Abstract:
An improved replacement axle spindle includes a cylindrical wall exhibiting increasing thickness at increasing distances from the inner end which is secured to an axle. The wall thickness increases in correspondence with the load borne by the replacement spindle resulting in no loss of necessary strength and load carrying ability. Several different profiles are embodied in the present invention: a first embodiment utilizes a straight internal taper; a second embodiment utilizes a dual internal taper, first at a small angle and then at a larger angle; another embodiment utilizes a parabolic internal taper and yet another embodiment utilizes a straight external taper. All may be utilized to replace a tractor or a trailer axle spindle. The spindles save weight and facilitate lubricant flow from the tractor differential into the axle roller bearing assemblies after a repair procedure.

Description:
FIELD 
       [0001]    The present disclosure relates to spindles for installation in the terminal portion of tractor and trailer axles and more specifically to improved replacement spindles for the terminal portion of tractor and trailer axles. 
       BACKGROUND 
       [0002]    The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art. 
         [0003]    The wheels of tractors and trailers are supported on stationary, transverse axles attached to suspension components of the tractor or trailer which are, in turn, attached to the vehicle frame. As such, the axles represent the interface between the rotating tire and wheel assemblies and the stationary structure of the vehicle. To reduce friction and extend the service life of the interface components, roller bearing assemblies are utilized in pairs on a stepped terminal portion of the axle at each wheel location. Generally speaking, a larger diameter roller bearing assembly is disposed on an inner, larger diameter bearing surface of the axle and a smaller diameter roller bearing assembly is disposed on an outer, smaller diameter bearing surface. 
         [0004]    Although well designed, given that many tractors, trailers, other long haul vehicles and delivery trucks log one hundred thousand miles of service per year or more, it is not surprising that these bearing assemblies and the axles upon which they rotate are subject to failure. Such failures are seldom predictable and they are therefore not especially amenable to preventative maintenance. Hence, the failure will frequently occur at some distance from a truck terminal or a qualified repair shop. 
         [0005]    In response to this problem, certain procedures have been developed to facilitate repair of tractor, trailer and long haul vehicle axles at the failure site. One of these is presented in U.S. Pat. No. 4,098,029. Here, weld material is built up on worn or damaged bearing surfaces and then ground down to achieve a coaxial, round bearing surface. Another approach is presented in U.S. Pat. No. 4,455,732. Here, an apparatus and method are taught which are directed to boring a concentric opening in the end of an axle into which is installed a replacement axle stub which is then welded in place. 
         [0006]    My U.S. Pat. No. 6,024,418 illustrates a more recent improvement in axle repair. In this repair method, a long spindle having both inner and outer bearing surfaces and threads is utilized with a sleeve or liner. After the damaged end of the axle has been removed, the spindle and liner are installed in the axle and welded at several locations away from regions of high stress. 
         [0007]    After an axle repair is complete, it is generally necessary to lubricate the ball bearing assemblies installed on the inner and outer bearing surfaces. One way this has been achieved when the repair involves a tractor axle involves lifting the side of the tractor opposite the repair location so that a small portion of the gear lubricant in the differential flows down the axle to the bearings to lubricate them. While satisfactory from a lubrication standpoint, the design of the spindle may be such that it inhibits such lubricant flow unless the tractor is tilted to an unacceptably large angle. Accordingly, there is a need for an improved spindle configuration that facilitates tractor axle bearing lubrication through the just described process. 
         [0008]    Additionally, while the replacement spindle utilized in this method is strong and exhibits a large factor of safety, the replacement spindle and sleeve may weigh forty pounds or more. If, as is often the case, all four spindles of a trailer are replaced at the same time, the added weight, i.e., taking into account the weight of the removed, damaged axle portion, may still total approximately one hundred pounds. Thus, there is also a need to provide a lower weight spindle replacement which provides the necessary strength and desired factor of safety. 
