Abstract:
A rotary cutter includes a hitch comprising upper and lower arm sections which define a parallel linkage extending between the deck of the rotary cutter and a ball clevis forming a forward end of the hitch. The ball clevis includes identical upper and lower halves which include block-like rear portions that are clamped together so that a ball is releasably retained between ring-like front portions of the clevis. Leveling of the deck is accomplished by a pair of adjustable leveling mechanism respectively coupled between rear parts of the separate arm sections and the deck. Provision is made for mounting a jack stand to one side of the clevis and for storing the jack stand on the deck.

Description:
[0001]    The present invention relates to hitches for towed implements and more specifically a relates to self-leveling hitch and clevis arrangements adapted for being hitched to a tractor drawbar.  
         Background of the Invention  
         [0002]    Tractor drawn implements, of which a pull-type rotary cutter is one example, require the implement hitch to be coupled to the tractor drawbar in such a way as to allow for rotation in three directions (turning, twisting and pitching). To accommodate pitching, a horizontal pivot is required which in turn allows the clevis to hang down resulting in chucking and excessive clevis/drawbar wear. Chucking can also cause premature driveline failures. Two examples of designs which attempt to address these problems are respectively disclosed in U.S. Pat. No. 3,998,471 granted to Luchemeier on Dec. 21, 1976, and in U.S. Pat. No. 5,386,680 granted to Friesen on Feb. 7, 1995.  
           [0003]    On some cutters, a link is pivotally attached between the mower deck and the clevis so as to form a parallel linkage with the hitch, thus resulting in the clevis being self-leveling as the cutter is raised and lowered, but this system does not allow for rotation during twisting or pitching except for the clearance between the drawbar pin and the slots in the clevis. With self-leveling, the clevis still rotates on the drawbar resulting in drawbar wear.  
         Summary of the Invention  
         [0004]    According to the present invention, there is provided an improved hitch and clevis assembly which overcomes the drawbacks associated with prior art hitch and clevis assemblies.  
           [0005]    A object of the invention is to provide a self-leveling clevis which does not include a separate link for keeping the clevis level.  
           [0006]    A more specific object of the invention is to provide a hitch that has separate arms that are coupled between the towed implement frame and the clevis so as to define a parallel linkage that maintains the clevis in a level attitude.  
           [0007]    Yet another object of the invention is to provide a hitch and self-leveling clevis assembly which operates such as to permit the clevis to rotate in three directions at its connection with the drawbar.  
           [0008]    A further specific object of the invention is to provide a hitch and self-leveling clevis assembly, as set forth in the immediately preceding object, wherein the clevis includes upper and lower halves having opposed surfaces shaped complementary to and engaging a hitch ball containing a vertical hitch pin receiving hole and a horizontal opening adapted for receiving the drawbar of a tractor, whereby the ball provides a surface on which the clevis is pivotable in three directions.  
           [0009]    These and other objects will become apparent from a reading of the ensuing description together with the appended drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    [0010]FIG. 1 is a left side perspective view, looking slightly downwardly, of the self-leveling hitch extending between a tractor drawbar and the front of a rotary cutter deck.  
         [0011]    [0011]FIG. 2 is a left front perspective view of the hitch.  
         [0012]    [0012]FIG. 3 is a right side perspective view of the front end of the hitch showing the ball clevis coupled to the tractor drawbar.  
         [0013]    [0013]FIG. 4 is a left side view of the self-leveling hitch.  
         [0014]    [0014]FIG. 5 is a rear view of the self-leveling hitch. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0015]    Referring now to FIG. 1, there is shown a front portion of a towed implement, here shown as a rotary cutter  10 , a drawbar  12  of a tractor (not shown) and a cutter hitch  14  coupling the cutter  10  to the drawbar  12 . Provided for transmitting power from a power take-off shaft (not shown), at a rear location of the tractor and an input shaft (not shown) of a gear box carried at a top location of a deck  16  of the rotary cutter  10  for distributing power for driving cutter blades (not shown) is a shielded, telescopic power shaft  18 .  
