Agricultural distributing machine, and method for operating an agricultural distributing machine

Abstract

The invention relates to a method for operating an agricultural distributing machine (10), in particular a seed drill, having a central frame (1) and at least two side frames (2.1, 2.2) which are each connected to the central frame (20) so as to be pivotable about a pivot axis (S), wherein, for each side frame (2.1, 2.2), at least two lifting devices (3.1, 3.2) which are arranged one behind the other in the direction of travel (L) are provided, by means of which lifting devices (3.1, 3.2) the associated side frame can be pivoted upwards relative to the central frame by joint actuation of the at least two lifting devices, wherein the side frames are each supported on the field (F) by front first wheel elements (4) and rear second wheel elements (5), and wherein the distributing machine can be turned at the headland (V) by means of a cornering manoeuvre, wherein, in order to perform the cornering manoeuvre at the headland (V), the lifting devices are actuated unevenly such that the front wheel elements (4) are moved relative to the rear wheel elements (5) and are lifted off the field (F).

Description

[0001] Agricultural spreading machine and methods for operating an agricultural spreading machine

[0002] The invention relates to a method for operating an agricultural distribution machine, in particular a seed drill, for sowing seed on a field, comprising a central frame and at least two side frames each pivotably connected to the central frame about a pivot axis, wherein at least two lifting devices arranged one behind the other in the direction of travel are provided for each side frame, by means of which the respective side frame can be pivoted upwards relative to the central frame when the at least two lifting devices are actuated together, wherein the side frames are each supported against the field by means of first wheel elements, in particular unsteered support wheels, and second wheel elements, in particular tire packers, arranged behind the first wheel elements in the direction of travel, and wherein the distribution machine can be turned at the headland by driving around a curve, so that it can be moved in the opposite direction across the field.Furthermore, the invention relates to an agricultural distribution machine.

[0003] Many seed spreaders used to apply seeds in rows across a field have a central frame and side frames arranged laterally to the central frame in the direction of travel. This results in a very large spreader, especially when operating across a field, extending across the entire width of the field. This allows for the application of seeds, fertilizers, or pesticides, for example, across a very wide corridor. To achieve this, the two side frames and the central frame can be equipped with multiple, adjacent application units, enabling the material to be applied in rows as the spreader moves across the field.

[0004] Due to the width of the spreading machine, it cannot usually be moved easily on normal roads. To adjust the width as needed...

[0005] P24-045, however, it is known to pivotally connect the two side frames to the central frame so that they can be pivoted from the working position to a transport position. For this folding or pivoting movement, lifting devices can be used, for example, whereby in practice, due to the forces involved, at least two lifting devices are usually used, arranged one behind the other in the direction of travel.

[0006] Since the loads exerted on the central frame by the side frames in the working position would be very high without additional support, not only the central frame but also, as a rule, both side frames are braced against the ground. Because the side frames typically extend somewhat in the direction of travel, two wheel assemblies arranged one behind the other are often provided. The rear wheel assemblies can be designed as tire packers, which bear the main load of the respective side frame. Smaller wheel assemblies, such as unsteered support wheels, are often provided in front of the rear wheel assemblies, offering additional support and good tracking.

[0007] Once the spreader has moved across a field in one direction, it must be turned 180 degrees at the end of the field, in the so-called headland, so that it can then move across the field in the opposite direction in the next pass. However, this turning maneuver can cause lateral movement, particularly of the front wheels of the side frames, especially if they are unsteered. This means that the front wheels are then partially dragged sideways across the field, which can lead to the formation of soil ridges and soil compaction in the headland.

[0008] Based on this, the invention sets itself the task of providing a distribution machine that enables soil-friendly cornering in the headland.

[0009] P24-045 This problem is solved in a spreading machine of the type mentioned above by operating the lifting devices for cornering at the headland unevenly, so that the front wheel elements are moved relative to the rear wheel elements and lifted off the field.

[0010] Raising the front wheel elements relative to the rear wheel elements reliably prevents the front wheels from being dragged across the field at the headland, thus preventing soil compaction and the formation of soil ridges. The rear wheel elements, on the other hand, pose no or only a significantly lower risk of soil ridge formation, particularly since their axle is much closer to the spreader's axis of rotation than the axle of the front wheels. Therefore, when the spreader turns or curves, the rear wheel elements exhibit a rolling motion, largely without any lateral movement that could disturb the soil.

