Tracked undercarriage for an agricultural machine as well as agricultural machinery

Abstract

The present application relates to a crawler track (1) for an agricultural machine (2), comprising a front main wheel (3), a rear main wheel (4), 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), a running belt (11) spanning the main wheels (3, 4) and a pivot point (12) by means of which the crawler track (1) can be pivotably connected to a body (42) of the machine (2) by forming a machine axle (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 arranged 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 arm (17). In order to provide a track drive for an agricultural machine which is more flexible in its application to different operating conditions of the machine compared to the prior art, the invention proposes a first piston-cylinder unit (18) which is coupled at its first end (19) to the support wheel swing arm (17) and at its second end (20) to the rear main frame (6), and a second piston-cylinder unit (28) which is coupled at its first end (40) to the front main frame (5) and at its second end (41) to the rear main frame (6).

Description

[0001] The present application relates to a crawler track for an agricultural working machine according to the preamble of claim 1. Furthermore, the present application relates to an agricultural working machine according to the preamble of claim 15.

[0002] The crawler track comprises a front main wheel and a rear main wheel. These main wheels are also known in technology as "idler wheels". Typically, one of the main wheels, usually the rear one, is rotationally driven, while the other main wheel serves passively to guide a running belt that spans the main wheels. The latter is also part of the crawler track. Viewed longitudinally of the crawler track, the main wheels are arranged opposite one another 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 in the fact that the main wheels are arranged directly or indirectly on their respective main frames and are each mounted so that they can rotate about a rotation axis.

[0003] In particular, the front main wheel can be mounted on a pivot arm, forming its axis of rotation, which is arranged on the front main frame. The pivot arm is connected to the main frame and forms a pivot joint, such that the pivot arm can pivot relative to the main frame. Since the axis of rotation of the main wheel is arranged at a distance from the pivot joint of the pivot arm, pivoting of the pivot arm relative to the front main frame is accompanied by a movement of the axis of rotation of the front main wheel on a circular path around the pivot joint. This movement leads to a change in 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 pivot arm can preferably further cooperate with a piston-cylinder unit, by means of which a pivoting movement of the pivot arm can be generated and thus the belt tension of the running belt can be adjusted. Such a piston-cylinder unit is referred to in technology as a "belt tensioning cylinder." Such an indirect arrangement of the rotational axis of the front main wheel on the front main frame is understood, for the purposes of the present application, as an arrangement of the front main wheel on the front main frame.

[0004] At least two support wheels are arranged in an intermediate area between the two main wheels. These are also known in technology as "mid rollers". The support wheels typically have a smaller diameter than the main wheels. Like the main wheels, they are in direct contact with the running belt. The support wheels are in contact with a lower section ("lower run") of the running belt, which 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 diverted into the ground via both the two main wheels and the two support wheels via the running belt.

[0005] The crawler track further comprises a pivot point by means of which it can be pivotally connected to the body of a respective work machine, forming a machine axle. In a typical agricultural work machine, such as a combine harvester or a forage harvester, a crawler track is arranged at opposite ends of a front axle of the respective work machine. The respective crawler track is pivoted to the front axle of the work machine at the pivot point mentioned, so that the work machine rests on a respective surface by means of the crawler tracks, and propulsion of the work machine can be achieved via the crawler tracks.

[0006] The two main frames, to which the main wheels are assigned, are pivotally coupled. This allows the main frames to pivot relative to each other around a common pivot axis. This pivot axis is preferably 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 plane spanned by the running belt. They are thus oriented parallel to each other.

[0007] The support wheels are mounted on a common support frame, arranged one behind the other relative to the longitudinal axis of the crawler track. Thus, the main wheels and the support wheels are arranged "in series" in the longitudinal direction of the crawler track, with the front main wheel forming the front end of the crawler track, followed by the two support wheels, and finally the rear main wheel forming the rear end of the crawler track.

[0008] A support wheel swing arm is provided to connect the support frame to the main frame, pivoting the support frame to the front main frame. The support wheel swing arm is articulated to both the front main frame and the support frame. The support wheel swing arm is therefore mechanically designed as a pendulum rod. The articulated connection of the two main frames, as well as the articulated connection of the support wheel swing arm to the front main frame, ensures that the main wheels and the support wheels can be raised separately when driving over an obstacle without the rest of the crawler track lifting off the ground.

[0009] Crawler tracks of the type described above are already known in the prior art. Reference is made to German patent application DE 10 2014 003 964 A1 as an example. The invention described therein is based on 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, coincides with the machine axis, which is located at the articulation point of the crawler track of a respective work machine.

[0010] In order to ensure that the force transferred via a crawler track into a particular subsoil is 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 which is connected at a first end to the support wheel swing arm and at a second end to the front main frame.

[0011] Furthermore, it is known that a crawler track can comprise at least one additional piston-cylinder unit that connects the front main frame and the rear main frame. The task of such piston-cylinder units is essentially to even out the power distribution across the individual wheels, even when driving over obstacles, i.e., when the crawler track is not fully supported on an at least substantially level surface. In other words, forces dissipated via the crawler track should be transferred as evenly as possible to the ground via the wheels.

