Abstract:
The present invention relates to a system and apparatus used in conjunction with drive mechanisms in vehicles for efficient energy transfer through a pinion assembly and associated bearings to the wheels of a vehicle. The apparatus includes various types of fasteners, a drive flange, pinion shaft, and an integrated bearing assembly.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    The present application is related to and claims the benefit of, under 35 U.S.C. § 119(e), U.S. Provisional Patent Application Serial No. 60/197,399, filed Apr. 14, 2000, which is expressly incorporated fully herein by reference. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to an apparatus and method used in conjunction with drive mechanisms in vehicles for efficient energy transfer through a pinion assembly and associated components, including bearings, to the wheels of a vehicle.  
           [0004]    2. Description of the Prior Art  
           [0005]    [0005]FIG. 1 illustrates a configuration of a typical axle differential pinion assembly. One end of the pinion connects to a drive shaft, which is connected to a motor and a transmission, which transmits torque. The opposite end of the pinion connects to a differential that transfers power to the wheels of the vehicle.  
           [0006]    Referring again to FIG. 1, tightening threaded fastener  180  against counterbore  193  of drive flange  190  transmits force through pinion shaft  100  to first and second bearings  200  and  210 , creating bearing preload. Bearing preload creates stiffness and affects the life of the bearing. Stiffness within the pinion shaft prevents vertical and axial movement of the shaft, which improves torque transmission efficiency and reduces noise. A light preload reduces the stiffness and creates noise within the bearing, reducing the life of the bearing. Conversely, a heavy preload also causes failure. Thus, the ability to control bearing preload precisely allows bearing manufacturers to control and predict the life of the bearing.  
           [0007]    The manner in which the bearing sits on the pinion shaft affects the efficiency of the configuration. Referring again to FIG. 1, bearings  200  and  210  are spaced apart along the pinion shaft. A wide bearing spread  205  prevents deflection of pinion shaft  100  and thus, creates stiffness. Wide bearing spread, however, necessitates machining bearing seats  145  and  155  separately (double machining). Double machining creates inaccuracies, which may cause misalignment. This potential misalignment may cause premature bearing failure. Also, because the assembly of the pinion and associated components controls the amount of preload, assembly directly affects the life of the bearing and thus the efficiency of the pinion assembly. Double machining also increases the cost of manufacture. The present invention attempts to solve these problems and provide a pinion assembly design that increases the efficiency of torque transmission, facilitates quick and accurate assembly and service, and controls bearing preload.  
         SUMMARY OF THE INVENTION  
         [0008]    The basic purpose of an axle differential is to transfer torque from the engine through a drive shaft to the wheels. Less than eighteen percent of the energy generated from fuel in an automobile reaches the wheels of the automobile in the form of torque. Therefore, one of the objects of the invention is to provide a system and apparatus that creates a more efficient torque transfer system.  
           [0009]    Other advantages of the present invention include, for example, increasing system strength, reducing system size, increasing pinion shaft stiffness, reducing bearing noise, reducing bearing misalignment, facilitating accurate manufacture, facilitating quick and accurate assembly and service, and controlling bearing preload.  
           [0010]    One object of the present invention is to provide a pinion assembly having an integral (i.e., single unit or unitary) bearing assembly in place of a plurality of bearing assemblies. Another object of the present invention is to provide a pinion assembly with formable or threaded fasteners. Yet another object of the present invention is to control preload of the bearing and stiffness of a pinion assembly. Another object of the present invention is to increase the stiffness of a pinion assembly. Still another object of the present invention is to decrease the assembly time of a pinion assembly. Another object of the present invention is to decrease the manufacture time of a pinion assembly.  
           [0011]    In one embodiment of the present invention, the apparatus for the pinion assembly may comprise a pinion shaft of varying diameters having a first and second end, wherein said first end may be adapted to fasten to a drive assembly; a roll-over fastener or a threaded fastener formed on the first end of the pinion shaft; a drive flange that may be connected to the first end of the pinion shaft by either a roll-over or threaded faster; and an integral bearing assembly. The integral bearing assembly may have a first and second end that may facilitate rotation between the pinion shaft and the integral bearing assembly. The integral bearing assembly may contain one or more rolling elements that each have an inner and outer race.  
           [0012]    In one embodiment of the present invention, the first end of the pinion assembly may abut the drive flange. In another embodiment of the present invention, the integral bearing assembly may have two rolling element bearings. In yet another embodiment of the present invention, the inner race of the second rolling element bearing may be formed into the second end of the pinion shaft.  
