Abstract:
A bearing for a vehicle suspension system is provided and includes an outer member and an inner member. The outer member defines a first inner surface and a first outer surface wherein the first outer surface is configured to engage an equalizer bar of the vehicle suspension system. The inner member defines a second outer surface and a bore therethrough defining a second inner surface. The inner member is configured to engage a frame of the vehicle suspension system. A first lubricious fabric liner is provided in communication with at least a portion of the first inner surface and the second outer surface. The first lubricious fabric liner slidingly engages at least a portion of one of the first inner surface and the second outer surface in response to relative movement between the equalizer bar and the frame of the vehicle suspension system.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/515,526; filed on Aug. 5, 2011, which is incorporated herein by reference in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention is generally related to bearings and is more particularly directed to a bearing operable with a vehicle suspension system. In particular, the present invention is directed to a self-lubricating assembly that is configured to engage the suspension system of a tracked vehicle. 
       BACKGROUND OF THE INVENTION 
       [0003]    A tracked vehicle generally refers to a self-propelled vehicle that runs on one or more continuous tracks instead of wheels. Some common tracked vehicles include construction vehicles such as bulldozers, military vehicles such as tanks, and even recreational vehicles such as snowmobiles. A tracked vehicle is propelled by one or more endless belts or treads that may be fabricated from metal or a suitable elastomeric material. The use of tracks instead of wheels provides the vehicle with increased contact over a larger surface area than is provided by the use of wheels. As a result, a tracked vehicle exerts a much lower force per unit area on the ground being traversed than a conventional wheeled vehicle of the same weight. This makes them suitable for use on soft, low friction and uneven ground such as mud, ice and snow. However, tracks are more complex than wheels and are susceptible to failure modes such as snapped or derailed tracks. 
         [0004]    A tracked vehicle typically includes a main frame that defines a portion of a body of the vehicle, and a pair of undercarriages mounted on the main frame. Each undercarriage typically includes a frame member rotatably coupled to a drive sprocket, an idler wheel, and one or more roller wheels. The tread or belt is looped around the drive sprocket, the idler wheel and the roller wheels. An equalizer bar connects the undercarriages together and is pivotally mounted to the main frame. The equalizer bar typically is connected to the undercarriages. 
         [0005]    Spherical plain bearings have traditionally been comprised of a ball positioned for rotational movement in an outer race. The outer race defines an inner surface contoured to receive and retain the ball therein. A lubricant is typically provided between the spherical outer surface of the ball and the inner surface of the outer race to reduce friction therebetween. 
       SUMMARY OF THE INVENTION 
       [0006]    According to aspects illustrated herein, there is provided a bearing for a vehicle suspension system that includes an outer member and an inner member. The outer member defines a first inner surface and a first outer surface wherein the first outer surface is configured to engage an equalizer bar of the vehicle suspension system. The inner member defines a second outer surface and a bore therethrough defining a second inner surface. The inner member is configured to engage a frame of the vehicle suspension system. A first lubricious fabric liner is provided in communication with at least a portion of the first inner surface and the second outer surface. The first lubricious fabric liner slidingly engages at least a portion of one of the first inner surface and the second outer surface in response to relative movement between the equalizer bar and the frame of the vehicle suspension system. 
         [0007]    According to other aspects illustrated herein, there is provided a vehicle suspension system that includes a frame, an equalizer bar in communication with the frame, and at least one bearing in communication with the frame and the equalizer bar. The bearing has an outer member that defines a first inner surface and a first outer surface. The bearing also has an inner member that defines a second outer surface and a bore therethrough defining a second inner surface. A first lubricious fabric liner positioned on at least a portion of the first inner surface and a second lubricious fabric liner positioned on the second inner surface. A shaft extends into the bore and is in communication with the frame and the equalizer bar. 