[0012] The conventional tracked undercarriages have the disadvantage that they cannot be dynamically configured for different operating conditions. However, the range of operating conditions can be considerable. For example, a combine harvester must manage an empty run on a public road, a drive with a fully loaded grain tank across a field during harvesting, and a turning maneuver on a headland. The requirements for power transfer to the ground are very different in each case.

[0013] The present application is therefore based on the object of providing a crawler track for an agricultural work machine which, compared to the prior art, can be used more flexibly with regard to different operating states of the work machine.

[0014] The underlying object is achieved according to the invention by means of a crawler track having the features of claim 1. Advantageous embodiments emerge from the associated subclaims.

[0015] The crawler track assembly according to the invention is characterized by a first piston-cylinder unit, which is coupled at its first end ("rocker end") to the support wheel rocker and at its second end ("frame end") to the rear main frame. As a result, the rear main frame and the support wheel rocker are coupled to one another in a force-transmitting manner by means of the piston-cylinder unit. Particularly preferably, apart from the first piston-cylinder unit and the articulated linkage of the support wheel rocker to the front main frame, the crawler track assembly is designed free of any further connections between the support wheel rocker on one side and the front or rear main frame on the other side. For example, the first piston-cylinder unit can be a hydraulic cylinder.

[0016] Furthermore, the crawler track according to the invention comprises a second piston-cylinder unit, the first end of which is coupled to the front main frame and the second end of which is coupled to the rear main frame. Preferably, an axis of action of the second piston-cylinder unit extends at a distance from the pivot axis by which the two main frames are connected. In this way, the second piston-cylinder unit is suitable for exerting a torque about the pivot axis on the two main frames or for receiving it from them.

[0017] The crawler track system according to the invention has many advantages. First, power distribution between the main wheels and the support wheels can be achieved solely by means of the first piston-cylinder unit between the support wheel swing arm and the rear main frame. This is illustrated by the following case distinctions: First, consider the case in which the front main wheel drives over an obstacle and is thereby raised relative to the support wheels and the rear main wheel. The raising of the front main wheel is accompanied by the raising of the front main frame, on which the support wheel swing arm is mounted. As explained above, the first piston-cylinder unit is articulated to the support wheel swing arm by its swing end. Accordingly, the first piston-cylinder unit is also raised slightly.The amounts of lift of the front main wheel and the first piston-cylinder unit are proportional to their respective distances relative to the pivot axis around which the front main frame is pivoted during the lifting of the front main wheel. Since the first piston-cylinder unit is coupled to the rear main frame at the end opposite the swing arm end, the rear main frame is also raised slightly in line with the lifting of the first piston-cylinder unit. Since both the support wheel swing arm is articulated to the support frame and the rear main frame is articulated to the rear main wheel, the rear main wheel and the support wheels remain at their previous height and are therefore not lifted off the ground.The first piston-cylinder unit ensures that the support wheels continue to be used to transfer forces and thus contribute to the transfer of force from the respective working machine down to the ground.

[0018] In the second case considered here, the support wheels drive over an obstacle and are raised accordingly. This is also accompanied by a raising of the support wheel swing arm, to which the first piston-cylinder unit is pivoted. Since the support wheel swing arm is otherwise only connected to the front main frame by forming a joint, the front main frame is only moved indirectly, namely as a result of a raising of the rear main frame via the first piston-cylinder unit and a concomitant raising of the connection point at which the front main frame is connected to the rear main frame, forming the joint axis. Since the front main wheel is assigned to the front main frame, forming its axis of rotation, the pivoting of the front main frame is not accompanied by a raising of the front main wheel.The latter therefore remains in contact with the ground via the running belt and can thus transfer forces acting on the crawler track into the ground. The same applies to the rear main wheel.

[0019] The principle described above applies analogously when the rear main wheel is raised as a result of driving over an obstacle, whereby the forces are introduced into the support wheels via the first piston-cylinder unit.

[0020] The crawler track according to the invention therefore has the particular advantage that, in its simplest design, it uses only the first piston-cylinder unit to ensure continuous, reliable transfer of forces into the ground via the two main wheels and the two support wheels. This allows the crawler track to be constructed particularly simply, eliminating the need for a second piston-cylinder unit, which is required in the prior art to ensure this functionality.

[0021] The second piston-cylinder unit, which the crawler track also has, serves a different purpose and offers several advantages. A first significant advantage is the passive and / or active counteraction against what is known as "tilting" of the crawler track due to the belt tension acting in the running belt. "Tilting" can occur when forces acting on the two main frames effectively generate a torque relative to the pivot axis, causing the main frames to pivot relative to each other about the pivot axis. To avoid this as much as possible, it is preferable if the pivot axis, when the crawler track is in a central position in which both main wheels and the support wheels are together on a level surface, is in a zero position, height-wise midway between an upper section of the running belt ("upper run") and a lower section of the running belt ("lower run").In this way, the running belt as such with its belt tension does not generate any torque around the pivot axis, since the forces acting in the upper and lower strands each have the same lever arm relative to the pivot axis and thus, to a certain extent, “cancel” each other out.

