Patent Publication Number: US-8528483-B2

Title: Constant contact side bearing assembly with improved heat dissipation for a railcar

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is related to and claims priority from Provisional Patent Application Ser. No. 61/180,655 filed on May 22, 2009. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates, in general, to energy absorption devices for railcars and, more particularly, this invention relates to a side bearing assembly which is employed between a bolster of a wheeled truck and an underside of the railcar body for accommodating “hunting” movements of the railcar and, yet more particularly, the instant invention relates to a constant contact side bearing having improved heat dissipation provided by openings formed through cap wall. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT 
     N/A 
     REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISC APPENDIX 
     N/A 
     BACKGROUND OF THE INVENTION 
     As is generally well known, constant contact side bearings are extensively employed on each truck of a railcar to accommodate and compensate for longitudinal vertical and side movements of the railcar body relative to such truck. As a result of such movements, heat is generated within the side bearing assembly and, more specifically, due to friction between the cap and the railcar body wear plate. While prior art side bearing assemblies have been found as capable of withstanding such heat, additional improvements are required. 
     Therefore, there is a need for a constant contact side bearing having improved heat dissipation. 
     SUMMARY OF THE INVENTION 
     The invention provides a constant contact side bearing assembly for a railcar. The constant contact side bearing assembly includes a housing. The housing includes a base having a substantially planar bottom surface thereof abuttingly engaging a bolster of a railway vehicle truck and defining a bottom end of the housing. There is a pair of mounting apertures that are formed through a thickness of the base and aligned along a mounting axis disposed each of generally perpendicular to an axis of the bolster and in a movement direction of the railcar. A generally cylindrical housing wall upstands on the base and defines an upstanding longitudinal axis of the housing, the upstanding longitudinal axis generally intersecting the mounting axis of the mounting apertures. There is also a pair of diametrically opposed channels that are disposed on and extend outwardly from an outer surface of the housing wall in open communication with an interior thereof and aligned along an axis disposed substantially perpendicular to the mounting axis. Each of the pair of diametrically opposed channels has a generally U-shaped cross-section in a plane transverse to the upstanding longitudinal axis of the housing. A top edge of the each of the pair of diametrically opposed channels is disposed generally planar with a top edge of the housing wall. A pair of diametrically opposed openings is provided and is formed through a thickness of the housing wall. Each of the pair of first diametrically opposed openings is disposed below a respective one of the pair of channels in general alignment therewith. A guide member is also disposed centrally on and upstands from an inner surface of the base. The constant contact side bearing assembly further includes a cap that is disposed for reciprocal axial movement relative to the housing. A compressible resilient member is provided and is disposed within a generally closed chamber formed by a combination of the housing and the cap. The compressible resilient member has an axial bore sized to receive the guide member. The final element of the constant contact side bearing assembly is means for dissipating heat. Such heat dissipating means is achieved by at least one air passage provided by a pair of pockets formed in the cap wall on each side of a tab operatively meshing with a respective channel and an opening formed through the vertical rear wall of each pocket. 
     The cap may have an elongated shape with the constant contact side bearing assembly further including a pair of spacers positioned within the housing on either side of the cap. 
     OBJECTS OF THE INVENTION 
     It is, therefore, one of the primary objects of the present invention to provide a constant contact side bearing assembly. 
     Another object of the present invention is to provide a constant contact side bearing assembly that has a pair of air passages disposed within the cap and aligned in a direction generally parallel to the mounting axis of the constant contact side bearing assembly. 
     Yet another object of the present invention is to provide a constant contact side bearing assembly that has grooves formed in the inner surface of the cap. 