           [0013]    In one embodiment of the present invention, bearing preload may be controlled by the apparatus described above and by positioning an inner race on a pinion shaft and providing a roll-over fastener to attach a pinion assembly to a drive flange. In one embodiment of the present invention, the integral bearing assembly may contain two bearings. In another embodiment of the present invention, the inner race of a second bearing may be ground into the second end of a pinion shaft.  
           [0014]    In an embodiment of the present invention, increased stiffness of the pinion assembly may be achieved by positioning an inner race on a pinion shaft and optimizing the distance between a pressure point and load lines and redistributing the forces along a pinion shaft. In other embodiments of the present invention, the fastener may be either a roll-over fastener or a threaded fastener. In another embodiment of the present invention, stiffness may be created by positioning the bearings of the pinion assembly closer to a pinion gear.  
           [0015]    In one embodiment of the present invention, assembly time for the pinion assembly apparatus may be decreased by controlling bearing flange to pinion gear distance. In another embodiment, assembly time may be decreased by integrating the bearing units. In yet another embodiment of the present invention, manufacture time of the pinion assembly may be decreased by minimizing the number of areas to be formed on the pinion apparatus. In another embodiment, manufacture time may be decreased by placing the inner race of a bearing assembly on the pinion shaft of the pinion apparatus. In still another embodiment of the present invention, minimizing the number of areas to be formed in the pinion apparatus may be achieved by forming one bearing seat. In another embodiment of the present invention, forming the bearing seat may be achieved by either forging, grinding, or machining the bearing seat. In yet another embodiment of the present invention, the inner race of the bearing closest to the end of the pinion shaft may be formed on the pinion shaft.  
           [0016]    Other objectives, features and advantages of the present invention will become apparent from the following detailed description. The detailed description and the specific examples, while indicating specific embodiments of the invention, are provided by way of illustration only. Accordingly, the present invention also includes those various changes and modifications within the spirit and scope of the invention that may become apparent to those skilled in the art from this detailed description.  
           [0017]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.  
           [0018]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the invention and together with the description, serve to explain the principles of the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]    [0019]FIG. 1 is a schematic drawing of a typical axle differential pinion assembly.  
         [0020]    [0020]FIG. 2 is a schematic drawing that illustrates the pressure points and loadlines in a pinion assembly.  
         [0021]    [0021]FIG. 3 is a schematic drawing of a integrated bearing/pinion assembly with a pinion shaft roll-over fastener.  
         [0022]    [0022]FIG. 4 is a schematic drawing of an alternative embodiment of the present invention with an integrated bearing assembly and a threaded fastener.  
         [0023]    [0023]FIG. 5 is a schematic drawing of a pinion assembly having the bearing fully integrated using a pinion shaft roll-over fastener.  
         [0024]    [0024]FIG. 6 is a schematic drawing of a pinion assembly having the bearing fully integrated using a threaded fastener. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0025]    Reference will now be made in detail to the present preferred embodiments and exemplary embodiments of the invention, examples of which are illustrated in the accompanying drawings. It is understood that the terminology used herein is used for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention. It must be noted that as used herein and in the appended claims, the singular forms “a,” “an,” and “the” include plural reference unless the context clearly dictates otherwise. Thus, for example, a reference to “shim” is a reference to one or more shims and includes equivalents thereof known to those skilled in the art and so forth.  
         [0026]    [0026]FIG. 2 illustrates the concepts of a pressure point and a load line in a pinion assembly. These two concepts are instrumental in creating pinion stiffness and strength. The pressure point  300  of a pinion is defined as the point at which the two bearing pressure lines ( 305 ,  310 ) intersect within the pinion. Bearing pressure lines  305  and  310  are straight lines that run through the center of rolling elements  315  and  320  and are perpendicular to the rolling elements. Load line  325  is defined as the normal force, or the force that pinion gear  330  exerts upon the end of the pinion, that is directed perpendicular to pinion gear  330  through its center onto the pinion. Placing pressure point  300  closer to load line  325  redistributes the forces along the pinion shaft, increasing the stiffness of the pinion; thus, the distance between pressure point  300  and load line  325  is preferably optimized to increase stiffness.  
         [0027]    [0027]FIG. 3 shows an embodiment of a pinion assembly of the present invention having an integrated bearing unit (i.e., single unit or unitary) and a roll-over fastener. Pinion shaft  400  preferably has two ends  410  and  420  and four substantially cylindrical or tubular (or equivalent shapes) sections  430 ,  440 ,  450 , and  460 . Pinion shaft  400  may be made of any material that is appropriate for withstanding typical loads, fatigue, wear, and stress, such as for example, steel or steel alloys and other materials with similar or related properties.  
