Abstract:
A packaged bearing assembly for a full floating axle fits on the end of an axle tube where it serves to couple a road wheel to the axle. The bearing assembly includes a housing having external formations for mounting brake components. It also has a hub provided with a drive flange located beyond the outboard end of the housing and a spindle that projects into the housing. Finally, the bearing assembly also has an antifriction bearing located within the housing and around the spindle of the hub to enable the hub to rotate relative to the housing and axle tube. The drive flange of the hub provides a mounting for a road wheel. An axle shaft extends through the axle tube and through the hub and is removably connected to the hub, so that it can be withdrawn without elevating the road wheel off of its supporting surface.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     Not applicable.  
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH  
       [0002]     Not applicable.  
       BACKGROUND OF THE INVENTION  
       [0003]     This invention relates in general to axles for automotive vehicles and more particularly to a full floating axle provided with a bearing assembly that enables an axle shaft to be easily removed.  
         [0004]     Most trucks and large SUVs have solid rear axles on which the driven wheels of such vehicles rotate. Many of these vehicles, particularly large and medium trucks, utilize a full-floating axle having axle shafts that support no weight. Instead, the weight is transferred to the driven wheels through axle tubes and bearing arrangements at the ends of the tubes. In semifloating axles, the drive wheels are coupled to the axle shafts, and as a consequence, the weight of the vehicle is transferred to the wheels through both the axle tubes and the axle shafts.  
         [0005]     Both types of axles require bearings, and the bearing systems to a measure are complex. They take an inordinate amount of time to assemble, and when repairs are required, the repairs do not proceed easily or with dispatch. For example, a full floating axle has a bearing arrangement that requires adjustment, so that the bearing operates with the proper setting, preferably slight preload. An axle shaft in a semifloating axle cannot be removed without removing the weight from the wheel at its end, and again the bearing arrangement will often interfere with the disassembly. Sometimes, one must remove a C-clip at the differential to release a shaft of a semifloating axle, and this requires opening the differential. Apart from that, the bearings of semifloating axles permit a measure of runout and lack the stability of preloaded bearings available with full floating axles.  
         [0006]     Automotive companies in recent years have turned more and more to packaged components. These components reduce the time to assemble a vehicle, and with some components, such as wheel ends, allow critical adjustments to be made by the supplier, thus removing those adjustments from the assembly line. While outside suppliers furnish axles, the axles are in their own right overly complex and do not rely on packaging for critical components, such as bearing assemblies. 
     
    
     DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0007]      FIG. 1  is a perspective view, partially broken away and in section, of a full floating axle constructed in accordance with and embodying the present invention;  
         [0008]      FIG. 2  is a longitudinal sectional view of the bearing assembly for the axle;  
         [0009]      FIG. 3  is a sectional view taken along line  3 - 3  of  FIG. 2 ;  
         [0010]      FIG. 4  is a perspective view, partially broken away and in section, of a modified full floating axle; and  
         [0011]      FIG. 5  is a longitudinal sectional view of the bearing assembly for the modified axle.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0012]     Referring now to the drawings, a solid axle A ( FIG. 1 ) of the full floating type has the capacity to support the chassis of an automotive vehicle on wheels B and to deliver torque to those wheels B to propel the vehicle. The axle A includes an axle tube  2  that is connected to the suspension system of the vehicle. In addition, the axle A has a bearing assembly  4  that is preferably furnished as a packaged component. It is fitted to one end of the tube  2  where it couples one of the wheels B to the axle A, enabling that wheel B to rotate at the end of the axle tube  2  with minimal friction. At the opposite end of the axle tube  2  the axle A has a differential  6 . Finally, the axle A has an axle shaft  8  that extends through the tube  2  from the differential  6  to the bearing assembly  4 . It transfers torque to the wheel B to propel the vehicle. Actually, the axle shaft  8  transfers torque to the wheel B through the bearing assembly  4 . The shaft  8  may be detached from the bearing assembly  4  and removed from the axle tube  2 , all with relative ease and without removing the weight of the vehicle from the wheel B.  
         [0013]     Considering the bearing assembly  4  first, it includes ( FIGS. 2 &amp; 3 ) a housing  12  that is fitted to the outboard and to the axle tube  2 , a hub  14  to which the road wheel B is secured, and bearings  16  that support the hub  14  in the housing  12  and enable it to rotate relative to the housing  12  about an axis X. The axle shaft  8  is connected to the hub  14  such that it can be easily detached and withdrawn from the hub  14  and axle tube  2 .  
