Abstract:
A wheel bearing arrangement has a spindle having inboard and outboard portions, where the outboard portion cooperates with a fluid driven motor and a land connects the outboard portion and the inboard portion. The wheel bearing arrangement further has inboard and outboard bearing systems located radially outb from the land. Each bearing system has a bearing located between inner and outer races, where the inner race contacts the spindle land and the outer race contacts a wheel hub. In addition, a spacer is located between the two bearing systems, where the spacer extends from the land to a radially inwardly extending hub portion and where the spacer sets the preload on both bearing systems and diffuses inboard traveling fluid pressure spikes. A spindle nut is located outboard from the outboard bearing system to secure the bearing systems on the spindle.

Description:
RELATED APPLICATION 
       [0001]    This is a Continuation-In-Part application of U.S. Non-provisional application Ser. No. 12/156,078 with a filing date of May 29, 2008, which application is incorporated herein in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a wheel bearing arrangement for a fluid driven motor. More particularly, the present invention relates to a preset wheel bearing spacer arrangement for a fluid driven motor. 
       BACKGROUND OF THE INVENTION 
       [0003]    Those skilled in the art know that some vehicles, such as trucks, farm vehicles, and heavy duty construction vehicles, have wheels that are driven by hydraulic drive motors located at each wheel end. In addition to the hydraulic motor, a hydraulically assisted wheel end may comprise a wheel brake drum, a steerable knuckle, hub, wheel, and tire assembly that is rotatably mounted radially outboard to the knuckle. 
         [0004]    The hub is drivingly connected to the motor so that when the motor is energized, the hub drivingly rotates about the centerline of the knuckle, via bearings which are located between the knuckle and the hub. A kingpin pivotably connects an end portion of an axle of a vehicle to the knuckle, which permits the vehicle to be steered about the centerline of the kingpin. The knuckle also has an outboard portion that defines a spindle. The knuckle outboard portion is adapted to cooperate with the fluid driven motor. In addition, pressure supply ports communicate fluid to the motor, via pressure supply lines that cause the motor to drivingly rotate, thus causing the wheel to move forward and backward. 
         [0005]    Typically, installations of heavy duty steer axle wheel bearings use a spindle nut to set the wheel bearing preload which is subject to operator error. Alternate unitized wheel bearing systems are generally assembly error proof but require expensive unitized bearings. Some conventional wheel end products use a large spacer and widely spaced wheel bearings to preset the bearing preload. However, a more compact system is needed that uses standard bearings and is still assembly error proof. 
         [0006]    One relevant art system is embodied by U.S. Pat. No. 6,099,273 which depicts bearings separated by one another with an unnumbered and not discussed structure therebetween. This structure may be a seal or gasket. Of course, since this structure is not discussed in this patent, its effect on bearing preload is not discussed either. 
         [0007]    Another relevant art system is embodied in U.S. Pat. No. 5,048,859 which teaches a threaded ring to adjust the preload on an inner race as well as to secure the position of the inner race. This reference, however, is silent on any structure disclosed therein as being a barrier to hydraulic pressure between the bearings. 
         [0008]    What is sought is an effective, low cost structure to preset the bearing preload in a hydraulic motor equipped wheel end assembly. Such a structure would not rely on a spindle nut to set the bearing preload, which is prone to assembly error. In addition, this structure should be compact so as to cooperate with a short length spindle. Further, this structure should limit hydraulic pressure spikes to the hub fluid seal. It would be desirable for such an arrangement to be less expensive to produce, easier to package, and more robust than current methods. 
       SUMMARY OF THE INVENTION 
       [0009]    A wheel bearing arrangement has a spindle that comprises an inboard portion and an outboard portion, where the outboard portion cooperates with a fluid driven motor, and a land connects the outboard portion and the inboard portion. The wheel bearing arrangement further has an inboard bearing system and an outboard bearing system where both systems are located radially outward from the land. Each of the bearing systems comprises a bearing located between an inner race and an outer race, where the inner race contacts the spindle land and the outer race contacts a wheel hub. In addition, a spacer sets the preload on both of the bearing systems, where the spacer is located between the two bearing systems and extends from the spindle land to a radially inwardly directed finger or shoulder of the wheel hub. Thereby, the spacer diffuses inboard traveling fluid pressure spikes. A spindle nut is located outboard from the outboard bearing system to hold the bearing systems on the spindle. 