       SUMMARY 
       [0009]    The present invention provides improved replacement axle spindles having a wall exhibiting increased thickness at increasing distances from the inner end which is secured to an axle. The wall thickness increases in correspondence with the load borne by the replacement spindle resulting in no loss of necessary strength and load carrying ability. Eight different combinations of profiles and liners are encompassed by the present invention: a first embodiment utilizes a straight internal taper with a single long liner; a second embodiment utilizes a dual internal taper, first at a small angle and then at a larger angle, with a single seal liner; a third embodiment utilizes a straight internal taper with a pair of short liners; a fourth embodiment utilizes a parabolic internal taper with a pair of short liners; a fifth embodiment utilizes a straight internal taper with a large diameter liner and seal liner; a sixth embodiment utilizes a long straight external taper; a seventh embodiment utilizes a short straight external taper with liners having different inside diameters and a eighth embodiment utilizes a short straight external taper that terminates in a larger diameter cylindrical end region and a single liner. The first five embodiments facilitate the flow of lubricant from a tractor differential into the axle roller bearing assemblies when the tractor is tilted since they exhibit a thin inner or inside edge which is proximate the inner wall of the axle housing and which does not present a significant step or barrier to the flow of lubricant. 
         [0010]    Furthermore, all eight embodiments provide a distinct and significant weight saving of from three to twelve pounds per spindle when compared to prior art hollow drive spindles or solid trailer spindles. When all four spindles of a trailer are replaced, as is frequently done, this represents a weight saving of from twelve to nearly fifty pounds. 
         [0011]    Thus it is an aspect of the present invention to provide a replacement drive axle spindle having a thin inner edge or lip. 
         [0012]    Thus it is a further aspect of the present invention to provide a replacement drive axle spindle having a thin inner edge or lip that facilitates lubricant flow to the axle bearing assemblies. 
         [0013]    Thus it is a still further aspect of the present invention to provide a replacement drive or trailer axle spindle weighing significantly less than prior art spindles. 
         [0014]    It is a still further aspect of the present invention to provide a replacement trailer axle spindle having a straight internal taper weighing significantly less than prior art spindles. 
         [0015]    It is a still further aspect of the present invention to provide a replacement drive axle spindle having a straight internal taper terminating at a thin inner edge or lip that facilitates lubricant flow to the axle bearing assemblies. 
         [0016]    It is a still further aspect of the present invention to provide a replacement trailer axle spindle having an internal taper of two distinct angles weighing significantly less than prior art spindles. 
         [0017]    It is a still further aspect of the present invention to provide a replacement drive axle spindle having an internal taper of two distinct angles terminating at a thin inner edge or lip that facilitates lubricant flow to the axle bearing assemblies. 
         [0018]    It is a still further aspect of the present invention to provide a replacement trailer axle spindle having a parabolic internal taper weighing significantly less than prior art spindles. 
         [0019]    It is a still further aspect of the present invention to provide a replacement drive axle spindle having a parabolic internal taper terminating at a thin inner edge or lip that facilitates lubricant flow to the axle bearing assemblies. 
         [0020]    It is a still further aspect of the present invention to provide a replacement trailer axle spindle having a straight external taper weighing significantly less than prior art spindles. 
         [0021]    It is a still further aspect of the present invention to provide a replacement drive axle spindle having a straight external taper terminating at a larger diameter terminal end portion. 
         [0022]    Further aspects, advantages and areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0023]    The drawings presented herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. Like reference numbers in the several drawing figures refer to the same component, element or feature. 
