gear is designed as a cam gear, in particular with several switching positions that can be selectively fitted with a cam. Designing the gear as a cam gear allows for a simple way to enable the drive to be disengaged from the metering shaft associated with the gear, depending on its rotational position. A gear with several switching positions, each of which can be selectively fitted with a cam, allows the user to choose the rotational position at which the gear disengages the drive to the associated metering shaft. In this way, the gear with several switching positions, each of which can be selectively fitted with a cam, can be adapted to the desired seeding patterns before sowing, similar to a mechanical programming process, and the user can then select between these patterns during sowing.For example, those switching wheels whose associated metering units are to be deactivated to form a tramline in a given operating state can each have a cam in the same switching position. This means that in one rotational position of the switching shafts, all of these switching wheels, via their cams, release the metering shafts of the corresponding metering units to form the tramline. In another switching position, one without cams, the metering shafts would not be deactivated by their associated switching wheels, and these metering units would then not form a tramline. By simply changing the rotational position of the switching shaft, and thus the switching wheels, it is possible to switch centrally between operation with tramline generation and operation without tramline generation.This can be particularly advantageous when the distance between adjacent tramlines needs to be greater than the width of the seed drill. The ability to equip the switching positions of the gear wheels with a cam allows, for example, the use of different metering units for creating a tramline for different sowing operations. Furthermore, by selecting the appropriate switching positions of the individual gear wheels of the seed drill, whether equipped with a cam or not, larger groups of metering units can be deactivated in other rotational positions, so that, for example, only the seeding units on the left or right side of the seed drill, or every other metering unit, are operated alternately.

[0036] In one design, the seed drill has actuating means that can be controlled by the shift shaft, in particular by the shift wheels, to actuate the clutches. Via these actuating means, the shift shaft, and especially the individual shift wheels, can act on the clutch depending on its rotational position. The actuating means, as an element mediating between the shift shaft or a shift wheel on one side and the clutch on the other, allow the shift shaft to be positioned at a distance from the drive shaft. This distance facilitates cleaning, maintenance, and repair work. Preferably, each shift wheel is assigned its own actuating means.

[0037] In this context, it has proven advantageous for the actuating means to have locking lugs for actuating the clutches. The actuating means, driven by the shift shaft and in particular a shift wheel, can engage with the clutch, especially a cam of the clutch, via its locking lug. If the drive shaft rotates while this engagement is active, the clutch engaged with the actuating means can disengage and disengage the metering shaft associated with this clutch. To move the actuating means into this position engaged with the clutch, the cam of the shift wheel can interact with an actuating projection on the actuating means and thus press the elastic actuating means into its detent position.If the shift wheel is moved into a rotational position where no cam acts on the actuating projection, the actuating mechanism can relax, allowing the detent lug to move away from the clutch and no longer engage with it. The drive shaft could then drive the metering shaft again.

[0038] In a further embodiment of the invention, the actuating means for selectively disabling the actuation of individual clutches are mounted on a bearing axis in such a way that their axial positions can be changed, and in particular, they can be axially displaced. By changing their axial position on the bearing axis, the actuating means can be moved axially away from the gears and / or the clutches such that the actuating means can no longer be actuated by the gears and / or the clutches can no longer be actuated by the actuating means. The bearing axis of the actuating means preferably runs parallel to the shift shaft and / or the drive shaft. By changing the axial position on the bearing axis, the position of the actuating means can also be changed axially along the shift shaft or the drive shaft. The actuating means can be mounted in a rotationally fixed manner on the bearing axis, which in particular cannot be rotated about its longitudinal axis.To increase the adaptability of the seed drill, the individual actuating devices can be changed independently of each other in their axial position.

[0039] In an advantageous embodiment, the seed drill has interchangeable spacers in its axial position along the bearing axis with the actuating elements. When the axial position of an actuating element changes along the bearing axis, the spacer can be exchanged with it. In this way, the actuating element and its associated spacer can occupy the same area along the longitudinal axis, regardless of the axial position of the actuating element. This prevents unintentional axial slippage of the actuating element during seed application, for example, due to vibrations, since the spacer occupies the position into which the actuating element would otherwise slip. The assembly of actuating elements and their associated spacer can be positively locked in the axial direction of the bearing axis.

[0040] In an advantageous embodiment, the metering wheels of the metering units can be replaced without disassembling the drive shaft and / or adjacent metering units. This allows the metering wheels of individual metering units to be removed and replaced for repair or to adapt to a different seed. The time-consuming and labor-intensive disassembly of the drive shaft required to access the metering wheels in prior art is thus eliminated. Since metering wheels of individual metering units can be replaced without disassembling adjacent metering units, and in particular without removing the metering wheels or metering shafts of these adjacent units, the time required for maintenance and repair of individual metering units can be reduced.