         [0010]    Further advantages of the present invention will be apparent from the following description and appended claims, reference being made to the accompanying drawings forming a part of a specification, wherein like reference characters designate corresponding parts of several views. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a partial cross-sectional view of a vehicle hydraulic assist wheel end in accordance with the present invention; 
           [0012]      FIG. 2  is a three dimensional view of a first embodiment of a spacer in accordance with the vehicle hydraulic assist wheel end of  FIG. 1 ; and 
           [0013]      FIG. 3  is a three dimensional view of a second embodiment of a spacer in accordance with the vehicle hydraulic assist wheel end of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0014]    It is to be understood that the present invention may assume various alternative orientations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions, directions, or other physical characteristics relating to the embodiments disclosed are not to be considered as limiting, unless the claims expressly state otherwise. 
         [0015]    Illustrated in  FIG. 1  is a preset wheel bearing arrangement  10  that comprises a wheel  9 , fluid driven motor  11 , wheel brake drum  12 , steerable knuckle  13 , and a wheel hub  16 . The hub  16  is rotatably mounted radially outboard to the knuckle  13 . The hub  16  is drivingly connected to the motor  11  so that when the motor  11  is energized, it causes the hub  16  to rotate. The motor  11  may be those produced by Poclain Hydraulics Industrie of France. 
         [0016]    The hub  16  and the drum  12  rotate about the centerline C of the knuckle  13  by way of bearings  17 A,  17 B which may be standard and are located between the knuckle  13  and the hub  16 . 
         [0017]    The knuckle  13  has a spindle  22  that is defined by an outboard portion  21  and an inboard portion  23 . The outboard portion  21  is adapted to cooperate with the fluid driven motor  11 . Preferably, the motor  11  has a circular recess  20  for receiving the outboard portion  21  of the cylindrical spindle  22 . A land  25  connects the outboard portion  21  and the inboard portion  23 . A spindle nut  19  is located outboard from the bearings  17 A,  17 B to hold the bearings  17 A,  17 B on the spindle  22 . 
         [0018]    A first fluid pressure supply port  27  is located on an upper surface  29  of the knuckle inboard portion  18  for communicating fluid to the motor  11 . Fluid flowing through the pressure supply port  27 , via pressure supply line  39  that is connected to pressure supply line  31 , rotates the motor  11  in a first direction, thus causing the hub  16  to move, for example, in a forward direction. Although not shown, another fluid pressure supply port is located elsewhere on a surface of the knuckle inboard portion  18  for also communicating fluid to the motor  11 . Fluid flowing through the second fluid pressure supply port, via a second pressure supply line (not shown but also common in the art), rotates the motor  11  in a second direction, thus causing the hub  16  to move, for example, in a rearward direction. 
         [0019]    Two fluid return drain lines  30 ,  36  are oriented substantially parallel one another near the centerline C of the knuckle  13  for draining fluid from the motor  11 . The lines  30 ,  36  extend from the outboard portion  21  to ports  33 ,  32  located in the connecting wall  24  of the knuckle  13 . Line  30  is shown draining hydraulic fluid from the motor  11  and a portion of the knuckle  13 , while line  36  is shown draining hydraulic fluid from another portion of the knuckle  13 . Although not shown in the particular cut away of  FIG. 1 , line  36  is also in fluid communication with the motor  11  itself. The lines  30 ,  36  may be connected to a sump system (not shown). 
         [0020]    A first internal drain port  34  is preferably located between the inboard bearing  17 A and the outboard bearing  17 B. The internal drain port  34  is substantially oriented perpendicularly to the return drain line  36 . The internal drain port  34  can be utilized to drain fluid to the return drain line  36 . 
         [0021]    Another internal drain port  37  is located outboard of the outboard bearing  17 B. The internal drain port  37  is substantially oriented perpendicularly to the return drain line  30 . The internal drain port  37  can be utilized to drain fluid to the return drain line  30 . 
         [0022]    The inboard portion of the knuckle  13  defines an upper boss  52  and a lower boss  56 . A kingpin  58 , which is located between the upper boss  52  and the lower boss  56 , pivotably connects an end portion of an axle  54  of a vehicle (not shown) to the knuckle inboard portion. The kingpin  58  also permits the vehicle to be steered about a centerline D of the kingpin  58 , wherein steering arms and tie rod arms (not shown) are typically disposed in the continuous channels of the bosses  52 ,  56 . See, for example, U.S. patent application Ser. No. 12/283,559 with a filing date of Sep. 12, 2008, which application is incorporated herein in its entirety. 
         [0023]      FIG. 1  also illustrates a compact spacer  35  located radially outward from the spindle  22  of the knuckle  13 . The spacer  35  preferably has an outboard surface  28  in contact with an inner race  40  of the outboard bearing  17 B. As shown in  FIG. 2 , the spacer  35  has a close fitting inboard surface  42  with one or more drain slots  86  (see  FIGS. 2 and 3 ) that are in contact with an inner race  44  of the inboard bearing  17 A, which also has an outer race  43 . A radially outermost peripheral surface  46  of the spacer  35  has a small annulus clearance  26  that is in close proximity (for example, 0.2-0.3 mm or 0.008-0.012 inches) with an inwardly extending hub portion  48 . 