         [0028]    First end  410  of pinion shaft  400  is preferably made of formable material such that the material may be rolled over an adjoining component for fastening purposes. First section  430  includes first end  410 , is preferably substantially or relatively cylindrical or tubular in shape with the exception of the portion of pinion shaft  400  that forms roll-over fastener  480  (although it may be of other equivalent shapes as well), preferably has the smallest shaft diameter of the sections, and extends from first end  410  to second section  440 .  
         [0029]    Second section  440  is preferably substantially or relatively cylindrical or tubular in shape (although it may be of other equivalent shapes as well), extends from first section  430  to third section  450  and has a diameter preferably greater than first section  430  but preferably smaller than third section  450 . The entire diameter of second section  440  may be formed (e.g., ground, machined, or forged) to serve as a integral bearing seat  445 . Integral bearing seat  445  is where the integral bearing assembly contacts pinion shaft  400  and is located around the circumference of second section  440  of pinion shaft  400 .  
         [0030]    Third section  450  of pinion shaft  400  is preferably relatively cylindrical or tubular in shape (although it may be of other equivalent shapes as well), extends from second section  440  to fourth section  460 , and preferably has a varying diameter greater than second section  440  but smaller than fourth section  460 . Third section  450  preferably has a machined, ground, or forged portion increasingly angled toward fourth section  460  that serves as the inner race  455  for the second bearing  505  in an integral (i.e., single unit or unitary body) bearing assembly  500 . Before third section  450  abuts fourth section  460  the diameter is preferably increased and there is a small lip  507 . After small lip  507 , the diameter of pinion shaft  400  remains relatively constant.  
         [0031]    Fourth section  460  is preferably shaped like a modified truncated cone and has varying diameters, all of which are preferably greater than the diameter of third section  450 . Fourth section  460  is angled at an increasing angle away from third section  450 . The angle is truncated at second end  420  of pinion shaft  400 .  
         [0032]    First end  410  of pinion shaft  400  is preferably made of formable material that is adapted to be rolled over counterbore  493  in drive flange  490  to serve as a roll-over fastener  480  that holds pinion shaft  400  in proper positioning within drive flange  490 . Drive flange  490  is coaxial with pinion shaft  400  and is held in place by roll-over fastener  480 .  
         [0033]    Drive flange  490  has two ends  491  and  499 , is coaxial with pinion shaft  400 , and is preferably held in place by roll-over fastener  480  and a spline coupling  495 . Drive flange  490  may be made of any material that is appropriate for withstanding typical loads, fatigue, wear and stress, such as for example, steel or steel alloys. First end  491  of drive flange  490  has a large diameter with a concentric concave angled aperture  492 . Aperture  492  may extend at a decreasing angle towards the interior end of the aperture and includes counterbore  493 . Counterbore  493  is inside the interior end of aperture  492 . Counterbore  493  is what roll-over fastener  480  curves into once it is rolled over and is preferably of a larger diameter than the hollow cylindrical section  494  of drive flange  490 . Spline coupling  495  of hollow cylindrical section  494  fits concentrically around a portion of first section  430 , and may be a typical spline coupling or fitting or any other mechanical equivalent. Hollow cylindrical section  494  of drive flange  490  extends from roll-over fastener  480  to second end  499 , which may abut integral bearing assembly  500 . Shims  496  and  497  may be placed between second end  499  of drive flange  490  and first span  501  of integral bearing assembly  500 .  
         [0034]    Integral bearing assembly  500  has two spans, first span  501  and second span  509 . Integral bearing assembly  500  may be made of any material that is appropriate for withstanding typical loads, fatigue, wear, and stress, including bearing steel or any other type of steel or steel alloy. First span  501  of integral bearing assembly  500  preferably has a bearing flange  503  that may abut drive flange  490  and fits concentrically around second section  440  of pinion shaft  400  on integral bearing seat  445 . Bearing flange  503  allows assembly of integral bearing assembly  500  to an outer housing. In an alternative embodiment, the position of bearing flange  503  may be reversed; thus, bearing flange  503  may be part of second span  509  of integral bearing assembly  500 . In the embodiment shown in FIG. 3, first bearing  504  is contained within first span  501  of integral bearing assembly  500  and is preferably a tapered roller bearing. The rolling elements of first bearing  504  roll in outer race  508  and inner race  502 . Second span  509  is the portion of integral bearing assembly  500  that is coaxial with third section  450  of pinion shaft  400  and contains second bearing  505 . Second bearing  505  is preferably a tapered roller bearing. The rolling elements of second bearing  505  roll in outer race  508 , which is shared by first bearing  504 ; however, the rolling elements  506  of second bearing  505  roll in inner race  455 , which is formed (e.g., ground, machined, or forged) into the increasing angle portion of third section  450 . The backsides of rolling elements  506  abut small lip  507 .  