[0041] Advantageously, the metering wheel, metering shaft, and drive element of a metering unit are components of a replaceable unit that can be removed from the metering unit's housing. The replaceable unit can be easily removed from the housing. In this way, the entire unit can be replaced with another unit that fits into the metering housing. Alternatively or additionally, the replaceable unit removed from the housing can be disassembled for maintenance or repair purposes, or for replacing individual components such as the metering wheel, and then reassembled and reinserted into the housing.

[0042] In this context, it has proven advantageous if the replacement unit has bearing elements, particularly teardrop-shaped ones, that can be received in complementary, non-circular recesses of the metering housing for the rotatable mounting of the metering shaft. These bearing elements allow the replacement unit to be easily mounted on the metering housing of the metering unit. Due to their complementary design to the non-circular recesses of the metering housing, the bearing elements themselves can be fixed to the metering housing in a rotationally stable manner. In particular, the bearing elements can be inserted into the recess of the metering housing for easy assembly and disassembly. The bearing elements allow the metering shaft to be rotatably mounted relative to the metering housing and simultaneously secured against translational movements.

[0043] It is possible for the metering shaft of a metering unit to be integrally formed with its associated metering wheel and / or its associated drive element. This integral design ensures reliable torque transmission from the drive element to the metering shaft and / or from the metering shaft to its associated metering wheel.

[0044] In a further embodiment of the invention, the metering shaft, in particular the bearing elements of the replacement unit, of a metering unit is radially fixed to a metering housing of the metering unit by a housing cover of the metering unit. The housing cover allows the metering shaft, in particular the bearing elements, of the replacement unit to be enclosed between the housing cover and the metering housing in such a way that it does not move radially relative to them. The housing cover can be releasably and / or pivotably arranged on the metering housing so that it can be moved into a position that releases the metering shaft, in particular the replacement unit. In this position of the housing cover, the interior of the metering unit can be accessed from the outside. In particular, the metering wheel, the metering shaft, and / or the replacement unit can be removed from the metering housing.

[0045] Further details and advantages of the invention are explained below by way of example with reference to the embodiment of the invention schematically depicted in the figures. These show: Fig. 1a a perspective view of a seed drill according to the invention coupled to an agricultural tractor; Fig. 1b a perspective view of a part of the seed drill from a rear oblique angle; Fig. 2 views of the seed drill against the direction of travel, from above and in the direction of travel; Fig. 3 a perspective, sectioned view of a hopper and a metering unit of the seed drill; Figs. 4 and 5 side views of different sections parallel to the direction of travel through the seed drill according to the invention; Figs. 6 to 8 perspective views of the components of the metering unit and other components of the seed drill arranged in the area of ​​the metering unit; Fig. 9 a sectioned side view of the components in the Figs. 6 to 8 components shown in conjunction with the seed drill's hopper, and Fig. 10 an exploded view of an exchange unit.

[0046] In Fig. 1a A seed drill 1 is shown, which is moved across an agricultural area N by an agricultural tractor 21 along a travel direction F. To sow the seed across the entire agricultural area N, the tractor 21 moves the seed drill 1 in several passes across the area N.

[0047] Although in Fig. 1a Although the seed drill 1 is depicted as a towed machine, the seed drill 1 can also be a self-propelled machine which does not require an additional tractor 21 for movement, or a mounted machine which is carried by the tractor 21.

[0048] The seed drill 1 comprises a hopper 2 in which the seed to be sown is received. To sow this seed on the agricultural area N, it is fed from the hopper 2 to individual seeding units 4. Each of these seeding units 4 has a coulter 4.1, which forms a furrow in the agricultural area N and into which the seed from the hopper 2 is placed. The seed is thus sown evenly across the agricultural area N in parallel rows via the seeding units 4, which are arranged parallel to each other. Although the seeding units 4 are shown as components of the seed drill 1, they can also be attachments of the actual seed drill 1.

[0049] To ensure that the seed is sown evenly on the usable area N, the seed drill 1 has several metering units 3 arranged side by side, which dispense the seed stored in the hopper 2 in metered quantities. These metering units 3 supply the seeding units 4 with seed.

[0050] In Fig. 1b These metering units 3, arranged on the storage container 2, are shown. The metering units 3 are arranged relative to the direction of travel F on the rear of the storage container 2. In this way, they face the seeding units 4, which simplifies the supply of seed to the seeding units by the metering units 3.

[0051] Since the storage container 2 in Fig. 1b Although shown without its side walls, this view allows a glimpse of the seed reservoir 2.1, in which the seed is received in the manner of loose bulk material.

[0052] In addition to the feed slides 16, which allow the respective receiving openings 3.9 of the metering units 3, through which the seed can enter the respective metering units 3 from the storage container 2, to be closed, the metering unit 3 furthest forward in the figure is shown without its housing. This allows the metering wheel 3.1 located inside the metering unit 3 to be seen. This metering wheel 3.1 is rotatably mounted in the metering unit 3 and serves to meter the seed.

