CRACKER TRACK FOR AN AGRICULTURAL MACHINE AND AGRICULTURAL MACHINE

Description

[0001] The present application relates to a crawler track for an agricultural machine according to the preamble of claim 1. Furthermore, the present application relates to an agricultural machine according to the preamble of claim 11.

[0002] The crawler track comprises a front main wheel and a rear main wheel. These main wheels are also known as "idler wheels" in technical terms. Typically, one of the main wheels, usually the rear one, is driven by a motor, while the other main wheel passively guides a track belt that spans both main wheels. The latter is also part of the crawler track. Viewed longitudinally along the crawler track, the main wheels are arranged opposite each other or one behind the other. The front main wheel is assigned to a front main frame, and the rear main wheel to a rear main frame. This assignment can consist, in particular, of the main wheels being mounted directly or indirectly on their respective main frames and each being rotatably mounted around a pivot axis.

[0003] In particular, the front main wheel can be mounted on a pivot arm attached to the front main frame, with its axis of rotation forming a pivot point. The pivot arm is connected to the main frame via a pivot joint, allowing it to pivot relative to the main frame. Since the axis of rotation of the main wheel is located at a distance from the pivot joint of the pivot arm on the latter, pivoting the pivot arm relative to the front main frame results in the pivot axis of the front main wheel moving in a circular path around the pivot joint. This movement alters the distance between the axis of rotation of the front main wheel and the axis of rotation of the rear main wheel, thereby changing the belt tension of the running belt.In such a configuration, the pivoting arm can preferably also interact with a piston-cylinder unit by means of which a pivoting movement of the pivoting arm can be generated, thus allowing the belt tension of the running belt to be adjusted. Such a piston-cylinder unit is referred to in the art as a "belt tensioning cylinder". Such an indirect arrangement of the axis of rotation of the front main wheel on the front main frame is understood, within the meaning of the present application, as an arrangement of the front main wheel on the front main frame.

[0004] In an intermediate section between the two main wheels, at least two support wheels are arranged. These are also known as "midrollers" in technical terms. The support wheels typically have a smaller diameter than the main wheels. Like the main wheels, they are in direct contact with the track, with the support wheels contacting a lower section of the track that typically comes into direct contact with the ground during operation of the crawler track. In this way, forces acting on the crawler track can be transferred to the ground via the track, both through the two main wheels and the two support wheels.

[0005] The tracked undercarriage also includes a pivot point by which it can be pivotally connected to the body of a respective agricultural machine, forming a machine axle. In a typical agricultural machine, such as a combine harvester or a forage harvester, a tracked undercarriage is arranged at opposite ends of the machine's front axle. The respective tracked undercarriage is articulated to the front axle of the machine at the aforementioned pivot point, so that the machine rests on the ground via the tracked undercarriage, and propulsion of the machine is achieved via the tracked undercarriage.

[0006] The two main frames, to which the main wheels are assigned, are pivotally coupled to each other. This allows the main frames to pivot relative to each other about a common pivot axis. Preferably, this pivot axis is identical to the machine axis at the pivot point of the crawler track. The pivot axis and the machine axis are each oriented horizontally and perpendicularly to a track plane defined by the track belt.

[0007] The support wheels are arranged on a common support frame, positioned one behind the other along a longitudinal axis of the track. Thus, viewed longitudinally along the track, the main wheels and the support wheels are arranged "in a row," with the front main wheel forming the front end of the track, followed by the two support wheels, and finally the rear main wheel forming the rear end.

[0008] A support wheel linkage is provided to connect the support frame to the main frames, allowing the support frame to pivot to the front main frame. The support wheel linkage is articulated to both the front main frame and the support frame. Mechanically, the support wheel linkage is therefore designed as a pendulum rod. The articulated connection of the two main frames, as well as the articulated connection of the support wheel linkage to the front main frame, ensures that the main wheels and the support wheels can be lifted independently when an obstacle is encountered, without the rest of the tracked undercarriage lifting off the ground.

[0009] Crawler tracks of the type described above are already known in the prior art. For example, reference is made to German patent application DE 10 2014 003 964 A1. The invention described therein relates to the fact that the axis referred to above as the pivot axis, about which the front main frame and the rear main frame are pivotally mounted relative to each other, and the machine axis, which is located at the pivot point of the crawler track to the axis of a respective working machine, coincide.

