Abstract:
A unitary plastic chain guide for a row unit is provided including 2 blocks, one disposed at each end of the chain guide, and a wall extending therebetween to guide the chain.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims priority from U.S. Provisional Pat. App. No. 61/099,551, which was filed Sep. 23, 2008 and is incorporated herein by reference for all that it teaches. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to agricultural harvesters. More particularly it relates to corn heads for agricultural harvesters. Even more particularly, it relates to row units for corn heads. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0003]      FIG. 1  is a perspective view of the inner workings of a row unit. 
           [0004]      FIG. 2  is a top view of the row unit arm assembly. 
           [0005]      FIG. 3  is a cross sectional view of the row unit taken at section  3 - 3  in  FIG. 1 . 
           [0006]      FIG. 4  illustrates the plastic chain guides from the same perspective as  FIG. 1 , but with the other components removed. 
           [0007]      FIG. 5  is a top view of the plastic chain guides with the other components removed. 
           [0008]      FIG. 6  is a bottom view of the plastic chain guides with the other components removed. 
           [0009]      FIG. 7  is a side view of a plastic chain guide with the other components removed. 
           [0010]      FIG. 8  is a top detailed perspective view showing just the forward portion of the plastic chain guides and particularly the elements of the open blocks with their constraining tabs and grooves. 
           [0011]      FIG. 9  is the same top detailed perspective view of  FIG. 8 , but with the support brackets inserted into the open blocks of the plastic chain guides. 
           [0012]      FIG. 10  is a bottom detailed perspective view of the arrangement of  FIG. 9  showing the underside of the support brackets and how they engage the constraining tabs to hold the front portion of the plastic chain guide in place. 
           [0013]      FIG. 11  is a perspective view of the gathering chain assemblies, their sprockets and the plastic chain guides in their proper orientation with the other elements removed for convenience of explanation using the same perspective as that of  FIGS. 1 and 4 . 
       
    
    
     DESCRIPTION OF THE INVENTION 
       [0014]    Referring to  FIGS. 1-3 , a row unit  10  for a row crop head of an agricultural harvester or combine is disclosed. Each row unit  10  includes a gearbox  12  and a clutch  14  attached to the upper parts of row unit arms  16  and  18 . Gearbox  12  and clutch  14  receive power from a row unit drive shaft, not shown, and then distribute the power to driving the various elements of row unit  10 . Arms  16  and  18  are substantially similar and may be a mirror image of each other, being positioned to support elements of row unit  10 . A shoe  13  is attached to a forward portion of each arm  16  and  18  to protect the distal ends of arms  16  and  18  from impact and shoe  13  may additionally provide a mounting point for a cover, not shown. 
         [0015]    The top of each row unit arm  16 ,  18  has a planar top surface  17  with threaded mounting holes  19  ( FIG. 3 ) for receiving threaded fasteners that secure the chain guides to the planar top surfaces of the  17  of the row unit arms. 
         [0016]    Proximate to each end of arms  16  and  18  there is rotatably connected a sprocket  20 , each of which have six teeth to advantageously allow for a narrower construct of each row unit  10 . A gathering chain assembly  22  and a gathering chain assembly  23  are respectively positioned on arms  16  and  18 . Chain assemblies  22  and  23  are driven in such a manner as the portion facing each other moves towards the top of arms  16  and  18  to assist in the ingress of the crop material. 
         [0017]    Plastic guides  24  and  26  are positioned along arms  16  and  18  to accommodate, guide, and dampen oscillatory movements of chain assemblies  22  and  23  ( FIGS. 1 ,  3 ,  11 ). Plastic guides  24  and  26  are preferably mirror images of each other. As such, the discussion of one guide is applicable to the other. Plastic guide  24  is held in position by a threaded fastener  30  proximate to the rear end of plastic guide  24 . The front end of plastic guide  24  is held in position by support bracket  28 , which is bolted to arm  16  with threaded fasteners  31 . Support bracket  28  captivates an end of plastic guide  24  but does not provide any, or at most very little, compressive force on plastic guide  24  thereby allowing some shifting in movement of the end of plastic guide  24  while holding guide  24  in position so that it can properly guide and direct chain assembly  22 . Support bracket  28  also serves the function of supporting the plastic points. “Points” are also known as “row crop dividers”. They extend forward, tapering to a point that faces in the direction of travel of the header. Crop approaching the header is pushed by the point to travel directly into the space between the two row unit arms. The points are lowered over the row unit to cover it in protected from the environment and rest upon the support brackets. Any impact against the points is communicated to support bracket  28  and then directly to the row unit arm, since support bracket  28  is fixed directly to the row unit arm. 
         [0018]    Referring to  FIGS. 3-11 , each plastic guide  24 ,  26  has a shelf  32 , ridges  34 , a wall  35 , support ribs  36 , a block  38 , an open block  40 , and a hole  44 . 
         [0019]    Wall  35  is a generally vertical and longitudinally extending wall that is disposed on the side of the gathering chain opposite the crop to support the back side of the chain and hold the chain in position adjacent to the gap between the deck plates as the chain is drawn rearward. It supports the chain during its working movement, as it travels from the front of the row unit to the rear of the row unit adjacent to gearbox  12 . Wall  35  prevents the chain from being pushed outward and away from the gap between the two deck plates and away from the plant stalks it is intended to engage and draw rearward. 
