Patent Publication Number: US-2005137048-A1

Title: Wheel differential bearing adjustment tool

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      This invention relates to bearing adjustments in wheel differentials and, in particular, to a tool for adjusting bearing preload.  
      2. Discussion of Related Art  
      A vehicle drive axle contains a wheel differential used to allows wheels on opposite sides of the axle to rotate at different speeds. The wheel differential includes a pinion gear that receives power input to the drive axle, a ring gear in mesh with the pinion gear and a differential case affixed to the ring gear for rotation therewith. The differential case supports a plurality of bevel gears used to transfer power to, and divide power between, axle shafts supporting the wheels on either side of the vehicle. The components of the wheel differential are held within the drive axle housing or differential carrier. The differential case is supported for rotation within the differential carrier by two sets of coaxial bearings.  
      As set forth in commonly assigned U.S. Pat. No. 6,659,651, the entire disclosure of which is incorporated herein by reference, each bearing set may include a threaded bearing cup configured to mate with corresponding threads in the differential carrier. The use of threaded bearing cups creates a need for an improved tool that can be used to adjust the bearing sets.  
      The inventors herein have recognized a need for a wheel differential bearing adjustment tool and a method of adjusting wheel differential bearings that will minimize and/or eliminate one or more of the above-identified deficiencies.  
     SUMMARY OF THE INVENTION  
      The present invention provides a wheel differential bearing adjustment tool as well as a method for adjusting wheel differential bearings.  
      A wheel differential bearing adjustment tool in accordance with the present invention may include a first plate configured to engage a bearing cup in a first bearing set supporting a differential case within a differential carrier. The tool may further include a second plate spaced from the first plate and configured to engage a bearing cup in a second bearing set supporting the differential case within the differential carrier. The tool may further include a threaded rod extending between the first and second plates and first and second threaded members disposed on opposite sides of the first and second plates, respectively, relative to the first and second bearing sets and threaded on the rod. Rotation of one of the first and second threaded members adjusts a position of at least one of the first and second bearing sets.  
      A method for adjusting wheel differential bearings in accordance with the present invention may include the steps of: engaging a first bearing cup in a first bearing set with a first plate, the first bearing set supporting a differential case within a differential. The method may further include the step of engaging a second bearing cup in a second bearing set with a second plate, the second bearing set spaced from the first bearing set and supporting the differential case within the differential. The method may further include the steps of coupling the first and second plates and rotating the first plate to adjust a position of the first bearing cup.  
      A wheel differential bearing adjustment tool and method for adjusting wheel differential bearings in accordance with the present invention are advantageous. The tool and method provide an efficient means for accurately adjusting bearing preload and facilitate the use of a threaded bearing cup as described in commonly assigned U.S. Pat. No. 6,659,651.  
      These and other advantages of this invention will become apparent to one skilled in the art from the following detailed description and the accompanying drawings illustrating features of this invention by way of example.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a partially exploded perspective view of a wheel differential bearing adjustment tool in accordance with the present invention.  
       FIG. 2-3  are plan views of one component of the tool of  FIG. 1 .  
       FIG. 4  is a cross-sectional view of the component of  FIG. 2  taken along lines  4 - 4 .  
      FIGS.  5 A-B are flowchart diagrams illustrating a method for adjustment of wheel differential bearings in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION  
      Referring now to the drawings wherein like reference numerals are used to identify identical components in the various views, FIGS.  1   2  illustrates a wheel differential bearing adjustment tool  10  in accordance with the present invention. Tool  10  includes plates  12 ,  14  and means, such as rod  16 , and members  18 ,  20 , for adjusting a position of at least one of said first and second bearing plates to thereby adjust the position of a bearing cup of a corresponding wheel differential bearing set. Tool  10  may also include washers  22 ,  24 .  