           [0024]      FIG. 1  is a perspective view of a trailer axle incorporating a replacement spindle having a single straight inner taper and a single long liner according to a first embodiment of the present invention; 
           [0025]      FIG. 2  is a full sectional view of a trailer axle incorporating a replacement spindle according to the first embodiment of the present invention taken along line  2 - 2  of  FIG. 1 ; 
           [0026]      FIG. 3  is a longitudinal, full sectional view of a trailer axle incorporating a replacement spindle having a single angle inner taper and a single long liner according to the first embodiment of the present invention taken along line  3 - 3  of  FIG. 1 ; 
           [0027]      FIG. 4  is a longitudinal, full sectional view of a tractor axle incorporating a replacement spindle having a dual angle inner taper and single seal liner according to a second embodiment of the present invention; 
           [0028]      FIG. 5  is a longitudinal, full sectional view of a trailer axle incorporating a replacement spindle having a single angle inner taper and a pair of short liners according to a third embodiment of the present invention; 
           [0029]      FIG. 6  is a longitudinal, full sectional view of a trailer axle incorporating a replacement spindle having a parabolic inner taper and a pair of short liners according to a fourth embodiment of the present invention; 
           [0030]      FIG. 7  is a longitudinal, full sectional view of a large diameter trailer axle incorporating a replacement spindle having a parabolic inner taper and a large diameter liner and seal liner according to a fifth embodiment of the present invention; 
           [0031]      FIG. 8  is a longitudinal, full sectional view of a trailer axle incorporating a replacement spindle having a straight internal passageway, a long straight external taper and a pair of short liners having different inside diameters according to a sixth embodiment of the present invention; 
           [0032]      FIG. 9  is a longitudinal, full sectional view of a trailer axle incorporating a replacement spindle having a straight internal passageway, a short straight external taper and a pair of short liners having different inside diameters according to a seventh embodiment of the present invention; and 
           [0033]      FIG. 10  is a longitudinal, full sectional view of a trailer axle incorporating a replacement spindle having a straight internal passageway, a straight external taper terminating in a larger diameter cylindrical end region and a single short liner according to an eighth embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0034]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, its application, or uses. 
         [0035]    With reference to  FIGS. 1 ,  2  and  3 , a truck, trailer or heavy duty vehicle axle assembly which has been repaired utilizing the method disclosed and claimed in U.S. Pat. No. 6,024,418, which is hereby fully incorporated by reference, is illustrated and designated by the reference number  10 . Accordingly, the heavy duty vehicle axle assembly  10  includes a vehicle axle  12  having a cylindrical inner surface  14  that has been shortened about a cutoff surface  16  to remove a visibly damaged section and any possibly damaged section (not illustrated). Typically, the removed section includes at least the inner and outer bearing surfaces and threads. A single piece, elongate sleeve or liner  18  has then been disposed at the distal end of a first embodiment of a replacement trailer spindle assembly  30  and this assembly has been installed within the vehicle axle  12  with the exterior surface of the sleeve or liner  18  preferably in contact with the inner surface  14  of the vehicle axle  12 . The typical trailer axle  12  also includes a brake spider  20  to which the various components of the trailer brakes (not illustrated) are attached. For reasons of clarity, the brake spider  20  has been broken away in  FIG. 1 . 
         [0036]    A plurality of, preferably two, oblong, horizontally oriented plug welds  22  which extend through the axle  12  and into the liner or sleeve  18  are disposed in a horizontally opposed pair. An annulus of weld material  24 A is also deposited (built up) about the replacement spindle assembly  30  adjacent the cutoff surface  16  and in securing contact with the sleeve or liner  18  and a collar  26 . The collar  26  has an inside diameter just slightly larger than the largest outside diameter of the replacement trailer spindle assembly  30  and is disposed about the spindle assembly  30  adjacent the cutoff surface  16 . The collar  26  includes a concentric, cylindrical oil seal surface  27  which is contacted by an elastomeric seal (not illustrated) disposed on the wheel hub which seals in bearing lubricant and seals out contaminants and foreign matter. 
         [0037]    Referring now to  FIGS. 1 and 3 , the replacement trailer spindle assembly  30  typically includes a first, larger diameter, inner bearing surface  32 , a second, smaller diameter, outer bearing surface  34  and a threaded terminal portion  36 . It should be appreciated that the more common axle configuration includes the first, larger diameter inner bearing surface  32  and the second, smaller diameter outer bearing surface  34  described. However, certain axles include inner and outer bearing surfaces having the same diameter. It should be appreciated that the present invention is equally suitable for use with these axles. 
         [0038]    The inner bearing surface  34  receives, positions and supports a first, typically larger inner roller bearing assembly (not illustrated), the outer bearing surface  34  receives, positions and supports a second, typically smaller diameter roller bearing assembly (not illustrated) and the threaded terminal portion  36  receives a complementarily threaded nut which retains a wheel hub (both not illustrated). The replacement spindle assembly  30  also defines a through passageway  38  having a uniformly tapering, i.e., frusto-conical, first region  40  and a cylindrical, i.e., uniform diameter, second region  42 . The tapering, frusto-conical, first region  40  results in a thickness of the end surface  44  which is substantially thinner than prior art configurations in which the wall thickness and the diameter of the through passageway are uniform. Accordingly, the improved replacement trailer spindle assembly  30  represents a significant weight saving. Since the replacement trailer spindle assembly  30  illustrated and described is not being utilized with a drive axle, a resilient plug  46  is disposed at the end of the spindle assembly  30  in the second region  42  of the through passageway  38  to prevent lubricant from entering the axle  12 . 