         [0035]    In a preferred embodiment, as shown in FIG. 3, roll-over fastener  480 , located in first section  430 , provides a higher level of bearing preload control. Rolling the formable end  410  of pinion shaft  400  into counterbore  493  pushes drive flange  490  closer to integral bearing assembly  500 , creating preload. Also, because the pinion/bearing manufacture may preferably roll roll-over fastener  480  into counterbore  493 , the manufacturer may control the bearing preload, directly affecting the life of the bearings and thus, the efficiency of the pinion assembly.  
         [0036]    Pinion shaft  400  preferably can have a greater diameter than other known pinion assembly configurations. Inner race  455  of second bearing  505  in integral bearing assembly  500  is formed (e.g., ground, machined, or forged) directly into a portion of third section  450  of pinion shaft  400 . Because there is no need for a separate inner ring, the diameter of pinion shaft  400  may be increased, which will increase pinion stiffness. Also, by increasing the diameter of pinion shaft  400 , the entire pinion assembly is stronger and the second end  509  of integral bearing assembly  500  can be moved closer to second end  420  of pinion shaft  400 . This increases the stiffness of pinion assembly  400  by optimizing the distance between the pressure point  300  and load line  325 , as previously shown in FIG. 2.  
         [0037]    Increasing the pinion shaft diameter should increase pinion assembly stiffness exponentially, which prevents deflection and allows more efficient energy (torque) transmission through pinion shaft  400  to the wheels.  
         [0038]    Also, the strength of the assembly is preferably increased by having inner race  455  of second bearing  505  in integral bearing assembly  500  formed (e.g., machined, ground, or forged) directly into third section  450  of pinion shaft  400 . By having inner race  455  ground into pinion shaft  400 , the backsides of rolling elements  506  are supported by small lip  507  of third section  450 , increasing the strength of the assembly of pinion shaft  400 .  
         [0039]    Integral bearing assembly  500  eliminates the need for double machining, which prevents misalignment of bearings  504  and  505  in pinion shaft  400  and removes machining inaccuracies, thus, decreasing manufacture, assembly, and service time. Because integral bearing assembly  500  is one piece, it may be considered a plug-in unit, providing easier and quicker assembly for car or axle manufacturers or service persons. Also, the bearings within integral bearing assembly  500  are closer to the drive gear, reducing vibrations within pinion shaft  400 , which decreases bearing noise and increases stiffness, allowing for longer bearing life.  
         [0040]    [0040]FIG. 4 depicts an alternative embodiment of an integral bearing assembly of the present invention. Pinion shaft  600  has two ends  610  and  620  and five cylindrical sections  630 ,  640 ,  650 ,  660 , and  670 . Pinion shaft  600  may be made of any material that is appropriate for withstanding typical loads, fatigue, wear, and stress, e.g., steel or steel alloys and other materials with similar or related properties. First end  610  of pinion shaft  600  is the beginning of first section  630 . First section  630  is preferably cylindrical, has the smallest diameter, and extends from first end  610  to second section  640 .  
         [0041]    Second section  640  is preferably substantially or relatively cylindrical or tubular in shape (although it may be of other equivalent shapes as well), extends from first section  630  to third section  650  and preferably has a diameter greater than first section  630  but smaller than third section  650 .  
         [0042]    Third section  650  is preferably substantially or relatively cylindrical or tubular in shape (although it may be of other equivalent shapes as well), extends from second section  640  to fourth section  660  and preferably has a uniform diameter greater than second section  640  but smaller than fourth section  660 . The entire diameter of third section  650  is preferably formed (e.g., ground, machined, or forged) to serve as integral bearing seat  645 . Integral bearing seat  645  is where the integral bearing assembly contacts pinion shaft  600  and is located around the circumference of second section  640  of pinion shaft  600 .  