[0010] To ensure that the force transmitted via a crawler track to the respective ground is distributed as evenly as possible across the individual wheels of the crawler track (both main wheels and support wheels), a crawler track typically comprises at least one piston-cylinder unit connected at one end to the support wheel arm and at the other end to the front main frame. It is also known that the crawler track comprises at least one further piston-cylinder unit connecting the front and rear main frames. The objective of such piston-cylinder units is essentially to distribute the force evenly across the individual wheels, even when obstacles are traversed, i.e., when the crawler track is not resting entirely on a substantially level surface.The task is to ensure that forces derived via the crawler tracks are transferred as evenly as possible through the wheels into the ground.

[0011] In the prior art, it has proven to be complex to design such crawler tracks, as the available installation space for arranging various piston-cylinder units is limited. Furthermore, coordinating the individual piston-cylinder units is complex in order to achieve the most uniform possible force transmission across the crawler tracks under different operating conditions, particularly under varying ground conditions.

[0012] The present application is therefore based on the task of providing a crawler track for an agricultural machine that is simpler in design than the prior art.

[0013] The underlying problem is solved according to the invention by means of a crawler track system with the features of claim 1. Advantageous embodiments are described in the dependent claims.

[0014] The crawler track according to the invention is characterized by a coupling element that is coupled at its first end ("arm end") to the support wheel arm and at its second end ("frame end") to the rear main frame. This coupling element provides a force-transmitting connection between the rear main frame and the support wheel arm. In a particularly preferred embodiment, the crawler track, apart from the aforementioned coupling element and the articulated linkage to the front main frame, is free of any further connections between the support wheel arm and the front or rear main frame.

[0015] The crawler track according to the invention has many advantages. In particular, force distribution between the main wheels and the support wheels is achieved solely by means of the single coupling link between the support wheel arm and the rear main frame. This is illustrated by the following examples: first, consider the case where the front main wheel travels over an obstacle and is thereby lifted relative to the support wheels and the rear main wheel. The lifting of the front main wheel is accompanied by the lifting of the front main frame, to which the support wheel arm is mounted. As explained above, the coupling link is articulated to the support wheel arm at its swing end. Accordingly, the coupling link is also lifted a certain distance.The lifting amounts of the front main wheel and the coupling link are proportional to their respective distances from the pivot axis around which the front main frame pivots when the front main wheel is lifted. Since the coupling link is connected to the rear main frame at its frame end opposite the end of the swing arm, the rear main frame is also lifted a certain distance in proportion to the lifting of the coupling link. Because both the support wheel swing arm and the rear main frame are pivotally mounted to the support frame, the rear main wheel and the support wheels remain at their original height and are therefore not lifted from the ground. The coupling link ensures that the support wheels continue to be used to transmit forces and thus contribute to the force transmission of the respective machine down to the ground.

[0016] In the second case considered here, the support wheels drive over an obstacle and are consequently lifted. This also involves a lifting of the support wheel arm, to which the coupling link is articulated. Since the support wheel arm is connected to the front main frame only by means of a pivot, the front main frame is moved only indirectly, namely as a result of the lifting of the rear main frame via the coupling link and the consequent lifting of the connection point where the front main frame is connected to the rear main frame via the pivot axis. Because the front main wheel is associated with the front main frame via its axis of rotation, the pivoting of the front main frame does not involve a lifting of the front main wheel.The latter therefore remains in contact with the ground via the track belt and can thus transfer forces acting on the crawler track into the ground. The same applies analogously to the rear main wheel.

[0017] The principle described above applies analogously when the rear main wheel is lifted as a result of driving over an obstacle, whereby the introduction of forces into the support wheels takes place via the coupling link.

[0018] Therefore, the crawler track according to the invention has the particular advantage that, in its simplest embodiment, it ensures a reliable and continuous transfer of forces to the ground via the two main wheels and the two support wheels, using only a single coupling link. This allows the crawler track to be designed particularly simply, and in particular eliminates the need for a second coupling link, which in the prior art is typically designed as a piston-cylinder unit.

[0019] In an advantageous embodiment of the crawler track, the coupling link is oriented such that a straight axis of the coupling link, which connects the swing arm end and the frame end of the coupling link, is inclined at a maximum angle of 15°, preferably at most 10°, and more preferably at most 5°, to a vertical. This embodiment has the advantage that the force distribution between the main wheels and the support wheels can be achieved particularly easily. In particular, no other compensating elements or the like are required to ensure a desired force transmission to the support wheel swing arm and the support wheels if the coupling link were oriented at an angle.