[0022] As explained above, however, when the crawler track is used, deflections of individual wheels inevitably occur, causing the pivot axis to move vertically, namely upwards from its zero position. This results in the vertically measured distances of the pivot axis from the lower and upper runs of the running belt changing and, in particular, are no longer equal. The result of such a movement of the pivot axis is that the forces acting in the running belt generate a torque on the two main frames about the pivot axis. Since the deflection of the pivot axis generally occurs upwards, the distance orThe lever arm for the forces acting in the lower run relative to the pivot axis is larger, so that the system of the two main frames statically strives to move the main frames below the pivot axis toward each other. This means, viewed from the side view of the crawler track, that the front main frame rotates counterclockwise and the rear main frame rotates clockwise. As a result, the pivot axis is moved further vertically upward, and the torque induced by the running belt is further amplified. The system reinforces itself accordingly.

[0023] The second piston-cylinder unit serves to counteract this upward movement of the pivot axis and thereby at least reduce or limit the so-called "standing up" of the crawler track. This is achieved by the second piston-cylinder unit, due to its coupling to the two main frames, actively or passively exerting forces on the two main frames, thereby impeding their relative pivoting movement. Preferably, the second piston-cylinder unit can actively apply a mutual torque to the two main frames around the common pivot axis.In this way, the second piston-cylinder unit, which can be designed to be single-acting or double-acting, for example, is suitable for actively counteracting the above-described erection of the crawler track when the pivot axis moves upwards from its zero position and, as a result, torques are introduced into the main frame by the belt tension of the running belt.

[0024] A further key advantage of the second piston-cylinder unit is that it can actively raise or lower the two main wheels as needed. This is particularly possible when the second piston-cylinder unit is actively designed, i.e., at least one working chamber of the second piston-cylinder unit is operatively connected to a pressure device that includes a pressure source or interacts with such a pressure source. By means of such a pressure source, the working chamber can be subjected to hydraulic pressure. In this way, the second piston-cylinder unit is suitable for actively applying an opposing torque to the two main frames about the common pivot axis. In other words, the second piston-cylinder unit is designed to actively exert forces on the two main frames.For example, the second piston-cylinder unit can be a hydraulic cylinder.

[0025] This has the advantage that the two main frames can be actively pivoted relative to each other about the pivot axis, rather than just causing an (active or passive) counteraction to a possible tilting of the crawler track due to belt tension. For example, by operating the second piston-cylinder unit, the two main frames can be actively pivoted towards each other above the pivot axis. This lifts the two main wheels or relieves the load on both main wheels in such a way that a payload acting on the crawler track is dissipated proportionally more via the support wheels and to a correspondingly lesser extent via the main wheels. In extreme cases, the main wheels can be completely lifted off the ground, so that they no longer contribute to dissipating the payload into the ground.

[0026] Such an influence on the power distribution to the individual wheels, deliberately deviating from the most equal distribution possible, which is ensured by the first piston-cylinder unit during normal harvesting operations as explained above, can be advantageous in various operating conditions of the respective work machine. For example, the main wheels can be relieved of load during a turning maneuver on a headland in order to protect the ground from the introduction of high shear forces across the entire length of the crawler track. Such raising is also advantageous, for example, when the work machine is traveling on the road, which inevitably involves cornering. Raising the main wheels makes such cornering considerably easier and protects the running belt from excessive wear.

[0027] In an advantageous embodiment of the crawler track, the first piston-cylinder unit is provided and configured to dampen movements that the support wheels and the rear main frame perform relative to one another. To achieve this, it can be particularly advantageous if at least one working chamber of the first piston-cylinder unit, preferably a cylinder-side working chamber, interacts with a pressure device. This can, for example, be a passive pressure device in the form of a gas reservoir. With this embodiment, the first piston-cylinder unit can act as a gas spring. This ensures good driving comfort for the respective work machine on which the crawler track is mounted. In particular, sudden deflections resulting from driving over obstacles and the resulting forces can be dampened.In addition to improving driving comfort, this also protects the components of the crawler track and the respective working machine as a whole.

[0028] Furthermore, it can be particularly advantageous for the first piston-cylinder unit to be double-acting. This is implemented, for example, in such a way that a first working chamber (for example the piston-side working chamber) of the first piston-cylinder unit interacts with an active pressure device and can thus be actively pressurized. This makes it possible to adjust the pressure in the second working chamber (in this example, the cylinder-side working chamber). To apply hydraulic pressure to the respective working chamber, this working chamber can, for example, interact with a pressure device that comprises a pressure source or interacts with such a pressure source. The latter can, for example, be formed by a hydraulic pump. A connection of the respective working chamber to a hydraulic system of the work machine to which the crawler track is connected is conceivable.

[0029] The hydraulic pressure in the second working chamber of the first piston-cylinder unit can preferably be adjusted such that the pressure is within a preset range. In other words, by applying pressure to the first working chamber, a pressure level in the second working chamber can be deliberately maintained within a specific range. This has the advantage that the first piston-cylinder unit can be maintained within a favorable range of its characteristic curve, i.e., the damping properties of the first piston-cylinder unit can be utilized in a particularly advantageous manner.