         [0043]    Fourth section  660  is preferably relatively cylindrical or tubular in shape (although it may be of other equivalent shapes as well), extends from third section  650  to fifth section  670 , and preferably has varying diameters, all of which are preferably greater than third section  650  but smaller than fifth section  670 . Fourth section  660  preferably has a formed (e.g., machined, ground, or forged) portion increasingly angled toward fifth section  670  that serves as the inner race  655  for the second bearing  705  in an integral bearing assembly  700 . Before fourth section  660  abuts fifth section  670 , the diameter is increased and there is a small lip  707 . After small lip  707 , the diameter of pinion shaft  600  remains relatively constant.  
         [0044]    Fifth section  670  is preferably shaped like a modified truncated cone and has varying diameters, all of which are greater than the diameter of fourth section  660 . Fifth section  670  is preferably angled at an increasing angle away from fourth section  660 . The angle is truncated at second end  620  of pinion shaft  600 .  
         [0045]    First end  610  of pinion shaft  600  is connected to the drive shaft, preferably by a method such as a spline coupling with a retainer ring or bolt and interference fit. A threaded fastener  680  may be placed over the first section  630  to hold pinion shaft  600  in proper positioning within drive flange  690 . Threaded fastener  680  may be made of any material that is appropriate for withstanding typical loads, fatigue, wear and stress, such as for example, steel or steel alloys. Drive flange  690  is coaxial with pinion shaft  600  and is held into place by threaded fastener  680  and spline coupling  695 .  
         [0046]    Drive flange  690  has a two ends  691  and  699 , is coaxial with pinion shaft  600 , and is held into place by threaded fastener  680 . Drive flange  690  may be made of any material that is appropriate for withstanding typical loads, fatigue, wear and stress, such as for example, steel or steel alloys. First end  691  has a large diameter with a concentric concave angled aperture  692 . Aperture  692  extends at a decreasing angle towards the interior end of drive flange  690  and includes counterbore  693 . Threaded fastener  680  rests in counterbore  693  and is preferably of a larger diameter than the hollow cylindrical section  694  of drive flange  690 . Spline coupling  695  of hollow cylindrical section  694  fits concentrically around a portion of first section  630  and may be a typical spline coupling or fitting or any other mechanical equivalent. Hollow cylindrical section  694  of drive flange  690  extends from threaded fastener  680  to second end  699 , which may abut integral bearing assembly  700 . Hollow cylindrical section  694  fits concentrically around second section  640  of pinion shaft  600 . Shims  696  and  697  may be placed between second end  699  of drive flange  690  and first span  701  of integral bearing assembly  700 .  
         [0047]    Integral bearing assembly  700  has two spans: first span  701  and second span  709 . Integral bearing assembly  700  may be made of any material that is appropriate for withstanding typical loads, fatigue, wear, and stress, including bearing steel or any other type of steel or steel alloy. First span  701  preferably has a bearing flange  703  that may abut drive flange  690  and fits concentrically around third section  650  of pinion shaft  600  on integral bearing seat  645 . Bearing flange  703  allows assembly of the integral bearing assembly  700  to an outer housing. In an alternative embodiment, the position of bearing flange  703  may be reversed; thus, bearing flange  703  may be part of second span  709  of integral bearing assembly  700 . In the embodiment shown in FIG. 4, first bearing  704  is preferably contained within first span  701  of integral bearing assembly  700  and is preferably a tapered roller bearing. The rolling elements  706  of first bearing  704  roll in outer race  708  and inner race  702 . Second span  709  is the portion of integral bearing assembly  700  that is coaxial with fourth section  660  of pinion shaft  600  and contains second bearing  705 . Second bearing  705  is preferably a tapered roller bearing. The rolling elements of second bearing  705  roll in outer race  708 , which is shared by first bearing  704 ; however, the rolling elements  706  of second bearing  705  roll in inner race  655 , which is formed (e.g., ground, machined or forged) into the increasing angle portion of fourth section  660 . The backsides of rolling elements  706  abut small lip  707  of fourth section  660  of pinion shaft  600 .  
         [0048]    In FIG. 4, threaded fastener  680 , located in first section  630 , contributes to controlling bearing preload. Tightening threaded fastener  680  against counterbore  693  of drive flange  690  pushes drive flange  690  closer to integral assembly  700 , creating bearing preload. Stiffness within the pinion assembly prevents vertical and axial movement of pinion shaft  600 , which improves torque transmission, efficiency, and reduces noise. A light preload reduces the stiffness of the pinion assembly and creates noise within the bearing, which may reduce the life of the bearing. Conversely, a heavy preload can also cause premature failure of the bearing. Thus, the ability to control bearing preload precisely allows bearing manufacturers to control and predict the life of the bearing.  
