Abstract:
A bearing assembly is provided having a roller bearing with an inner case fitted around the journal portion of an axle. An outer raceway combines with the inner raceway to receive roller elements. A backing ring is centered to the shaft fillet. An annular wear ring is positioned between the inner case and the backing ring. An annular sealant bead or a sealant ring form a seal between the shaft shoulder and the backing ring.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     This invention relates to sealed shaft journal bearings and more particularly to an improved bearing assembly, providing a seal or a sealant bead between a shoulder of the shaft and a backing ring.  
         [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 car 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 on the journal. Seals mounted within each end of the bearing cup provide sealing contact with wear rings bearing against the outer ends of the respective bearing cones at each end of the assembly.  
         [0003]     In a typical rail car installation, the axle journal is machined with a fillet at the inboard end, and a backing ring having a surface complementary to the contour of the fillet and an abutment surface for engaging the inboard end of the inner wear ring accurately positions 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 an 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.  
       SUMMARY OF THE INVENTION  
       [0004]     The bearing assembly is a roller bearing that includes an inner race or cone fitted around the journal portion of the axle or shaft. The inner case 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]     An annular wear ring is interposed between and engages the inner race and the backing ring. In one embodiment, the backing ring includes a shoulder that receives a corner of the wear ring.  
         [0007]     An annular sealant bead is interposed between and engages the shaft shoulder and the backing ring.  
         [0008]     In another embodiment, a first sealant ring is interposed between and engaging the shaft shoulder and the backing ring. A second sealant ring is interposed between and engaging the wear ring and the backing ring.  
         [0009]     Such sealant bead on sealant rings form a seal to keep water, abrasives and other contaminants from entering the sealed bearing from along the shaft and between the shaft and backing ring. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     In the drawings,  
         [0011]      FIG. 1  is a sectional view of a shaft journal having mounted thereon a tapered roller bearing assembly in accordance with the present invention;  
         [0012]      FIG. 2  is a sectional view of a shaft journal having mounted thereon a tapered roller bearing assembly in accordance with a second embodiment of the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0013]     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.  
         [0014]     The bearing assembly  10  is preassembled before being mounted and clamped on journal  12  by cap  30 . The bearing assembly includes a unitary bearing cup or outer raceway  32  having a pair of raceways  34 ,  36  formed one adjacent each end thereof which cooperate with a pair of bearing cones  38 ,  40 , respectively, to support the two rows of tapered rollers  42 ,  44 , respectively, therebetween. A center spacer  46  is positioned between cones  38 ,  40  to maintain the cones in accurately spaced relation relative to one another.  
         [0015]     The bearing cup  32  is provided with cylindrical counterbores  48 ,  50  at its opposite ends outboard of the raceways  34 ,  36 , and a pair of seal assemblies  52 ,  54  are pressed one into each of the cylindrical counterbores  48 ,  50 . The seals  52 ,  54  include resilient sealing elements  56 ,  58 , respectively, which rub upon and form a seal with a pair of seal wear ring sleeves  60 ,  62 , respectively, having their inwardly directed ends in engagement with the outwardly directed ends of bearing cones  38 ,  40 , respectively. The other end of wear ring sleeve  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 sleeve  60  are also dimensioned to provide an interference fit so that the wear ring 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  116  when the bearing is mounted on the shaft. The outwardly directed end of sleeve  62  bears against the retaining cap  30 .  
         [0016]     Sealant bead  75  is seen to be located between backing ring  66  and the shoulder portion of fillet  22 . Sealant bead  75  is most frequently a silicone sealant such as Dow Corning 737. Sealant bead  75  can be formed by applying a sealant coating to the intersection of fillet  22  and counterbore  168  and then upon press fitting backing ring  66 , a seal is formed. Sealant bead  75  forms a seal to water and abrasives that may enter sealed bearing  10  along the outer edge of axle  14 .  
         [0017]     Referring now to  FIG. 2  of the drawings, a bearing assembly indicated generally by the reference numeral  110  in  FIG. 2  is shown mounted on a journal  112  on the free, cantilevered end of a shaft or axle  114 , typically a rail car axle. Journal  112  is machined to very close tolerances and terminates at its inner end in a contoured fillet  122  leading to a cylindrical shoulder of axle  114 . At the free end of the axle, journal portion  112  terminates in a slightly conical or tapered guide portion  124  dimensioned to facilitate installation of the bearing assembly onto the journal. A plurality of threaded bores  126  are formed in the end of axle  112  for receiving threaded cap screws, or bolts  128  for mounting a bearing retaining cap  130  on the end of the shaft to clamp the bearing in position as described more fully herein below.  
         [0018]     The bearing assembly  110  is preassembled before being mounted and clamped on journal  112  by cap  130 . The bearing assembly includes a unitary bearing cup or outer raceway  132  having a pair of raceways  134 ,  136 , formed one adjacent each end thereof which cooperate with a pair of bearing cones  138 ,  140 , respectively, to support the two rows of tapered rollers  142 ,  144 , respectively, therebetween. A center spacer  146  is positioned between cones  138 ,  140  to maintain the cones in accurately spaced relation relative to one another.  
         [0019]     The bearing cup  132  is provided with cylindrical counterbores  148 ,  150  at its opposite ends outboard of the raceways  134 ,  136 , and a pair of seal assemblies  152 ,  154  are pressed into each of the cylindrical counterbores  148 ,  150 . The seals  152 ,  154  include resilient sealing elements  156 ,  158 , respectively, which rub upon and form a seal with a pair of seal wear ring sleeves  160 ,  162 , respectively, having their inwardly directed ends in engagement with the outwardly directed ends of bearing cones  138 ,  140 , respectively. The directed end of an annular backing ring  166  which, in turn, has a counterbore  168  at its other end which is dimensioned to be received in an interference or non-interference relation on the cylindrical shoulder  118  of shaft  114 . The counterbore  164  and the outer diameter of wear ring sleeve  160  are also dimensioned to provide an interference fit so that the wear ring is pressed into the backing ring  166  which is accurately machined to provide a contoured inner surface  170  complementary to and engaging the contour of fillet  116  when the bearing is mounted on the shaft. The outwardly directed end of sleeve  162  bears against the retaining cap  30 .  
         [0020]     First sealant ring or gasket  175  is seen to be located between backing ring  166  and the shoulder portion of fillet  122 . Second sealant ring or gasket  177  is seen to be located between such corner of wear ring  160  and shoulder  164  of backing ring  166 .  
         [0021]     First sealant ring  175  and second sealant ring  177  are usually comprised of a nitrile rubber or another suitable rubber or a synthetic. Sealant rings  175  and  177  form a seal to water and abrasives that may enter sealed bearing  110  along the outer edge of axle  114 .