[0053] As in the Figs. 6 to 8 As can be seen more precisely, this metering wheel 3.1 has several metering chambers along its circumference, which are separated from each other by individual teeth. In these chambers, the rotating metering wheel 3.1 transports the seed flowing from the seed reservoir 2.1 into the metering unit 3 downwards. For metering, the metering wheel 3.1 interacts with the bottom flap 3.7 located below the metering wheel 3.1.

[0054] The bottom flap 3.7 is biased towards the metering wheel 3.1 and acts as a scraper, removing any seed protruding from the metering areas of the metering wheel 3.1 as it slides over it. In this way, the metering wheel 3.1 dispenses only the predetermined seed dose on the side of the metering unit 3 opposite the seed reservoir 2.1, the dose that fits within its metering areas and between these areas and the bottom flap 3.7. To increase the seed dose, the distance between all bottom flaps 3.7 of the individual metering units 3 and their associated metering wheels 3.1 can be adjusted collectively using the lever 17. This adjustment can be made in several steps corresponding to the detent positions of the lever 17. For this purpose, the bottom flaps 3.7 are pivotally mounted around the bearing axis 18. Due to this adjustable larger distance between the metering wheel 3.1 and the bottom flap 3.7, the rotating metering wheel 3.1. Convey a larger quantity of seed past the bottom flap 3.7 and dispense it as a seed dose.

[0055] In the seed drill 1 according to the invention, the metering wheel of the metering unit is driven by a metering shaft 3.2 of the metering unit 3. To drive the individual metering shafts 3.2 of the respective metering units 3, the seed drill 1 according to the invention has a drive shaft 5 for driving this metering shaft 3.2. This drive shaft 5 is arranged in the direction of travel in front of the metering wheels 3.1. In this way, the metering units 3 are freely accessible from the rear in the direction of travel F for maintenance, repair, and servicing work without being blocked by the drive shaft 5, which extends transversely to the direction of travel F.

[0056] In addition to the drive shaft 5, in the Fig. 1 and 2 Additionally, a shift shaft 10 arranged in the direction of travel F in front of the drive shaft 5 is shown, which is connected to the Figs. 6 to 9 This will be discussed in more detail later. However, it can be seen that the switching shaft 10 is essentially arranged at the same height as the metering shafts 3.2 of the individual metering units 3.

[0057] How to Figs. 1b to 2c As can be seen, the metering units 3 arranged side by side in the illustrated embodiment of the seed drill 1 are identical in construction. In this way, all metering wheels 3.1 of the metering units 3 are driven via the drive shaft 5.

[0058] In the illustrated embodiment of the seed drill 1, the drive shaft 5 is arranged not only in the direction of travel F in front of the metering wheels 3.1, but also above the metering shaft 3.2. The drive shaft 5 therefore runs in the same area occupied by the hopper 2. The drive shaft 5 penetrates the hopper 2 and, in particular, its seed reservoir 2.1 several times, as shown especially in the Fig. 2a and2b This can be seen. Parts of the drive shaft 5 are thus arranged inside the reservoir 2, while other areas of the drive shaft 5 are arranged outside the reservoir 2, but are surrounded by it on several sides.

[0059] The sections of the drive shaft 5 located outside the storage container 2 form drive sections 5.1 for driving the metering shafts 3.2. Since the drive sections 5.1, as well as the metering units 3, are located outside the storage container, this allows for simple drive of the metering wheels 3.1 by the drive sections 5.1. This is because the drive sections 5.1 do not need to protrude from the interior of the storage container 2 to drive the metering units 3 located outside the storage container 2. Furthermore, this prevents contact between the seed located inside the storage container 2 and the drive sections 5.1 of the drive shaft 5 that drive the metering units 3, thus preventing blockage by the seed or contamination of the seed.

[0060] The areas of the drive shaft 5 arranged in the storage container 2 form stirring areas 5.2, which can be used to stir the seed in order to prevent clumping of the seed during application and to prevent bridging between the drive areas 5.1.

[0061] Along the longitudinal axis of the drive shaft 5, the drive sections 5.1 and the stirring sections 5.2 are arranged alternately. Between the drive section 5.1 and the stirring section 5.2, the drive shaft 5 thus penetrates the storage container 2 from the outside, in order to penetrate the storage container 2 from the inside out at the end of the stirring section 5.2 towards the next drive section 5.1.

[0062] To separate the drive sections 5.1 and the stirring sections 5.2 of the drive shaft 5 from each other and to prevent seed from escaping towards the drive sections 5.1, the storage container 2 has periodically inwardly curved walls in the area of ​​the drive shaft 5, which are Fig. 3 These are shown in more detail below. This wall includes, in particular, the roof-shaped cover element 2.2, which covers the drive section 5.1 located beneath it and separates it from the interior of the storage container 2. In addition to these cover elements 2.2, the storage container 2 has wall-like enclosures 2.3 extending transversely to the drive shaft 5 to separate the interior of the storage container 2, and in particular the seed reservoir 2.1, from the drive section 5.1.