[0030] For example, it is conceivable that the first piston-cylinder unit is designed to transmit large forces into the ground via the crawler track. This means that the first piston-cylinder unit transmits large forces between its swing arm end and its frame end. Designing the first piston-cylinder unit for such a load case, which sensibly accounts for a large part of a typical usage profile of the respective work machine, means that the damping characteristics of the first piston-cylinder unit are optimized for this load case. If a different load case occurs in which the crawler track, for example, has to transfer significantly lower forces into the ground, the first piston-cylinder unit typically operates away from its best possible operating point, meaning the damping characteristics are not ideal.In such a case, the pressure device can apply additional hydraulic pressure to one working chamber to "simulate" a higher load on the crawler track. The pressure in the second working chamber increases, so that the first piston-cylinder unit is kept within an ideal range of its characteristic curve, despite the comparatively low payload introduced into the crawler track. As a result, the damping characteristics of the first piston-cylinder unit can be influenced, allowing it to function effectively over a wide load range.

[0031] Accordingly, it may be advantageous if the first piston-cylinder unit is configured such that the pressure in the first piston-cylinder unit, for example, in a cylinder-side working chamber thereof, is at least substantially the same for smaller payloads acting on the crawler track as it is for larger payloads. In other words, the pressure level in the first piston-cylinder unit should, if possible, be within a preset range that enables a gentle damping behavior of the first piston-cylinder unit.

[0032] Furthermore, a design of the crawler track may be advantageous in which at least one pressure device is assigned to at least one piston-cylinder unit, preferably to all piston-cylinder units. This can be a passive or an active pressure device.

[0033] A "passive pressure device" within the meaning of the present application can, in particular, be formed by a gas reservoir. Such a device generally comprises two pressure chambers fluidically separated by a membrane, one pressure chamber being filled with pressurized gas ("gas chamber") and the other pressure chamber ("fluid chamber") being in fluid contact with a hydraulic fluid of a hydraulic system, the hydraulic system including at least one working chamber of a respective piston-cylinder unit. In this way, the hydraulic fluid can be displaced from the working chamber of the piston-cylinder unit and flow into the fluid chamber of the gas reservoir, in the process deforming the membrane and compressing the gas in the gas chamber. The gas thereby builds up an increasing counterpressure.Conversely, the gas pushes the diaphragm—and thus the hydraulic fluid in the fluid chamber—back into the working chamber of the piston-cylinder unit as soon as the volume of the latter increases or the counterpressure of a piston of the piston-cylinder unit drops and falls below the pressure prevailing in the gas chamber of the pressure device. In this case, the pressure device effectively pushes the piston of the piston-cylinder unit back. These processes are passive within the meaning of the present application, since the pressure device is not intended or configured to actively exert a variable pressure on the hydraulic system, for example, by means of a pump. The passive pressure device can indeed be preloaded and thus exert pressure on the hydraulic system. Otherwise, however, it only reacts to changes introduced into the hydraulic system from outside.

[0034] In contrast, an "active pressure device" within the meaning of the present application is one by means of which a pressure in a hydraulic system can be actively changed. For this purpose, the pressure device can interact with a pressure source, for example, a pump, be formed by a pressure source, or comprise a pressure source. Preferably, an active pressure device also comprises a passive element, for example, in the form of a described gas reservoir. Consequently, a combination of a passive pressure device in interaction with a pressure source within the meaning of the present application can also be considered an "active pressure device."

[0035] According to the above explanations, a design is particularly preferred in which the first piston-cylinder unit is double-acting, with a first working chamber, preferably the piston-side working chamber, interacting with an active pressure device and a second working chamber, preferably the cylinder-side working chamber, interacting with a passive pressure device. As a result, the first piston-cylinder unit can achieve the best possible damping over wide payload ranges in the manner explained above. The second piston-cylinder unit is single-acting in this design, with one working chamber (either a piston-side or a cylinder-side working chamber) interacting with an active pressure device. The second piston-cylinder unit can thus both counteract the described tilting of the crawler track and also cause the two main wheels to be raised or lowered.After all, the crawler track in this design comprises a total of three pressure devices, two of which are assigned to the first piston-cylinder unit and one to the second piston-cylinder unit.

[0036] In an advantageous embodiment of the crawler track, the piston-cylinder unit is aligned such that a straight link axis of the first piston-cylinder unit, which connects the swing arm end and the frame end of the first piston-cylinder unit, is inclined by a maximum of 15°, preferably by a maximum of 10°, and more preferably by a maximum of 5°, relative 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 the desired amount of force introduction into the support wheel swing arm and the support wheels.

[0037] Furthermore, it can be particularly advantageous if the pivot axis of the two main frames and the machine axis coincide. In this embodiment, the crawler track has a central main joint which forms the articulation point and at which it is connected to a respective axle of a work machine, forming the machine axis. The pivot axis, at which the front main frame and the rear main frame are pivotally connected to one another, is also formed on this central main joint. Preferably, the articulation point - and thus the machine axis and the pivot axis - is located centrally on the crawler track, viewed in the longitudinal direction of the crawler track, so that a horizontally measured distance of the axis of rotation of the front main wheel from the pivot axis is at least substantially the same as a horizontally measured distance of the axis of rotation of the rear main wheel from the pivot axis.This design also contributes to a simplification of the crawler track, as the kinematics of the possible relative movements of the individual elements to each other are simplified compared to a design in which the pivot axis and machine axis are arranged separately. Furthermore, it is preferable if the pivot axis or machine axis, when the crawler track is in a central position, are located vertically midway between the upper and lower strands of the running belt.