[0011] In this context, it has proven advantageous for the rear wheel elements to remain in contact with the ground when turning at the headland. This allows the forces acting on the side frames to provide sufficient support, even at the headland and when the front wheel elements are lifted. The forces and torques acting on the central frame can thus be kept comparatively low, which protects the material overall.

[0012] Designing the rear wheel elements as tire packers is particularly advantageous because they ensure comparatively high support forces distributed over a relatively large area, thus keeping the pressure on the ground within manageable limits. Furthermore, the tire packer smooths the soil and prevents excessive compaction. In addition to tire packers, rollers or similar rollable support elements can also be used.

[0013] P24-045 With regard to the front wheel element, it has proven advantageous for it to be designed as an unsteered support wheel. An unsteered support wheel offers better guidance than a steered support wheel and is also simpler in design, which also results in lower costs.

[0014] According to an advantageous further development of the method, it has proven beneficial if the front wheel elements of both side frames are moved by the front lifting device in such a way that the front wheel elements are moved relative to the rear wheel elements and lifted off the field together. The front wheel elements of both side frames can be lifted simultaneously at the headland, so that it is irrelevant whether the vehicle is turning left or right at the headland. Simultaneous lifting thus reduces the steering effort. Furthermore, while it may be provided that one or more separate lifting devices are used to lift the wheel element(s) of each side frame, simultaneous lifting can also be achieved via one or more common lifting devices that lift both side frames. This will be explained in more detail below.

[0015] According to a particularly advantageous embodiment of the inventive method, the side frame is elastically twisted by the relative movement of the lifting device. This design allows the front wheel elements to be lifted from the ground by twisting the side frame, eliminating the need to move the wheel elements relative to the respective side frame.

[0016] This results in a comparatively simple control system and design overall. The elastic twisting ensures that the side frame does not suffer permanent damage from the relative actuation of the lifting devices, but rather can return to its original position after turning at the headland.

[0017] P24-045 which causes the front wheel elements to touch the ground or field and supports the respective side frames.

[0018] According to a further development, it has proven advantageous for the lifting devices to be designed as lifting cylinders. A lifting cylinder enables uniaxial movement, allowing the front wheel elements to be reliably lifted. The hydraulic cylinders can be connected to a pressure source, such as a pump, compressor, or accumulator, which provides hydraulic pressure, enabling the hydraulic cylinders to be extended and retracted as desired. The pressure source can be part of the spreading machine or of a tractor pulling the spreading machine.

[0019] It has proven advantageous to hydraulically decouple the lifting cylinders in the headland, allowing each cylinder to be extended or retracted independently. This can be achieved, for example, by separating the cylinders using valves, enabling them to be operated individually and independently, or extended or retracted selectively.

[0020] Specifically, it has proven advantageous to retract the front lifting device(s) for turning at the headland. This allows the side frames to twist as described above and the front wheel elements to lift off the ground.

[0021] Furthermore, it has proven advantageous if the rear lifting device(s) are not retracted or operated when cornering at the headland. In this way, the front lifting device(s) can be operated, and in particular adjusted, relative to the rear lifting device(s). The rear lifting device(s) can also maintain their position when cornering, so that the front lifting cylinder(s) are retracted relative to the rear lifting cylinder(s). This prevents any negative effects.

[0022] P24-045 While support loads on the tractor can be affected by the fact that the connection between the spreader and the tractor could be compromised, it can also be designed so that the rear lifting device(s) are extended, at least slightly, when turning at the headland. This increases the contact pressure of the rear wheel elements, which is advantageous for stability and especially for the support loads. After turning at the headland, i.e., in the normal working position, the lifting devices can be returned to their initial position, in which the side frames are supported against the field by both the front and rear wheel elements.

[0023] To achieve reliable lifting of the front wheel elements, in practice it may be sufficient to retract the front lifting device(s) by just a few centimeters, e.g., 4-5 cm. Depending on the geometry, this can then result in a lifting distance of just a few centimeters, e.g., 10 cm, for the front wheel elements. Therefore, to avoid creating ridges of earth when turning at the headland, it is not necessary to lift the front wheel elements particularly high.