[0063] As in Fig. 1b and 2bAs can be seen, several of the cover elements 2.2 are arranged adjacent to each other in such a way that their inclined surfaces point perpendicular to the direction of travel F. Adjacent cover elements 2.2 thus act together like funnels perpendicular to the direction of travel. As the seed in the seed reservoir 2.1 slides downwards due to gravity, the adjacent cover elements 2.2 guide it towards the stirring areas 5.2, which are located between the adjacent cover elements 2.2. Due to the roof shape, each cover element 2.2 acts in a funnel-like manner with the next cover element 2.2 to its left and right.

[0064] To further enhance the stirring of the seed in the stirring area 5.2, the drive shaft 5 has stirring elements 8 in this area. These disc-shaped stirring elements 8 are arranged non-rotatably on the drive shaft 5 and, to increase the stirring effect, have prominent projections parallel to the drive shaft 5 extending from the disc of the stirring elements 8.

[0065] As in Fig. 3As shown, the drive section 5.1 of the drive shaft 5 is located outside the reservoir 2, beneath the cover element 2.2. In this drive section 5.1, the drive shaft 5 has a coupling element 7, which interacts with a drive element 3.3 of the metering unit 3 to couple the drive shaft 5 to the metering shaft 3.2. The coupling element 7 and the drive element 3.3 are designed as meshing gears. A clockwise rotation of the drive shaft 5 is thus transmitted to the coupling element 7, which also rotates clockwise and sets the drive element 3.3 into counterclockwise rotation. This counterclockwise rotation of the drive element 3.3 is then transmitted by it to the metering unit 3.2. Fig. 3 The drive element 3.3 transmits the power to the concealed metering shaft 3.2, which in turn transmits the power to the metering shaft 3.2. Fig. 3also driven by the drive element 3.3 the metering wheel 3.1 of the metering unit 3 in a counterclockwise direction of rotation, whereby these directions of rotation are given for the perspectives in Figs. 3 to 5 The metering wheel 3.1, rotating counterclockwise in this manner, can receive seed flowing in from the seed reservoir 2.1 through the receiving opening 3.9 of the metering unit 3, as described above, convey it downwards towards the bottom flap 3.7, and dispense it in metered form on the side of the metering unit 3 opposite the receiving opening 3.9. This design is also used in the Fig. 4 and 5 shown.

[0066] In Fig. 4 A side view of seed drill 1 is shown, in which, as already mentioned in Fig. 1bThe side wall of the reservoir 2 is not shown, nor is the housing 3.5 of the metering unit 3 at the front of the illustration. However, the shaft bearing 20 can be seen, which rotatably supports the drive shaft 5, which passes through the reservoir 2 multiple times, on the side wall of the reservoir 2. Also visible, besides the inlet slide 16, which can close the receiving opening 3.9 of the metering unit 3, is the spring 19, already described above, which biases the bottom flap 3.7 towards the metering wheel 3.1.

[0067] The in Fig. 4 and 5 The dosing housing 3.5 shown, as well as the housing cover 3.6 which is pivotably arranged on the dosing housing 3.5, do not belong to the front dosing unit, but to the identical dosing unit 3 located behind it in the direction of the illustration. The same applies to the [unclear - possibly referring to the part shown in the figure]. Fig. 4The drive element 3.3, which also belongs to the rear dosing unit 3, can be identified. Since for the in Fig. 4 Although the drive element 3.3 is not shown in the metering unit 3 at the front, the resulting view of the drive element 3.3 of the metering unit 3 behind it clearly shows that the drive element 3.3 engages in the area of ​​the drive section 5.1 of the drive shaft 5 between two adjacent housings 2.3 of the storage container 2 in order to interact with the coupling element 7 of the drive shaft 5 located there. Like this coupling element 7, the drive element 3.3 is separated from the seed reservoir 2.1 by the cover element 2.2 and the housings 2.3 of the storage container 2.

[0068] Based on Fig. 4 as well as from Fig. 5The figure, which shows a cross-section in the stirring area 5.2 and thus allows a precise view of the stirring element 8, reveals a significant advantage of the seed drill 1 according to the invention. During metering, in which the metering wheel 3.1 rotates counterclockwise in these illustrations and conveys seed towards the bottom flap 3.7, the bottom flap 3.7, pre-tensioned by the spring 19, exerts an upward force on the metering wheel 3.1 and thus also on the metering shaft 3.2. This force acting on the metering shaft 3.2 can accelerate its wear.

