Abstract:
A wheel hub assembly including first and second bearing assemblies positioned on opposite sides of a spacer. The spacer includes at least one opening to allow lubricant to flow through the spacer. The spacer includes a first section deformable such that an overall length of the spacer is reduced a predetermined amount in response to the application of a predetermined load to set a distance between the first and second bearing assemblies. The assembly further includes a spindle having external threads and a nut having internal threads engaged with the spindle to secure the bearing assemblies and spacer within the wheel hub assembly.

Description:
[0001]    This application claims priority to provisional application serial No. 60/299,689 filed on Jun. 20, 2001 and provisional application serial No. 60/301,565 filed on Jun. 28, 2001. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    This invention relates to a method and device for adjusting the distance between inner and outer bearing assemblies of a wheel hub to assure proper and consistent alignment.  
           [0003]    Typically, a wheel assembly will include inner and outer bearing assemblies to support rotation of a wheel hub about a spindle. A nut threaded onto corresponding threads of the spindle secures the wheel hub between bearing assemblies such that the wheel hub freely rotates on the bearing assemblies. The nut is fastened with sufficient torque to apply a predetermined amount of pressure to the bearing assemblies in order to properly support the wheel hub. Insufficient torque can cause misalignment of the wheel hub and premature wear on the bearing assemblies and excessive torque can cause excessive heat build up and damage to the bearing assemblies.  
           [0004]    It is known in the art to provide a spacer between the inner and outer bearing assemblies to maintain a predetermined space between the inner and outer bearing assemblies no matter what torque is applied to the nut. The spacer is designed to be essentially incompressible under any load that can be exerted by tightening of the nut. The spacer, wheel hub and bearing assemblies are then assembled to the spindle where the nut is tightened to secure the wheel hub.  
           [0005]    The spacer in such assemblies forms a cavity about the spindle. A leak resistant seal is formed between the bearing assemblies and the spacer because of the pressure exerted by the nut. The wheel hub is filled with lubricant for the bearings assemblies. The pressure between the spacer and the bearings prevents fluid from entering the cavity as the wheel hub is filled with lubricant. The result is that the level of lubricant is artificially high because of the empty unfilled space of the cavity. The lubricant reaches a fill line indicating that the wheel hub has been filled with the proper amount of lubricant, without actually having the required amount. The leak resistant seal between the spacer and the bearing assemblies allows lubricant to slowly enter the cavity thereby dropping the lubricant level. Insufficient lubricant in the wheel hub can lead to premature bearing assembly wear and failure.  
           [0006]    For these reasons, it is desirable to develop a spacer to set the distance between bearing assemblies that will accommodate the proper lubrication of the bearing assemblies.  
         SUMMARY OF THE INVENTION  
         [0007]    The subject invention is a method and device for adjusting the distance between bearing assemblies to assure proper and consistence alignment and provide for complete filling of lubricant within a wheel hub.  
           [0008]    The subject invention provides a means of accurately and repeatedly setting the distance between bearing assemblies for a wheel hub assembly. Preferably the invention is used for wheel hub assemblies installed on heavy vehicles such as trucks and trailers pulled by such trucks. The invention includes a spacer assembled over the spindle and between the inner and outer bearing assemblies. The spacer may either be of a predetermined length machined to precise tolerances or a deformable spacer deformed under a load. The spacer with the predetermined machined length is machined to the precise length required for each specific application and configuration. The deformable spacer includes a first section having a wall thickness sized to deform a predetermined amount under a predetermined load. The amount of deformation changes an overall length of the spacer to set the distance between bearing assemblies. The spacers along with the bearing assemblies are then assembled to a spindle of the vehicle.  
           [0009]    The spacer of this invention also includes at least one opening to provide for the free flow of lubricant through the spacer. The assembled spacer forms a leak resistance seal between the bearing assemblies that initially prevents oil from filling a cavity created about a wheel spindle. The opening positioned within the spacer allows lubricant to fill the cavity and thereby properly fill the wheel hub with lubricant. Further, the opening provides for the free flow of oil into and out of the cavity such that the bearings are supplied with the proper amount of lubricant during operation. The openings can be of any configuration including circular holes, slots and notches at the ends of the spacer. The only limitation being that the any opening must not weaken the spacer such that the spacer further deforms from pressure exerted by the nut.  
           [0010]    The spacer disclosed of this invention accomplishes the adjustment of the bearing assemblies and provides for the proper lubrication of the bearing assemblies. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows:  
         [0012]    [0012]FIG. 1 is a cross section view of a non-driven wheel hub assembly;  
         [0013]    [0013]FIG. 2 is a cross section view of a driven wheel hub assembly;  
         [0014]    [0014]FIG. 3 is a cross section view of a spacer;  
         [0015]    [0015]FIG. 4 is cross section view of the wheel hub assembly and spacer; and  
         [0016]    [0016]FIG. 5 is a cross section view of the wheel hub assembly on an assembly fixture. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0017]    Referring to the Figures, wherein like numerals indicate like or corresponding parts throughout the several views, the subject invention is a wheel hub assembly generally shown at  10  in FIG. 1. The wheel hub assembly  10  includes a wheel hub  12  rotatably supported on a spindle  14  by inner and outer bearing assemblies  16 , 18 . The bearing assemblies  16 , 18  include inner and outer bearing cones  15 ,  17  installed onto the spindle to engage inner and outer bearing cups  20 , 22  pressed into a central portion  24  of the wheel hub  12 . A spacer  26  is in load bearing contact between the inner and outer bearing assemblies  16 , 18 . Internal threads of a nut  28  engage external threads of the spindle  14  to secure the wheel hub assembly  12  to the spindle  14 . The tightened nut exerts an axial force, indicated by arrow A along an axis  34  through the outer bearing assembly  18 , the spacer  26 , the inner bearing assembly  16  and finally to the spindle  14 . The spacer  26  limits a length  32  between the inner and outer bearing assemblies  16 , 18  such that regardless of the torque applied to the nut  28 , proper pressure will be exerted between the wheel hub  12  and the bearing assemblies  16 , 18 .  