[0024] In the working position, the front and rear lifting devices can be hydraulically coupled, allowing them to be operated together. Specifically, the lifting devices can be retracted simultaneously, thereby raising the side frames into the transport position. This requires neither relative nor uneven operation of the lifting devices. In the working position, the lifting devices or lifting cylinders can also be extended together. To operate the lifting devices together and extend or retract them accordingly, they can be connected to a common pressure source.

[0025] According to an advantageous further development, the position of the wheel elements and / or the lifting devices is detected by a sensor device. This allows for the most accurate possible determination at any given time.

[0026] P24-045 allows for statements regarding the position of the wheel elements and the twisting of the side frame. Excessive stroke or twisting, which could potentially lead to plastic deformation or even destruction, can thus be prevented. It can therefore be designed so that no further relative actuation of the lifting devices is possible beyond a certain threshold. For example, if the front lifting cylinder(s) have already retracted so far that there is a risk of damage to the side frame, further retraction of the front lifting cylinder(s) can be prevented.

[0027] The sensor system allows for the determination of specific parameters, which can then be used, for example, to ascertain the position of the front wheel elements or the torsion of the frame. For instance, the sensor system can be configured to determine the forces acting on the wheel elements, the angular position of the side frame, the stroke or piston position and / or the pressure in the hydraulic cylinder(s), or even the position of the vehicle.

[0028] Furthermore, it can be provided that, for example, the lateral forces acting on the front wheel elements are determined and that the front wheel elements are then lifted when the corresponding lateral forces exceed a certain value. This allows the front wheel elements to be lifted automatically when turning at the headland.

[0029] According to a particularly advantageous embodiment, the lifting devices are actuated unevenly for a predetermined time unit. As an alternative to sensor-controlled actuation, time-controlled actuation is structurally simpler to implement. It can be provided that, in the headland, the front wheel elements are pivoted upwards for a predetermined time unit until they reach a predefined position. To vary the position of the wheel elements, this time unit can also be variable or adjustable. For example, it can be provided that the front lifting cylinder(s) are pivoted for a predetermined time unit.

[0030] The front lifting cylinder(s) can be retracted for a specified time unit as specified in P24-045. In this raised position, the spreader can then be turned at the headland. After the turning maneuver, the front lifting cylinder(s) can be extended for the same time unit, resulting in the same starting position. By predetermining the retraction and extension times, excessive relative actuation, and in particular excessive shortening of the front lifting device(s), can be prevented, thus also preventing damage to the side frames. This is based, of course, on the assumption that the extension and retraction speeds of the lifting devices are known in advance and advantageously remain largely constant. It can also be provided that the lifting cylinder(s) can be manually actuated or controlled. The front wheel elements can thus be raised, for example, at the push of a button.

[0031] With regard to the aforementioned task, an agricultural distribution machine, in particular a seed drill for sowing seed in a field, is further proposed, comprising a central frame and at least two side frames, each pivotably connected to the central frame about a pivot axis, wherein at least two lifting devices arranged one behind the other in the direction of travel are provided for each side frame, by means of which the respective side frame can be pivoted upwards relative to the central frame when the at least two lifting devices are actuated together, wherein the side frames are each supported against the field by first wheel elements, in particular unsteered support wheels, and second wheel elements, in particular tire packers, arranged behind the first wheel elements in the direction of travel, and wherein the distribution machine can be turned at the headland by driving around a curve, so that it can be moved across the field in the opposite direction.wherein a control unit is provided which, in a headland mode, can actuate the at least two lifting devices for turning in the headland in such an uneven manner that the front wheel elements are moved relative to the rear wheel elements and lifted off the field.

[0032] P24-045 In the headland, the control unit can be switched to headland mode automatically or manually. In headland mode, the front wheel elements can then be raised to prevent the pushing up of earth ridges. This results in the advantages already explained with regard to the method. Reference is also made to the above-mentioned explanations of the method with regard to the design of the spreading machine. The method of the type described above can advantageously be carried out with such a spreading machine. The spreading machine is therefore suitable and advantageously designed for carrying out the method.