[0069] Particularly in configurations where the metering shaft is attached to the metering housing 3.5 by the pivoting housing cover 3.6, this force can also lead to the housing cover 3.6 pivoting open unintentionally, causing the metering shaft 3.2, including the metering wheel 3.1, to shift relative to the metering housing 3.5 and, in the worst case, to jump out of it. This force is counteracted by arranging the drive shaft 5, which drives the metering shafts 3.2, in the direction of travel in front of the metering wheels 3.1 and, in particular, by arranging the drive shaft 5 above the metering shafts 3.2. This is because, during torque transmission from the drive shaft 5 via the coupling element 7 and the drive element 3.3 to the metering shaft 3.2, the arrangement of the drive shaft 5 results in a force acting on the metering shaft 3.2 that has a component opposite to that exerted by the bottom flap 3.7.The forces exerted on the metering shaft 3.2 by the drive shaft 5 and the bottom flap 3.7 partially cancel each other out, resulting in a significantly lower overall force acting on the metering shaft 3.2. This lower overall force reduces both wear and the risk of the housing cover 3.6 unintentionally swinging open and the metering shaft 3.2 and metering wheel 3.1 slipping.

[0070] Further details of the interaction of these components of the seed drill 1, and in particular of the switching shaft 10 which is mounted on the hopper 2 via a bearing arm in the direction of travel in front of the drive shaft 5, will be explained below with reference to the figures showing these elements in more detail. Figs. 6 to 9 discussed in more detail.

[0071] The Figs. 6 to 9Figure 1 shows a metering unit 3 of the seed drill 1 from different perspectives and partially without the metering housing 3.5. Like each of the structurally identical metering units, this metering unit 3 also has its own metering shaft 3.2, which extends transversely to the direction of travel F. This metering shaft 3.2 of the metering unit 3 serves both to drive and to support the metering wheel 3.1 in the metering housing 3.5.

[0072] The illustrated metering wheel 3.1 has a total of four circumferential rows of teeth, with the individual teeth defining the metering areas of the metering wheel 3.1 used for metering the seed. Two of these rows are identical, but offset from each other by half the tooth spacing in the circumferential direction. Furthermore, the two in Fig. 6The tooth rows shown on the left have larger teeth than the two tooth rows shown on the right. The metering area of ​​the two left tooth rows of the metering wheel 3.1 serves to meter coarser seed, while the metering areas of the two right tooth rows of the metering wheel 3.1 serve to meter finer seed. Although these rows of metering areas are formed integrally as a single metering wheel 3.1 in the illustrated embodiment, they can nevertheless each be formed by a separate metering wheel 3.1. In this case, the metering unit 3 would have several metering wheels 3.1, which are driven jointly by the metering shaft 3.2 of the metering unit 3. Similarly, the metering wheel 3.1 could also have only rows of metering areas of the same dimensions, so that the metering wheel 3.1 is designed only for metering fine seeds or only for metering coarse seeds. Nevertheless, the metering wheel 3.1 also exhibit only a single, extensive series of dosing areas.

[0073] Since each metering unit 3 has its own metering shaft 3.2, this design allows the metering wheels 3.1 to be mounted on their respective metering shaft 3.2, which is independent of the metering wheels 3.1 of the other metering units 3.

[0074] In the illustrated embodiment of the metering unit 3, the metering shaft 3.2 is held between the metering housing 3.5 and the housing cover 3.6, which is pivotably mounted on the metering housing 3.5. In its radial direction, the metering shaft 3.2 is thus radially fixed to the metering housing 3.5 by the housing cover 3.6 of the metering unit 3. To allow rotation of the metering shaft 3.2 about its longitudinal axis, the metering shaft 3.2 is rotatably mounted in bearing elements 3.4 on sides of the metering housing 3.5 opposite the direction of travel F. These bearing elements 3.4 have a substantially teardrop-shaped geometry with a circular and a tapered section, as is particularly evident in Fig. 7The bearing elements 3.4 are received in a complementary recess in the metering housing 3.5, which has a tapered shape, and in a circular segment-shaped recess in the housing cover 3.6. In this way, the bearing elements 3.4, together with the metering shaft 3.2, can be reproducibly inserted into the same position in the metering housing 3.5. Due to their non-circular shape, the bearing elements 3.4 counteract rotation once they are inserted into the metering housing 3.5.

[0075] The housing cover 3.6 is designed such that it partially encloses the metering wheel 3.1 against the direction of travel F and to the sides, in order to protect those areas from external influences that are not already protected from such external influences by the metering housing 3.5. As in Fig. 8As can be seen, the housing cover 3.6 also partially protects the drive element 3.3 of the metering unit 3 against external influences. However, the housing cover 3.6 only partially surrounds the drive element 3.3 on the rear side facing away from the direction of travel F and partially on the side surface facing the metering wheel 3.1. The side surface of the drive element 3.3 facing away from the metering wheel 3.1 is not covered by the housing cover 3.6.

[0076] Without the drive shaft 5 being in the Figs. 6 to 8 Although the figures show the disc-shaped stirring element 8 of the stirring area 5.2, which is arranged in the direction of travel F in front of the receiving opening 3.9 of the metering unit 3, the coupling element 7, which is engaged with the drive element 3.3 of the metering unit 3, is also shown.