         [0018]    Referring to FIG. 2, a competed wheel hub assembly for a driven axle is generally indicated at  40 . The wheel hub assembly  40  includes a wheel hub  42  supported by inner and outer bearing assemblies  44 ,  46 . The spacer  26  is set over a driven axle  48 . As in the previous embodiment the spacer  26  sets a length  50  between the inner and outer bearing assembly  44 , 46  such that regardless of the torque applied to tighten nut  52 , the pressure between the wheel hub  42  and the bearing assemblies  44 , 46 , will be consistent. The length  50  between the wheel bearing assemblies  44 , 46  is set to control the pressure exerted between the wheel hub  42  and the wheel bearing assemblies  44 , 46 .  
         [0019]    Referring to FIG. 3, the spacer  26  is shown independent of the wheel hub assemblies  10 ,  40 . The spacer shown in FIG. 3 is a deformable type spacer, it is within the contemplation of this invention to use a fixed length non-deformable spacer. The spacer  26  includes a first section  60  having a thin wall  62 . The thin wall  62  is of such a thickness  64  to yield a predetermined amount from an original length in proportion to a specific load. Preferably, the first section is annular and semi-spherical in shape. A worker skilled in the art would understand that other shapes could be used for the first section  60 . Further, different assembled lengths of the spacer  26  are obtained by varying the load applied or by varying the thickness  64  of the thin wall  62 .  
         [0020]    A second section  66  includes a taper  68  to a first diameter  70 . A third section  72  is cylindrical in shape and includes a second diameter  74  sized to fit over the spindle of the driven or non-driven axle and to contact a load-bearing portion of the bearing assemblies  16 , 18 . A worker in the art will understand that the diameters  70 , 74  are dependent on the specific application and various configurations would fall within the contemplation of this invention.  
         [0021]    Referring to FIGS. 3 and 4, the spacer  26  includes a plurality of openings  76  disposed in the second and third sections  66 ,  72  of the spacer  26 . Pressure applied by the nut  28  creates a leak resistant seal between the spacer  26  and the bearing assemblies  16 , 18 . Absent the openings  76 , the leak resistant seal  77  would prevent lubricant from entering a cavity  78  formed between the spindle  14  and the spacer  26 . This condition would initially prevent lubricant from fully filling the wheel hub  12  because lubricant would not enter the cavity  78 . The openings  76  provide for the flow of lubricant into and out of the cavity  78  such that upon initial fill of the wheel hub  12 , a true level of lubricant is indicated. Further, the openings  76  are necessary to prevent lubricant from seeping into the cavity  78  and becoming trapped, thereby reducing the amount of lubricant available for lubrication of the bearing assemblies  16 , 18 .  
         [0022]    The openings  76  can be holes  80 , slots  82  or notches  84 . In this embodiment the slots  82  are disposed in the second section  66  and the holes  80  are disposed in the third section  72 . Preferably, the openings are disposed within the second and third sections  66 ,  72 , however the openings  76  may be disposed within any non-deforming section of the spacer  26 . These openings allow lubricant to fill the cavity  78  as the wheel hub  12  is filled and substantially eliminate potential oil starvation of the bearing assemblies  16 , 18 . The openings  76  can be of any shape or configuration that does not reduce the structural integrity of the spacer  26 .  
         [0023]    The invention includes a method of adjusting a length  90  between bearing assemblies  16 , 18 . Referring to FIG. 5, the wheel hub assembly  10  is shown in cross section. The method includes the installation of the spacer  26  between the inner and outer bearing assemblies  16 , 18 , along with the wheel hub  12  onto a fixture  92 . The fixture  92  is of the same size and configuration as a spindle or drive axle to which the wheel hub assembly  10  is to be installed. A force, indicated by arrow B, along the axis  34  is applied to the outer bearing assembly  18 . The magnitude of the force is predetermined to exert sufficient pressure to deform the spacer  26  at the thin wall  62  a predetermined level. In response to the predetermined level of force, the length  90  of the spacer  26  is changed to a deformed length  94 . The deformed length  94  is the proper distance between the bearing assemblies  16 , 18  for that particular wheel hub  12 . The bearing assemblies  16 , 18 , and deformed spacer  26 , along with the wheel hub  12  are then assembled to the spindle  14  of the driven  48  or non-driven axle of the vehicle.  
         [0024]    The foregoing description is exemplary and not just a material specification. The invention has been described in an illustrative manner, and should be understood that the terminology used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the present invention are possible in light of the above teachings. The preferred embodiments of this invention have been disclosed, however, one of ordinary skill in the art would recognize that certain modifications are within the scope of this invention. It is understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. For that reason the following claims should be studied to determine the true scope and content of this invention.