[0038] In a further advantageous embodiment, the swing arm end and the frame end of the first piston-cylinder unit are arranged on the same side of a vertically oriented center plane, viewed in the longitudinal direction of the crawler track, which includes the pivot axis and is oriented perpendicular to a belt plane spanned by the running belt. This center plane conceptually separates the crawler track into a front section and a rear section, with 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. According to the above description, the pivot axis is preferably located in correspondence with its position on the machine axis and further preferably in a center of the crawler track viewed in the longitudinal direction.

[0039] The arrangement of the first piston-cylinder unit on one side of the center plane, preferably on the side of the front section, contributes to particularly simple kinematics of the crawler track. The distance of the first piston-cylinder unit from the pivot axis can be used to adjust the force ratio by applying forces to the support wheel swing arm and thus the support wheels or by using them to dissipate forces into the ground. The closer the swing end of the first piston-cylinder unit is to the support frame along the support wheel swing arm, the greater the force transfer from the support wheels.For example, the swing arm end can be arranged exactly in the middle of the support wheel swing arm, so that forces introduced into the support wheel swing arm by means of the first piston-cylinder unit are split equally between the articulation of the support wheel swing arm to the front main frame and the support frame. A displacement of the swing arm end along the support wheel swing arm accordingly leads to a distribution of the forces between the front main frame and the support frame that deviates from the 50 / 50 split. Preferably, the swing arm end of the first piston-cylinder unit is located, viewed 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, more preferably at most 1 / 8, of a correspondingly measured wheel distance between the rotation axes of the main wheels.

[0040] Furthermore, a design 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 substantially at a common height, at least when the crawler track is in its central position. When the crawler track is in its central position, the pivot axis is preferably in its zero position. For the purposes of the present application, the central position of the crawler track describes a state of the crawler track in which it is resting on a level surface, i.e., neither the main wheels nor the support wheels are driving over an obstacle. Such a central position of a crawler track is illustrated in the figures of the exemplary embodiment. If the pivot axis is deflected vertically from its zero position, this can lead to the above-described tilting of the crawler track, which the second piston-cylinder unit counteracts.

[0041] The present object is further achieved according to the invention by means of an agricultural working machine having the features of claim 15.

[0042] The work machine comprises a body and two crawler tracks, namely a left and a right crawler track. The crawler tracks are each connected to the body via a pivot point. In particular, the crawler tracks can be connected to a front axle of the work machine. The work 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 in accordance with the present application. The resulting advantages have already been explained above.

[0043] The invention is explained in more detail below using an exemplary embodiment illustrated in the figures. It shows: Fig. 1: A schematic side view of an agricultural machine equipped with two crawler tracks, Fig. 2: A cross-section through a crawler track, Fig. 3: A schematic diagram of a crawler track according to the invention.

[0044] In Fig. 1 shows an agricultural work machine 2 in the form of a self-propelled combine harvester, the body 42 of which interacts with two crawler tracks 1. The crawler tracks 1 are connected to a front axle of the work machine 2. The crawler track 1 has a front main wheel 3, a rear main wheel 4, and two support wheels 9, 10. The crawler track 1 also comprises a running belt 11 that spans the two main wheels 3, 4. The main wheels 3, 4 are arranged opposite one another along a longitudinal axis 16 of the crawler track 1. The support wheels 9, 10 are arranged in an intermediate region between the main wheels 3, 4. Overall, forces diverted from the work machine 2 into the crawler track 1 are transferred into the ground via both the main wheels 3, 4 and the support wheels 9, 10.

[0045] The design of a crawler track 1 according to the invention is fundamentally similar to other crawler tracks. One such track is shown as an example in Fig. 2. The crawler track 1 there has a front main frame 5 and a rear main frame 6. The two main frames 5, 6 are connected to one another at a central pivot point 12 of the crawler track 1, forming a pivot axis 14 in a manner pivotable relative to one another. 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 work machine 2. The machine axis 13 and the pivot axis 14 are oriented horizontally and perpendicularly to a belt plane spanned by the running belt 11. In Fig. 2 the belt plane is formed by the drawing plane or parallel to it.

[0046] Furthermore, the pivot axis 14 is arranged centrally with respect to a length of the crawler track 1 measured along the longitudinal axis 16 of the crawler track 1, so that a vertical center plane 29, which is also oriented perpendicular to the belt plane of the running belt 11 and contains the pivot axis 14, divides the crawler track 1 into two at least substantially equal sections, 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 in Fig. 2, the pivot axis 14 is arranged centrally in a zero position in which it is viewed in the vertical direction, that is to say in relation to a height of the crawler track 1, so that a vertically measured distance of the pivot axis 14 from a lower run 39 of the running belt 11 is exactly as large as a vertically measured distance of the pivot axis 14 from an upper run 38 of the running belt 11. As a result, forces acting in the running belt 11 as a result of a belt tension of the running belt 11 do not cause any torque about the pivot axis 14, as long as the latter is in its Fig. 2 shown zero position.

[0047] A support wheel swing arm 17 is pivoted to the front main frame 5, forming a joint 34. At an end of the support wheel swing arm 17 opposite the joint 34, the latter is connected to a support frame 15—also forming a joint 35. The two support wheels 9, 10 are each rotatably mounted on this support frame 15.