[0077] As long as the coupling element 7 is arranged in a rotationally fixed manner on the drive shaft 5, the drive shaft 5 (not shown) is positively connected to the metering wheel 3.1 of the metering unit 3 via the coupling element 7, the drive element 3.3 and the metering shaft 3.2, and drives the metering wheel 3.1, provided that the drive shaft 5 itself is driven.

[0078] In some operating situations of the seed drill 1, however, it is necessary that some of the metering units 3 do not dispense seed, so that no seed is sown in some of the seed rows. This can be the case, for example, if every second metering unit 3 is to be deactivated to increase the spacing of the individual seed rows, or if individual seed rows are to be deliberately left clear to form a track for another vehicle that will later cultivate the area. In order to disengage the drive of the metering wheel 3.1 of a metering unit 3, the metering shaft 3.2 of the corresponding metering unit 3 must be decoupled from the drive shaft 5. For this purpose, the [missing information] Figs. 6 to 9The coupling element 7 shown is assigned a clutch 9, which can decouple the coupling element 7 from the drive shaft 5. By actuating the clutch 9, the coupling element 7, which is otherwise fixed to the drive shaft 5, is decoupled in such a way that it can rotate freely relative to the drive shaft 5. As a result, torques from the drive shaft 5 are no longer transmitted to the coupling element 7, so that the coupling element 7 no longer drives either the drive element 3.3 or the metering shaft 3.2 in this decoupled position.

[0079] In the illustrated embodiment, the coupling 9 is designed as part of the coupling element 7, which allows for simple joint assembly of the coupling element 7 and the coupling 9 on the drive shaft 5.

[0080] To actuate the clutch 9 and decouple the coupling element 7 from the drive shaft 5, the clutch has radially projecting cams 9.1 along its circumference. These cams 9.1 allow the clutch 9 to be fixed in its absolute position relative to the rotating drive shaft 5 and thus actuated. As the drive shaft 5 continues to rotate, the relative rotation of the clutch 9 relative to the drive shaft 5 causes the clutch 9 to disengage and decouple the coupling element 7 from the drive shaft 5. When the clutch 9 is released again via its cams 9.1, it re-couples the coupling element 7 to the drive shaft 5. The metering shaft 3.2 and the metering wheel 3.1 are then driven again by the drive shaft 5.

[0081] In order to centrally control the actuation of the clutch 9, the seed drill 1 has a switching shaft 10 with which individual metering shafts 3.2 of the metering units 3 can be switched without a drive by actuating the respective clutch 9. This switching shaft 10 is, for example, in Fig. 3 and Fig. 9 shown in more detail. This shift shaft 10 is equipped with shift wheels 11, which are designed in the manner of cam wheels. Each of these shift wheels 11 has several shift positions 13 along its circumference, which can optionally be fitted with a cam 12.

[0082] These shift wheels 11 are arranged on the shift shaft 10 such that their shift positions 13 are aligned with each other along the shift shaft 10. In a rotational position of the shift shaft 10, all shift wheels arranged on it are thus aligned identically. The shift shaft 10 can move to a number of rotational positions for the drive release of metering shafts 3.2, which corresponds to the number of shift positions 13 of the shift wheels 11 used. Depending on whether the shift position 13, which has a T-shaped cross-section, is equipped with a complementary cam 12 or not, the shift wheel 11 can, in this rotational position, release the drive of the metering wheel 3.1 associated with it or not. By equipping or omitting the shift position 13 with a cam 12, the shift wheel 11 can be mechanically programmed.

[0083] In order to enable the greatest possible flexibility of the seed drill 1, each metering shaft 3.2 is assigned both a gear wheel 11 and a clutch 9.

[0084] To connect the gear 11, located in the direction of travel F in front of and below the drive shaft 5 and the clutch 9, to the clutch 9, the seed drill 1 has an actuating element 14. This actuating element 14, which can be controlled by the gear 11 to actuate the clutch 9, is arranged in a rotationally fixed manner on the bearing axis 18 in the form of a curved arm. Extending from the receptacle 14.4 that receives the bearing axis 18, the actuating element 14 has a body 14.1 curved at an angle of approximately 90° towards the drive shaft 5. Towards its free end, this body 14.1 tapers relative to its end adjacent to the receptacle 14.4. This reduced thickness of the body 14.1 at its free end makes the actuating element 14 flexible, allowing it to be elastically deformed to actuate the clutch 9.

[0085] At its free end, the actuating means 14 has a locking lug 14.3 which can engage with the cams 9.1 to actuate the clutch 9.