         [0008]    According to still other aspects illustrated herein, there is provided a suspension system of a tracked vehicle. The suspension system includes a first and a second undercarriage pivotally connectable to a main frame of the tracked vehicle an equalizer bar pivotally connectable to the main frame and the first and second undercarriages. A first spherical plain bearing has an outer race and an inner ring and is in communication with the first undercarriage and the equalizer bar. Similarly, a second spherical plain bearing has an outer race and an inner ring and is in communication with the second undercarriage and the equalizer bar. A first lubricious fabric liner is positioned on at least a portion of an inner engagement surface of the outer race of each of the first and second spherical plain bearings. A second lubricious fabric liner is positioned on at least a portion of an inner surface of a bore defined through the inner ring of each of the first and second spherical plain bearings. A first shaft extends through the inner ring of the first spherical plain bearing and is in communication with the first undercarriage and the equalizer bar. Similarly, a second shaft extends through the inner ring of the second spherical plain bearing and is in communication with the second undercarriage and the equalizer bar. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a side view of a tracked vehicle having a suspension system incorporating a self-lubricating bearing in accordance with the present invention. 
           [0010]      FIG. 2  is a partial perspective, schematic, view of the suspension system of the tracked vehicle of  FIG. 1   
           [0011]      FIG. 3  is a partial exploded perspective view of a frame coupling member incorporating a bearing of the present invention. 
           [0012]      FIG. 4  is a cross-sectional view of a spherical plain bearing in accordance with the present invention. 
           [0013]      FIG. 5  is a cross-sectional view of a portion of the spherical plain bearing assembly of  FIG. 4 . 
           [0014]      FIG. 6  is a cross-sectional view of another portion of the spherical plain bearing assembly of  FIG. 4 . 
           [0015]      FIG. 7  is an enlarged cross sectional schematic illustration of a woven low friction liner. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    As shown in  FIGS. 1 and 2 , a portion of a tracked vehicle is generally designated by the reference number  10  and is hereinafter referred to as the “vehicle  10 .” The tracked vehicle  10  may be a bulldozer, tank or other military vehicle, or the like. The vehicle  10  includes a longitudinally extending main frame  12  having two undercarriages  14  positioned below the main frame  12  and forming a part of a suspension system  16  of the vehicle  10 . Each of the undercarriages  14  extends in a longitudinal direction designated by the arrow labeled “X-X” along laterally opposing sides of the main frame  12 . 
         [0017]    Each of the undercarriages  14  includes a frame member  24  mounted therein. A drive sprocket  18  is rotatably coupled to the frame member  24 . Similarly, an idler wheel  20  is rotatably mounted to the frame member  24  at an end thereof generally opposite the drive sprocket  18 . A plurality of roller wheels  22  (five shown) are rotatably mounted to the frame member  24  and are positioned between the drive sprocket  18  and the idler wheel  20 . While five roller wheels  22  have been shown and described, the present invention is not limited in this regard as more than five or less than five roller wheels can be employed without departing from the broader aspects of the present invention. A belt  28  of linked tracks forms an endless loop around the drive sprocket  18 , the idler wheel  20 , the roller wheels  22 , and the frame member  24  of each undercarriage  14 . While a belt of linked tracks has been shown and described, the present invention is not limited in this regard as other configurations forming an endless belt around a drive sprocket, such as, for example, an elastomeric belt, a tread and the like, may be used without departing from the broader aspects of the invention. 
         [0018]    Each drive sprocket  18  is coupled to a drive axle  30  such that a rear end  13  of each frame member  24  is connected to the drive axle, concentric about an axis  34 . The present invention is not limited to the connection of the drive sprockets  18  to the drive axle  30 ; for example, the drive sprockets may be independently coupled to and driven by suitable drive motors. Forward ends  15  of both frame members  24  are interconnected via an equalizer bar  40  extending transversely below the main frame  12 . The equalizer bar  40  is connected to the main frame  12  via a coupling member  42  extending from the main frame  12  (not shown in  FIG. 2 ). While the equalizer bar  40  has been shown and described, the present invention is not limited in this regard as other sufficiently rigid members may be used for connecting the undercarriages to the main frame, such as, for example, a stabilizer bar, without departing from the broader aspects of the invention. 