[0033] Furthermore, it has proven advantageous for the control unit to be able to actuate the lifting devices in such a way that both the front and rear wheel elements are pressed onto the field in a working mode. The control unit is thus switchable between the working mode, in which the spreader can be moved across a field in as straight a line as possible, and the headland mode, in which the spreader can be turned by driving around a curve at the headland. In addition, the control unit can retract the lifting devices together, and especially completely, in a transport mode, so that both side frames can be raised almost uniformly.

[0034] With regard to the side frames, it has proven advantageous for each to have a front cross member extending essentially transversely to the direction of travel and a rear cross member arranged behind it in the direction of travel. In working mode, both cross members are arranged parallel to the field, and in headland mode, the front cross member is angled. When the control unit is in working mode and the wheel elements or side frames are correspondingly in working mode, the side frames can be aligned approximately parallel to the field. The side frames can therefore have a flat geometry. Consequently, the two cross members can then also lie in the same plane and extend essentially parallel to the field.

[0035] In P24-045 headland mode, the front crossmember can then be angled. The rear crossmember can still extend parallel to the field, resulting in a twisting of the side frame that lifts the front wheel elements off the field.

[0036] From a design perspective, it has proven advantageous to connect the side frames to the central frame via pivot bearings. These pivot bearings allow for relative movement of the side frames with respect to the central frame. It is advantageous to provide at least two pivot bearings per side frame, which can be arranged one behind the other. If the lifting cylinders are actuated unevenly or relative to each other, the front pivot bearing, for example, can thus perform a greater rotational movement than the rear pivot bearing. The pivot axes of the side frames can extend in the direction of travel, and the respective pivot axes can be arranged parallel to each other.

[0037] To allow for twisting of the side frames, it has proven advantageous for them to be torsionally flexible. To ensure this flexibility, the side frames can be relatively lightweight, as very heavy, solid frames would not be torsionally flexible. Furthermore, this high degree of flexibility allows the hydraulic pressure, or the energy required for the uneven actuation of the lifting devices or hydraulic cylinders, to be kept within manageable limits.

[0038] According to an advantageous embodiment of the invention, it is proposed that the front lifting device(s), and in particular also the rear lifting device(s), be connected on one side to a side frame and on the other side to the other side frame. In this respect, it may be sufficient to provide only two lifting devices, namely a front lifting device and a rear lifting device. By connecting the lifting devices to the two side frames, these can be pivoted upwards relative to the central frame when the lifting devices are retracted.

[0039] P24-045 Furthermore, simultaneous twisting of the two side frames may be provided if only the front lifting device is retracted and the rear lifting device is not operated or extended.

[0040] Alternatively, it can be provided that at least two lifting devices are provided for each side frame. While this leads to a more complex design and may also entail increased control effort, it allows the two side frames to be lifted or twisted independently of each other. This also makes it possible, for example, to lift only the front wheel elements of one side frame.

[0041] It may also be provided that a sensor device is included for at least indirectly detecting the position of the wheel elements, in particular the front wheel element, and / or the lifting devices, in particular the front lifting device. Furthermore, the twisting of the side frames can also be determined via a sensor device, so that excessive mechanical stress can be prevented. The sensor device may, for example, include force, pressure, or position sensors. Inductive sensors are advantageously used.

[0042] With regard to the sensor system, it has proven advantageous to couple it with the control unit to limit relative actuation of the lifting devices. In this respect, a control loop can be provided between the sensor system or the respective sensors and the lifting devices, allowing for reliable movement of the front wheel elements while simultaneously monitoring the maximum possible lifting movement and twisting. The control unit can thus prevent further relative actuation of the lifting devices if a predefined threshold is exceeded. This prevents damage or destruction of the components.

[0043] Furthermore, it has proven advantageous if the control unit has a switching valve which controls the lifting devices in a first

[0044] The P24-045 switching valve has two positions: one that couples the front lifting devices and another that separates them. The front lifting devices and the rear lifting devices can be fluidly coupled or decoupled via the switching valve. When the lifting cylinders are coupled, they can be operated together, i.e., extended or retracted simultaneously. This allows the side frames to be moved back and forth between the working and transport positions. To actuate the lifting cylinders unevenly, so that the front wheel elements can be raised for turning at the headland, the switching valve can be moved to the second position via the control unit. The lifting cylinders can then be decoupled and thus extended and retracted independently. In headland mode, the switching valve can separate the lifting devices.