[0086] To move the actuating element 14 from its rest position, in which the locking lug 14.3 does not come into contact with the clutch 9 or the cams 9.1, to a detent position in which the locking lug 14.3 engages with the cams 9.1 to actuate the clutch 9, an actuating projection 14.2 is provided in the thinner area of ​​the body 14.1. The actuating projection 14.2 extends from the body 14.1 towards the shift shaft 10 and, in particular, the associated shift wheel 11. This actuating projection 14.2 extends to such a close proximity to the shift wheel 11 that the actuating projection 14.2 does not touch the shift wheel 11 itself. However, if the shift position 13 adjacent to the actuating projection 14.2 is equipped with a cam 12, this cam 12 presses against the actuating projection 14.2. The cam 12 allows the actuating means 14 to be pressed towards the clutch 9 in such a way that the locking lug 14.3 can engage with the cams 9.1 of the clutch 9.The switching wheels 11 of the switching shaft 10 press on the associated actuating means 14 in a manner similar to a mechanical music box.

[0087] As in Fig. 3 and Fig. 8 As can be seen, the actuating element 14 is connected not only to the elastically deformable body 14.1, but also to a handle 14.5. This handle 14.5 is guided under the bearing axis 18 in the opposite direction of travel F and allows the actuating element 14 to be actuated from the rear of the seed drill 1, which is located opposite the direction of travel F. The actuating element 14 is mounted in a position on the bearing axis 18 that allows for changes in its axial position.

[0088] In the in the Fig. 7 and 8In the depicted views, the actuating element 14 is fixed in its axial position by the spacer 15, so that it cannot change its position along the bearing axis 18. This spacer 15 also has a receptacle 15.2 surrounding the bearing axis 18 and a handle 15.1 extending in the opposite direction of travel F. To change the axial position of the actuating element 14 along the bearing axis 18, the handle 15.1 can be manually grasped from the rear of the seed drill 1 and pulled away from the bearing axis 18.

[0089] The actuating element 14 can then be moved along the bearing axis 18 to the position originally occupied by the spacer 15 using the handle 14.5. The spacer 15 can then be manually inserted into the original position of the actuating element 14. In this position, the actuating element 14 is also protected from slipping along the bearing axis by the spacer 15.

[0090] By exchanging the actuating element 14 and the spacer 15 along the bearing axis 18, the actuating element 14 is changed in its position relative to the switching wheel 11 such that the switching positions 13 of the switching wheel 11, equipped with cams 12, can no longer come into contact with the actuating projection 14.2. This axial change in position displaces the actuating element 14 laterally, thus disabling the actuation of the clutch 9 associated with it. The actuating element 14, which can be changed in its axial position, therefore allows the actuation of its associated clutch 9 to be selectively disabled for the duration that the actuating element 14 is in its position reversed with the spacer 15. This manual intervention allows individual metering shafts 3 to be...2 exclude the drive release from the rotation position dependent via their assigned switching wheels 11, while the remaining metering shafts 3.2 can continue to be switched drive-free via their assigned switching wheels 11 depending on their rotation positions by means of the switching shaft 10.

[0091] In Fig. 10 An exchange unit 6 is shown, comprising the metering wheel 3.1, the metering shaft 3.2, and the drive element 3.3 of a metering unit 3. This exchange unit 6 also includes two bearing elements 3.4 for rotatably mounting the metering shaft 3.2 on the metering housing 3.5, and a fixing element 3.8 for axially fixing the two bearing elements 3.4 and the metering wheel 3.1 on the metering shaft 3.2. This axial fixing element 3.8 is shown in the Fig. 6 and 7 Not shown to allow a better view of the teardrop-shaped bearing element.

[0092] The replacement unit 6 allows the metering wheel 3.1, together with the metering shaft 3.2 and the drive element 3.3, to be removed from the metering housing 3.5 as a single unit for maintenance or replacement. This is achieved simply by folding down the housing cover 3.6, allowing the entire replacement unit 6 to be removed from the metering housing 3.5. Disassembly of adjacent metering units 3 is not necessary, as each metering unit 3 has its own separate metering shaft 3.2. Due to the position of the drive shaft 5 relative to the metering shaft 3.2, it is also unnecessary to completely or partially disassemble the drive shaft 5 when replacing the entire replacement unit 6.

[0093] The axial fixing of the bearing elements 3.4 and the metering wheel 3.1 on the metering shaft 3.2 is carried out, as already described above, via the axial fixing element 3.8, which is designed in the manner of a nut with bayonet closure and can be locked onto the metering shaft 3.2.

[0094] To connect the metering wheel 3.1 to the metering shaft 3.2 in a rotationally fixed manner, the metering shaft 3.2 has several longitudinally extending, inwardly directed grooves into which complementary, radially inwardly directed projections of the metering wheel 3.1 can engage. The essentially triangular grooves thus cooperate with the triangular projections of the metering wheel 3.1 to fix the metering wheel 3.1 to the metering shaft 3.2 in a rotationally fixed manner.