         [0049]    Drive flange  690  attaches to a drive shaft associated with the engine and interacts with a drive gear to transmit and control the amount of torque through pinion shaft  600  to a differential.  
         [0050]    Pinion shaft  600  preferably can have a greater diameter than other known pinion assembly configurations. Inner race  655  of second bearing  705  in integral bearing assembly  700  is ground directly into fourth section  660  of pinion shaft  600 . Because there is no need for a separate inner ring, the diameter of pinion shaft  600  may be increased, which will increase the stiffness of pinion  600 . Also, by having inner race  655  of second bearing  705  in integral bearing assembly  700  formed (e.g., ground, machined, or forged) directly into fourth section  660  of pinion shaft  600 , the diameter of pinion shaft  600  may be greater than when inner race  655  is not formed in pinion shaft  600 . A greater pinion diameter increases the strength and stiffness of the pinion assembly. Additionally, the distance between the pressure point  300  and load line  325  (as shown in FIG. 2) can be optimized. By forming inner race  655  into a portion of fourth section  660  of pinion shaft  600 , the backsides of rolling elements  706  are supported by small lip  707  of truncated cone-shaped fourth section  660 , meaning that the inner race may be formed into pinion shaft  600  closer to the second end  620  of pinion shaft  600 . Moving inner race  655  along pinion shaft  600  closer to second end  620  of pinion shaft  600  also moves rolling elements  706  closer to second end  620  of pinion shaft  600  and consequently shifts the pressure point  300  closer to the load line  325  (as shown in FIG. 2), which also increases stiffness of the pinion assembly.  
         [0051]    Integral bearing assembly  700  eliminates the need for double machining, which removes machining inaccuracies and prevents misalignment of bearings  704  and  705  in pinion shaft  600 . Because integral bearing  700  is one piece, it is considered a plug-in unit, providing easier and quicker assembly for car or axle manufacturers. Also, the bearings within integral bearing assembly  700  are closer to the drive gear, reducing vibrations within pinion shaft  600 , which decreases bearing noise and allows for longer bearing life.  
         [0052]    [0052]FIG. 5 is another embodiment of the present invention that utilizes a integral bearing assembly and a roll-over fastener. Pinion shaft  800  preferably has two ends  810  and  820  and three substantially cylindrical or tubular (or equivalent shapes) sections  830 ,  840 , and  850 . Pinion shaft  800  may be made of any material that is appropriate for withstanding typical loads, fatigue, wear, and stress, such as for example, steel or steel alloys and other materials with similar or related properties.  
         [0053]    First end  810  of pinion shaft  800  is preferably of a formable material such that the material may be rolled over an adjoining component for fastening purposes. First section  830  includes first end  810 , is preferably substantially or relatively cylindrical or tubular in shape with the exception of the portion of pinion shaft  800  that forms roll-over fastener  880  (although it may be of other equivalent shapes as well), has the smallest diameter of the sections, and extends from first end  810  to second section  840 .  
         [0054]    Second section  840  is preferably substantially or relatively cylindrical or tubular in shape (although it may be of other equivalent shapes as well), extends from first section  830  to third section  850 , and has a diameter greater than first section  830  but smaller than third section  850 . The entire diameter of second section  840  may be formed to serve as a integral bearing seat  845 . Integral bearing seat  845  is where integral bearing assembly  900  contacts pinion shaft  800  and is located around the circumference of second section  840  of pinion shaft  800 .  
         [0055]    Third section  850  is preferably shaped like a modified truncated cone and has varying diameters, all of which are greater than the diameter of second section  840 . Where third section  850  abuts second section  840  the diameter is increased. Next, third section  850  is angled at any increasing angle away from second section  840  of pinion shaft  800 . The angle is truncated at second end  820  of pinion shaft  800 .  
         [0056]    First end  810  of pinion shaft  800  is preferably made of formable material that is adapted to be rolled over counterbore  893  in drive flange  890  to serve as a roll-over fastener  880  which holds pinion shaft  800  in proper positioning within drive flange  890 . Drive flange  890  is coaxial with the pinion shaft and is held in place by roll-over fastener  880 .  