      Plates  12 ,  14  are provided to engage outboard sides of bearing cups (best shown in  FIG. 6 ) in two spaced bearing sets (not shown) supporting a differential case for rotating within a differential carrier. Plates  12 ,  14  may be identical in shape and/or appearance and be made from conventional metals and metal alloys. Each plate  12 ,  14  may be substantially circular in shape with a diameter sized relative to the size of the bearing cup. Each plate  12 ,  14  may also define an aperture  26  extending therethrough for a purpose described hereinbelow. The aperture  26  may be disposed about a central axis extending through each plate  12 ,  14 . Referring to  FIGS. 2-3 , each plate  12 ,  14 , has an inboard side  28  configured to engage a corresponding bearing cup and an outboard side  30  facing away from the bearing cup.  
      Referring to  FIG. 2 , inboard side  28  is configured to engage a corresponding bearing cup. Side  28  defines a central, axially extending hub  32  and a plurality of spokes  34  radiating from hub  32 . Spokes  34  terminate at an undulating wall  36  before reaching a radially outer periphery of plates  12 ,  14 . Wall  36  extends circumferentially around plate  12 ,  14 , moving inward and outward to define a plurality of equidistant, angularly spaced notches  38 . Each notch  38  is centered on a corresponding spoke  34 . Hub  32 , spokes  34  and wall  36  together define a plurality of angularly spaced hollows  40 . The notches  38  formed by wall  36  are configured to receive one or more radially inwardly extending members on a ring affixed to the bearing cup. The ring may have a diameter substantially equal to the diameter of plate  12  or  14  and a complementary shape relative to wall  36 .  
      Referring to  FIG. 3 , outboard side  30  faces away from a bearing cup. Referring to  FIG. 4 , side  30  defines an axially extending hub  42 . Referring again to  FIG. 3 , hub  42  may be hexagonal in shape so that hub  42  can be grasped by a tool to cause rotation of plate  12  or  14 . It should be understood, that the illustrated shape of hub  42  and that the shape of hub  42  may be varied without departing from the spirit of the present invention. Further, it should be understood that a side  30  could include a variety of structural features to enable receipt of tools used to rotate plate  12  or  14 . Side  30  may also include one or more positional indicators  44 . In the illustrated embodiment, each indicator  44  comprises a radially extending line. It should be understood, however, that the form of the indicators  44  may vary without departing from the scope of the present invention. Indicators  44  may be angularly spaced on side  30  and may be equidistant from one another. In the illustrated embodiment, indicators  44  are spaced by approximately eighteen degrees. Side  30  may finally include an identifier  46  to identify the tool and/or bearing sets which in the illustrated embodiment comprises textual information. It should be understood, however, that a variety of identifiers could be used.  
      Referring again to  FIG. 1 , rod  16  is provided to join plates  12 ,  14 . At least a portion of rod  16  is threaded and the entire rod may be threaded as shown in the illustrated embodiment. Rod  16  is configured to be received within apertures  26  in plates  12 ,  14  and extends outboard of plates  12 ,  14  upon assembly. As described in greater detail hereinbelow, rod  16  also extends through each bearing set (and each bearing cup) supporting the differential case within the differential.  
      Threaded members  16 ,  18 , which may comprise nuts, provided to secure plates  12 ,  14  on rod  16 . Nuts  16 ,  18  are disposed on outboard sides  30  of plates  12 ,  14 , opposite the inboard sides  28  against which the bearing sets are disposed. Members  16 ,  18  may be hexagonal in shape to enable a tool to grasp members  16 ,  18 .  
      Washers  20 ,  22  may be used in a conventional manner to ensure a tight fitting engagement between members  16 ,  18  and plates  12 ,  14 . Washers  20 ,  22  may comprise flat washers.  
      Referring now to FIGS.  5 A-B, a method for adjusting wheel differential bearings in accordance with the present invention will be described. The inventive method may begin with the step  48  of engaging a bearing cup of one of the bearing sets supporting the differential case within the differential using one of plates  12 ,  14 . As will be understood to those of skill in the art, the bearing sets may be referred to as the “plain half” bearing set and the “flanged half” bearing set based on the location of the ring gear as attached to the differential case. The method may continue with the step  50  of engaging a bearing cup in the other bearing set supporting the differential case within the differential carrier using another of plates  12 ,  14 .  