[0095] In the illustrated embodiment, the drive element 3.3 is integrally formed with the metering shaft 3.2, so that it does not need to be additionally fixed to it in a rotationally fixed manner. Alternatively, the drive element 3.3 can be connected to the metering shaft 3.2 as a separate component in a rotationally fixed manner, similar to the fixing element 3.8.

[0096] The use of the seed drill 1 described above can significantly reduce wear and tear and the occurrence of interruptions during sowing. Reference sign

[0097] 1 Seed drill 2 Hopper 2.1 Seed reservoir 2.2 Cover element 2.3 Housing 3 Metering unit 3.1 Metering wheel 3.2 Metering shaft 3.3 Drive element 3.4 Bearing element 3.5 Metering housings 3.6 Housing cover 3.7 Bottom flap 3.8 Fixing element 3.9 Intake opening 4 Seeding unit 4.1 Seed coulter 5 Drive shaft 5.1 Drive area 5.2 Stirring area 6 Exchange unit 7 Coupling element 8 Stirring element 9 Coupling 9.1 Cam 10 Shift shaft 11 Shift wheel 12 Cam 13 Shifting position 14 Actuating device 14.1 Body 14.2 Control projection 14.3 Detent lug 14.4 Intake 14.5 Handle 15 Spacer 15.1 Handle 15.2 Mount 16 Inlet slide 17 Lever 18 Bearing axle 19 Spring 20 Shaft bearing 21 Tractor unit F Direction of travel NN Usable area

Claims

1. Seed drill which is movable in a direction of travel (F) in order to spread seed over agricultural land (N), comprising - a hopper (2) for receiving the seed, - a plurality of metering units (3) arranged side by side, which each comprise at least one rotatably mounted metering wheel (3.1) for metering the seed and a metering shaft (3.2) for driving the metering wheel (3.1), and - a drive shaft (5) for driving the metering shafts (3.2), the drive shaft (5) being arranged in front of the metering wheels (3.1) in the direction of travel (F), characterized in that the drive shaft (5) is arranged so as to penetrate the hopper (2).

2. Seed drill according to claim 1, characterized in that the drive shaft (5) is arranged above the metering shafts (3.2).

3. Seed drill according to either claim 1 or claim 2, characterized in that each of the plurality of metering units (3) arranged side by side comprises a drive element (3.3) for driving the metering shafts (3.2).

4. Seed drill according to any of the preceding claims, characterized in that the drive shaft (5) is arranged partially in the seed reservoir (2.1) of the hopper (2), which reservoir can be filled with seed.

5. Seed drill according to any of the preceding claims, characterized in that the drive shaft (5) comprises drive regions (5.1) for driving the metering shafts (3.2), which drive regions are arranged in particular outside the hopper (2), and stirring regions (5.2) for stirring the seed, which stirring regions are arranged in particular in the hopper (2).

6. Seed drill according to claim 5, characterized in that the drive regions (5.1) and the stirring regions (5.2) are arranged alternately along the drive shaft (5).

7. Seed drill according to any of the preceding claims, characterized in that the drive shaft (5) comprises coupling elements (7), arranged in particular in the drive regions (5.1), for frictionally coupling the drive shaft (5) to the metering shafts (3.2).

8. Seed drill according to claim 7, characterized in that clutches (9) are associated with the coupling elements (7), in particular one clutch (9) with each coupling element (7), for optionally decoupling the metering shaft (3.2) associated with a coupling element (7) from the drive shaft (5).

9. Seed drill according to any of the preceding claims, characterized by a switching shaft (10) for optionally disconnecting the drive of individual metering shafts (3.2).

10. Seed drill according to claim 9, characterized in that the switching shaft (10) comprises at least one switching wheel (11), in particular a plurality of switching wheels (11), which allows rotation position-dependent disconnection of the drive of a metering shaft (3.2) associated with the switching wheel (11).

11. Seed drill according to claim 10, characterized in that the switching wheel (11) is designed as a cam wheel, in particular comprising a plurality of switching positions (13) that can optionally be equipped with a cam (12).

12. Seed drill according to any of claims 9 to 11, characterized by actuating means (14) which can be controlled by the switching shaft (10), in particular by the switching wheels (11), in order to actuate the clutches (9).

13. Seed drill according to claim 12, characterized in that the actuating means (14) for optionally disabling the actuatability of individual clutches (9) are mounted on a bearing pin (18), in particular axially displaceably, so as to allow changes in the axial positions of the actuating means.

14. Seed drill according to any of the preceding claims, characterized in that the metering wheels (3.1) of the metering units (3) can be replaced without dismounting the drive shaft (5) and / or adjacent metering units (3).

15. Seed drill according to any of the preceding claims, characterized in that the metering wheel (3.1), the metering shaft (3.2) and the drive element (3.3) of a metering unit (3) are parts of a replaceable unit (6) that can be removed from a metering housing (3.5) of the metering unit (3).