         [0019]    In the illustrated embodiment, the coupling member  42  is pivotally connected to the equalizer bar  40  approximately at a midpoint thereof using a pivot pin  46 . The equalizer bar  40  can pivot about an axis  44 . Although the coupling member  42  is shown as being a plate connected to the equalizer bar  40  using the pivot pin  46 , the present invention is not limited in this regard, and other configurations are possible including but not limited to a bearing or any one of a number of pivotably connectable fasteners. The ends of the equalizer bar  40  are each connected to the frame members  24  using respective coupling members  50 . 
         [0020]    As shown in  FIG. 3 , each of the coupling members  50  is defined by two brackets  52  that are secured to or integrally formed with the frame member  24 . A spherical plain bearing, designated by the reference number  60  and hereinafter referred to as “bearing  60 ”, is positioned in a bore  61  defined by the equalizer bar  40 . A shaft  49  extends through the bearing  60 . The ends of the shaft  49  are secured to the brackets  52  using pins or any other suitable means. The present invention is not limited to the use of brackets  52 ; for example, any configuration suitable for connecting the equalizer bar  40  to the frame member  24  and employing the bearing  60  may be employed including but not limited to a bearing or any one of a number of pivotably connectable fasteners. While a spherical plain bearing is shown and described, the present invention is not limited in this regard as the features and elements described herein with respect to the spherical plain bearing apply to other bearing assemblies, such as, for example, ball bearings, journal bearings, needle bearings, thrust bearings and the like, without departing from the broader aspects of the invention. 
         [0021]    As further shown in  FIG. 3 , the frame members  24  are spaced apart from one another such that one coupling member  50  is in pivotable engagement with one frame member  24  and the equalizer bar  40  proximate to one end of the equalizer bar  40  via a bearing  60 . Similarly, another coupling member  50  is in pivotable engagement with another frame member  24  and the equalizer bar  40  proximate to the other end of the equalizer bar  40  via another bearing  60 . Accordingly, the frame members  24  may move relative to one another via the coupling members  50 ; and each frame member  24  may move relative to main frame  12  via the coupling member  42 . 
         [0022]    As shown in  FIG. 4 , one embodiment of the bearing  60  includes an inner member such as an inner ring  62  positioned in an outer member such as an outer race  64 . The outer member may be formed integral with the equalizer bar. The inner ring  62  defines an outer spherical surface  63 . As shown in the illustrated embodiment, the outer race  64  defines an inner engagement surface  66  complementarily shaped to slidingly engage outer spherical surface  63  of inner ring  62 . The outer race  64  may be carburized or have a reduced hardness, as compared to the inner ring  62 , to improve resistance to forces that may cause fracturing. During use of the bearing  60 , one or both of the outer spherical surface  63  and the inner engagement surface  66  are movable relative to each other. In the illustrated embodiment, the inner ring  62  defines a bore  70  extending therethrough, the bore being adapted to receive a portion of the shaft  49 , which is connected to the frame member  24  via the bracket  52 . While the bore  70  has been shown and described as extending through the inner ring  62 , the present invention is not limited in this regard as the bore can also extend only partway through the inner ring. The shaft  49  can also be part of the inner ring  62 . 
         [0023]    The outer race  64  includes grooves  73  in which seals  72  are positioned. The seals  72  extend circumferentially around the inner engagement surface  66 . As is shown, the seals  72  are positioned proximate the edges of the inner engagement surface  66  to prevent or inhibit the ingress of dirt or other debris into the bearing  60  between the outer spherical surface  63  and the inner engagement surface  66 . The inner ring  62  also includes grooves in which seals  74  are positioned. The seals  74  are located in the surface defining the bore  70 , each seal  74  being positioned proximate a respective edge of the inner ring through which the bore extends. 