         [0014]     The housing  12  within its interior has a central bore  20  and at each end of the bore  20  a counterbore that serves as a bearing seat  22 . Beyond each bearing seat  22 , the housing  12  is fitted a seal  24 . At the inboard end of the housing  12 , beyond the inboard seal  24 , a cylindrical socket  26  opens out of the housing  12 . The socket  26  receives the outboard end of the axle tube  2 , and here the tube  2  is welded or otherwise securely fastened to the housing  12 . On its exterior the housing  12  has several formations for accommodating brake components. Among these formations are a flange  28  that projects generally upwardly and a boss  30  that projects downwardly. While both lie at the inboard end of the housing  12 , the flange  28  is set farther inwardly toward the differential  6  than the boss  30 . The flange  28  serves as a support for brake shoes, while the boss  30  houses a slave cylinder that spreads the brake shoes apart and against a brake drum.  
         [0015]     The hub  14  includes a drive flange  36  located opposite the outboard end of the housing  12  and a spindle  38  that projects axially from the drive flange  36  into the central bore  20  of the housing  12 . Projecting in the opposite direction from the drive flange  36  is a wheel pilot  40 . Within its interior, the hub  14  has a through bore  42  that at one end of the hub  14  opens out of the spindle  38  and at the other end opens out of the wheel pilot  40 .  
         [0016]     The drive flange  36  has lug bolts  44  set firmly in it, and they project axially away from the outboard face of the drive flange  36 . The wheel B and a brake drum fit around the wheel pilot  40 , which centers them with respect to the axis X. The lug bolts  44  hold the wheel B against the drive flange  36 . The wheel pilot  40  has an end face  48  that lies perpendicular to the axis X and threaded holes  50  that extend axially and open out of the end face  48 .  
         [0017]     The spindle  38  emerges from the drive flange  36  at a shoulder  52  and at its opposite end is deformed outwardly in the provision of a formed end  54 . Initially, the spindle  38  at its inboard end exists as an axial extension of the remainder of the spindle  38 , no greater in diameter. But once the bearings  16  are installed in the housing  12  and over the spindle  38  the axial extension is deformed outwardly in a roll-forming procedure to provide the formed end  54  that captures the bearings  16  on the hub  14 . U.S. Pat. No. 6,443,622 and U.S. patent application Ser. No. 11/283,160, filed Nov. 18, 2005, disclose procedures for converting the extended end of the spindle  38  into the formed end  54  and are incorporated herein by reference.  
         [0018]     The bearings  16  fit into the bearing seats  22  of the housing  12  and around the spindle  38  of the hub  14  where they lie captured between the shoulder  52  and the formed end  54 . Each bearing  16  includes an outer race in the form of a cup  60 , an inner race in the form of a cone  62 , and rolling elements in the form of tapered rollers  64  located in a single row between the cup  60  and cone  62 . The cup  60  has a tapered raceway  68  presented inwardly toward the axis X and a back face  70  at the small diameter end of the raceway  68 . The cone  62  has a tapered raceway  72  presented outwardly toward the raceway of the cup  60  and a thrust rib  74  at the large diameter end of the raceway  72 . The thrust rib  74  extends out to a back face  76 . The tapered rollers  64  contact the tapered raceways  68  and  72  along their tapered side faces, there being basically line contact between the side faces and raceways  68  and  72 , and the rollers  64  abut the thrust rib  74  along their large end faces. The geometry is such that the tapered rollers  64  are on apex, meaning that the conical envelopes in which their side faces lie and the conical envelopes in which the tapered raceways  68  and  74  lie have their apices at a common point along the axis X.  
         [0019]     The cups  60  of the two bearings  16  fit into the bearing seats  22  in the housing  12  with their back faces  70  against the shoulders at the ends of those seats  22 . The cones  62  fit over the spindle  38  of the hub  14 , with the back face  76  of the outboard cone  62  being against the shoulder  52  on the spindle  38  and the back face  76  of the inboard cone  62  being against the formed end  54 . The large ends of the tapered rollers  64  for the outboard bearing  16  are presented away from the large ends of the tapered rollers  64  of the inboard bearings  16 , so that the bearings  16  are mounted in opposition in the indirect configuration. As such, the bearings  16  not only transfer radial loads between the hub  14  and housing  12 , but thrust loads in both axial directions as well. Moreover, the opposite ends, that is the front faces, of the two cones  62  abut, so that the thrust exerted on the outboard cone  62  during the roll forming operation is transferred through the two cones  62  to the shoulder  52  where it is resisted. The location of front faces on the two cones  62  determines the setting for the bearings  16  and it should be one of slight preload, thus giving the hub  14  a full measure of stability.  