[0020] Furthermore, it can be particularly advantageous if the pivot axis of the two main frames and the machine axis coincide. In this configuration, the crawler track has a central main joint that forms the pivot point and to which it is connected to a respective axle of a working machine, forming the machine axis. The pivot axis is also formed at this central main joint, to which the front and rear main frames are pivotally connected. Preferably, the pivot point—and thus the machine axis and the pivot axis—is located centrally on the crawler track when viewed longitudinally, so that the horizontally measured distance of the front main wheel's axis of rotation from the pivot axis is at least essentially the same as the horizontally measured distance of the rear main wheel's axis of rotation from the pivot axis.This design also contributes to a simplification of the crawler track, since the kinematics of the possible relative movements of the individual elements to each other is simplified compared to a design in which the pivot axis and machine axis are arranged separately.

[0021] In a further advantageous embodiment, the swing arm end and the frame end of the coupling element are arranged, viewed longitudinally along the crawler track, on the same side of a vertically oriented median plane that includes the pivot axis. This median plane, which is oriented perpendicular to a track belt plane spanned by the track belt, conceptually divides the crawler track into a front section and a rear section, the front section comprising the front main frame and the front main wheel, and the rear section comprising the rear main frame and the rear main wheel. As described above, the pivot axis is preferably located in accordance with the machine axis and, more preferably, at the longitudinal center of the crawler track.

[0022] The arrangement of the coupling link on one side of the central plane, preferably on the side of the front section, also contributes to particularly simple kinematics of the crawler track. The force ratio in which the support wheel arm, and thus the support wheels, are subjected to forces or used to transfer forces into the ground can be adjusted by changing the distance of the coupling link from the pivot axis. The closer the end of the coupling link is to the support frame along the support wheel arm, the greater the force transmission by the support wheels. For example, the end of the coupling link can be positioned exactly in the middle of the support wheel arm, so that forces introduced into the support wheel arm via the coupling link are distributed equally between the linkage of the support wheel arm to the front main frame and the support frame.A shift in the swing arm end along the support wheel swing arm results in a distribution of forces between the front main frame and the support frame that deviates from a 50 / 50 split. Preferably, the swing arm end of the coupling link is located, in a direction parallel to the longitudinal axis of the crawler track, at a distance from the pivot axis of at most 1 / 4, preferably at most 1 / 6, and more preferably at most 1 / 8, of a correspondingly measured wheel spacing between the axes of rotation of the main wheels.

[0023] Furthermore, such a configuration of the crawler track can be advantageous in which the axes of rotation of the two main wheels and the pivot axis are, at least when the crawler track is in a neutral position, essentially at the same height. When the crawler track is in its neutral position, the pivot axis is in its zero position. For the purposes of this application, the neutral position of the crawler track describes a state in which the track rests on a level surface, meaning that neither the main wheels nor the support wheels are driving over an obstacle. Such a neutral position of a crawler track is illustrated in the figures of the exemplary embodiment. The arrangement of the pivot axis at the same height as the axes of rotation of the main wheels ensures that no torque is generated about the pivot axis due to belt tension of the track.Due to the essentially identical vertical distance of an upper section of the track from the pivot axis compared to the vertical distance of a lower section of the track from the pivot axis, the forces acting on the track cancel each other out due to their identical lever arm relative to the pivot axis, so no torque occurs. Such a torque only occurs when the pivot axis is vertically displaced from its neutral position, which can happen as a result of lifting one of the wheels of the crawler track.

[0024] If the pivot axis deflects from its neutral position in the vertical direction, as occurs, for example, when at least one of the wheels of the track is lifted upon crossing an obstacle, a torque about the pivot axis caused by the track belt and its tension is typically to be expected. This is because, as a rule, the distances of the upper and lower sections of the track belt from the pivot axis will differ due to the vertical displacement of the pivot axis. Consequently, the lever arms between the lower and upper sections of the track belts are different, meaning that the torques generated by the belt tension about the pivot axis do not cancel each other out.The greater the vertical deflection of the pivot axis, the greater the effective torque acting on the pivot axis, causing the front main frame to pivot relative to the rear main frame around the pivot axis. The system is self-reinforcing.

[0025] Due to these circumstances, it can be particularly advantageous if the crawler track includes at least one spring element. This is preferably passively designed, with the spring force generated by the spring element resulting solely from the deflection of the spring. A first end of the spring element is connected to the front main frame and a second end of the spring element to the rear main frame. In this way, the spring element connects the two main frames, so that when the two main frames pivot relative to each other about the pivot axis, the spring element is stretched or compressed. This results in a change in the spring force exerted by the spring element, which is transmitted equally to the front and rear main frames at each end of the spring element.The spring element is arranged such that an effective axis of the spring element, along which the spring force acts, is located at a distance from the pivot axis. In this way, the spring force exerts a torque about the pivot axis on the two main frames. Since, by its very nature, the spring force acts in opposite directions at the ends of the spring element on the front and rear main frames, the front and rear main frames are subjected to opposing torques about the common pivot axis.