     In addition to the several objects and advantages of the present invention which have been described with some degree of specificity above, various other objects and advantages of the invention will become more readily apparent to those persons who are skilled in the relevant art, particularly, when such description is taken in conjunction with the attached drawing Figures and with the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a 3-D view of a constant contact side bearing assembly of the instant invention; 
         FIG. 2  illustrates a 3-D view of the housing member employed within the constant contact side bearing assembly of  FIG. 1 ; 
         FIG. 3  illustrates a 3-D view of the cap member employed within the constant contact side bearing assembly of  FIG. 1 ; 
         FIG. 4  is a cross-sectional view of the constant contact side bearing assembly along lines IV-IV of  FIG. 1 ; 
         FIG. 5  is a top planar view of the constant contact side bearing assembly constructed in accordance with another embodiment of the invention; 
         FIG. 6  is a cross-sectional elevation view of the constant contact side bearing assembly along lines VI-VI of  FIG. 5 ; 
         FIG. 7  is a top planar view of a constant contact side bearing assembly constructed in accordance with yet another embodiment of the invention; 
         FIG. 8  is a partial cross-sectional elevation view of the constant contact side bearing assembly along lines VIII-VIII of  FIG. 7 ; and 
         FIG. 9  is an environmental planar view illustrating use of the constant contact side bearing assembly of  FIG. 1 ,  5  or  7  within a railcar. 
     
    
    
     BRIEF DESCRIPTION OF THE VARIOUS EMBODIMENTS OF THE INVENTION 
     Prior to proceeding to the more detailed description of the present invention, it should be noted that, for the sake of clarity and understanding, identical components which have identical functions have been identified with identical reference numerals throughout the several views illustrated in the drawing figures. 
     The present invention provides a constant contact side bearing assembly, generally designated as  10 , for a railcar  2  having improved heat dissipation. Now in a particular reference to  FIGS. 1-4  and  9 , the side bearing assembly  10  comprises a housing, generally designated as  20 , a cap, generally designated as  70 , and a resilient compressible element, generally designated as  140 . 
     The housing  20 , best shown in  FIG. 2 , includes a generally oval base  30  having a generally planar bottom surface  32  thereof abuttingly engaging the upper surface of the bolster  6  of a railcar truck  4  and defining a bottom end  22  of the housing  20 . A pair of mounting apertures  38  are formed through a thickness of the base  30  and are aligned along a mounting axis  39  disposed each of generally perpendicular to an axis  5  of such bolster  6  and in a movement direction of such railcar  2 . Each mounting aperture  38  is disposed in close proximity to and spaced from an end  36  of the base  30 . The housing  20  has a generally cylindrical housing wall  40  upstanding on the base  30  and defining an upstanding longitudinal axis  24  of the housing  20  that generally intersects the mounting axis  39  of the mounting apertures  38 . The housing wall  40  has each of a predetermined height and a predetermined diameter. As is conventional, the ends  36  of the base  30  extend past the outer side surface  42  of the housing wall  40  so as to allow unobstructed access to the apertures  38 . 
     Two diametrically opposed channels  50  are disposed on and extend outwardly from the outer surface  42  of the housing wall  40  in open communication with an interior  46  thereof and aligned along an axis disposed substantially perpendicular to the mounting axis  39  and aligned with the axis  5  of the bolster  6 . Each channel has a generally U-shaped cross-section in a plane transverse to the longitudinal axis  24  of the housing  20 . A top edge  52  of each channel  50  is positioned generally planar with a top edge  48  of the housing wall  40 . 
     A pair of first diametrically opposed openings  60  are formed through a thickness of the housing wall  40 . Each of the pair of first diametrically opposed openings  60  is disposed below a bottom edge  54  of a respective channel  50  in general alignment therewith. Thus, the bottom edge  54  of the channel  50  is spaced in a vertical direction from the bottom surface  32  of the base  30  when the constant contact side bearing assembly  10  is mounted on the railcar truck  4 . 
     There is also a pair of second diametrically opposed openings  62  formed through the thickness of the housing wall  40 . Each of the pair of second diametrically opposed openings  62  is disposed above a respective one of the pair of ends  32  of the base  30 . Finally, a first elongated guide member  66  is disposed centrally on and upstands from a substantially planar inner surface  34  of the base  30 . 
     The cap  70 , best shown in  FIG. 3 , is disposed for reciprocal axial movement relative to the housing  20 . The cap includes a generally cylindrical cap wall  80  defining a longitudinal axis  82  disposed coaxially with the longitudinal axis  24  of the housing  20 . The cap wall  80  has each of a predetermined height and a predetermined diameter. The cap  70  also has a generally open bottom end  72  defining a bottom edge  84  of the cap wall  80 . There is also a generally closed top end  90  having a cross-sectional shape in the plane transverse to the longitudinal axis  82  of the cap  80  defined by a pair of diametrically opposed end portions  92  and a center portion  94 . Each of the pair of end portions  92  has a convex end edge surface  96  complementing an exterior side surface  86  of the cap wall  80 . The center portion  94  has a pair of convex edges  98 . The top end  90  carries thereon each of a top edge  88  of the cap wall  80  and a substantially planar outer surface  89 . 