[0045] To extend and retract the lifting devices independently, each lifting device can be connected to a pressure source via a valve. If the lifting devices are separate, the valves can be used to individually control whether each lifting device should be extended or retracted.

[0046] To implement the timing control described above, a timing device can be provided which, after start-up, ensures uneven actuation of the lifting devices for a predetermined period, in particular the timed retraction of the front lifting device(s). After this time has elapsed, the front wheel elements can then be reliably raised to enable soil-friendly cornering. Once the spreader has been turned and can then move straight across the field again, the first lifting device can be extended back to its initial position. The timing device can be part of the control unit and actuate the valves to control the lifting devices.

[0047] P24-045 Further details and advantages of the invention will be explained in more detail below with reference to the accompanying drawings. These show:

[0048] Fig. 1 shows a schematic top view of an agricultural spreading machine being pulled across a field;

[0049] Fig. 2 shows a perspective side view of an agricultural spreading machine;

[0050] Fig. 3 shows a top view of an agricultural spreading machine;

[0051] Fig. 4 shows a circuit diagram for controlling the lifting cylinders of an agricultural spreading machine.

[0052] Figure 1 shows a field F with a spreading machine 10, which is pulled in a straight line across field F by a tractor 9. The tractor 9 travels in the track F1 until it reaches the end of field F, in particular a turning area. The spreading machine 10 has a central frame 1 to which side frames 2.1 and 2.2 are arranged. The tractor 9 is coupled to the central frame so that the spreading machine 10 can be pulled across field F by the tractor 9.

[0053] The side frames 2.1 and 2.2 project laterally from the central frame 1, so that the spreading machine 10 covers a relatively large area. The side frames are equipped across their width with several application units and / or processing tools, which can be used, for example, to apply fertilizer or seed to field F in several rows SR side by side and / or to cultivate the soil. The spacing of the rows SR depends on the spacing of the application units.

[0054] Due to the relatively large width of the side frames 2.1, 2.2, these are supported against the field F via wheel elements 4, 5, so that a good

[0055] P24-045 stability is achieved. The wheel elements 4, 5 are not shown in Fig. 1, but can be seen in Figs. 2 and 3. The front wheel element(s) 4 are designed as unsteered support wheels, which are rigidly connected to the respective side frames 2.1, 2.2. The rear wheel elements 5, on the other hand, are designed as tire packers, which bear the main load of the side frames 2.1, 2.2 and which also lead to a certain degree of soil compaction.

[0056] As can be seen particularly in the illustration of Fig. 3, the two side frames 2.1, 2.2 are pivotally connected to the central frame 1, so that the side frames 2.1, 2.2 can be folded up. This can be important, for example, for road transport, since the spreading machine 10, in its unfolded working position where the side frames 2.1, 2.2 are arranged essentially parallel to the track F, is considerably too wide for normal roads. The side frames 2.1, 2.2 can therefore be pivoted up into a transport position. The pivot axes S of the two side frames 2.1, 2.2 are arranged parallel to each other and extend parallel to the longitudinal direction of the vehicle, i.e., in the direction of travel L.

[0057] To move the two side frames 2.1, 2.2 back and forth between the working position and the transport position, or to fold them up and down, two lifting devices 3.1, 3.2 are provided in the illustrated embodiment according to Fig. 3. These lifting devices extend transversely to the longitudinal direction of the vehicle and are arranged one behind the other in the direction of travel L. The lifting devices 3.1, 3.2 are each designed as lifting cylinders, which can be hydraulically actuated, i.e., selectively extended and retracted, via a control unit 6, which will be explained in more detail below. The lifting devices 3.1, 3.2 are connected at one end to one side frame 2.1 and at the other end to the other side frame 2.2, so that when the lifting devices 3.1, 3.2 are retracted together, both side frames 2.1, 2.2 are pivoted into the transport position, thereby lifting the wheel elements 4, 5 from the platform F. When the two lifting devices 3.1, 3.2 out.