         [0039]    Referring now to  FIG. 4 , a second embodiment of a replacement spindle assembly designated by the reference number  50  is illustrated. The replacement spindle assembly  50  is a drive axle spindle assembly and is thus being installed in the drive axle  12 ′ of a tractor. The drive axle  12 ′ defines a through passageway  14 ′. As in the foregoing embodiment, the damaged section of the drive axle  12 ′ is removed, leaving a cutoff surface  16 . The drive axle  12 ′ is then bored to form an enlarged diameter region  20  which receives an elongate, single piece sleeve or seal liner  18 ′ and the replacement drive axle spindle assembly  50 . The single piece sleeve or liner  18 ′ includes an oil seal surface  51  at its outer end. At its inner end, a circumferential weld  24 B extends around the sleeve or liner  18 ′ and secures it to the replacement drive axle spindle assembly  50 . A pair of horizontally opposed, vertically oriented, oblong plug welds  22 ′ (one of which is illustrated in  FIG. 4 ) are disposed in openings formed in the drive axle  12 ′ and extend into the sleeve or liner  18 ′. Finally, an annulus of weld material  24 A is deposited (built up) about the replacement drive spindle assembly  50  adjacent the cutoff surface  16 . The drive axle  12 ′ typically includes and supports a brake flange  48  proximate its outer end to which the various components of the tractor brakes (not illustrated) are secured. 
         [0040]    The replacement drive axle spindle assembly  50  includes a first, larger diameter inner bearing surface  52 , a second, smaller diameter outer bearing surface  54  and a threaded terminal portion  56 . The inner bearing surface  52  receives, positions and supports a first, larger diameter inner roller bearing assembly (not illustrated), the outer bearing surface  54  receives, positions and supports a second, smaller diameter roller bearing assembly (not illustrated) and the threaded terminal portion  56  receives a complementarily threaded nut which retains a wheel hub (both not illustrated). The replacement spindle assembly  50  also defines a through passageway  58  having a first, uniformly tapering, i.e., frusto-conical, region  60  disposed at a first, small acute angle α to the axis of the replacement spindle assembly  50 , a second, uniformly tapering, i.e., frusto-conical, region  62  disposed at a second, larger acute angle β to the axis of the replacement spindle assembly  50  and a longer, cylindrical, i.e., uniform diameter, region  64 . The first, small acute angle α of the first, frusto-conical region  60  is preferably about five degrees or, alternatively, in the range of from three to seven degrees and the second, larger acute angle β is preferably about fifteen to twenty-five degrees or, alternatively, in the range of from ten to thirty degrees. Certain applications and situations, however, may require angles outside the just recited ranges and it should be understood that such values are within the scope of the present invention. 
         [0041]    The two tapering, frusto-conical regions  60  and  62  result in a thickness of an end surface  66  which is substantially thinner than prior art configurations in which the wall thickness and the diameter of the through passageway were uniform. Accordingly, the improved replacement drive axle spindle assembly  50  represents a significant weight reduction. Additionally, the reduced thickness of the end wall  66  facilitates providing lubrication to the axle roller bearing assemblies by the simple expedient of tilting the tractor or vehicle so that the just replaced drive spindle assembly  50  is lower than the differential. 
         [0042]    Referring now to  FIG. 5 , a third embodiment of a replacement spindle assembly designated by the reference number  70  is illustrated. Here, while the replacement trailer spindle assembly  70  includes the single taper region of the first embodiment replacement trailer spindle assembly  30 , instead of utilizing a single sleeve or liner  18 , this embodiment utilizes a pair of axially short liners  18 ″ which result in further weight reduction. The pair of short liners  18 ″ are disposed adjacent the cutoff surface  16  and the inner end of the spindle assembly  70 , respectively, and are secured in both locations by a respective annulus of weld material  24 A and  24 B. The annulus of weld material  24 A also secures the collar  26  having the oil seal surface  27 . The pair of horizontal plug welds  22  (one of which is illustrated in  FIG. 5 ) extend into the inner liner  18 ″ and secure the replacement spindle assembly  70  to the axle  12 . Since this embodiment is characterized as a replacement trailer spindle assembly, it also includes the brake spider  20  and the resilient plug  46  (illustrated in  FIGS. 1 and 3 ) at the outer end of the spindle assembly  70 . 