[0048] In the example shown, the front main wheel 3 is only indirectly mounted on the front main frame 5. This is done here in such a way that the front main wheel 3 is mounted on a pivot arm 33, which in turn is pivotally mounted on the front main frame 5. In this way, the distance between the axis of rotation 7 of the front main wheel 3 and the pivot axis 14 can be changed by pivoting the pivot arm 33 relative to the front main frame 5. This is used to set or adjust the belt tension of the running belt 11. To achieve this, the crawler track 1 shown comprises a belt tensioning cylinder 30 formed by a piston-cylinder unit, which is mounted with its first end 36 on the pivot arm 33 and with its second end 37 on the front main frame 5.By changing the deflection of the belt tensioning cylinder 30, the pivot arm 33 can be pivoted relative to the main frame 5, whereby the rotation axis 7 is displaced horizontally in the manner described, thereby changing its horizontally measured distance from the rotation axis 8 of the rear main wheel 4. Accordingly, the belt tension of the running belt 11 is changed by such a movement.

[0049] The crawler track 1 shown further comprises two additional piston-cylinder units 31, 32, the first coupling the front main frame 5 to the rear main frame 6, and the second coupling the support wheel swing arm 17 to the front main frame 5. In conjunction, 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. The task is generally to transfer the forces as evenly as possible via the main wheels 3, 4 and the support wheels 9, 10 into the ground. For this purpose, working chambers of the two piston-cylinder units 31, 32 can be fluidically coupled to one another, so that the displacement of a hydraulic fluid from a working chamber of one piston-cylinder unit 31, 32 results in a corresponding inflow of the fluid into a working chamber of the other piston-cylinder unit 31, 32.This kinematically couples the components of the front main frame 5, the rear main frame 6, and the support wheel swing arm 17 or support frame 15 to achieve 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, in particular, even when the wheels 3, 4, 9, 10 are raised intermittently when driving over an obstacle.

[0050] A crawler track 1 according to the invention is shown in Fig. 3. It comprises a first piston-cylinder unit 18, which interacts with a first pressure device 45 and a second pressure device 46.

[0051] The first piston-cylinder unit 18 couples the support wheel swing arm 17 to the rear main frame 6. Accordingly, a swing arm end 19 of the first piston-cylinder unit 18 is pivotally connected to the support wheel swing arm 17, while a frame end 20 of the first piston-cylinder unit 18 is pivotally connected to the rear main frame 6. In this way, the first piston-cylinder unit 18 acts mechanically as a pendulum rod that can only transmit normal forces, but does not allow the transmission of transverse forces and torques between the support wheel swing arm 17 and the rear main frame 6. The first piston-cylinder unit 18 results in the front main frame 5, the support wheel swing arm 17, and the rear main frame 6 being kinematically coupled to one another.In this way, the first piston-cylinder unit 18 alone ensures that when one of the wheels 3, 4, 9, 10 is lifted, the remaining wheels 3, 4, 9, 10 remain in contact with the ground, and accordingly, power continues to be transferred into the ground via these wheels 3, 4, 9, 10. This has already been explained using two examples in the above description.

[0052] In contrast to the crawler track 1 according to Fig. 2, it is therefore not necessary to install two separate piston-cylinder units 31, 32 for orderly load transfer in order 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 without restricting its functionality.

[0053] In the example shown, the first piston-cylinder unit 18 is oriented at least substantially vertically, so that a link axis 21 connecting the swing end 19 and the frame end 20 is oriented at least substantially parallel to a vertical 22. This is particularly evident from Fig. 3. Furthermore, the first piston-cylinder unit 18 is located entirely on one side of the pivot axis 14, wherein in the example shown it is located in the front section of the crawler track 1 on this side of the center plane 29. Furthermore, the first piston-cylinder unit 18 is 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 wheel distance 24, also measured horizontally, between the rotation axes 7, 8 of the two main wheels 3, 4. In this arrangement, at least when the crawler track 1 is in its Fig. 3, a force transmitted to the crawler track 1 at the articulation point 12 is diverted into the ground via the two main wheels 3, 4 and the two support wheels 9, 10, one quarter each. Furthermore, in the example shown, the swing arm end 19 of the piston-cylinder unit 18 is arranged approximately centrally on the support wheel swing arm 17, so that a horizontally measured distance of the swing arm end 19 from the two joints 34, 35 is equal. This has the effect that a vertical force transmitted to the support wheel swing arm 17 via the first piston-cylinder unit 18 is diverted approximately half to the front main frame 5 and half to the support frame 15.

[0054] In the example shown, the first piston-cylinder unit 18 is double-acting and accordingly comprises a cylinder-side working chamber 48 and a piston-side working chamber 47. The first piston-cylinder unit 18 interacts with the two pressure devices 45, 46 such that the first pressure device 45 is assigned to the piston-side working chamber 47 and the second pressure device 46 is assigned to the cylinder-side working chamber 48. The first pressure device 45 is formed here by an active pressure device. In the example shown, this comprises a pressure source 50, which can be formed by a hydraulic pump. Furthermore, the first pressure device 45 comprises a passive gas reservoir 43. In this way, the first pressure device 45 is suitable for damping pressure fluctuations in the piston-side working chamber 47 and, if necessary, actively influencing them.