         [0057]    Drive flange  890  has two ends  891  and  899 , is coaxial with the pinion shaft and is preferably held in place by roll-over fastener  880  and a spline coupling  895 . Drive flange  890  may be made of any material that is appropriate for withstanding typical loads, fatigue, wear and stress, such as for example, steel or steel alloys. First end  891  has a concentric concave angled aperture  892 . Aperture  892  may extend at a decreasing angle towards interior end  899  and includes counterbore  893 . Counterbore  893  is inside interior end  899  of drive flange  890 . Counterbore  893  is what roll-over fastener  880  curves into once it is rolled and is preferably of a larger diameter than the hollow cylindrical section  894  of drive flange  890 . Spline coupling  895  of hollow cylindrical section  894  fits concentrically around a portion of first section  830  and may be a typical spline coupling or fitting or any other mechanical equivalent. Hollow cylindrical section  894  extends from roll-over fastener  880  to second end  899  of drive flange  890 , which may abut integral bearing assembly  900 . Shims  896  and  897  may be placed between second end  899  of drive flange  890  and first span  901  of integral bearing assembly  900 .  
         [0058]    Integral bearing assembly  900  has two spans, first span  901  and second span  909 . Integral bearing assembly  900  may be made of any material that is appropriate for withstanding typical loads, fatigue, wear, and stress, including bearing steel or any other type of steel or steel alloy. First span  901  of integral bearing assembly  900  preferably has a bearing flange  903  that may abut drive flange  890  and fits concentrically around second section  840  of pinion shaft  800  on integral bearing seat  845 . Bearing flange  903  allows assembly of the integral bearing assembly  900  to an outer housing. In an alternative embodiment, the position of bearing flange  903  may be reversed; thus, bearing flange  903  may be part of second span  909 . In the embodiment shown in FIG. 5, first bearing  904  is contained within first span  901  of integral bearing assembly  900  and is preferably a tapered roller bearing. The rolling elements of first bearing  904  roll in outer race  908  and inner race  902 . Second span  909  contains second bearing  905 , which is preferably a tapered roller bearing. The rolling elements of second bearing  905  also roll in outer race  908  and inner race  902 .  
         [0059]    In a preferred embodiment, as shown in FIG. 5, roll-over fastener  880 , located in first section  830 , provides a higher level of bearing preload control. Rolling the formable end  810  of pinion shaft  800  into counterbore  893  pushes drive flange  890  closer to integral bearing assembly  900 , creating preload. Also, because the pinion/bearing manufacture may preferably roll roll-over fastener  880  into counterbore  893 , the manufacturer may control the bearing preload, directly affecting the life of the bearings and thus, the efficiency of the pinion assembly.  
         [0060]    Integral bearing assembly  900  eliminates the need for double machining, which prevents misalignment of bearings  904  and  905  in pinion shaft  800  and removes machining inaccuracies, thus, decreasing manufacture, assembly, and service time. Because integral bearing  900  is one piece, it may be considered a plug-in unit, providing easier and quicker assembly for car or axle manufacturers or service persons.  
         [0061]    [0061]FIG. 6 depicts an alternative embodiment of an integral bearing assembly of the present invention. Pinion shaft  1000  has two ends  1010  and  1020  and four cylindrical sections  1030 ,  1040 ,  1050 , and  1060 . Pinion shaft  1000  may be made of any material that is appropriate for withstanding typical loads, fatigue, wear, and stress, e.g., steel or steel alloys and other materials with similar or related properties. First end  1010  of pinion shaft  1000  is the beginning of first section  1030 . First section  1030  is cylindrical, preferably has the smallest diameter, is threaded, and extends from first end  1010  to second section  1040 .  
         [0062]    Second section  1040  is preferably substantially or relatively cylindrical or tubular in shape (although it may be of other equivalent shapes as well), extends from first section  1030  to third section  1050  and preferably has a diameter greater than first section  1030  but smaller than third section  1050 .  
         [0063]    Third section  1050  is preferably substantially or relatively cylindrical or tubular in shape (although it may be of other equivalent shapes as well), extends from second section  1040  to fourth section  1060  and has a uniform diameter that may be greater than second section  1040  but smaller than fourth section  1060 . The entire diameter of third section  1050  is preferably formed (e.g., ground, machined, or forged) to serve as integral bearing seat  1045 . Integral bearing seat  1045  is where the integral bearing assembly contacts pinion shaft  1000  and is located around the circumference of second section  1040  of pinion shaft  1000 .  
         [0064]    Fourth section  1060  is preferably shaped like a modified truncated cone and has varying diameters, all of which are preferably greater than the diameter of third section  1050 . Where fourth section  1060  abuts third section  1050  the diameter is increased. Next, fourth section  1060  is angled at any increasing angle away from third section  1050  of pinion shaft  1000 . The angle is truncated at second end  1020  of pinion shaft  1000 .  