[0058] P24-045 in the transport position, the two side frames

[0059] 2.1. 2.2 are pivoted downwards together until the wheel elements 4 and 5 rest on the field F. The lifting devices 3.1 and 3.2 then allow control over the force with which the wheel elements 4 and 5 are pressed onto the field F.

[0060] When the spreader 10 reaches the end of field F, it is turned 180 degrees in the headland V located at the end of field F. The tractor 9 can then pull the spreader 10 in the opposite direction across field F. To achieve the highest possible seed coverage of field F, the side frames 2.1, 2.2 and the application units should, of course, not pass over the seed rows SR that have already been sown with fertilizer or seed on the return journey. Instead, the tracks F1, F2, F3 are chosen so that the seed rows SR are arranged at a relatively constant distance from each other. A 180-degree turn from track F1 to the adjacent track F2 is also referred to as a connecting pass.Especially during such a connecting journey, the curve radius in the headland V is comparatively narrow, which leads to the unsteered front wheel elements 4 being partially dragged across the field F, which can lead to the pushing up of earth embankments.

[0061] To prevent such earth embankments, the two lifting devices 3.1 ,

[0062] 3.2 are now operated unevenly. That is, the two lifting devices 3.1, 3.2 are not retracted together, as would be the case when the side frames 2.1, 2.2 are moved into the transport position, but only the front lifting device 3.1 is retracted, while the rear lifting device 3.2 is not operated. This results in the rear wheel elements 5 remaining on platform F and thus reliably supporting the weight of the respective side frames 2.1, 2.2, while at the same time the front wheel elements 4 lift slightly off platform F, which is sufficient to prevent the pushing of earth embankments.

[0063] P24-045 Due to the relative movement of the lifting devices 3.1, 3.2, the two side frames 2.1, 2.2 are elastically deformed or twisted. This is because the rear part of the side frames 2.1, 2.2 remains essentially parallel to the field F due to the rear lifting device 3.2, whereas the front part of the side frames 2.1, 2.2 is angled and thus forms an acute angle with the field F.

[0064] The side frames 2.1, 2.2 each have a front and a rear crossbeam 2.3, 2.4, which move relative to each other when the lifting devices 3.1, 3.2 are actuated unevenly. If the two crossbeams 2.3, 2.4 are aligned parallel to each other in the working position and extend parallel to the field F, then when cornering at the headland V, the front crossbeam 2.3 is pivoted upwards a short distance about the pivot axis S, and the respective side frame 2.1, 2.2 is thus elastically twisted.

[0065] To twist the side frames 2.1, 2.2 accordingly and lift the front wheel elements 4 from field F, the spreading machine 10 is operated in a headland mode. The spreading machine 10 can be switched manually or via sensor control between a field mode, in which the spreading machine 10 can be moved across field F and the wheel elements 4, 5 roll on field F, and the headland mode.

[0066] The control of the lifting devices 3.1 and 3.2 will now be explained in more detail with reference to the circuit diagram in Fig. 4. First, a pump designated 6.2 is provided as a pressure source, supplying hydraulic pressure and which can be located, for example, on the central frame 1 or alternatively on the tractor unit 9. The actual control unit 6 primarily serves to supply the hydraulic pressure provided by the pump 6.2 to the lifting devices 3.1 and 3.2 in order to extend or retract the corresponding lifting cylinders as desired.

[0067] P24-045 The switching valve 6.1 is fluidically arranged between the two lifting devices 3.1, 3.2. When the switching valve 6.1 is open, as shown in Fig. 4, the right and left pressure chambers of the lifting cylinders are fluidly coupled. Thus, the two lifting devices 3.1, 3.2 can then be extended or retracted simultaneously, e.g., to move the two side frames 2.1, 2.2 back and forth between the working position and the transport position.