         [0043]    The replacement trailer spindle assembly  70  includes a first, larger diameter inner bearing surface  72 , a second, smaller diameter outer bearing surface  74  and a threaded terminal portion  76 . The inner bearing surface  72  receives, positions and supports a first, larger diameter inner roller bearing assembly (not illustrated), the outer bearing surface  74  receives, positions and supports a second, smaller diameter roller bearing assembly (not illustrated) and the threaded terminal portion  76  receives a complementarily threaded nut which retains a wheel hub (both not illustrated). The replacement spindle assembly  70  defines a through passageway  78  having a frusto-conical region  80  and a cylindrical, i.e., uniform diameter, region  82 . The frusto-conical region  80 , as one moves from an end surface  84  toward the threaded terminal portion  76 , defines a region in which the wall thickness uniformly increases. This configuration, as well, results in a width of the end surface  84  which is substantially thinner than prior art designs in which the wall thickness and the diameter of the through passageway were uniform. Accordingly, the improved replacement trailer spindle assembly  70  represents a significant weight saving over prior art configurations which is further enhanced by the use of a pair of short liners  18 ″. 
         [0044]    Referring now to  FIG. 6 , a fourth embodiment of a replacement spindle assembly designated by the reference number  90  is illustrated. Here, the replacement trailer spindle assembly  90  utilizes the pair of narrow or short liners  18 ″ described in connection with the third embodiment of the replacement trailer spindle assembly  70  directly above but includes another inner surface profile. The pair of short liners  18 ″ are disposed adjacent the cutoff surface  16  and the inner end of the spindle assembly  90 . The short liner  18 ″ adjacent the cutoff surface  16  is secured by the annulus of built up weld material  24 A to the axle  12  and to the collar  26  having the oil seal surface  27 . The short liner  18 ″ adjacent the inner end of the spindle assembly  90  is secured by the annulus of weld material  24 B. The pair of horizontal plug welds  22  (one of which is illustrated in  FIG. 6 ) extend into the inner shorter liner  18 ″ and secure the replacement spindle assembly  90  to the axle  12 . Since this embodiment is characterized as a replacement trailer spindle assembly, it also includes the resilient plug  46  (illustrated in  FIGS. 1 and 3 ) at the outer end of the spindle assembly  90  as well as the brake spider  20  which receives and supports the brake mechanism of the trailer. 
         [0045]    The replacement trailer spindle assembly  90  includes a first, larger diameter inner bearing surface  92 , a second, smaller diameter outer bearing surface  94  and a threaded terminal portion  96 . The inner bearing surface  92  receives, positions and supports a first, larger diameter inner roller bearing assembly (not illustrated), the outer bearing surface  94  receives, positions and supports a second, smaller diameter roller bearing assembly (not illustrated) and the threaded terminal portion  96  receives a complementarily threaded nut which retains a wheel hub (both not illustrated). The replacement trailer spindle assembly  90  also defines a through passageway  98  having a parabolically tapering region  100  and a cylindrical, i.e., uniform diameter, region  102 . 
         [0046]    The parabolically tapering region  100 , as one moves from an end surface  104  toward the threaded terminal portion  96 , defines a region in which the wall thickness increases at a decreasing rate. This configuration tends to mimic or correlate the wall thickness of the replacement trailer spindle assembly  90  with the load and bending moments exerted upon it in service. This configuration, as well, results in a thickness of the end surface  104  which is substantially thinner than prior art configurations in which the wall thickness and the diameter of the through passageway were uniform. Accordingly, the improved replacement spindle assembly  90  represents a significant weight saving over prior art configurations. 