     There is also a pair of diametrically opposed tabs  100  disposed on the exterior side surface  86  of the cap wall  80  and aligned along the axis disposed substantially perpendicular to the mounting axis  39 . Each of the pair of diametrically opposed tabs  100  is sized for operative engagement with and axial reciprocal movement within a respective one of the pair of channels  50  so as to prevent rotation of the housing  70  about the longitudinal axis  82  during use of the constant contact side bearing assembly  10 . 
     At least a pair and, preferably, a quartet of pockets  110  is defined by a combination of the pair of diametrically opposed end portions  92  of the top end  90  and the pair of diametrically opposed tabs  100 . More specifically, each pocket  110  is defined by each of a first side surface  112  disposed in the substantially vertical plane on one side of the tab  100 , a side wall  114  disposed in the substantially vertical plane and carrying a second side surface thereon, a rear wall  116  disposed in the substantially vertical plane and carrying a rear surface thereon and a ledge  118  disposed in a substantially horizontal plane and carrying thereon a bottom surface of the pocket  110 . The rear wall  116  may have a curved convex cross-section in a plane transverse to the longitudinal axis  82  of the cap  70 . Then, all four rear walls  116  are radially and equally spaced relative to the longitudinal axis  82  of the cap  70 . 
     At least a pair and, preferably, a quartet of third openings  120  is also provided. Each of the quartet of third openings  120  is formed through the rear vertical wall  116  of a respective pocket  110  in open communication with the interior of the cap  70 . Each third opening  120  has a generally elongated shape in the plane transverse to the longitudinal axis  82 . The bottom edge of each third opening  120  is generally aligned with the bottom surface of the pocket  110  carried by the ledge  118 . Furthermore, such bottom surface of the pocket  110  is positioned in a vertical direction on the cap wall  80  so that it remains aligned with or above the top edge  48  of the housing  20  during reciprocal motion of the cap  70  under all load conditions and further in view of the component wear occurring during use of the constant contact side bearing assembly  10 . 
     Given the above described location of the pockets  110 , each pair of third openings  120  forms an air passage in a substantially horizontal plane and in a direction substantially parallel to the mounting axis  39 . When the pair of air passages is provided, the air passages are equally spaced from the mounting axis  39 . 
     A pair of diametrically opposed wear indicators, such as pockets  128 , are disposed in the outer surface  104  of the top end  90  of the cap  70 . 
     A second elongated guide member  130  is disposed centrally on and upstands from a substantially planar inner surface  106  of the top end  90  of the cap  70 . 
     The one piece compressible resilient member, such as elastomeric spring  140 , is disposed within a generally closed chamber  28  formed by a combination of the housing  20  and the cap  70  for urging the cap  70  upwardly into contact with the underside of the railcar body (not shown). The elastomeric spring  140  has an axial bore  142  thereof sized to receive each of the first and second guide members,  66  and  130  respectively. The elastomeric spring  140  may be manufactured from any resilient compressible material capable of meeting performance mandated by the American Association of Railroads (AAR). By way of an example only, such elastomeric spring  140  may be manufactured from any thermoplastic or thermoset material. In the presently preferred form, the material of the elastomeric spring  140  is at least one of a copolyester polymer and a copolyamide material. 
     It is also within the scope of the instant invention to provide an indicator means (not shown) for indicating a nominal working height of the resilient side bearing assembly after such resilient side bearing assembly has been installed on the truck portion of the railway car. Such indicator means, as taught in the U.S. Pat. No. 4,793,720 issued to Merker, Jr. and owned by the assignee of the instant invention, includes a first portion positioned on the friction head member while a second portion of such indicator means is positioned on the housing member of the resilient side bearing assembly. Teachings of the U.S. Pat. No. 4,793,720 are incorporated into this document by reference thereto. 
