Abstract:
An upper support mechanism for an unloader auger tube of a combine having a ball mechanism fixed atop the unloader auger tube and a bushing having a generally spherical opening for swivellably receiving the ball member. The bushing is slidable up and down within a cylindrical opening formed in a sleeve member fixed with the combine frame. The bushing is made of a material that generally does not require lubrication as it rubs against the ball member or the sleeve member.

Description:
BACKGROUND OF THE INVENTION 
     It is known to provide agricultural vehicles such as combines with a container for temporarily storing grain that the combine has harvested and threshed. Operatively connected with these containers are unloading tubes through which the grain from the container passes during grain unloading operations. An auger is typically positioned within the unloading tube for directing grain from the container into and through the unloading tube. As grain is unloaded from the combine&#39;s grain container through the unloading tube in this manner the grain is expelled into a truck or grain cart traveling next to the combine. 
     Many conventional unloading tubes include a generally upright lower portion operatively connected with and extending upwardly from a lower portion of the combine grain container. An upper portion of the unloader tube extends generally horizontally and is operatively coupled with the upper end portion of the upright portion. Augers are typically positioned within the lower and upper portions of the unloader tube. A gearbox is provided at the junction of the upper and lower portions of the unloader tube for operatively connecting the auger sections in the two portions of the unloader tube. 
     Conventional unloader tubes are adapted to pivot between two positions about the central axis of the lower portion of the tube. In a first position the upper portion of the unloader tube is positioned generally longitudinally with respect to the vehicle and is located in close proximity along the side of the vehicle, as shown in FIG.  1 . The unloader tube can be swung outwardly from this position about the central axis of the lower portion to a position whereat the upper portion of the tube extends generally laterally outwardly from the side of the combine. The outer end of the unloader tube is positioned relatively high in the air such that a grain truck or cart can be positioned under the end of the tube to receive the grain being propelled from the tube. 
     The unloader tubes tend to be relatively heavy structures, since they house the augers and bear a large amount of weight when they carry heavy amounts of grain during operation. The unloader tubes must therefore be braced to withstand these forces during operation. The lower portion of the unloader tubes are held firmly in position by a sturdy support ring structure that supports the lower portion of the tube and allows the unloader to tube to pivot. Conventional combines also typically include an upper support structure above the tube&#39;s lower portion. The upper support mechanism helps keep the lower portion of the tube generally upright and helps keep the lower portion from toppling over due to the weight of the tube, augers and grain within the tube. 
     One type of conventional upper support mechanism includes a pin member closely aligned with the axis of the lower portion of the unloader tube. The pin is received within a tubular structure fixed with the side of the combine. The lower portion of the tube is manufactured and assembled to relatively exact tolerances so that the pin member is relatively precisely located in alignment with the axis of the lower portion of the tube. Also, the tubular structure and the brackets which hold it in place are manufactured and assembled to relatively exact tolerances so that the axis of the tubular structure is held in position in relatively precise alignment with the axis of the pin member. The processes of manufacturing and assembling all these parts to exact tolerances are relatively costly and time consuming, and raises the complexity and cost of the combine. 
     Another type of conventional upper support mechanism includes a metal pin member generally aligned with the axis of the lower portion of the unloader tube. The lower portion of the tube is not manufactured or assembled to exact tolerances, so the pin may be slightly misaligned from the axis of the lower portion of the unloader tube. This misalignment can cause the pin to shift in various directions as the unloader tube swings between its two positions. The pin is slidably received within a metal bearing member held within a metal housing. The bearing is free to swivel within the metal housing, and the pin is free to slide up and down within the bearing member. Therefore misalignment of the pin and housing member from the exact axis of the lower portion of the unloader tube is compensated for by the freedom of motion of the pin with respect to the housing member. This type of upper support mechanism is relatively inexpensive to manufacture and assemble since it is not manufactured to exact tolerances. However, the metal bearing member swivels in contact with the metal housing member, and the pin slides in contact with the bearing, and therefore the support requires lubrication so as to avoid excessive wear. This type of upper support mechanism therefore requires regular maintenance so that lubrication can be applied to the bearing surfaces within the structure. 
     It would therefore be desirable to provide an upper support mechanism which helps retain a combine unloader tube in its proper upright position during operation such as when filled with grain, and which does not require lubrication at regular intervals. It would also be desirable for such a mechanism to not require manufacturing or assembly processes having exact tolerences. It would be desirable for such a mechanism to allow for motion that might occur due to slight misalignments of the upper support structure from the actual axis of the lower portion of the unloader tube. It would be desirable to reduce the cost and complexity of the assembly process and the mechanism itself. 
     SUMMARY OF THE INVENTION 
     The preferred embodiment of the present invention is an upper support for a combine auger unloader tube, and includes a ball mechanism fixed atop the unloader tube. The ball member is swivellably received within a generally spherical socket formed by a bushing member made of an ultra high molecular weight polyethylene material. The bushing is slidably received within a generally cylindrical opening formed in a sleeve that is fixed to the side of the combine. The bushing is allowed to slide up and down within the cylindrical opening in the sleeve. The swivelling motion allowed by the ball and socket arrangement and the up and down motion allowed by the bushing within the cylindrical opening of the sleeve accommodate motion of the unloader tube associated with the upper support mechanism being slightly offcenter with respect to the pivot axis of the unloader tube. Therefore, the unloader tube and upper support mechanism can be manufactured with less than exact tolerances, which reduces the complexity of the mechanism and the cost of manufacturing. 
     The bushing is comprised of a material such as ultra high molecular weight polyethylene that can rub in contact with a smooth metal surface generally without requiring lubrication to prevent wearing. The bushing according to the present invention generally does not require lubrication between the contact surfaces of the ball mechanism and the spherical opening in the bushing, or between the contact surfaces of the bushing and the cylindrical opening in the sleeve. Therefore, routine maintenance procedures of regularly lubricating an upper support mechanism are generally eliminated. 
     The bushing is formed of two halves that fit snuggly together around the ball mechanism during the assembly process. The design of the two halves allows the parts to be formed with manufacturing processes that are relatively simple and cost effective. When snapped together the two halves form the spherical opening in the center of the bushing which swivellably receives the ball mechanism during operation. Pegs and mating openings formed in the two halves retain the two parts together when snapped onto the ball mechanism. The surface of the cylindrical opening in the sleeve also serves to confine the two parts of the bushing and in abutment with each other during operation. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic side view of a combine such as is used for harvesting and threshing of grain crops. 
     FIG. 2 is a side view of an upper pivot support mechanism according to the present invention which supports the unloader tube. 
     FIG. 3 is a front view of the upper pivot support mechanism shown in FIG.  2 . 
     FIG. 4 shows the two halves of the bushing according to the present invention. 
     FIG. 5 is an assembled view of the two halves of the bushing shown in FIG.  4 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIG. 1, there is shown a side view of a combine  10  capable of harvesting and threshing grain crops. The combine  10  includes a grain container  12  into which the threshed grain is directed. An unloader tube  14  is provided through which grain from the container  12  passes for emptying the contents of the container  12  into a grain truck or grain cart alongside the combine  10 . The unloader tube  14  includes a generally upright lower portion  16  that is operatively connected with a bottom portion of the combine&#39;s grain tank  12 . Grain from within the grain tank  12  is directed into the lower portion  16  of the unloader tube  14  and is directed upwardly therein by an auger positioned within the lower portion of the tube  14  . The tube  14  makes a bend  18  at the upper end of the lower portion  16 . An upper portion  20  of the tube  14  is connected to the bend portion  18  and extends generally horizontally when positioned in close proximity alongside the combine  10 . A gearbox within the bend portion  18  transmits rotational energy from the auger within the lower portion  16  to an auger within the upper portion  20  of the tube  14 . 
     The unloader auger tube  14  is pivotal from the position shown in FIG. 1 whereat the upper portion  20  is positioned in close proximity alongside the combine  10  to a position whereat the upper portion  20  extends laterally outwardly from the combine  10 . As the unloader tube  14  is swung outwardly the end  22  of the tube  14  swings upwardly slightly, since the axis  24  of the lower portion  16  about which the tube  14  swings is at a slight angle to true vertical. This allows the end  22  of the tube  14  to be positioned above large grain trucks or grain carts during the unloading process. 
     The unloader tube  14  is relatively heavy due to the weight of the tube  14 , the augers and the grain within the tube  14 . To resist the forces associated with this large amount of weight, the tube  14  is provided with upper and lower support mechanisms. At the lower end of the lower portion  16  of the tube  14  is a lower or ring support mechanism (not shown) that supports a large portion of the weight of the tube  14  during operation, and allows the lower tube  16  to pivot about its axis. An upper support  26  according to the present invention is also provided generally directly above the lower portion  16  of the tube  14 . The upper support  26  helps retain the lower portion  16  of the tube  14  in its position as the tube  14  is swung about, and prevents the weight of the tube  14  from toppling the tube  14  over. 
     The upper support  26  includes a bracket  28  fixed as by welds to the unloader tube  14 . Welded to the top surface of the bracket  28  is a ball mechanism  30  that includes a generally spherical portion  32  fixed with an upright shaft portion  34 . The spherical portion  32  is received within a bushing member  36  made of an ultra high molecular weight polyethelene material. The bushing member  36  is formed by two halves which fit together to define a generally spherical central opening  38  within which the ball  30  is positioned during operation. The bushing  36  is positioned within a generally cylindrical opening  40  in a metal sleeve member or gudgeon  42 . The bushing  36  fits snuggly within the opening  40  in the sleeve  42  but is provided enough clearance to allow the bushing  36  to slide up and down within the sleeve  42 . The sleeve  42  is fixed as by welds to a plate  44  that is fixed via bolts  46  to an angled wall  48  on the side of the combine  10 . 
     The ball mechanism  30  can swivel within the opening  38  in the bushing  36 , and the bushing  36  can shift up and down within the cylindrical opening  40  in the sleeve  42 . This allows the upper support mechanism  26  according to the present invention to accommodate motion associated with inexact positioning of the upper support mechanism  26  with respect to the axis  24  of the lower portion  16  of the tube  14 . Therefore, the tube mechanism  14  and upper support mechanism  26  can be manufactured generally without exact tolerances, and therefore the complexity and cost of the structure is correspondingly reduced. 
     The bushing  36  is made of an ultra high molecular weight material that can rub in contact with the inner surface of the cylindrical opening  40  in the sleeve  42  without requiring lubrication. The bushing  36  and sleeve  42  will therefore tend not to wear, gall or overheat in the absence of lubrication, thereby eliminating the need to regularly grease the mechanism. Similarly, the material of the bushing  36  allows the ball member  30  to rub in contact with the spherical opening  38  defined within the bushing  36  without requiring the surfaces to be lubricated. This eliminates the need to regularly grease these contact surfaces. Other materials that would not require lubrication could also be used, such as certain plastics, nylon, brass or bronze. 
     The bushing  36  is formed of two halves  50 ,  52  that are snapped together around the ball member  32  during assembly. Sets of pegs  54  and mating openings  56  fit together to generally retain the two halves  50 ,  52  of the bushing  36  together. The inner diameter of the cylindrical opening  40  in the sleeve  42  generally abuts the outer generally cylindrical surface  58  of the assembled bushing  36 , which serves to confine the two pieces  50 ,  52  of the bushing  36  in abutment with each other during operation, thereby further securing the pieces  50 ,  52  together. This design is relatively simple in construction and functions effectively to provide a bearing surface for the spherical ball member  32  and yet is easily manufactured and assembled. 
     The ball mechanism  30  can be provided using a conventional ball hitch commonly fixed to vehicles for towing trailers. Many conventional ball hitches include a chrome finish and a threaded lower portion. However, the ball mechanism  30  according to the present invention does not have a chrome finish, and includes a lower portion without threads.