         [0016]    Right- and left-hand, transversely spaced, upright hitch mounting brackets  20  and  22 , each in the form of transversely spaced parallel plates, are welded to respective upper front locations of the cutter deck  16  located equidistant from a longitudinal, vertical center plane of the rotary cutter  10 . The hitch  14  includes separate upper and lower arm sections  24  and is  26 , respectively, having their respective rear ends vertically pivotally coupled to the brackets  20  and  22 , and from which the arm sections converge forwardly (see also FIG. 5) to a ball clevis  28  to which forward ends of the arm sections are individually pivotally coupled.  
         [0017]    Specifically, referring now also to FIG. 2, it can be seen that the rear ends of the arm sections  24  and  26  are defined by respective rear connecting portions  30  and  32 , each being in the form of a pair of transversely spaced, vertical, generally triangular plates. The connecting portion  30  is received between, and has an upper rear corner pivotally connected, as by a transverse mounting pin  34 , to an upper forward location of the plates of the hitch mounting bracket  20 . Similarly, the connecting portion  32  is received between and has an upper rear corner pivotally connected, as by a transverse mounting pin  36 , to an upper forward location of the plates of the hitch mounting bracket  22 . Referring now also to FIG. 3, it can be seen that the forward ends of the arm sections  24  and  26  are defined by respective front connecting portions  38  and  40 , each of which are in the form of a pair of transversely spaced straps, with the straps of the connecting portion  38  being disposed above, and in vertical alignment with, the straps of the connecting portion  40 . The clevis  28  is made of identical, upper and lower halves  42  and  44 , respectively, having ring-like forward ends and block-like rear ends. The clevis halves  42  and  44  are clamped to each other by a pair of fore-and-aft spaced bolts  46  extending vertically through the block-like rear ends. The straps of the front connecting portion  38  of the upper arm section  24  straddle, and are pivotally coupled to the block-like rear end of the upper clevis half  42  by a horizontal pivot pin  48  located in a bore located in the clevis half  42  between the spaced bolts  46 . Similarly, the straps of the front connecting portion  40  of the lower arm section  26  straddle, and are pivotally coupled to, the block-like rear end of the lower clevis half  44  by a horizontal pivot pin  50  spaced vertically below the pivot pin  48 . It is here noted that the left-hand end of each of the pins  48  and  50  includes a head defined by a washer welded to the stem of the pin.  
         [0018]    As can best be seen in FIG. 4, the pivot pins  34  and  36 , respectively, for coupling the rear ends of the upper and lower arm sections  24  and  26  to the hitch supports  20  and  22 , are spaced vertically from each other by the same distance that the pivot pins  48  and  50 , respectively coupling the front ends of the arm sections to the clevis halves  42  and  44 , are spaced from each other. Thus, it will be appreciated that the separate arm sections  24  and  26  form a parallel linkage which results in the clevis  28  remaining level throughout the vertical pivoting of the arm sections  24  and  26  during operation of the rotary cutter  10  over uneven terrain.  
         [0019]    Referring once again to FIGS. 2 and 3, it can be seen that the ring-shaped forward ends of the clevis halves  42  and  44  are respectively engaged with top and bottom portions of a ball  52 . The clevis halves  42  and  44  are provided with respective spherically shaped surface portions (not shown) that are complementary to respective outer surface portions of the ball  52  so that the ball is captured by the clevis halves but is gripped loose enough that the clevis halves slide upon the ball surface. The ball  52  contains an opening  54  which is rectangular in cross section and receives the rear portion of the tractor drawbar  12 . The drawbar  12  is provided with a vertical hole which is aligned with a vertical hole  58  extending through the ball  52 , with a hitch pin  60  being received in these aligned holes so as to connect the hitch  14  to the tractor and to provide a vertical axis about which the hitch  14  may pivot.  