     It has been found that in operation of the railcar  2 , the third openings  120 , which are essentially aligned in a direction of the railcar  2  movement, promulgate air flow through the chamber  28  for convection cooling, thus dissipating the heat generated during friction of the outer surface  104  of the top end  90  of the cap  70  with the railcar body wear plates (not shown). The frictional heating can be also exaggerated by increased cap to housing tolerances in a plane of hunting or truck rotation. Further heat dissipation is facilitated by the second openings  62  that are also aligned in a direction of the railcar  2  movement. Thus, the third openings  120  and, more particularly, air passages formed thereby either by themselves or in combination with the second openings  62  provides means, that are aligned in a direction of the railcar  2  movement, for dissipating heat generated during friction of the outer surface  104  of the cap  70  with the railcar body wear plates (not shown). 
     Now in reference to  FIGS. 5-6 , therein is provided a side bearing assembly, generally designated as  200 , which is constructed in accordance with another embodiment of the invention. The side bearing assembly  200  includes the above described housing  20  and the one piece elastomeric spring  140 . The side bearing assembly  200  also includes a cap, generally designated as  210 , which is constructed generally identical to the above described cap  70  except that the substantially planar inner surface  214  of the closed end  212  includes a predetermined plurality of grooves  220  disposed in a radial, or any other pattern, relative to the longitudinal axis  216  of the cap  210 . 
     The side bearing assembly  200  further includes a spacer  230  manufactured from a rigid material, for example such as metal or any other material capable of withstanding operational loads. The spacer  230  is positioned between a substantially planar top end surface  142  of the elastomeric spring  140  and the substantially planar inner surface  214  of the closed end  212  of the cap  210 . The grooves  220  having ends extending at least even with the outer edge of the spacer  230  and, preferably extending past such peripheral edge, permit dissipation of heat generated in the outer upper surface of the cap  210  first into the chamber  228  of the side bearing assembly  200  and then outwardly from this chamber through various openings in the housing  20  and the cap  210 . The spacer  230  is provided in order to prevent degradation of the top end surface  142  of the elastomeric spring  140  and may be provided integral therewith by bonding or any other suitable method. It is also within the scope of the instant invention to provide grooves  220  in the upper surface  232  of the spacer  230  in combination with or alternative the grooves  220  disposed within the cap  210 . 
     Although, the cap  210  is illustrated in  FIG. 5  as having the above described pockets  110 , it is within the scope of the instant invention to provide cap  210  without such pockets  110 . 
     Now in reference to  FIGS. 7-8 , therein is provided a side bearing assembly, generally designated as  300 , which is constructed in accordance with another embodiment of the invention. The side bearing assembly  300  includes the above described housing  20  and the one piece elastomeric spring  140 . The side bearing assembly  300  also includes a cap, generally designated as  310 , that has a generally elongated shape and that is positioned for reciprocal axial movement within the housing  20 . The cap wall of the cap  310  has each of a pair of opposed side wall portions  312  aligned in a direction substantially parallel to the mounting axis  39  and a pair of opposed convex end portions  314 . Although, the side wall portions  312  are illustrated as having substantially planar outer surfaces  316 , at least a middle section of such side wall portions  312  may be curved outwardly in a direction of the channels  50  to cooperate with the peripheral shape of the compressible elastomeric member  140 . 
     The housing  310  also carries the above described guide member  130 . Furthermore, the opening  120 , or a similar opening, may be centrally formed through each convex wall portion  314 , wherein the bottom edge of the opening  120  is disposed in alignment with or above the top edge of the housing  20 . 
     There is also a pair of spacers  320  that are shaped to engage the inner surface of the housing  20  and, more particularly, operatively mesh with channels  50 . Each spacer  320  carries a tab  100  thereon and also has a locking tab  322  caged within a respective one of the pair of diametrically opposed openings  60  of the housing  20 . The inner surface  324  of the spacer  320  abuttingly engages the outer surface  316  of the side wall portion  312  of the cap  310 . Although the spacer  320  is illustrated in  FIG. 8  as a solid member, the spacer  320  may be also provided as a hollow member. Furthermore, when the side wall portion  312  has convex shape, inner wall  324  will have a complimentary concave shape. 
     Thus, the present invention has been described in such full, clear, concise and exact terms as to enable any person skilled in the art to which it pertains to make and use the same. It will be understood that variations, modifications, equivalents and substitutions for components of the specifically described embodiments of the invention may be made by those skilled in the art without departing from the spirit and scope of the invention as set forth in the appended claims.