[0026] Here, the spring element is preferably configured such that, when the crawler track is in its neutral position (and thus when the pivot axis is in its neutral position), it is either in a passive state, in which the spring element develops neither tensile nor compressive forces, or in a state pre-tensioned with tensile or compressive stress, depending on the arrangement. Since the pivot axis typically cannot move downwards from its neutral position, only the case where the pivot axis moves vertically upwards from its neutral position needs to be considered. Accordingly, with regard to the effect of the track tension, only a state in which the crawler track "stands up" upwards needs to be considered, meaning that the pivot axis is deflected further upwards as a result of its vertical upward movement due to the effect of a torque caused by the track belt.The spring element now serves to counteract this movement and at least reduce or limit the so-called "raising" of the crawler tracks. If the spring element is arranged such that its two ends move away from each other during the described rising movement of the crawler tracks, the spring element is preferably designed as a tension spring pre-tensioned with a tensile stress. Conversely, the spring element can also be arranged such that its two ends are located at points on the front and rear main frames that move towards each other as a result of the crawler tracks rising. In this case, the spring element is preferably designed as a compression spring pre-tensioned with a compressive stress.In any case, the spring element should act in such a way as to counteract the pivoting of the front main frame relative to the rear main frame caused by the erection of the crawler track.

[0027] Alternatively or additionally to a described spring element, it is also conceivable that the crawler track has an active piston-cylinder unit, the first end of which is connected to the front main frame and the second end to the rear main frame. The piston-cylinder unit is designed and configured to actively apply opposing torques to the main frames around their common pivot axis. In contrast to the passive spring element, this allows for the active application of forces. For example, such a piston-cylinder unit could be a hydraulic cylinder. Designing the crawler track with such a piston-cylinder unit has the advantage that the two main frames can be deliberately pivoted relative to each other around the pivot axis, and thus the action does not merely counteract any potential movement of the crawler track.For example, by operating the piston-cylinder unit, the two main frames can be deliberately pivoted towards each other around the pivot axis, thus reducing the force transmitted to the ground via the two main wheels and correspondingly increasing the force transmission via the support wheels. Such operation can be advantageous, for instance, in the area of ​​a headland to protect the ground from high shear forces. This type of operation is also conceivable when a machine is traveling on a road.

[0028] In a particularly preferred configuration, the crawler track system incorporates both a passive spring element and an active piston-cylinder unit. This allows for particularly easy adjustment of the various operating conditions. The spring element and the piston-cylinder unit can optionally be designed as a single assembly, with the spring element forming part of the piston-cylinder unit and acting on the piston at one end and the cylinder of the piston-cylinder unit at the other. As explained above regarding the spring element, this results in an effect on both the front and rear main frames.

[0029] Furthermore, a design of the crawler track in which the coupling element is formed by a piston-cylinder unit can be advantageous. As such, the coupling element is preferably designed and configured to dampen movements that the support wheels and the rear main frame perform relative to each other. To achieve this, it can be particularly advantageous if a cylinder-side main pressure chamber of the coupling element interacts with a gas accumulator, allowing the coupling element to act as a gas spring. This ensures good ride comfort for the respective machine on which the crawler track is mounted. In particular, sudden deflections resulting from driving over obstacles and the forces generated by them can be dampened. In addition to improving ride comfort, this also protects the components of the crawler track and the machine as a whole.

[0030] If the coupling element is formed by a piston-cylinder unit, it can be particularly advantageous if it is designed to be double-acting. In this case, a secondary pressure chamber on the piston side can be pressurized, thereby allowing a pressure to be set in a main pressure chamber on the cylinder side. This can be achieved, in particular, by maintaining the pressure in the main pressure chamber within a preset range. In other words, by applying pressure to the secondary pressure chamber on the piston side, a pressure level in the main pressure chamber on the cylinder side can be deliberately kept within a specific range. This has the advantage that the coupling element can be kept within a favorable region of its characteristic curve, meaning that the damping properties of the coupling element can be utilized to a particularly advantageous extent.

[0031] The present problem is further solved according to the invention by means of an agricultural machine having the features of claim 11.

[0032] The machine comprises a body and two crawler tracks, namely a left and a right crawler track. Each crawler track is connected to the body via a pivot point. In particular, the crawler tracks can be connected to a front axle of the machine. The machine is characterized in that at least one of the crawler tracks, preferably both crawler tracks, is / are formed by a crawler track according to the invention as defined in the present application. The advantages resulting from this have already been explained above.

