Abstract:
An oil-bath wheel spindle and hub assembly including a heat dissipating oil seal cap with a transparent window for observing the lubricant level and thermal conductive vanes forming a heat sink to transfer heat away from the wheel spindle and hub assembly to ambient atmosphere.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    This invention relates in general to wheel hub lubrication systems and, in particular, to an improved oil-bath wheel hub lubrication system that eliminates the necessity of an air vent to relieve excess internal pressure.  
           [0003]    More specifically, but without restriction to the particular embodiment and/or use which is shown and described herein for purposes of illustration, this invention relates to an improved oil-bath wheel hub lubricating system that utilizes a heat sink incorporated into the structure of the lubricating system closure cap to dissipate heat build-up which occurs due to hard braking or extended travel over hot roadways.  
           [0004]    2. Description of Related Art  
           [0005]    As is known to those skilled in the art, trailer wheel and axle assemblies rotatably mount a vehicle wheel hub on a wheel spindle which is in turn supported by an axle connected to the trailer by springs. The wheel hub defines a cavity for containing a lubricant, grease or oil, to lubricate bearings carried by the wheel spindle, and upon which the wheel hub is mounted for rotational movement. While in all such wheel mountings it is preferable to keep moisture out of the wheel mounting structure, in the mounting of wheels on boat trailers the problems associated with moisture entering the mounting structure is exacerbated because of the frequency with which the trailer wheels are immersed in or submerged under water. Water, especially salt water, and other contaminants entering into the wheel hub lubrication cavity can quickly cause the wheel bearings to fail.  
           [0006]    When boat trailer wheels are submerged in water shortly after extended travel over a roadway, or after continuous braking, the internal pressure within the sealed wheel hub mounting structure which increases because of heat build-up is suddenly decreased when the wheel hub is immersed in or submerged under water, thereby creating a negative pressure in the lubrication cavity which could draw water into the wheel mounting structure if the inner seal is not sealing correctly. The presence of water within this structure degrades the effectiveness of the lubricant, and can cause the internal components thereof to rust. Accordingly, many wheel hub mounting structures have been developed in an attempt to solve this problem.  
           [0007]    One attempt to solve this problem is through the use of an oil-bath wheel spindle and hub assembly that has an open vent to the atmosphere to prevent internal pressure build-up, but which prevents water from entering into the interior of the wheel hub. Such a wheel hub and spindle assembly is disclosed in L. N. Johnson, U.S. Pat. No. 5,098,168, wherein there is disclosed a waterproof hub and spindle assembly having an air chamber open on the bottom and adapted to trap air therein as the hub and spindle assembly is submerged. The air in the chamber is compressed as submersion increases which pressurizes the lubricating chamber to prevent contaminants, such as water, from entering into the bearing structure. Another attempt to solve this problem is disclosed in D. B. Law, U.S. Pat. No. 3,077,948, wherein an excess supply of lubricant, such as wheel bearing grease, is maintained in an attachment to the wheel hub, and the grease supply is pressurized so that a supply of grease will be available for lubricating purposes so long as an adequate supply of grease is maintained in the attachment, and the appropriate pressure is applied with a grease gun just before launching.  
           [0008]    While these and other such attempts have met with some success, the present invention addresses this problem by utilizing a structure which functions to dissipate heat build-up in the wheel hub, to thereby minimize or eliminate any internal pressure increase within the wheel hub due to heat build-up.  
         SUMMARY OF THE INVENTION  
         [0009]    It is an object of this invention to improve wheel spindle and hub assemblies.  
           [0010]    It is another object of this invention to improve wheel spindle and hub assemblies used on trailers by dissipating heat build-up in the wheel hub and spindle assembly to minimize or eliminate pressure increase within the lubricant containing cavity.  
           [0011]    A further object of this invention is to maintain the integrity of the wheel spindle and hub seals of a trailer by preventing excessive heat build-up when the trailer is moving over a roadway or the trailer brakes are being applied.  
           [0012]    Yet another object of this invention is to prevent a reduced pressure from being created within the lubricant containing cavity of a wheel spindle and hub assembly when a boat trailer is immersed water.  
           [0013]    These and other objects are attained in accordance with the present invention wherein there is provided an oil-bath wheel spindle and hub assembly having a heat dissipating oil seal cap forming a heat sink to transfer heat away from the wheel spindle and hub assembly to ambient atmosphere. 
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0014]    Further objects of this invention, together with additional features contributing thereto and advantages accruing therefrom, will be apparent from the following description of a preferred embodiment of the present invention which is shown in the accompanying drawings with like reference numerals indicating corresponding parts throughout and which is to be read in conjunction with the following drawings, wherein:  
         [0015]    [0015]FIG. 1 is a frontal perspective view of a portion of a wheel having a spindle and hub assembly with an embodiment of the heat dissipating oil seal cap of this invention;  
         [0016]    [0016]FIG. 2 is an enlarged perspective view of a portion of a wheel hub and spindle assembly with the heat dissipating oil seal cap illustrated in FIG. 1;  
         [0017]    [0017]FIG. 3 is a perspective view of a portion of the wheel hub and heat dissipating oil seal cap illustrated in FIG. 2, with portions cut away to better illustrate a portion of the wheel spindle and the construction of the heat dissipating oil seal cap;  
         [0018]    [0018]FIG. 4 is a frontal view of the heat dissipating cap illustrated in FIG. 1;  
         [0019]    [0019]FIG. 5 is a side view of the heat dissipating cap illustrated in FIG. 4; and  
         [0020]    [0020]FIG. 6 is a cross sectional view of the heat dissipating cap illustrated in FIG. 4 taken along lines  6 - 6 . 