         [0047]    Referring now to  FIG. 7 , a fifth embodiment of a replacement spindle assembly, designated by the reference number  110 , is illustrated. Here, the replacement trailer spindle assembly  110  is utilized with an axle  112  having a significantly greater inside and outside diameter than those described above, which is typical of many newer axle assemblies. Accordingly, the replacement trailer spindle assembly  110  utilizes a short liner  114 A and a seal liner  114 B both having significantly greater radial thickness than the sleeves or liners  18 ′ and  18 ″ described above. The pair of liners  114 A and  114 B include a short inner, annular sleeve or liner  114 A and an outer, stepped seal liner  114 B having an oil seal surface  114 C which are both received on a first, constant diameter, larger bearing surface  116 . The inner, annular sleeve or liner  114 A is disposed adjacent the inner end of the spindle assembly  110  and the outer, stepped seal liner  114 B is disposed adjacent the cutoff surface  16  and are secured in their respective locations by an annulus of built-up weld material  24 A and  24 B, respectively. The pair of horizontal plug welds  22  (one of which is illustrated in  FIG. 7 ) extend into the inner, annular sleeve or liner  114 A and secure the replacement spindle assembly  110  to the axle  112 . Since this embodiment is characterized as a replacement trailer spindle assembly, it also includes the resilient plug  46  (illustrated in  FIGS. 1 and 3 ) at the outer end of the spindle assembly  110  as well as the brake spider  20 . 
         [0048]    It should be appreciated that on occasion, the inner diameter of the axle  112  may not be constant, that is, it may be larger (or smaller) at the location where the inner liner  114 A seats relative to where the seal liner  114 B seats. This can readily be compensated for and accommodated by manufacturing the inner liner  114 A or the seal liner  114 B with the same inner diameter (to receive the spindle assembly  110 ) but with larger or smaller outside diameters. It should be appreciated that other pairs of liners, seals and seal liners, illustrated in the other drawing figures, may be fabricated with different outside diameters to accommodate size differences in inside diameters of axles although this issue manifests itself most frequently with newer, larger axle diameter axles such as that illustrated in  FIG. 7 . 
         [0049]    The replacement trailer spindle assembly  110  includes the first, larger diameter inner bearing surface  116 , a second, smaller diameter outer bearing surface  118  and a threaded terminal portion  120 . The inner bearing surface  116  receives, positions and supports a first, larger diameter inner roller bearing assembly (not illustrated), the outer bearing surface  118  receives, positions and supports a second, smaller diameter roller bearing assembly (not illustrated) and the threaded terminal portion  120  receives a complementarily threaded nut which retains a wheel hub (both not illustrated). The replacement trailer spindle assembly  110  also defines a through passageway  122  having a parabolically tapering region  124  and a cylindrical, i.e., uniform diameter, region  126 . 
         [0050]    The parabolically tapering region  124 , as one moves from an end surface  128  toward the threaded terminal portion  120 , defines a region in which the wall thickness increases at a decreasing rate. This configuration tends to mimic or correlate the wall thickness of the replacement trailer spindle assembly  110  with the load and bending moments exerted upon it in service. This configuration, as well, results in a thickness of the end surface  128  which is substantially thinner than prior art configurations in which the wall thickness and the diameter of the through passageway were uniform. Accordingly, the improved replacement spindle assembly  110  represents a weight saving over prior art configurations. Additional significant weight savings are achieved by the use of two short liners  114 A and  1148  rather than a single long liner. 
         [0051]    Referring now to  FIG. 8 , a sixth embodiment of a replacement spindle assembly is illustrated and designated by the reference number  130 . Here, the replacement trailer spindle assembly  130  is utilized with the vehicle axle  12  of conventional size defining the internal cylindrical surface  14 . As in the previous drawing figures, a damaged portion of the axle (not illustrated) has been removed, leaving the circular cutoff surface  16 . The trailer spindle assembly  130  includes a straight walled, i.e., constant diameter, internal through passageway  132 , a first, larger diameter inner bearing surface  134 , a second, smaller diameter outer bearing surface  136  and a threaded terminal portion  138 . As in the other embodiments, the inner bearing surface  134  receives, positions and supports a first, larger diameter inner roller bearing assembly (not illustrated), the outer bearing surface  136  receives, positions and supports a second, smaller diameter roller bearing assembly (not illustrated) and the threaded terminal portion  138  receives a complementarily threaded nut which retains a wheel hub (both not illustrated). Since it is a trailer axle, the resilient plug  46  is disposed at the end of the spindle assembly  130  to inhibit flow of lubricant into the axle  12 . Also, the brake spider  20  is secured about the vehicle axle  12 . 