[0055] The pressure source 50 is connected to the piston-side working chamber 47 by means of a line such that a hydraulic pressure provided by the pressure source 50 acts in the piston-side working chamber 47 of the first piston-cylinder unit 18. Thus, the pressure source 50 is suitable for retracting a piston of the first piston-cylinder unit 18 into the associated cylinder, thereby increasing the volume of the piston-side working chamber 47 while reducing the volume of the cylinder-side working chamber 48. This increases the pressure in the cylinder-side working chamber 48 and thereby artificially maintains it 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 cylinder-side working chamber 48 lies outside a favorable range.In particular, an attempt is made to keep the first piston-cylinder unit 18 within a favorable range of its characteristic curve in order to optimally utilize the damping properties of the first piston-cylinder unit 18. By applying pressure to the piston-side working chamber 47, the pressure in the cylinder-side working chamber 46 can be adjusted such that it always lies within a predefined, advantageous range. The damping characteristics of the first piston-cylinder unit 18 can thus be maintained within a favorable range of its characteristic curve, regardless of the load on the crawler track 1.

[0056] The second pressure device 46 is passive and comprises a passive gas reservoir 43 with a compressible gas volume. The gas volume of the passive gas reservoir 43 is separated by a membrane from a hydraulic fluid located in the cylinder-side working chamber 48 of the first piston-cylinder unit 18 and exchanged with the second pressure device 46 via a line. The gas reservoir 43 of the first pressure device 45 is constructed analogously.

[0057] The pressure devices 45, 46 enable a damping function, which is performed by the first piston-cylinder unit 18. In this way, shock loads acting on the wheels 3, 4, 9, 10, for example, as a result of driving over an obstacle, are dampened to prevent sudden loads.

[0058] The front main frame 5 and the rear main frame 6 are additionally directly coupled to one another by means of a second piston-cylinder unit 28. This is connected at a first end 40 to the front main frame 5 and at a second end 41 to the rear main frame 6, so that opposing forces can act directly on the front main frame 5 and the rear main frame 6 by means of the second piston-cylinder unit 28. Since an axis of action of the second piston-cylinder unit 28 extends at a distance from the pivot axis 14, a force exerted by the second piston-cylinder unit 28 causes a torque on the two main frames 5, 6 about the pivot axis 14.

[0059] In the example shown, the second piston-cylinder unit 28 is designed to be single-acting, with a piston-side working chamber 49 of the second piston-cylinder unit 28 interacting with a pressure device 44 that includes both a hydraulic pressure source 50 and a passive gas reservoir 43. By means of the pressure source 50, the piston-side working chamber 49 of the second piston-cylinder unit 28 can be actively pressurized with hydraulic pressure. Since the working chamber 49 is arranged on the piston side here, a piston of the second piston-cylinder unit 28 is retracted into an associated cylinder as a result of the application of hydraulic pressure to the piston-side working chamber 49. This leads to a shortening of the second piston-cylinder unit 28 and thus to a movement of the two ends 40, 41 of the second piston-cylinder unit 28 towards one another. At least when the crawler track 1 is in a central position, as shown in Fig. 3, such a movement is equivalent to the two main wheels 3, 4 being raised and thus relieved of load, while the two support wheels 9, 10 contribute a greater proportion to the transfer of the forces acting on the crawler track 1. In this way, it is possible to specifically reduce the forces diverted into the ground via the two main wheels 3, 4, which can be advantageous, for example, during a turning maneuver of the work machine 2 in the area of ​​a headland or when the respective work machine 2 is traveling on the road.

[0060] Furthermore, the second piston-cylinder unit 28 can be used to passively or actively counteract the above-explained erection of the crawler track 1. By means of the gas reservoir 43, a movement of the piston within the cylinder of the second piston-cylinder unit 28 can be dampened. For an active influence, alternatively or additionally, the piston-side working chamber 49 can be pressurized with hydraulic pressure by means of the pressure source 50. In other words, the second piston-cylinder unit 28 has, among other things, the function of counteracting the erection of the crawler track 1 as a result of a vertical displacement of the pivot axis 14 starting from its Fig.3 and thereby control it. Said setting up is due to the fact that a vertically measured distance of the pivot axis 14 from the upper run 38 of the running belt 11 is reduced as a result of a vertical upward displacement of the pivot axis 14, while a similarly measured distance of the pivot axis 14 from the lower run 39 of the running belt 11 is increased. As a result, as a result of belt tension of the running belt 11, a torque about the pivot axis 14 is exerted on the front main frame 5 and the rear main frame 6, which torque promotes a further upward movement of the pivot axis 14. The further the pivot axis 14 is raised, the greater the torque that supports this effect, resulting in a self-reinforcing upward deflection of the pivot axis 14.