     
    
       [0021]    This and additional embodiments of the invention may now be better understood by referring to the following detailed description of the invention wherein the illustrated embodiment is described.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0022]    Throughout this description, the preferred embodiment and examples shown should be considered as exemplars, rather than limitations on the apparatus and methods of the present invention.  
         [0023]    Referring now to the drawings, there is shown in FIG. 1 a tire  10 , mounted on a rim  12 , which in turn is bolted to a wheel hub  14  supported for rotation on a wheel spindle  16  by inner and outer bearings, not shown, as is known to those skilled in the art. The mounting of the wheel hub  14  for rotation about the spindle  16  forms a cavity between the interior surface of the hub  14  and the external surface of the spindle  16 , which is sealed at both the inner and outer ends thereof by appropriate seals, not shown, to form a lubricant retaining chamber, as is also known to those skilled in the art. Such typical structures are illustrated in the inventor&#39;s prior U.S. Pat. No. 5,098,168, and in U.S. Pat. Nos. 3,064,982; 3,177,041 and 3,395,950. The lubricant receiving cavity forms a lubrication chamber  18  which carries there within a lubricant, or bearing oil, to reduce frictional forces of the wheel hub  14  rotating about the spindle  16 .  
         [0024]    Referring now to FIGS. 2 and 3, there is illustrated an enlarged view of a portion of the wheel hub  14  and spindle  16  as shown in FIG. 1, to better illustrate an embodiment of a heat dissipating end cap  20 . The heat dissipating end cap  20  is formed of a thermal conductive material and preferrably press fit onto an outboard end of the wheel hub  14 , but a threaded connection may also be used. A suitable seal such as an “O” ring  21 , is positioned between the outboard opening in the wheel hub  14  and the inner end of the heat dissipating end cap  20  to form a closure of the outer end of the lubricant receiving cavity, or lubrication chamber  18 , formed between the wheel hub  14  and the spindle  16 .  
         [0025]    The heat dissipating end cap  20  is formed with an opening which extends from an outer surface thereof  22  into the interior of the lubrication chamber  18  so that oil may be introduced into the lubrication chamber  18  to fill the lubrication chamber  18  to a desired level. A threaded closure, such as a threaded plug  25 , forms a removable closure through which oil may be changed or added to the lubrication chamber  18 . Unlike a grease filled lubrication chamber wherein you cannot pre-load the lubrication chamber on bearing cavity  18 , the use of the oil bath of the instant invention permits a pressure pre-load of the bearing cavity or lubrication chamber  18 , preferably between 5-10 ft. lbs.  
         [0026]    To facilitate the maintenance of a proper quantity of oil within the lubrication chamber  18 , the outboard face of the heat dissipating end cap  20  carries a transparent window  26  sealed thereto through which the oil level may be conveniently observed. For convenience, the transparent window  26  may be marked with a scribed circle or line  27  to provide a visual reference point to insure a proper amount of lubricant is contained within the lubrication chamber  18 .  
         [0027]    The outer surface  22  of the heat dissipating end cap  20  is formed with a plurality of finned structures  28 , forming thermal conductive vanes, which increase the surface area of the end cap for dissipating heat build-up when the tire is moving over a roadway, or when the trailer is braking as occurs on hills and grades. While in the preferred embodiment the thermal conductive vanes  28  are formed with the vanes  28  lying in planes extending through the longitudinal axis of the wheel hub  14  and spindle  16  assembly, it is to be understood that the vanes  28  could also be formed in a ribbed configuration lying in planes extending normal to the longitudinal axis of the wheel hub  14  and spindle assembly  16 .  
         [0028]    In operation, as a trailer moves over a roadway, the rotation of the wheel hub  14  about the spindle  16  will “bathe” the lubrication chamber  18 , and bearings carried within, with sufficient oil to maintain proper bearing operation within the lubrication chamber. While such movement insures dispensing of oil on all parts and moving surfaces, the movement also creates heat caused by the frictional forces generated by this rotation of the wheel hub  14  about the spindle  16 . Accordingly, to minimize or eliminate such heat buildup, and the attendant internal pressure build-up, the thermal conductive vanes  28 , formed on the outer surface  22  of the end cap  20 , function as heat sinks to draw out heat generated within the lubrication chamber  18  and dissipate the heat into the atmosphere. In this manner the heat generated within the lubrication chamber  18  will be dissipated and can not cause the pressure within the lubrication chamber  18  to increase, thereby potentially blowing out the wheel bearing seals, or creating a negative pressure within the lubrication chamber  18  when the wheel hub  14  and spindle  16  assembly is rapidly cooled as the trailer wheel is immersed or submerged in water.  
         [0029]    While this invention has been described in the specification and illustrated in the drawings with reference to preferred embodiments, the structures of which have been disclosed herein, it will be understood by those skilled in the art to which this invention pertains that various changes maybe made, and equivalents may be substituted for elements of the invention without departing from the scope of the claims. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed in the specification and shown in the drawings as the best mode presently known by the inventors for carrying out this invention, nor confined to the details set forth, but that the invention will include all embodiments, modifications and changes as may come within the scope of the following claims.