[0033] The invention is explained in more detail below with reference to an exemplary embodiment shown in the figures. These show: Fig. 1: A schematic side view of an agricultural machine equipped with two crawler tracks, Fig. 2: A cross-section through a crawler track according to the prior art, Fig. 3: A schematic representation of a first crawler track according to the invention, Fig. 4: A schematic representation of a second crawler track according to the invention, Fig. 5: A schematic representation of a third crawler track according to the invention, Fig. 6: A schematic representation of a fourth crawler track according to the invention.

[0034] In Figure 1Figure 2 depicts an agricultural machine in the form of a self-propelled combine harvester, whose body 42 interacts with two crawler tracks 1. The crawler tracks 1 are connected to a front axle of the machine 2. Each crawler track 1 has a front main wheel 3, a rear main wheel 4, and two support wheels 9, 10. Furthermore, the crawler track 1 includes a track belt 11 that spans the two main wheels 3, 4. The main wheels 3, 4 are arranged opposite each other along a longitudinal axis 16 of the crawler track 1. The support wheels 9, 10 are located in an intermediate area between the main wheels 3, 4. Overall, forces transmitted from the machine 2 to the crawler track 1 are transferred to the ground via both the main wheels 3, 4 and the support wheels 9, 10.

[0035] The basic design of a crawler track 1 according to the invention is the same as that of known crawler tracks according to the prior art. An example of such a track is shown in Figure 2 The crawler track 1 shown has a front main frame 5 and a rear main frame 6. The two main frames 5, 6 are connected to each other at a central pivot point 12 of the crawler track 1, forming a pivot axis 14, in a manner that allows them to pivot relative to each other. In the example shown, the pivot axis 14 coincides with a machine axis 13 formed at the pivot point 12, about which the crawler track 1 as a whole is pivotably mounted about a respective axis of the working machine 2. The machine axis 13 and the pivot axis 14 are oriented horizontally and perpendicularly to a belt plane that is stretched by the track belt 11. Figure 2The plane of the belt is formed by the plane of the drawing. Furthermore, the pivot axis 14 is arranged centrally with respect to the longitudinal axis 16 of the crawler track 1, such that a vertical median plane 29, which is also oriented perpendicular to the plane of the belt 11 and includes the pivot axis 14, divides the crawler track 1 into two sections of at least essentially equal size, namely a front section and a rear section. The front section includes the front main frame 5 and the front main wheel 3, while the rear section comprises the rear frame 6 and the rear main wheel 4. Furthermore, when the crawler track 1 is in a central position, which is in Figure 2As illustrated, the pivot axis 14 is arranged centrally when viewed in the vertical direction, such that a vertically measured distance of the pivot axis 14 from a lower section 39 of the running belt 11 is the same as a vertically measured distance of the pivot axis 14 from an upper section 38 of the running belt 11. As a result, forces acting on the running belt 11 due to belt tension do not produce a torque about the pivot axis 14, provided the latter is in its Figure 2 the zero position shown, which the pivot axis 14 assumes when the crawler track 1 is in its central position.

[0036] A support wheel swing arm 17 is articulated to the front main frame 5 by means of a joint 34. At an end of the support wheel swing arm 17 opposite the joint 34, the latter is connected – also by means of a joint 35 – to a support frame 15. The two support wheels 9, 10 are each rotatably mounted on this support frame 15.

[0037] In the example shown, the front main wheel 3 is only indirectly mounted to the front main frame 5. This is achieved by mounting the front main wheel 3 on a pivot arm 33, which in turn is pivotally mounted to the front main frame 5. In this way, a distance between the pivot axis 7 of the front main wheel 3 and the pivot axis can be determined. 14 by swiveling the swivel arm 33 relative to the front main frame 5 can be changed. This is used to adjust the tension of the running belt. 11to recreate this. To achieve this, the tracked undercarriage shown includes 1 a band tensioning cylinder formed by a piston-cylinder unit 30, which with its first end 36 on the swivel arm 33 and with its second end 37 is mounted on the front main frame 5. By changing the deflection of the belt tension cylinder 30, the swivel arm 33 can be pivoted relative to the main frame 5, thereby shifting the axis of rotation 7 horizontally as described and changing the belt tension of the running belt 11 accordingly.

[0038] The crawler track 1 shown further comprises two additional piston-cylinder units 31, 32, the first of which connects the front main frame 5 to the rear main frame 6and the second one couples the support wheel swing arm 17 with the front main frame 5. Working together, the piston-cylinder units 31, 32 are designed and configured to distribute the forces acting on the crawler track 1 to the main wheels 3, 4 and the support wheels 9, 10. For this purpose, the pressure chambers of the two piston-cylinder units 31, 32 can be fluidically coupled, so that the displacement of a hydraulic fluid from the pressure chamber of one piston-cylinder unit 31, 32 results in a corresponding flow of fluid into the pressure chamber of the other piston-cylinder unit 31, 32. This kinematically couples the components front main frame 5, rear main frame 6 and support wheel swing arm 17 or support frame 15 to effect the aforementioned force distribution and, in particular, to keep the wheels 3, 4, 9, 10 in continuous contact with the ground.This should be maintained especially when wheels 3, 4, 9, 10 are lifted at different times when driving over an obstacle.