      Once plates  12 ,  14  are engaged to the bearing cups, the method may continue with the step  52  of coupling plates  12 ,  14 . Step  52  may include several substeps  54 ,  56 ,  58 . In substep  54 , rod  16  is inserted through the plain and flanged half bearing sets and through the aligned apertures  26  in plates  12 ,  14 . In substep  56 , washers  20 ,  22  are placed on rod  16  and engage the outboard sides  30  of plates  12 ,  14 . Finally, in substep  58 , threaded members  16 ,  18  are threaded onto rod  16  on the outboard sides  30  of plates  12 ,  14 .  
      Once tool  10  has been assembled, the method may continue with the step  60  of inserting the assembly comprised of the differential carrier, the ring gear, the plain and flanged half bearing sets and the tool  10  into the differential housing in a conventional manner. The method may then continue with the step  62  of determining whether the bearing cups in the bearing sets are properly aligned within the differential carrier. Step  62  can be performed, for example, by determining whether a gap exists between the threads on the bearing cups and the threads on the differential carrier and/or by determining whether the bearing cage in the bearing set is parallel to the edge of the bearing cup of the bearing set. If the bearing sets are not properly aligned, the assembly is removed from the differential carrier and steps  60 ,  62  are repeated.  
      After the bearing sets are aligned within the differential carrier, the method continues with the step  64  of rotating one of plates  12 ,  14  to adjust the position of a corresponding bearing cup. In one embodiment of the invention step  64  may involve rotating the plate  12  or  14  engaging the bearing cup of the flanged half bearing set. Step  64  may include several substeps  66 ,  68 ,  70 . In substep  66 , plate  12  is grasped with a tool. For example, a ratchet and socket may be used to grasp hub  42  on the respective plate  12  or  14 . In substep  68 , the tool is rotated in a first direction until the ring gear contacts a pinion gear in the differential carrier. In substep  70 , the tool is rotated in a second direction, opposite the first direction, a predetermined distance using positional indicators  44  on the outboard side  30  of the plate  12  or  14 .  
      Them method may continued with the step  72  of rotating the other plate  12  or  14  to adjust the position of the bearing cup in the other bearing set. Step  72  may also have several substeps  74 ,  76 ,  78 . In one embodiment of the invention step  72  may involve rotating the plate  12  or  14  engaging the bearing cup of the plain half bearing set. In substep  74 , the plate  12  or  14  is grasped with a tool. Again, for example, a ratchet and socket may be used to grasp hub  42  on the respective plate  12  or  14 . In substep  76 , the tool is rotated in a first direction until the resistance begins (zero preload). In substep  78  the tool is rotated further in the first direction a predetermined distance using positional indicators  44  on the outboard side  30  of the plate  12  or  14 .  
      The method may continue with the step  80  of seating the bearing cups by, for example, using a rubber mallet on the bearing cups in a conventional manner. In step  82 , the ring and pinion gear backlash is determined using a conventional measurement device and set. In step  84 , tool  10  is removed by unscrewing members  16 ,  18 , removing washers  20 ,  22 , sliding rod  16  out from the bearing sets and plates  12 ,  14  and removing plates  12 ,  14 . Finally, in step  86 , bearing caps are affixed to the differential carrier. The ring and pinion gear backlash may be rechecked at this point and reset if necessary.  
      A wheel differential bearing adjustment tool and method for adjusting wheel differential bearings in accordance with the present invention is advantageous. In particular, the inventive tool and method provide an efficient means for accurately adjusting bearing preload and facilitate the use of bearing sets employing threaded bearing cups.  
      While the invention has been shown and described with reference to one or more particular embodiments thereof, it will be understood by those of skill in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. For example, it should be understood that the configuration of bracket  34 , arm  82 , and guide member  86  or bracket  202  and guide members  236 ,  238  could be replicated on each side of the vehicle frame  10 .