         [0024]    The inner ring  62  can be fabricated from any suitable material including but not limited to steel, steel alloys, nickel alloys, aluminum, aluminum alloys, silicon nitride, silicon carbide, zirconium, and the like. The outer race  64  can be fabricated from any suitable material including but not limited to steel, steel alloys, aluminum, aluminum alloys, magnesium, magnesium alloys, and the like. 
         [0025]    As further shown in  FIG. 5 , the outer race  64  includes a first self-lubricating liner such as a first lubricious fabric liner  65  bonded to a portion of the inner engagement surface  66 . The present invention is not limited to the first lubricious fabric liner  65  being bonded to a portion of the inner engagement surface  66 , as the first lubricious fabric liner  65  may be bonded to the entire inner engagement surface  66  or to all or a portion of an outer engagement surface  68  of the inner ring  62 . Also, the first lubricious fabric liner  65  may simply be positioned between the inner engagement surface  66  and the outer engagement surface  68  rather than being bonded to either engagement surface. 
         [0026]    As further shown in  FIG. 6 , the inner ring  62  also includes a second self-lubricating liner such as a second lubricous fabric liner  67  that is bonded to a portion of an inner engagement surface  71  defining the bore  70  of the inner ring  62 . Again, the present invention is not limited to the second lubricious fabric liner  67  being bonded to a portion of the inner engagement surface  71 , as the second lubricious fabric liner  67  may be bonded to the entire inner engagement surface  71  or to all or a portion of an outer engagement surface  75  of the shaft  49  (shown in  FIG. 3 ). Also, the second lubricious fabric liner  67  may simply be positioned between the inner engagement surface  71  and the outer engagement surface  75  rather than being bonded to either engagement surface. 
         [0027]    The slideable engagement of the first lubricious fabric liner  65  on the inner engagement surface  66  with the outer engagement surface  68 , and the slideable engagement of the second lubricious fabric liner  67  on the inner engagement surface  71  with the shaft  49 , results in providing a constant lubrication within the two wear paths. Use of such fabric liners obviates the need for added lubrication, for example oil or grease. However, the present invention is not limited in this regard as an added lubricant such as oil or grease may be used in the bearing  60 . 
         [0028]    The first and second lubricous fabric liners  65  and  67  are manufactured from a material having low friction characteristics or qualities. In one embodiment, as shown for example in  FIG. 7 , the first and second lubricous fabric liners  65  and  67  comprise a woven fabric generally designated by the reference number  80 . The woven fabric  80  includes a plurality of fibers  80 A and  80 B interwoven with one another and polytetrafluoroethylene (PTFE)  82  interwoven therewith. The fibers  80 A and  80 B include, for example, a polyester material, a stainless steel material and/or glass material. The fibers  80 A and  80 B interwoven with the PTFE enhance bondability of the first and second lubricous fabric liners  65  and  67 . In one example, the first and second lubricous fabric liners  65  and  67  are manufactured from Fabroid®, in particular Fabroid G, which is commercially available from RBC Bearings, Oxford, Connecticut, United States. In another embodiment, the first and second lubricous fabric liners  65  and  67  are manufactured from Fiberglide, which is also commercially available from RBC Bearings. In addition, other materials (e.g., boron nitride, calcium fluoride, cerium fluoride, tungsten disulfide, copper, brass, and the like) may be used to form the first and second lubricous fabric liners  65  and  67  and are considered within the scope of the invention. The first and second lubricous fabric liners  65  and  67  have properties and characteristics sufficient to withstand high loads with insignificant wear. Thus, bearing  60  and the first and second lubricous fabric liners  65  and  67  are operational for extended life when compared to prior art bearings. 
         [0029]    Although this invention has been shown and described with respect to the detailed embodiments thereof, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed in the above detailed description, but that the invention will include all embodiments falling within the scope of the appended claims.