[0061] By means of the second piston-cylinder unit 28, an increase in the distance between the two ends 40, 41 of the second piston-cylinder unit 28, which occurs during the setting up, can be counteracted. In the example shown, this occurs by increasing the pressure in the piston-side working chamber 49, which stabilizes the piston in the cylinder, i.e., prevents it from extending further. Accordingly, a balance is created in the second piston-cylinder unit 28 with the force resulting from the acting torque, which in turn results from the raising of the pivot axis 14 and causes the setting up. The setting up can be slowed down or stopped accordingly. List of reference symbols 1 crawler track 2 working machines 3 front main wheel 4 rear main wheel 5 front main frame 6 rear main frame 7 axis of rotation 8 axis of rotation 9 Support wheel 10 support wheel 11 Running belt 12 articulation point 13 Machine axis 14 Swivel axis 15 support frames 16 Longitudinal axis 17 Support wheel swing arm 18 first piston-cylinder unit 19 Swing end 20 frame end 21 Link axis 22 vertical 23 Distance 24 wheelbase 25 26 27 28 second piston-cylinder unit 29 Middle Level 30 belt tensioning cylinders 31 Piston-cylinder unit 32 piston-cylinder unit 33 Swivel arm 34 joint 35 joint 36 End 37 End 38 Upper Drum 39 Lower strand 40 End 41 End 42 Body 43 gas storage facilities 44 Printing device 45 Printing device 46 Printing device 47 work space 48 workspace 49 work space 50 pressure source QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2014 003 964 A1

[0009]

Claims

[1] Crawler track (1) for an agricultural working machine (2), comprising - a front main wheel (3), - a rear main wheel (4) opposite the front main wheel (3) viewed in the longitudinal direction of the crawler track (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) arranged in an intermediate area between the main wheels (3, 4), - a running belt (11) spanning the main wheels (3, 4), - a linkage point (12) by means of which the crawler track (1) can be pivotably connected to a body (42) of the working machine (2) to form a machine axis (13), wherein the two main frames (5, 6) are pivotally coupled to one another about a common pivot axis (14), wherein the support wheels (9, 10) are arranged one behind the other on a common support frame (15) relative to a longitudinal axis (16) of the crawler track (1), wherein the support frame (15) is pivotally connected to the front main frame (5) by means of a support wheel swing arm (17), characterized by a first piston-cylinder unit (18) which is coupled at its first end (19) to the support wheel swing arm (17) and at its second end (20) to the rear main frame (6) and thereby couples the support wheel swing arm (17) and the rear main frame (6) to one another, and by a second piston-cylinder unit (28) which is coupled at its first end (40) to the front main frame (5) and at its second end (41) to the rear main frame (6). [2] Crawler track (1) according to one of the preceding claims, characterized bythat the first piston-cylinder unit (18) is provided and arranged to dampen movements which the support wheels (9, 10) and the rear main frame (6) carry out relative to one another. [3] Crawler track (1) according to one of the preceding claims, characterized by that the second piston-cylinder unit (28) is provided and arranged to actively apply a mutual torque to the main frames (5, 6) about the common pivot axis (14). [4] Crawler track (1) according to one of the preceding claims, characterized by that at least one of the piston-cylinder units (18, 28), preferably both piston-cylinder units (18, 28), is assigned at least one pressure device (44, 45, 46). [5] Crawler track (1) according to one of the preceding claims, characterized byin that the first piston-cylinder unit (18) is designed to be double-acting, wherein a piston-side working chamber (47) interacts with a pressure device (45) by means of which the piston-side working chamber (47) can be pressurized, whereby a pressure in a cylinder-side working chamber (48) can be adjusted such that it is within a preset range. [6] Crawler track (1) according to claim 5, characterized by that the first piston-cylinder unit (18) cooperates with two pressure devices (45, 46), wherein the first pressure device (45) is operatively connected to the piston-side working chamber (47) and the second pressure device (46) is operatively connected to the cylinder-side working chamber (48). [7] Crawler track (1) according to claim 6, characterized by that one of the pressure devices (45) is formed by a gas reservoir. [8] Crawler track (1) according to one of the preceding claims, characterized bythat the second piston-cylinder unit (28) is single-acting. [9] Crawler track (1) according to one of the preceding claims, characterized by that a pressure device (44) is assigned to the second piston-cylinder unit (28), wherein the pressure device (44) is preferably operatively connected to a piston-side working chamber (49) of the second piston-cylinder unit (28). [10] Crawler track (1) according to one of claims 4 to 9, characterized by that at least one pressure device (44, 45, 46), preferably all pressure devices (44, 45, 46), comprises a gas storage device or is formed by a gas storage device. [11] Crawler track (1) according to one of claims 4 to 10, characterized bythat at least one pressure device (44, 45, 46) comprises a hydraulic pressure source (50) or is connected to a hydraulic pressure source (50), by means of which a variable hydraulic pressure can be actively applied to a working chamber (47, 48, 49) of at least one of the piston-cylinder units (18, 28). [12] Crawler track (1) according to one of the preceding claims, characterized by that the second piston-cylinder unit (28) is arranged such that a pressure in the second piston-cylinder unit (28) is within a preset range regardless of a payload acting on the crawler track (1). [13] Crawler track (1) according to one of the preceding claims, characterized by that the pivot axis (14) of the two main frames (3, 4) coincides with the machine axis (13). [14] Crawler track (1) according to one of the preceding claims, characterized bythat the axes of rotation (7, 8) of the two main wheels (3, 4) and the pivot axis (14) are at least substantially at a common height level when the crawler track (1) is in a central position in which the crawler track (1) stands on a level surface. [15] Agricultural working machine (2), comprising - a body (42), - a left crawler track (1), - a right-hand crawler track (1), wherein the crawler tracks (1) are each connected to the body (42) via a linkage point (12), characterized by that at least one of the crawler tracks (1) is designed according to one of the preceding claims.

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