         [0052]    The first, larger diameter inner bearing surface  134  extends along the middle portion of the spindle assembly  130  and receives a seal liner  140  having an oil seal surface  142  adjacent its outer end. The first, larger diameter bearing surface  134  merges with a long frusto-conical, i.e., constant taper, surface  144  which merges with a short, straight, i.e., constant diameter, cylindrical surface  146  adjacent a thin inner end  148  of the spindle assembly  130 . A first, thinner short liner  150 A is disposed adjacent the inner end of the seal liner  140  and the circular cutoff surface  16  and these components are secured together by built up weld material  24 A. Similarly a second, thicker short liner  150 B is disposed on the short straight surface  146  near the thin inner end  148  of the spindle assembly  130  and secured there by built-up weld material  24 B. Finally, the pair of horizontally opposed plug welds  22  (one of which is illustrated in  FIG. 8 ) extend through the axle  12  and into the thicker short liner  150 B to secure the spindle assembly  130  to the axle  12 . 
         [0053]    Referring now to  FIG. 9 , a seventh embodiment of a replacement spindle assembly is illustrated and designated by the reference number  160 . Here, the replacement trailer spindle assembly  160  is utilized with the vehicle axle  12  of conventional size defining the internal cylindrical surface  14 . As in the previous drawing figures, a damaged portion of the axle (not illustrated) has been removed, leaving the circular cutoff surface  16 . The trailer spindle assembly  160  includes a straight walled, i.e., constant diameter, internal through passageway  162 , a first, larger diameter inner bearing surface  164 , a second, smaller diameter outer bearing surface  166  and a threaded terminal portion  168 . As in the other embodiments, the inner bearing surface  164  receives, positions and supports a first, larger diameter inner roller bearing assembly (not illustrated), the outer bearing surface  166  receives, positions and supports a second, smaller diameter roller bearing assembly (not illustrated) and the threaded terminal portion  168  receives a complementarily threaded nut which retains a wheel hub (both not illustrated) and the resilient plug  46 . 
         [0054]    The replacement trailer spindle assembly  160  utilizes two axially short liners  170 A and  170 B similar to those described in connection with the sixth embodiment of the replacement trailer spindle assembly  130 , above, and includes the straight, i.e., constant diameter, inner surface  162 . One of the two short liners  170 A is disposed adjacent the cutoff surface  16  on the inner bearing surface  164 . The trailer spindle assembly  160  also includes an axially short region of constant external taper, i.e., a frusto-conical surface  172  and a cylindrical, i.e., constant diameter end region  174 . The other short liner  170 B, which is thicker, is located on the constant diameter end region  174  of the spindle assembly  160 . The short liner  170 A adjacent the cutoff surface  16  is secured by built-up weld material  24 A to the axle  12  and to a collar or sleeve  176  having an oil seal surface  178 . The thicker, inner short liner  170 B disposed on the constant diameter end region  174  of the spindle assembly  160  is secured by built-up weld material  24 B. The pair of horizontal plug welds  22  (one of which is illustrated in  FIG. 9 ) extend into the thicker, inner short liner  170 B and secure the replacement spindle assembly  160  to the axle  12 . Since this embodiment is characterized as a replacement trailer spindle assembly, it also includes the brake spider  20  which receives and supports the brake mechanism (not illustrated) of the trailer. 
         [0055]    Referring now to  FIG. 10 , a eighth embodiment of a replacement spindle assembly is illustrated and designated by the reference number  180 . The replacement trailer spindle assembly  180  is again utilized with the vehicle axle  12  of conventional size defining the internal cylindrical surface  14 . As in the previous drawing figures, a damaged portion of the axle (not illustrated) has been removed, leaving the circular cutoff surface  16 . The trailer spindle assembly  180  includes a straight walled, i.e., constant diameter, internal through passageway  182 , a first, larger diameter inner bearing surface  184 , a second, smaller diameter outer bearing surface  186  and a threaded terminal portion  188 . As in the other embodiments, the inner bearing surface  184  receives, positions and supports a first, larger diameter inner roller bearing assembly (not illustrated), the outer bearing surface  186  receives, positions and supports a second, smaller diameter roller bearing assembly (not illustrated) and the threaded terminal portion  188  receives a complementarily threaded nut which retains a wheel hub (both not illustrated). 
