Abstract:
A track roller unit for a vehicle has at least one pivotable subframe, at least one further pivotable subframe, wherein each of the subframes rotatably accommodates at least one land wheel, at least one subframe is pivotably mountable on the vehicle, and at least the further substrate is pivotally mounted on the one subframe.

Description:
CROSS-REFERENCE TO A RELATED APPLICATION 
       [0001]    The invention described and claimed hereinbelow is also described in German Patent Application DE 10 2006 015 153.4 filed on Mar. 30, 2005. This German Patent Application, whose subject matter is incorporated here by reference, provides the basis for a claim of priority of invention under 35 U.S.C. 119(a)-(d). 
       BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to a track roller unit. 
         [0003]    Publication DE 1 205 844 makes known a rail belt track assembly composed of two oscillating levers which are joined by lateral sliding joints and which are supported on a bolt, as the common rotation point. Track assembly wheels are supported on the ends of both oscillating levers, and an endless rail belt wraps around the drive assembly wheels. A compression spring is located between the two oscillating levers, which pulls the oscillating levers toward each other and limits the motion of the oscillating levers relative to each other. 
         [0004]    The disadvantage of this known rail belt track assembly is the fact that the known rail belt track assembly cannot evenly distribute the mass of the vehicle on the ground when the vehicle is driven over an obstacle. 
       SUMMARY OF THE INVENTION 
       [0005]    The object of the present invention, therefore, is to avoid the disadvantages of the related art and, in particular, to create a crawler track assembly, with which the crawler track assembly transfers the mass of the vehicle over the entire ground contact surface in a ground-saving manner by virtue of the fact that the load is distributed evenly over the ground, even when the vehicle is driven over an obstacle or uneven ground. 
         [0006]    In keeping with these object and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a track roller unit for a vehicle, comprising at least one pivotable subframe; at least one further pivotable subframe, each of said subframes rotatably accommodating at least one land wheel, at least said first subframe being pivotably mountable on the vehicle; at least said one further substrate being pivotally mounted on said first subframe. 
         [0007]    Due to the fact that the first subframe, at least, is pivotably mounted on the vehicle and the at least one further subframe is pivotably mounted on the first subframe, it is ensured that the weight of the vehicle is transferred to the ground in a ground-saving manner, even when the vehicle is driven over uneven ground or an obstacle, by virtue of the fact that the load is distributed evenly over the ground. 
         [0008]    In an advantageous embodiment of the present invention, the first subframe is mounted on the vehicle such that it can pivot around a first pivot axis, and the further subframe is mounted on the first subframe such that it can pivot around a second pivot axis; this results in a simple, easily-installable design of the track roller unit. 
         [0009]    Due to the fact that the first pivot axis is advantageously located approximately in the middle between the land wheels, a symmetrical arrangement of the crawler track assembly on the vehicle results. 
         [0010]    In a further advantageous embodiment of the present invention, the second pivot axis is located off-center between the land wheels in the region of the land wheels, the second pivot axis being located closer to the axis of rotation of the land wheel on the further subframe than to the axis of rotation of the land wheel on the first subframe, so that the land wheel on the further subframe is hinge-mounted to the first subframe via a short lever. 
         [0011]    Due to the fact that at least one damping element is located between the first subframe and the further subframe—the damping element being connected with the first subframe and the second subframe—the vibrations in the track roller unit are suppressed, and/or the vibrations can diminish more quickly in the track roller unit. 
         [0012]    In an advantageous embodiment of the present invention, the damping element is hinge-mounted on the subframe above and/or below the second axis of rotation, so that the vibrations of the deflected second subframe are suppressed. 
         [0013]    In an advantageous embodiment of the present invention, the damping element is designed as a piston-cylinder unit, in order to attain effective damping that is a function of the deflection speed of the land wheels. 