[0039] A first variant of a crawler track system 1 according to the invention is shown in Figure 3This is illustrated. It differs from the known crawler track 1, in particular by a coupling link 18, which couples the support wheel arm 17 to the rear main frame 6. Accordingly, one end 19 of the coupling link 18 is pivotally connected to the support wheel arm 17, while one end 20 of the coupling link 18 is pivotally connected to the rear main frame 6. In this way, the coupling link 18 acts mechanically as a pendulum rod, which can only transmit normal forces, but does not allow the transmission of torques between the support wheel arm 17 and the rear main frame 6. The coupling link 18 results in the front main frame 5, the support wheel arm 17, and the rear main frame 6 being kinematically coupled to each other. In this way, the coupling link alone is responsible for... 18 achieved that when one of the wheels is lifted 3, 4, 9, 10 the remaining wheels 3, 4, 9, 10remain in contact with the ground and thus continue to transmit force via these wheels 3, 4, 9, 10 into the subsurface. This has already been explained with reference to two examples in the preceding description. In contrast to the crawler track 1 according to the prior art, it is therefore not necessary to install two separate piston-cylinder units 31, 32 to kinematically couple the support wheel swing arm 17 and the front main frame 5 and the rear main frame 6. Accordingly, the crawler track 1 according to the invention is significantly simplified compared to the prior art, without any limitation of functionality. The crawler track 1 according to the invention is particularly advantageous Figure 3free from additional coupling links that, for example, couple the support wheel swing arm 17 to the front main frame 5 or the two main frames 5, 6 to each other. Compared to the prior art, the crawler track 1 is therefore of a particularly simple design without any disadvantage in terms of its functionality.

[0040] In the example shown, the coupling element 18 is at least substantially vertically oriented, such that it is at least substantially parallel to a vertical 22. This is particularly evident from the following: Figure 3 .Furthermore, the coupling element 18 is located entirely on one side of the pivot axis 14, and in the example shown, it is situated in the front section of the crawler track 1 on this side of the central plane 29. The coupling element 18 is also arranged such that it is located at a horizontally measured distance 23 from the pivot axis 14, which corresponds approximately to one-eighth of a horizontally measured wheel spacing 24 between the axes of rotation 7, 8 of the two main wheels 3, 4. With this arrangement, at least when the crawler track 1 is in its Figure 3In the central position shown, a force transmitted at the pivot point 12 to the crawler track 1 is distributed into the ground in equal quarters via the two main wheels 3, 4 and the two support wheels 9, 10. Furthermore, in the example shown, the swing arm 19 of the coupling link 18 is arranged approximately centrally on the support wheel arm 17, such that the horizontal distance of the swing arm 19 from the two joints 34, 35 is equal. This results in a vertical force transmitted via the coupling link 18 to the support wheel arm 17 being distributed approximately half to the front main frame 5 and half to the support frame 15.

[0041] In another variant of a crawler track 1 according to the invention, which is in Figure 4As shown, the coupling element 18 is formed by a piston-cylinder unit. Otherwise, the embodiments are designed identically. The design of the coupling element 18 as a piston-cylinder unit has the advantage that the coupling element 18 is equipped with a damping effect, whereby sudden forces acting on the main wheels 3, 4 and / or the support wheels 9, 10 are only transmitted to the axle of the respective working machine 2 in a damped manner. In this design, the coupling element can 18 in particular designed in the manner of a gas spring, wherein a cylinder-side main pressure chamber of the coupling element 18 It is filled with a gas that is compressible as a result of the application of a force. Furthermore, the main pressure chamber can interact with a gas storage unit (not shown) for this purpose.

[0042] Another variant of a crawler track 1 according to the invention, which is in Figure 5as depicted is in contrast to the one in Figure 4The second variant shown is further developed such that the crawler track 1 also has a spring element 25. This spring element is connected at a first end 26 to the front main frame 5 and at a second end 27 to the rear main frame 6, so that spring forces induced by the spring element 25 act in opposite directions directly on the front main frame 5 and the rear main frame 6. In the example shown, the spring element 25 is passive, so that forces induced by the spring element 25 are solely due to a deflection of the spring element 25. Here, the spring element 25 is designed in the form of a piston-cylinder unit, wherein a piston of the piston-cylinder unit, guided in a cylinder, is tensioned against the cylinder by a spring.In the example shown, the piston is connected to the front main frame 5 at the first end of the spring element 25 and the cylinder is connected to the rear main frame 6 at the second end 27 of the spring element 25.