         [0056]    Here, the replacement trailer spindle assembly  180  utilizes only one axially short liner  190  similar to those liners described in connection with the embodiments  70  and  90  of the replacement trailer spindle assembly, above, and includes a straight, i.e., constant diameter, through passageway  182 . The short liner  190  is disposed adjacent the cutoff surface  16  on the inner bearing surface  184 . The trailer spindle assembly  160  includes an axially short region of constant external taper, i.e., a frusto-conical surface  192  and an integrally formed larger cylindrical, i.e., constant diameter, end region  194 . The short liner  190  adjacent the cutoff surface  16  is secured by built-up weld material  24 A to the axle  12  and to the collar or sleeve  26  having the oil seal surface  27 . The pair of horizontal plug welds  22  (one of which is illustrated in  FIG. 10 ) extend into the integrally formed larger cylindrical, i.e., constant diameter, end region  194  and secure the replacement spindle assembly  180  to the axle  12 . Since this embodiment is characterized as a replacement trailer spindle assembly, it also includes the resilient plug  46  (illustrated in  FIGS. 1 and 3 ) at the outer end of the spindle assembly  180  as well as the brake spider  20  which receives and supports the brake mechanism (not illustrated) of the trailer. 
         [0057]    It will be appreciated that the foregoing three embodiments of the replacement spindle according to the present invention illustrated in  FIGS. 8 ,  9  and  10  all achieve the weight saving of the other embodiments while being more readily and easily manufactured due to the constant diameter of the internal through passageways  132 ,  162  and  182 . Furthermore, it should be understood that as an alternative to the single taper, frusto-conical outside surfaces  144 ,  172  and  192 , the outside surface may define other profiles disclosed above, such as two distinct angles of taper or a parabolic curve, both of which, when utilized on the outside of a replacement spindle, are considered to be within the scope of this invention. 
         [0058]    In addition to facilitating lubrication of the bearings of a tractor axle, the replacement spindle assemblies  30 ,  50 ,  70 ,  90 ,  110 ,  130 ,  160  and  180  all achieve significant weight reduction when compared to prior art spindle configurations. For example, a commonly used prior art replacement tractor (drive) spindle weighs approximately twenty-one pounds. A replacement spindle made in accordance with any of the configurations according to the present invention weighs approximately sixteen pounds. A commonly used prior art replacement trailer spindle assembly weighs between thirty-two and thirty-four pounds. A replacement trailer spindle assembly made in accordance with any of the configurations of the present invention weighs approximately twenty-two pounds. Additionally, utilization of the pair of sleeves  114 A and  114 B or  150 A and  1508  rather than a single piece sleeve can result is a weight saving of one to four pounds at each axle. 
         [0059]    In every embodiment and application, it should be appreciated that the material and weight saving is achieved without a reduction in the necessary strength of the replacement spindle as more material is removed from that region (the inner end) of the replacement spindle subjected to the lowest forces and bending moments and less material is removed from the middle where forces and bending moments are higher. No material is removed from the outer end of the replacement spindle (relative to prior art drive spindle configurations) where the forces and bending moments are the highest. 
         [0060]    It should also be appreciated that while each embodiment  30 ,  50 ,  70 ,  90 ,  110 ,  130 ,  160  and  180  of the replacement spindle assembly has been described as containing a specific combination of features, i.e., a particular taper configuration, utilization of one or two liners or sleeves, whether the spindle was a tractor (drive) or trailer spindle and thus how it was mounted to the vehicle axle and whether a resilient end plug was utilized to seal the end of the spindle, these foregoing descriptions are essentially illustrative and exemplary and it should be understood that any and all various combinations of the disclosed components and elements of the invention are deemed to be within its purview. 
         [0061]    Hence, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention and the following claims.