         [0014]    To absorb the impacts introduced into the track roller unit via the uneven ground, in an advantageous refinement of the present invention, at least one spring element is located between the first subframe and the second subframe, the spring element being designed as an elastic rubber element. 
         [0015]    Due to the fact that, in an advantageous embodiment of the present invention, the track roller unit includes a track-supporting roller assembly, and the track-supporting roller assembly is pivotably mounted on one of the subframes and is preloaded by a damping system hinge-mounted to this subframe or the second subframe, the track roller unit can adapt itself flexibly to the uneven ground. 
         [0016]    In an advantageous embodiment of the present invention, the damping system is fixedly mounted on the subframe, so that the damping system remains on the subframe when the track-supporting roller assembly is replaced. 
         [0017]    Due to the fact that the damping system is connected to the particular subframe above or below the first pivot axis, a damping system can be located between the land wheels in a space-saving manner. 
         [0018]    To optimize the adaptability of the track-supporting roller assembly to an uneven ground surface, the track-supporting roller assembly—according to an advantageous refinement of the present invention—is mounted on an intermediate frame such that it can pivot around a third pivot axis, the intermediate frame being pivotably mounted on at least one subframe. 
         [0019]    The support load of the vehicle is transferred to the ground such that it is evenly distributed over the ground contact surface of the track roller unit by virtue of the fact that the third pivot axis is located approximately in the middle between the land wheels in the area between the land wheels and below the first pivot axis and below the second pivot axis. 
         [0020]    To increase the contact pressure of the crawler belt on the ground, the track-supporting roller assembly advantageously includes a pendulum with several track-supporting rollers, the pendulum being pivotably connected with the intermediate frame. 
         [0021]    Further advantageous embodiments are the subject of further subclaims and are described in greater detail below with reference to exemplary embodiments shown in a plurality of figures. 
         [0022]    The novel features of which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]      FIG. 1  shows a side view of a combine harvester equipped with track roller units according to the present invention. 
           [0024]      FIG. 2  shows a side view of a track roller unit according to the present invention. 
           [0025]      FIG. 3  shows a second inventive embodiment of the crawler track assembly. 
           [0026]      FIG. 4  shows a further, inventive embodiment of the crawler track assembly. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0027]    A side view of a vehicle  2  designed as a combine harvester  1  is shown in  FIG. 1 . Instead of wheels, which are typically used, crawler track assemblies  3  are mounted on the front of combine harvester  1 , on both sides. Together with two steerable wheels  4  located in the rear region of combine harvester  1 , crawler track assemblies  3  form the ground drive of combine harvester  1 . 
         [0028]      FIG. 2  shows an enlarged schematic side view of a first embodiment of an inventive crawler track assembly  3 . Crawler track assembly  3  includes a first pivotable subframe  7  and a further pivotable subframe  8 , on the free ends of which a land wheel  9 ,  10  is supported such that it can rotate around an axis of rotation  11 ,  12 . An endless crawler belt  13  wraps around the two land wheels  9 ,  10 . 
         [0029]    According to the present invention, to ensure that crawler belt  13  covers the largest possible ground contact area, even when the vehicle is driven on uneven ground, in order to transfer the weight of combine harvester  1  to ground  14  in a ground-saving manner by distributing the load evenly over the ground, first subframe  7  is pivotably mounted on combine harvester  1 , and further subframe  9  is pivotably mounted on first subframe  7 . 
         [0030]    First subframe  7  is pivotably mounted on combine harvester  1  such that it can pivot around a pivot axis  15  extending transversely to direction of travel FR of combine harvester  1 , the first pivot axis being located approximately in the middle between land wheels  9 ,  10 . Second subframe  8  is pivotably connected with first subframe  7  such that it can pivot around a further pivot axis  16  extending in parallel with first pivot axis  15 , second pivot axis  16  being located closer to axis of rotation  12  of land wheel  10  on further subframe  8  than to axis of rotation  11  of land wheel  9  on first subframe  7 . 