[0068] However, if the switching valve 6.1 is in the other switching position, so that the lifting devices 3.1 and 3.2, or the two lifting cylinders, are separated from each other, the two lifting devices 3.1 and 3.2 can be actuated separately and thus extended and retracted independently. When switching from field mode or working mode to headland mode, the switching valve 6.1 is closed or moved into its position separating the two lifting devices 3.1 and 3.2. The separate control of the lifting devices 3.1 and 3.2 can then be regulated via the valves of the control unit 6.5 and the pilot control block 6.4.

[0069] Furthermore, the circuit diagram shows three sensors 7.1, 7.2, 7.3 of a sensor device 7, which are not necessarily present. If present, sensors 7.1, 7.2 serve to monitor the position of the lifting devices 3.1, 3.2 by sensing the position of the piston of the lifting devices 3.1, 3.2 and reporting this to the control unit 6. This can also be seen schematically in the representation of Fig. 2.

[0070] Sensor 7.3 ensures that the two lifting devices 3.1 and 3.2 are not operated too independently of each other. This means that the difference in length between the at least partially retracted front lifting device 3.1 and the rear lifting device 3.2 in headland mode is not too great. If the front lifting device 3.1 were retracted too far relative to the rear lifting device 3.2, this could lead to plastic deformation of the side frames 2.1 and 2.2.

[0071] P24-045, since these are naturally only elastically deformable to a certain degree.

[0072] As soon as the corresponding sensor 7.3 detects excessive relative movement of the two lifting devices 3.1, 3.2, which could lead to damage to the side frames 2.1, 2.2 during further retraction of the front lifting device 3.1, further operation can be prevented. For example, the switching valve 6.1 can be opened so that it is then only possible to operate both lifting devices 3.1, 3.2 together.

[0073] In an alternative and, in particular, preferred embodiment, the sensor 7.3 can be omitted. This is especially true if the retraction movement of the front lifting cylinder is limited. Besides monitoring with a sensor 7.3, one way to achieve such a limitation is through a time-controlled retraction movement. For example, the front lifting device 3.1 can be retracted for a period of 3 seconds. This time unit is dimensioned such that the resulting position and the consequent twisting of the side frame 2.1, 2.2 do not damage the frame. During the turning maneuver or cornering at the headland V, the first lifting device 3.1 can then remain fixed in this position. Once the maneuver is complete, the lifting device 3.1 can be extended again.This extension movement can be controlled by a sensor, but also purely by time. Specifically, this means that the front lifting device 3.1 is extended again for the same duration it was retracted, until the side frames 2.1, 2.2 have returned to their original, unwound position and the front wheel elements 4 are once again touching the field F.

[0074] Overall, the described method or the distribution machine 10 prevents damage to the soil during turning.

[0075] P24-045 reliably prevent headland V due to a lateral movement of the unsteered front wheel elements 4.

[0076] P24-045 Reference number:

[0077] 1 Central frame

[0078] 2.1 Side frame

[0079] 2.2 Side frames

[0080] 2.3 front crossmember

[0081] 2.4 rear crossmember

[0082] 3.1 front lifting device

[0083] 3.2 Rear lifting device

[0084] 4 first / front wheel elements

[0085] 5 second / rear wheel elements

[0086] 6 Control unit

[0087] 6.1 Switching valve

[0088] 6.2 Pump

[0089] 6.4 Input control block

[0090] 6.5 Control unit

[0091] 7 Sensor device

[0092] 7.1 Sensor

[0093] 7.2 Sensor

[0094] 7.3 Sensor

[0095] 9 tractor

[0096] 10 distribution machine

[0097] F field

[0098] L Direction of travel

[0099] S swivel axis

[0100] SR Seed Row

[0101] V Headland

[0102] P24-045

Claims

Patent claims 1. Method for operating an agricultural distribution machine (10), in particular a seed drill for sowing seed on a field, with a central frame (1) and at least two side frames (2.1, 2.2) each pivotably connected to the central frame (1) about a pivot axis (S), wherein at least two lifting devices (3.1, 3.2) arranged one behind the other in the direction of travel (L) are provided for each side frame (2.1, 2.2), by means of which the respective side frame (2.1, 2.2) can be pivoted upwards relative to the central frame (1) when the at least two lifting devices (3.1, 3.2) are actuated together, wherein the side frames (2.1, 2.2) each is supported against the field (F) by first wheel elements (4), in particular unsteered support wheels, and second wheel elements (5), in particular tire packers, arranged behind the first wheel elements (4) in the direction of travel (L), and wherein the spreading machine (10) can be turned in the headland (V) by a curve, so that it can be moved in the opposite direction over the field (F), characterized in that the lifting devices (3.1 , 3.2) are actuated unevenly for the curve in the headland (V), so that the front wheel elements (4) are moved relative to the rear wheel elements (5) and lifted off the field (F).

