Abstract:
A bearing assembly is provided having a roller bearing with an inner raceway fitted around the journal portion of an axle. An outer raceway combines with the inner raceway to receive roller elements. An improved lubricant seal arrangement is provided between the wear ring and the supporting outer raceway comprising a slinger element.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates to shaft journal bearings and, more particularly, to an improved bearing assembly seal arrangement for use in a railway freight car. 
         [0002]    Roller bearing assemblies incorporating two rows of tapered roller bearings preassembled into a self-contained, pre-lubricated package for assembly onto journals at the ends of axles or shafts are known. Such bearing assemblies are used as rail car bearings assembled onto journals at the ends of the axles. Bearings of this type typically employ two rows of tapered roller bearings fitted one into each end of a common bearing cup with their respective bearing cones having an inner diameter dimensioned to provide an interference fit with the shaft journal and with a cylindrical sleeve or spacer positioned between the cones providing accurate spacing and proper lateral clearance on the journal. Seals mounted within each end of the bearing cup provide sealing contact with wear rings bearing against the outer ends or back face of the respective bearing cones at each end of the assembly. Such seals are shown in U.S. Pat. Nos. 5,975,533, 7,607,836, and 7,534,047. 
         [0003]    In a typical rail car installation, the axle journal is machined with a fillet at the inboard end. A backing ring having a surface complementary to the contour of the fillet and an abutment surface for engaging the inboard end of an inner wear ring accurately position the bearing assembly on the journal. An end cap mounted on the end of the axle by bolts threaded into bores in the end of the axle engages the outboard wear ring and clamps the entire assembly on the end of the axle. The wear rings typically have an inner diameter dimensioned to provide interference fit with the journal over at least a portion of their length so that the entire assembly is pressed as a unit onto the end of the journal shaft portion of the axle. 
       SUMMARY OF THE INVENTION 
       [0004]    The bearing assembly of the present invention is a roller bearing that includes an inner race or cone fitted around the journal portion of the axle or shaft. The inner race includes an outwardly directed raceway. An outer race or cup has an inwardly directed raceway. Roller elements are located between and contacting the inner and outer raceways. 
         [0005]    A backing ring has a contoured surface complementary to and engaging the contoured surface of a fillet formed on the shaft. The fillet leads from the journal to the shoulder of the shaft. The contoured surfaces cooperate to fix the backing ring against axial movement along the shaft. 
         [0006]    The bearing assembly includes a seal assembly that provides a barrier for lubricant to be retained within the seal assembly and for contaminants to be kept out. A slinger is provided to interact with a wear ring and a seal element to provide an improved seal. The inter-related relationship between the seal element, wear ring, and slinger act to retain the lubricant within the seal assembly and to keep contaminants out. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    In the drawings, 
           [0008]      FIG. 1  is a sectional view of a shaft journal having mounted thereon a tapered roller bearing assembly in accordance with a first embodiment of the present invention; 
           [0009]      FIG. 2  is a detailed partial view in cross section of a tapered roller bearing seal assembly in accordance with the first embodiment of the present invention; 
           [0010]      FIG. 3  is a detailed view in partial cross section of a tapered roller bearing assembly in accordance with a second embodiment of a present invention, and 
           [0011]      FIG. 4  is a detailed view in partial cross section of a tapered roller bearing assembly in accordance with a third embodiment of the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0012]    Referring now to  FIG. 1  of the drawings, a bearing assembly indicated generally by the reference numeral  10  on  FIG. 1  is shown mounted on a journal  12  on the free, cantilevered end of a shaft or axle  14 , typically a rail car axle. Journal  12  is machined to very close tolerances and terminates at its inner end in a contoured fillet  22  leading to a cylindrical shoulder  18  of axle  14 . At the free end of the axle, journal portion  12  terminates in a slightly conical or tapered guide portion  24  dimensioned to facilitate installation of the bearing assembly onto the journal. A plurality of threaded bores  26  are formed in the end of axle  14  for receiving threaded cap screws, or bolts  28  for mounting a bearing retaining cap  30  on the end of the shaft to clamp the bearing in position as described more fully herein below. 
         [0013]    Bearing assembly  10  is preassembled before being mounted and clamped on journal  12  by retaining cap  30  and bolts  28 . The bearing assembly includes a unitary bearing cup or outer raceway  32  having a pair of inner facing raceways  34 , 36  formed one adjacent each end thereof which cooperate with a pair of bearing cones  38 , 40 , having outer facing raceways respectively, to support the two rows of tapered rollers  42 , 44 , respectively there between. A center spacer  46  is positioned between cones  38 ,  40  to maintain the cones in accurately spaced position relative to one another allowing for proper bearing lateral clearance. 