[0043] The spring element 25 has the function of preventing the above-described erection of the crawler track 1 as a result of a vertical displacement of the pivot axis. 14 starting from their in Figure 5 The depicted zero position is reduced upwards and thereby controlled. This setup is necessary because a vertically measured distance of the swivel axis is required. 14 as a result of a displacement of the same from an upper section 38 of the running belt 11 is reduced, while a similarly measured distance of the pivot axis 14 from a lower section 39 of the running belt 11 It is enlarged. This results in tension on the running belt. 11a torque about the pivot axis 14 on the front main frame 5 and the rear main frame 6, resulting in a self-reinforcing deflection of the pivot axis 14 upwards. The spring element 25 serves to counteract an increase in the distance between the two ends 26, 27 of the spring element resulting from such a movement of the two main frames 5, 6. 25 to counteract this. In the example shown, this is achieved by the spring of the spring element acting between the piston and the cylinder. 25 It is compressed, thereby counteracting the piston's extension from the cylinder. This causes the two ends to become compressed. 26, 27 of the spring element 25 pulled towards each other, thereby applying a torque to the two main frames 5, 6 that counteracts the erection of the crawler track 1.

[0044] In another variant of a crawler track according to the invention 1,the in Figure 6 As shown, the crawler track 1 is also equipped with a passive spring element 25. However, unlike the third variant, this one is according to Figure 5 arranged elsewhere, whereby the intended effect, namely the application of a torque that causes the crawler track 1 to stand upright when the pivot axis is displaced, 14 counteracts, is identical. Here, the spring element 25 is designed as a compression spring, which is compressed during the uprighting of the crawler track 1 and thereby counteracts the uprighting. Furthermore, the crawler track 1 in the example shown has an active piston-cylinder unit 28, the first end of which 40 with the front main frame 5 and its second end 41 interact with the rear main frame 6. The piston-cylinder unit 28 is connected to a hydraulic pressure source located in Figure 6not shown. This creates, in particular, the possibility of pressurizing a piston-side pressure chamber of the piston-cylinder unit 28, thereby retracting the piston into the cylinder. This leads to a shortening of the piston-cylinder unit 28 and thus to a movement of both ends. 40, 41The piston-cylinder unit 28 moves towards each other. At least when the crawler track 1 is in a neutral position, such a movement means that the two main wheels 3, 4 are lifted and thus relieved of load, while the two support wheels 9, 10 contribute a greater share to dissipating the forces acting on the crawler track 1. In this way, it is possible to selectively reduce the forces transmitted to the ground via the two main wheels 3, 4, which can be advantageous, for example, during a turning maneuver of the machine 2 in the area of ​​a headland or during road travel.

[0045] Furthermore, it is conceivable that the coupling element, designed as a piston-cylinder unit, 18 It is designed to be double-acting. In this design, a main pressure chamber on the cylinder side is fluidically connected to, for example, a gas accumulator to fulfill a damping function, so that the coupling element18 can act as a gas spring. Furthermore, a secondary pressure chamber on the piston side can be actively pressurized, for example by means of a coupling to a hydraulic pressure source of the respective working machine 2. This makes it possible to maintain the pressure in the main pressure chamber "artificially" within a predetermined range. This can be advantageous, for example, if a force acting on the crawler track 1 is so small that the pressure in the main pressure chamber lies outside an advantageous range. In particular, attempts are being made to optimize the coupling element. 18 to keep it within an advantageous range of its characteristic curve in order to maintain the damping properties of the coupling element. 18 to make the best possible use of it. By applying pressure to the secondary pressure chamber, the pressure in the main pressure chamber can be regulated so that it always remains within a predefined, advantageous range. Reference symbol list

[0046] 1 Track drive 2 Working machine 3 Front main wheel 4 Rear main wheel 5 Front main frame 6 Rear main frame 7 Pivot axis 8 Pivot axis 9 Support wheel 10 Support wheel 11 Running belt 12 Linkage point 13 Machine axle 14 Swivel axle 15 Support frame 16 Longitudinal axis 17 Support wheel arm 18 Coupling link 19 Swing arm end 20 Frame end 21 Link axle 22 Vertical 23 Spacing 24 Wheel spacing 25 Spring element 26 End 27 End 28 Piston-cylinder unit 29 Center plane 30 Belt tension cylinder 31 Piston-cylinder unit 32 Piston-cylinder unit 33 Swivel arm 34 Joint 35 Joint 36 End 37 End 38 Section 39 Section 40 End 41 End 42 Body