2. Method according to claim 1, characterized in that the rear wheel elements (5) remain in contact with the field (F) during cornering in the headland (V).

3. Method according to one of claims 1 or 2, characterized in that the front wheel elements (4) of both side frames (2.1 , 2.2) are moved by the front lifting device (3.1 ) such that the front wheel elements (4) are relative to the rear P24-045 Wheel elements (5) are moved and lifted together from the field (F).

4. Method according to one of the preceding claims, characterized in that the side frame (2.1 , 2.2) is elastically twisted by the relative actuation of the lifting devices (3.1 , 3.2).

5. Method according to one of the preceding claims, characterized in that the lifting devices (3.1 , 3.2) are designed as lifting cylinders.

6. Method according to one of the preceding claims, characterized in that the front lifting devices (3.1 , 3.2) are retracted for cornering in the headland (V).

7. Method according to one of the preceding claims, characterized in that the rear lifting devices (3.1 , 3.2) are not retracted for cornering in the headland (V).

8. Method according to claim 7, characterized in that the lifting devices (3.1 , 3.2) are actuated in a working position via a common hydraulic pressure.

9. Method according to one of the preceding claims, characterized in that the lifting devices (3.1 , 3.2) are actuated unevenly for a predetermined unit of time.

10. Agricultural distribution machine, in particular seed drill for spreading seed on a field (F), with a central frame (1 ) and at least two side frames (2.1 , 2.2) each pivotably connected to the central frame (1 ) about a pivot axis (S), wherein for each side frame (2.1 , 2.2) at least two lifting devices (3.1 , 3.1 ) arranged one behind the other in the direction of travel (L) are arranged. P24-045 3.2) are provided, by means of which the respective side frame (2.1, 2.2) can be pivoted upwards relative to the central frame (1) when the at least two lifting devices (3.1, 3.2) are actuated together, wherein the side frames (2.1, 2.2) are each supported relative to the field (F) by first wheel elements (4), in particular unsteered support wheels, and second wheel elements (5), in particular tire packers, arranged behind the first wheel elements (4) in the direction of travel (L), and wherein the spreading machine (10) can be turned in the headland (V) by a curve, so that it can be moved in the opposite direction across the field (F), characterized by a control unit (6) which, in a headland mode, can actuate the at least two lifting devices (3.1, 3.2) unevenly for turning in the headland (V) such that the front wheel elements (4) are relative to the rear Wheel elements (5) are moved and lifted off the field (F).

11. Device according to claim 10, characterized in that the side frames (2.1 , 2.2) each have a front cross member (2.3) extending substantially transversely to the direction of travel (L) and a rear cross member (2.4) arranged behind it in the direction of travel, wherein the two cross members (2.3, 2.4) are arranged parallel to the field (F) in a working mode and wherein the front cross member (2.3) is inclined in the headland mode.

12. Device according to one of claims 10 or 11, characterized in that the side frames (2.1 , 2.2) are designed to be torsionally flexible.

13. Device according to one of claims 10 to 12, characterized by a sensor device (7) for at least indirectly detecting the position of the wheel elements (4, 5), in particular the front wheel element (4) and / or the lifting devices (3.1 , 3.2), in particular the front lifting device (3.1 ). P24-045 14. Device according to claim 13, characterized in that the sensor device (7) for limiting relative actuation of the lifting devices (3.1 , 3.2) is coupled to the control unit (6), whereby further relative actuation is prevented when a predetermined threshold is exceeded.

15. Device according to one of claims 10 to 14, characterized in that the control unit (6) has a switching valve (6.1 ) which couples the lifting devices (3.1 , 3.2) together in a first switching position and which separates the lifting devices (3.1 , 3.2) from each other in a second switching position. P24-045

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