         [0020]    Each wall  35  comprises ridges  34  that extend longitudinally along the length of the wall  35 . These ridges are disposed to extend toward the chain in the gap between the plates of each link of the chains. This provides support for the rollers of each chain-link. Ridges  34  provide structural support and rigidity along the length of guides  24  and  26 . Ridges  34  extend along the surfaces of guides  24  and  26  to accommodate the difference in depth between links and rollers of chain assemblies  22  and  23  such that the chain is supported primarily by the rollers resting against the ridges, and not by the plates of each link dragging against (and wearing) wall  35 . The height to which ridges  34  extend is selected to appropriately accommodate rollers and links of chain assemblies  22  and  23  and to ensure that the gathering chain is primarily supported by force applied to the back side of the rollers. 
         [0021]    Shelf  32  extends generally horizontally from the top of wall  35  and is disposed over the top of the gathering chain to restrain the gathering chain from being lifted above the surface of the deck plate. Shelf  32  is substantially horizontal and extends along an upper edge of wall  35 . Shelf  32  is positioned above moving chain assemblies  22  and  23 . The gathering chain is prevented from moving upward off the surface of the row unit on which the guide is mounted. 
         [0022]    Block  38  acts to guide chain assemblies  22  and  23  and also to damp chain oscillations that may occur on the slack side as chain assemblies  22  and  23  move about sprockets  20 . Contact of chain assemblies  22  or  23  with block  38  on the slack side of the chain during operation with there being less tension there is a likelihood of chain oscillations. The position and composition of block  38  assists in dampening the chain oscillations that may even be exhibited in the form of a standing wave oscillation during operation. This advantageously reduces vibration in the system and prolongs life of chain assemblies  22  and  23 . Features of support bracket  28  fit into a portion of open block  40  and particularly into hole  44  so that a portion of support bracket  28  attaches to arm  16  or  18 , thereby positioning guides  24  and  26  in a captivated manner without compressing guides  24  and  26 . Hole  44  has substantially angular features to accommodate support bracket  28 . Blocks  38  also include cavities  46 , which may be sized and positioned to assist in the damping effect of block  38 . As can be seen looking into hole  44 , constraining tabs  48  are positioned to interact with features of support bracket  28 . Further, open block  40  includes a groove  10  providing for a biasing mechanism, associated with the tensioning of chain assemblies  22  and  23 . 
         [0023]    Support ribs  36  are spaced apart along the length of the guide. They are fixed to and extend outward from the side of wall  35  that faces away from the chain (i.e. the back side of wall  35 ). Support ribs  36  stiffen the guide. By supporting the back side of wall  35 , they reduce the degree to which the guide (and particularly wall  35 ) flexes when the chain is pushed against wall  35 . 
         [0024]    Block  38  is fixed to the rear end of wall  35 , which is the end closest to the gearbox and to the combine. Block  38  has a hole that is configured to receive a threaded fastener  30  ( FIG. 1 ). Block  38  acts to guide chain assemblies  22  and  23  to damp chain oscillations that may occur on the slack side as chain assemblies  22  and  23  move about sprockets  20 , and to anchor the rear end of the guide to the upper surface of the row unit arm. 
         [0025]    Contact of chain assemblies  22  or  23  with block  38  on the slack side of the chain during operation with there being less tension there is a likelihood of chain oscillations. The position and composition of block  38  assists in dampening the chain oscillations that may be exhibited in the form of a standing wave oscillation during operation. This advantageously reduces vibration in the system and prolongs life of chain assemblies  22  and  23 . 
         [0026]    As  FIG. 11  shows, the chain leaving sprocket  20  (located at the rear of the row unit), and headed toward sprocket  20  (located at the front of the row unit) is guided along a straight path by block  38 . Block  38  is close enough to contact the slack portion of the gathering chains and prevent them from oscillating side-to-side as they travel from the rear to the front of the row unit. The directions of travel of the two gathering chains are indicated by the arrows in  FIG. 11 . Blocks  38  also include cavities  46 , located on the underside of block  38  which may be sized and positioned to assist in the damping effect of block  38 . These cavities are enclosed by the upper surface of the row unit arm on which they are mounted to substantially prevent crop material from entering the cavities. 
         [0027]    Each open block  40  at the front of the plastic guide arms functions as a retainer to retain the forward end of the plastic chain guide to the row unit arm. Open block  40  is configured to be held in place by support bracket  28 . In the preferred form shown here, open block  40  extends completely around support bracket  28 , which bracket is received in hole  44 . 
         [0028]    Support bracket  28  fits into hole  44  of the plastic guide and is fixed to the top surface of the row unit arm with fasteners  31 . This engages and retains open block  40 , thus keeping the front end of the plastic guide from moving. Support brackets  68  are supported directly on the arms  16 ,  18  (i.e. they are fixed to the top surface of row unit arms  16 ,  18 ) thereby captivating guides  24 ,  26 . This permits the support brackets  28  to be compressed tightly and directly against the arms. Hole  44  has substantially angular features to accommodate support bracket  28  (see e.g.  FIGS. 19 ,  20 ). As can be seen looking into hole  44  in  FIG. 18 , constraining tabs  48  are positioned to interact with features of support bracket  28 . Support bracket  28  rests upon these constraining tabs  48  Further, open block  40  includes a groove  10  providing for a biasing mechanism, associated with the tensioning of chain assemblies  22  and  23 . 
         [0029]    Plastic, guides  24 ,  26  are preferably made of a strong plastic with good temperature and wear characteristics, such as a glass-filled polyester. Thermosetting plastics or composites (e.g. stiffening fibers embedded in a plastic matrix) are preferred. If a thermoplastic is used, it is preferably one with a high density and good wear characteristics, such as nylon or an ultra high molecular weight polyethylene.