         [0020]     The seals  24  have lips which bear against the thrust ribs  74  for the two cones  62  to thereby establish dynamic fluid barriers along the cones  62 . Thus, the seals  24  isolate the interior of the bearings  16 , retaining a lubricant, such as grease, in the bearing  16  and excluding contaminants, such as water and dirt.  
         [0021]     The axle shaft  8  extends through the axle tube  2  and through the hub  14  rotating in the former and being coupled to the latter. At its inboard end, the axle shaft  8  is connected through a spline to gearing within the differential  6 , so that the differential  6  may transfer torque to the shaft  8 , yet the shaft  8  may be withdrawn from the differential  6 . At the hub  14 , the axle shaft  8  passes completely through the through bore  42 , beyond which it has a flange  80  that overlies the end face  48  of the wheel pilot  40  on the hub  14 , its diameter being no greater than that of the wheel pilot  40 . The axle shaft  8  is secured to the hub  14  with cap screws  82  that pass through the shaft flange  80  and thread into the threaded holes  50  in the wheel pilot  40 .  
         [0022]     The chassis of a vehicle rests on the axle A, and the axle A in turn is supported on the wheel B with the weight of the vehicle chassis being transferred through the bearing assembly  4 . The axle A, being a full floating axle, transfers none of the chassis weight through the axle shaft  8 . In operation, the differential  6  transfers torque to the axle shaft  8  which in turn transfers it to the hub  14  of the bearing assembly  4 . Assuming that the torque is sufficient, the hub  14  will rotate and with it the wheel B, and of course the rotating wheel B propels the vehicle. The two bearings  16  transfer radial loads—in essence the weight of the vehicle chassis—from the housing  12  to the hub  14  and any thrust loads as well—indeed, thrust loads in both axial directions.  
         [0023]     One may withdraw the axle shaft  8  for repair or replacement, simply by removing the cap screws  82  from their threaded holds  50  in the pilot  40  of the hub  14  and pulling the shaft  8  out of the through bore  42  in the hub  14  and from the axle tube  2 . And no need exists to remove the weight of the vehicle chassis from the axle tube A. The wheel B remains on the road surface supporting the vehicle as the axle shaft  8  is removed.  
         [0024]     A modified bearing axle C ( FIGS. 4 &amp; 5 ) differs from the axle A in that it has an axle shaft  86  that is coupled to the hub  14  of the bearing assembly  4  through mating splines  88 —one at the end of the through bore  42  in the hub  14  and the other at the outboard end of the shaft  86 . To this end, the spline  88  on the end of the shaft  86  possesses a diameter slightly greater than the diameter of the remainder of the shaft  86  so as to prevent the spline  88  in the hub  14  from interfering with the removal of the shaft  86 . In addition, the axle shaft  86  has a threaded hole  90  at its outboard end, so that the shaft  86  may be engaged by a tool and pulled from the hub  14  and axle tube  2 .  
         [0025]     Apart from that, the wheel pilot  40  of the hub  14 , in lieu of having threaded holes  50 , has a socket  92  that opens axially out of its end and a groove  94  that opens radially into the socket  92 . The socket  92  receives a stamped metal plug  96 , while the groove  94  receives a spring clip  98 . The plug  96  prevents the axle shaft  86  from migrating out of the hub  14 , whereas the spring clip  98  retains the plug  96  in the socket  92 .  
         [0026]     To withdraw the axle shaft  86 , one removes the spring clip  98 , thereby releasing the plug  96  which is withdrawn form the socket  90 . Then the axle shaft  86  is engaged with a tool that threads into the threaded hole  90  in the end of the shaft  86 , and through the tool a withdrawal force is applied to the shaft  86 .  
         [0027]     Variations are possible. For example, the outer raceways  68  for the bearings  16  may be machined directly into the housing  12 . Likewise, the outboard inner raceway  72  and thrust rib  74  may be machined directly into the spindle  38  of the hub  14 , leaving only the inboard inner cone  62  as an initially separate race to be installed over the hub spindle  38 . Moreover, the outer raceways  68  may be on a single double cup retained in the housing  12  by snap rings or other devices. For that matter, other types of bearings having inclined raceways, such as angular contact ball bearings or spherical roller bearings, may be substituted for the tapered roller bearings  16 . Indeed, deep groove ball bearings or even a single row cylindrical roller bearing may be substituted for the tapered roller bearings  16 . The housing  12  may have formations that accommodate components of a disk brake in lieu of a drum brake.