         [0065]    First end  1010  of pinion shaft  1000  is connected to the drive shaft, preferably by a method such as a spline coupling with a retainer ring or bolt and interference fit. A threaded fastener  1080  may be placed over the first section  1030  to hold pinion shaft  1000  in proper positioning within drive flange  1090 . Threaded fastener  1080  may be made of any material that is appropriate for withstanding typical loads, fatigue, wear and stress, such as for example, steel or steel alloys. Drive flange  1090  is coaxial with pinion shaft  1000  and is held into place by threaded fastener  1080  and spline coupling  1095 .  
         [0066]    Drive flange  1090  has a two ends  1091  and  1099 , is coaxial with pinion shaft  1000 , and is held into place by threaded fastener  1080 . Drive flange  1090  may be made of any material that is appropriate for withstanding typical loads, fatigue, wear and stress, such as for example, steel or steel alloys. First end  1091  of drive flange  1090  has a large diameter with a concentric concave angled aperture  1092 . Aperture  1092  extends at a decreasing angle towards the interior end of drive flange  1090  and includes counterbore  1093 . Counterbore  1093  is what threaded fastener  1080  rests in and is preferably of a larger diameter than the hollow cylindrical section  1094  of drive flange  1090 . Spline coupling  1095  of hollow cylindrical section  1094  fits concentrically around a portion of first section  1030  and may be a typical spline coupling or fitting or any other mechanical equivalent. Hollow cylindrical section  1094  of drive flange  1090  extends from threaded fastener  1080  to second end  1099 , which may abut integral bearing assembly  1100 . Hollow cylindrical section  1094  fits concentrically around second section  1040  of pinion shaft  1000 . Shims  1096  and  1097  may be placed between second end  1099  of drive flange  1090  and first span  1101  of integral bearing assembly  1000 .  
         [0067]    Integral bearing assembly  1100  has two spans, first span  1101  and second span  1109 . Integral bearing assembly  1100  may be made of any material that is appropriate for withstanding typical loads, fatigue, wear, and stress, including bearing steel or any other type of steel or steel alloy. First span  1101  of integral bearing assembly  1100  preferably has a bearing flange  1103  that may abut drive flange  1090  and fits concentrically around third section  1050  of pinion shaft  1000  on integral bearing seat  1045 . Bearing flange  1103  allows assembly of the integral bearing assembly  1100  to an outer housing. In an alternative embodiment, the position of bearing flange  1103  may be reversed; thus, bearing flange  1103  may be part of second span  1109 . In the embodiment shown in FIG. 6, first bearing  1104  is contained within first span  1101  of integral bearing assembly  1100  and is preferably a tapered roller bearing. The rolling elements of first bearing  1104  roll in outer race  1108  and inner race  1102 . Second span  1109  contains second bearing  1105 , which is preferably a tapered roller bearing. The rolling elements of second bearing  1105  also roll in outer race  1108  and inner race  1102 .  
         [0068]    In FIG. 6, threaded fastener  1080 , located in first section  1030 , contributes to controlling bearing preload. Tightening threaded fastener  1080  against counterbore  1093  of drive flange  1090  pushes drive flange  1090  closer to integral assembly  1100 , creating bearing preload. Stiffness within the pinion assembly reduces vertical and axial movement of pinion shaft  1000 , which improves torque transmission, efficiency, and reduces noise. A light preload reduces the stiffness of the pinion assembly and creates noise within the bearing, which may reduce the life of the bearing. Conversely, a heavy preload can also cause premature failure of the bearing. Thus, the ability to control bearing preload precisely allows bearing manufacturers to control and predict the life of the bearing.  
         [0069]    Drive flange  1090  attaches to a drive shaft associated with the engine and interacts with a drive gear to transmit and control the amount of torque through pinion shaft  1000  to a differential.  
         [0070]    Integral bearing assembly  1100  eliminates the need for double machining, which removes machining inaccuracies and prevents misalignment of bearings  1104  and  1105  in pinion shaft  1000 . Because integral bearing  1100  is one-piece, it is considered a plug-in unit, providing easier and quicker assembly for car or axle manufacturers. Also, the bearings within integral bearing assembly  1100  are closer to the drive gear, reducing vibrations within pinion shaft  1000 , which decreases bearing noise, allowing for longer bearing life.  
         [0071]    Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims: