Patent Publication Number: US-2010107946-A1

Title: Wheel Hub And Bearing Assembly For Use In Agricultural Material Delivery Equipment

Description:
FIELD OF THE INVENTION 
     The present invention relates to equipment for delivery of agricultural material, such as a planter, and in particular to a packer wheel and bearing assembly for such equipment. 
     BACKGROUND OF THE INVENTION 
     Packer wheels have long been used with agricultural seeding equipment and fertilizer or other chemical applicators. Such wheels are used to pack the soil above the applied material. As such, the packer wheels operate in a harsh environment and must be durable. Recently developed packer wheels use plastic materials to mold the wheel hub. However, a conventional roller bearing can not be pressed into the plastic hub to produce sufficient holding force to prevent the bearing from slipping relative to the wheel without overstressing the hub material in at least the worst case scenario for the hub and bearing tolerances. 
     SUMMARY OF THE INVENTION 
     A wheel and bearing assembly, adapted for use in a packer wheel of an apparatus for delivering agricultural material, such as a planter, has a plastic or synthetic hub. To install a bearing in the hub without exceeding the strength of the hub material, the bearing is pressed into a mounting insert made of metal or other high strength material. The insert has a non-circular outer surface and is placed into a complementary shaped cavity in the hub thereby preventing the insert and the bearing outer race from rotating relative to the hub. The fitting between the insert and the hub is only tight enough to hold the insert in place during handling. Alternatively, the non-circular external shape could be incorporated into the outer race of bearing. This eliminates the need for the bearing mounting insert to achieve the desired effect of fixing the outer race from rotation relative to the hub. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of the apparatus for delivering agricultural material to the ground including the packer wheel assembly according to the present invention; 
         FIG. 2  is a sectional view through the packer wheel assembly of the apparatus of  FIG. 1 ; and 
         FIG. 3  is a partially exploded perspective view of the packer wheel assembly of  FIG. 2 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference to  FIG. 1  an apparatus for delivering agricultural material to the ground having the packer wheel assembly according to the present invention is shown and designated as  10 . Apparatus  10  includes a tool bar  12  that extends transversely to a forward travel direction designated by the arrow  14 . A material delivery assembly  16  is shown mounted to the tool bar  12  by a U-blots  18  in a known manner. Multiple assemblies  16  are mounted to the tool bar and spaced laterally there along. 
     The delivery assemblies each include at least one furrow forming shank  20 , the lower end  22  of which penetrates the ground to form a furrow as the apparatus  10  is moved in the forward travel direction indicated by the arrow  14 . In the embodiment shown, a pair of material delivery conduits  24 ,  26  are located behind the shank  20 . Agricultural materials such as seed, fertilizer or other chemicals can be delivered to the furrow through the material delivery conduits  24 ,  26 . A second furrow forming shank  28  and another material delivery conduit  30  are provided in the assembly  16 . A packer wheel assembly  32  is mounted to arms  34  of the assembly  16  and follow behind the two furrow forming shanks  20 ,  28  to press the soil on the furrows or immediately to the side of the furrows. The material delivery assembly  16  is more fully described in U.S. Pat. No. 6,986,313 which is incorporated herein by reference. The packer wheel assembly of the present invention can be used with other mechanisms for forming a furrow and depositing agricultural material therein and is not limited to use with the assembly  16  shown in  FIG. 1 . 
     The packer wheel assembly is shown in detail in  FIGS. 2 and 3 . The packer wheel assembly is constructed of a two-piece hub having left and right members  36 ,  38 . When assembled, the two hub members are joined together by nut and bolt assemblies  40 . A natural or synthetic rubber tire  42  surrounds the outer periphery of the hub. The wheel assembly is mounted to the arms  34  through a spindle in the form of a bolt  44  and nut (not shown). The bolt passes through left and right bearings  46 ,  48  and a sleeve  50  is sandwiched between the bearings. There is a small clearance between the sleeve  50  and the inner bore  52  of the hub members  36 ,  38  to allow the wheel hub to freely rotate relative to the sleeve. 
     The bearings  46 ,  48  are pressed into the inner bore of bearing mounting inserts  52 . The outer surface of the inserts is non-circular and fits into complementary shaped cavities  54  in the hub members. In the embodiment shown, the outer surface of the inserts is hexagonal in shape. The cavities  54  are likewise hexagonal, with rounded corners  56  to reduce the stress concentration at the corners. An optional gasket  58  can be used to form a seal between the hub and the bearing outer race and the insert if desired. 
     The hub members are synthetic, such as 30% glass filled nylon. To press fit the bearing into the nylon would cause the hoop stress in the nylon to exceed the strength of the nylon in the worst case tolerance condition for the hub members and bearings. The mounting inserts, which are made of metal, are pressed onto the bearings and provide the bearing with a non-circular outer surface. When placed in the hub cavities, the non-circular outer surface of the inserts hold the bearings from rotation relative to the hub. While any non-circular outer surface will function for the bearing inserts, the hexagonal shape is preferred due to the readily available material and since the six sides produce less stress at the corners than a four sided polygon. The inserts fit in the hub only tight enough to hold the inserts and bearing in the cavities during handling. The bearing inserts allow a metal bearing to have its outer race fixed to the plastic, or synthetic hub without exceeding he hub material strength. As an alternative to the bearing mounting insert, the non-circular shape can be incorporated into the bearing outer race itself. 
     While the bearing mounting insert is particularly beneficial in the context of a wheel hub made of plastic, the bearing mounting insert can be used with wheel hubs made of any materials including plastics, ceramics and all metals. This is particularly important where the design of the hub does not permit the hub to be designed to support a press fit of the bearing. 
     Having described the preferred embodiment, it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the accompanying claims.