         [0014]    Bearing cup  32  is provided with cylindrical counterbores  17 , 19  at its axially outer ends and a pair first end sections  48 ,  50  of seal sections  52 , 54  are pressed one into each of the cylindrical counterbores  17 , 19  in cup  32 . Each second end section  55 ,  63  of seal section  52 , 54  may include resilient sealing elements  56 ,  58  which rub upon and form a seal with radial outer surfaces  37 , 61  of a pair of seal wear rings  60 , 62  having an inwardly directed end in engagement with the outwardly directed ends of bearing cones  38 , 40  respectively. Seal section  54  is similar to seal section  52  and will not be described in detail. The other end of wear ring  60  is received in a cylindrical counterbore  64  in the axially outwardly directed end of an annular backing ring  66  which, in turn, has a counterbore  68  at its other end which is dimensioned to be received in interference and non-interference relation on the cylindrical shoulder  18  of shaft  14 . The counterbore  64  and the outer diameter of wear ring  60  are also dimensioned to provide an interference fit so that wear ring  60  is pressed into the backing ring  66  which is accurately machined to provide a contoured inner surface  70  complementary to and engaging the contour of fillet  22  when the bearing is mounted on the shaft. The outwardly directed end of wear ring  62  bears against a counterbore  31  in a retaining cap  30 . 
         [0015]    Referring now to  FIG. 2 , a detailed view of seal assembly portion of bearing assembly  10  is provided. Seal section  52  is seen to comprise a generally cylindrical piece, having a larger diameter first end section  48  pressed or fit into a complementary counterbore  17  in a cup  32 . Seal section  52  includes an intermediate section  27  normal to first end section  48  and a main intermediate cylindrical section  53  that extends parallel to end section  48 , wherein main intermediate cylindrical section  53  has a smaller diameter than first end section  48 . 
         [0016]    Second end section  55  of seal section  52  extends from main intermediate section  53  at a normal angle thereto. Resilient sealing element  56  is fitted onto second end section  55 . Resilient sealing element  56  is comprised of a rubber or elastomer compound, such as nitrile rubber compound. Resilient sealing element  56  includes a main section that includes an opening to receive second end section  55  of seal section  52 . 
         [0017]    Slinger section  72  comprises a generally cylindrical structure having a base section  74  attached to outer surface  37  of seal wear ring  60  and end section  76  extending from base section  74 . Slinger section  72  is usually a unitary structure comprised of a structural plastic or steel. 
         [0018]    Referring now to  FIG. 3 , a second embodiment of the roller bearing seal assembly of the present invention is shown generally at  110 . Elements such as bearing cup  32 , backing ring  66 , seal section  52  and seal wear ring  60  are similar to  FIGS. 1 and 2  and are similarly numbered. 
         [0019]    Slinger section  172  comprises a generally cylindrical structure having a base section  174  attached to outer surface  37  of seal wear ring  60 , an intermediate section  178  extending from base section  174 , and end section  176  extending from and at an angle of approximately 90 degrees to intermediate section  178 . Intermediate section  178  is seen to have a protrusion  178 A that contacts the axially inward facing surface  55 A of second end section  55  of seal section  52 . Slinger section  172  is usually a unitary structure comprised of a structural plastic or steel. Slinger end section  176  extends toward and is adjacent the radial outer surface of main intermediate cylindrical section  53  of seal section  52 . 
         [0020]    Referring now to  FIG. 4 , a third embodiment of the roller bearing seal assembly of the present invention is shown generally at  210 . Elements such as seal section  52  and seal wear ring  60  with radial outer surface  37  are similar to  FIGS. 1 and 2  and are similarly numbered. However, backing ring  266  is seen to have an annular protrusion  268  extending axially from its outer radial surface. 
         [0021]    Slinger section  272  comprises a generally cylindrical structure having a base section  274  attached to outer surface  37  of seal wear ring  60 , an intermediate section  278  extending from base section  274 , and end section  276  extending from and normal to intermediate section  278 . Slinger section  272  is usually a unitary structure comprised of a structural plastic or steel. Intermediate section  278  is seen to have a protrusion  278 A that contacts the axially inward facing surface  55 A of second end section  55  of seal section  52 . Slinger end section  276  extends at a radius and an angle of approximately 90 degrees from intermediate section  278  and extends toward and is adjacent the radial outer surface of main intermediate cylindrical section  53  seal section  52 .