         [0024]    The bearings  17 A,  17 B rotatingly support the hub  16  about the knuckle  13 . The inboard bearing  17 A, the inner race  44 , and the outer race  43  form an inboard bearing system  14 . The outboard bearing  17 B, the inner race  40 , and an outer race  45  form an outboard bearing system  15 . 
         [0025]    Hence, the bearings  17 A,  17 B, which may be similar or physically the same part, are closely spaced and considered a double tapered bearing set. The selective spacer  35 , which is located between the inner races of the bearings  17 A,  17 B, blocks fluid pressure spikes (for example, oil pressure spikes) in the spindle  22 , from reaching a hub fluid seal  70 , while still allowing a small metered amount of fluid to lubricate the inboard bearing  17 A. 
         [0026]    Such pressure spikes can cause erratic operation of the wheel and can cause early failures within the preset wheel bearing arrangement  10  which, for example, may cause early failure of the hub fluid seal  70 . The spacer  35  functions to limit, by way of the small annulus clearance  26 , fluid pressure spikes from reaching the hub fluid seal  70 . Yet, the small annulus clearance  26  and/or the spacer drain slots  86  allow the fluid to drain through the drain port/line  34 / 36  and then to the exterior to the spindle  22 . 
         [0027]      FIG. 3  illustrates an alternate embodiment spacer  35 ′. Here, the small annulus clearance  26  of spacer  35  is replaced with a seal  80 , such as an O-ring that is disposed on the surface  46 , in a groove, to positively seal off fluid, for example oil, against the hub inner surface  46  and then an added small orifice hole  82  through the spacer and, possibly in conjunction with the slots  86 , provide fluid leak pathways that are utilized to block fluid pressure spikes in the wheel end from reaching the hub fluid seal  70 . Consequently, the spacer  35 ′ allows a small metered amount of fluid to lubricate the inboard bearing  17 A via the small orifice hole  82  and/or slots  86 . 
         [0028]    Therefore, it has been discovered that a single part, the spacer  35 ,  35 ′, not only functions as a bearing spacer, but also functions as a fluid pressure spike diffuser. It has further been discovered that in disposing the spacer  35 ,  35 ′ between the bearing cones  17 A,  17 B, the thickness of the spacer determines the preload (or end play) of the bearings, regardless of how much torque is applied to the spindle nut  19 . This is different from conventional heavy duty wheel ends, where the amount of torque on a spindle nut (and/or the advancement of nut rotations) will determine the bearing preload setting. 
         [0029]    Hence, the invention provides a system, wherein a spacer  35 ,  35 ′ is selected from a set of spacers in order to provide the necessary dimensional bearing spacing needed for that application. Subsequently, a spindle nut torque can be used to securely clamp the bearing systems  14 ,  15  together. Conventionally, a bearing spacer does not fill up the space between the bearing cones to block fluid flow, as described in detail above. Here, the spacers  35 ,  35 ′ work with the fluid leak pathways  46 ,  82 ,  86  to drain the area between the bearings  17 A,  17 B, down through the drain port  34 , and then the fluid drains down through the center of the spindle  22  by way of drain line  36 . 
         [0030]    Spacers  35 ,  35 ′ of various sizes may be used, which at least permits the use of the same spindle  12  and motor  11  while adapting to wheel assemblies of varying sizes. Preferably, the spacers  35 ,  35 ′ are of a unitary, one piece construction. 
         [0031]    To summarize, the hydraulic motor wheel end  10  requires a separate close clearance  26  or alternatively the orifice  82 , which controllably limits fluid pressure spikes to the inboard wheel bearing  17 A, thereby preventing the hub seal  70  from being exposed to high fluid pressure that could destroy or limit the effectiveness of the hub seal  70 . At the same time, a small metered amount of the fluid is provided to lubricate the inboard bearing  17 A. Then, the spindle nut  19  is used to secure the wheel bearings  17 A,  17 B but not to set the bearing preload. 
         [0032]    It can be appreciated that at least two preset wheel bearing arrangements  10 , as discussed in detail above, could be utilized in a vehicle. 
         [0033]    It is to be understood that the patent drawings are not intended to define precise proportions of the elements of the invention but that the patent drawings are intended to be utilized in conjunction with the rest of the specification. Unless expressly specified to the contrary, it should also be understood that the illustrated differences between various elements of the invention, which may be in fractions of a unit of measurement, are not intended to be utilized to precisely measure those differences between the various elements. 
         [0034]    In accordance with the provisions of the patent statutes, the principles and modes of operation of this invention have been described and illustrated in its preferred embodiments. However, it must be understood that the invention may be practiced otherwise than specifically explained and illustrated without departing from its spirit or scope.