         [0020]    Referring now to FIGS. 1, 2 and  5 , there is shown structure for effecting raising or lowering of the clevis  28 , for accommodating tractor drawbars of different heights, by individually inducing a force for lifting or lowering the arm sections  24  and/or  26  about the pivot pins  48  and  50 . Specifically, extending horizontally between and welded to the straps making up the connecting portion  30  of the upper hitch arm section  24  is a rod which defines a stop  62 . A bell crank  64 , in the form of a pair of parallel, generally triangular plates, has a first comer mounted for pivoting about the pivot pin  34  and includes a front corner with the plates straddling and being welded to a threaded cylindrical tube  66 , which receives a cap screw  68  having its lower end engaged with the stop  62 . A jam nut  70  is received on the screw  68  for holding the latter in a desired position of adjustment. The bell crank  64  has a lower rear corner pivotally attached to a clevis forming a forward end of a fore-and-aft extending leveling rod (not shown) having a rear end pivotally attached to a lug fixed to a transverse wheel axle (also not shown) pivotally mounted to a rear location of the deck  16  and held in a desired disposition by a hydraulic motor, or the like. Thus, it will be appreciated that, as viewed in FIG. 2, raising of the hitch  28  from its illustrated position is permitted by withdrawing the screw  68  so as to allow upward movement of the stop  62  about the pin  34 , while lowering of the hitch is permitted by advancing the screw  68  so that the stop  62  engages the screw  68  at a lower location.  
         [0021]    Similarly, a bell crank  72 , in the form of a pair of parallel, generally triangular plates having an upper corner mounted for pivoting about the pivot pin  36 , and having a lower front corner arranged with the plates straddling and being welded to a threaded cylindrical tube  74 , which receives a cap screw  76  having its lower end engaged with a stop  78  formed by a rod extending horizontally between and welded to the plates forming the connection portion  32  of the lower arm section  26 . A jam nut  80  is received on the screw  76  and serves to retain it in a desired adjusted position. A lower rear corner of the bell crank  72  is provided with a pair of vertically spaced holes, one of which receives a pin  81  that is captured between the plates forming the bell crank  72  and pivotally attaches the bell crank to a link  82 , which is formed by a pair of parallel straps having upper ends located above the pin  81  and pinned, as at  83 , to a clevis forming a forward end of a second leveling rod (not shown) having a rear end coupled to a second lug fixed to the wheel axle at the rear of the deck  16 . It is here noted that the pin  83  is captured between the plates forming the bell crank  72  and is located at a level approximately equal to that of the connection of the lower rear end of the bell crank  64  with the leveling rod on that side. The link  82  extends downwardly from the pin  81  and has a lower end pivotally attached, as at a pin  84 , to a short link  86  that extends fore-and-aft and has its rear end received between, and pivotally attached, as by a pin  87 , to lower projections of the hitch mounting bracket  22 . Adjustment of the screw  76  results in the hitch arm section  26 , and hence the clevis  28 , being raised or lowered in a manner similar to that effected by adjustment of the screw  68 , as described above.  
         [0022]    When it is desired to unhook the hitch  14  from the tractor drawbar  12 , a jack stand (not shown) may be mounted to the clevis  28 . For this purpose, a triangular support plate  88 , as can best be seen in FIGS. 1, 2 and  4 , is mounted to the left-hand side of the clevis  28  by the pins  48  and  50 , it being noted that the welded washers defining the heads at the left-hand ends of the pins  48  and  50  serve to retain the plate  88  in place. Welded to a rear corner location of the plate is a jack stand mounting tube  90  which is provided with a cross hole  92  that serves to receive mounting hardware of the jack stand. Of importance is the fact that, due to being mounted on the pins  48  and  50 , the plate  88  remains in a constant attitude throughout any vertical adjustments made for accommodating drawbars of different heights, with the tube  90  being oriented such that the jack stand, when coupled to it, has a substantially vertical disposition. A mounting tube  94  (see FIG. 1), similar in construction to the mounting tube  90 , is provided on the left-hand plate of the support bracket  22  for the purpose of providing a location for storing the jack stand, in a substantially horizontal orientation, during operation of the rotary cutter  10 .