         [0031]    When the vehicle is driven over an obstacle or uneven ground, further subframe  8  is permanently swiveled around second pivot axis  16  relative to first subframe  7 ; as a result, the position of land wheel  10  and, therefore, its axis of rotation  12 , changes relative to pivot axes  15 ,  16 . 
         [0032]    A damping element  26  designed as a piston-cylinder unit  25  is located above second axis of rotation  16  between first subframe  7  and further subframe  8 , which is hingedly connected with first subframe  7  on the piston rod side, and is hingedly connected with further subframe  8  on the piston rod side. Piston-cylinder unit  25  can be designed, e.g., as a hydraulic damping element  26  filled with oil, or as a pneumatic damping element  26  filled with gas. 
         [0033]    It is within the scope of the present invention to locate several damping elements  26  between first subframe  7  and second subframe  8 , which can be hinge-mounted to subframes  7 ,  8  above and/or below second pivot axis  16 . 
         [0034]    In the exemplary embodiment shown, a track-supporting roller assembly  30  is located on first subframe  7 , which is composed of a pendulum  31  with several track-supporting rollers  32 ,  33  located one behind the other in direction of travel FR of combine harvester  1 . Pendulum  31  is connected with an intermediate frame  35  such that it can pivot around a third pivot axis  34 , intermediate frame  35  being connected with first subframe  7  such that it is height-adjustable around a fourth pivot axis  36 . Third pivot axis  34  is located approximately in the middle between land wheels  7 ,  8  in the region of land wheels  7 ,  8  below first pivot axis  15  and second pivot axis  16 . 
         [0035]    A further damping system  37  is fixedly mounted on subframe  8  between intermediate frame  35  and further subframe  8 , below first pivot axis  15 . Damping system  37  preloads track-supporting roller assembly  30  and absorbs the impacts transferred to track-supporting roller assembly  30  when the vehicle is driven over uneven ground. An embodiment is feasible with which track-supporting roller assembly  30  is pivotably mounted on one of the subframes  7 ,  8 , and track-supporting roller assembly  30  is preloaded by damping element  37 . 
         [0036]    The position of land wheel  9  supported on first subframe  7  is changeable relative to land wheel  10  supported on further subframe  8  using a tensioning device  38  that is known per se and is therefore not explained in detail such that crawler belt  13  that is wrapped around the two land wheels  9 ,  10  can be tightened. 
         [0037]    It is also within the framework of the present invention that one or both land wheels  9 ,  10  of crawler track assembly  3  shown can be driven, it being possible for driven land wheel(s)  9 ,  10  to drive crawler belt  13  in a form-fit or frictional manner. 
         [0038]    In contrast to the first embodiment shown in  FIG. 2 , with the second embodiment of an inventive crawler track assembly  3  shown in  FIG. 3 , track-supporting roller assembly  30  is located on further subframe  8 . With this crawler track assembly  3 , further spring element  38  is located between intermediate frame  35  and further subframe  8 . 
         [0039]    A third embodiment of an inventive crawler track assembly  3  is shown in  FIG. 4 . As with the first embodiment shown in  FIG. 2 , track-supporting roller assembly  30  is mounted on subframe  7 . Spring element  37  is also located between intermediate frame  35  and further subframe  8 , spring element  37  extending from a first region below first subframe  7  to a further region above first subframe  7 . Spring element  37  penetrates first subframe  7 . 
         [0040]    It is also feasible to locate inventive crawler track assembly  3  on the front and/or rear axle of a vehicle  2  designed as a tractor. 
         [0041]    It is within the scope of the ability of one skilled in the art to modify the exemplary embodiments described in a manner not presented, or to use them in other machines to achieve the effects described, without leaving the framework of the invention. 
         [0042]    It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the type described above. 
         [0043]    While the invention has been illustrated and described as embodied in a track roller unit, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. 
         [0044]    Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, be applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.