Claims

1. A track roller unit (1) for an agricultural working machine (2), comprising - a front main wheel (3), - a rear main wheel (4) which is opposite the front main wheel (3) viewed in the longitudinal direction of the track roller unit (1), - a front main frame (5) associated with the front main wheel (3), - a rear main frame (6) associated with the rear main wheel (4), - at least two support wheels (9, 10) disposed in an intermediate region between the main wheels (3, 4), - a track belt (11) encompassing the main wheels (3, 4), - an articulation point (12), by means of which the track roller unit (1) can be pivotably connected to a body (42) of the working machine (2) through the formation of a machine axis (13), wherein the two main frames (5, 6) are pivotably coupled to each other about a common pivot axis (14), wherein the support wheels (9, 10) are disposed one behind the other with respect to a longitudinal axis (16) of the track roller unit (1) on a common support frame (15), wherein the support frame (15) is pivotably connected to the front main frame (5) by means of a support wheel rocker arm (17), characterized by a coupling link (18), which is coupled to the support wheel rocker arm (17) at a rocker arm end (19) of the coupling link (18) and to the rear main frame (6) at a frame end (20) of the coupling link (18) and thereby couples the support wheel rocker arm (17) and the rear main frame (6) with each other.

2. The track roller unit (1) according to claim 1, characterized in that the coupling link (18) is orientated in a manner such that a link axis (21) which is straight in itself and connects the rocker arm end (19) and the frame end (20) is inclined by at most 15°, preferably by at most 10°, more preferably by at most 5°, to a vertical (22).

3. The track roller unit (1) according to one of the preceding claims, characterized in that the pivot axis (14) of the two main frames (3, 4) coincides with the machine axis (13).

4. The track roller unit (1) according to one of the preceding claims, characterized in that the rocker arm end (19) and the frame end (20) of the coupling link (18) are disposed on the same side of a vertically orientated central plane (29) containing the pivot axis (14).

5. The track roller unit (1) according to one of the preceding claims, characterized in that, viewed in a direction parallel to the longitudinal axis (16) of the track roller unit (1), the rocker arm end (19) of the coupling link (18) is disposed at a distance (23) from the machine axis (13) of at most 1 / 4, preferably at most 1 / 6, more preferably at most 1 / 8, of a correspondingly measured wheel spacing (24) between the axes of rotation (7, 8) of the main wheels (3, 4).

6. The track roller unit (1) according to one of the preceding claims, characterized in that the axes of rotation (7, 8) of the two main wheels (3, 4) and the pivot axis (14) lie at least substantially at a common height level when the track roller unit (1) is located in a central position in which the track roller unit (1) stands on a level substrate.

7. The track roller unit (1) according to one of the preceding claims, characterized by a spring element (25), which is preferably passive, the first end (26) of which being connected to the front main frame (5) and the second end (27) of which being connected to the rear main frame (6), wherein the spring element (25) is provided and configured to apply a mutual torque to the main frames (5, 6) about the common pivot axis (14) at least when the pivot axis (14) is above a neutral position which the respective main wheel (3, 4) takes up when the track roller unit (1) is located in a central position in which the track roller unit (1) stands on a level substrate.

8. The track roller unit (1) according to one of the preceding claims, characterized by an active piston and cylinder unit (28), the first end of which (40) being connected to the front main frame (5) and the second end (41) of which being connected to the rear main frame (5), wherein the piston and cylinder unit (28) is provided and configured to actively apply a mutual torque to the main frames (5, 6) about the common pivot axis (14).

9. The track roller unit (1) according to one of the preceding claims, characterized in that the coupling link (18) is formed by a piston and cylinder unit, wherein preferably, the piston and cylinder unit is provided and disposed to damp movements which the support wheels (9, 10) and the rear main frame (6) execute relative to each other.

10. The track roller unit (1) according to claim 9, characterized in that the piston and cylinder unit is constructed to be double-acting, wherein a piston-side secondary pressure chamber can be pressurized, as a result of which a pressure in a cylinder-side primary pressure chamber can be adjusted in a manner such that the pressure in the primary pressure chamber is within a preset range.

11. An agricultural working machine (2), comprising - a body (42), - a left track roller unit (1), - a right track roller unit (1), wherein the track roller units (1) are respectively connected to the body (42) via an articulation point (12), characterized in that at least one of the track roller units (1) is constructed in accordance with one of the preceding claims.