Abstract:
A resilient pad having a base with two side arms and two side lips for resiliently holding the base on a pedestal wear plate, the pad being configured with dome shaped portions disposed substantially perpendicular to the direction of the pad and being spaced apart from each other, where the pad, when installed with a pedestal wear plate serves to improve the force load handling and preferably re-distributes the load bearing surface from the edges and center of the adapter to the flat load bearing surface of the adapter, thus eliminating load on areas that have no support. Because the spring arms do not depend on bending of the base for their resiliency, the pad of the invention provides improved service stress capabilities and allows for longer life of the wear plate.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a pad for handling force loads to prevent wear on the load bearing surface of a pedestal of a rail vehicle, and more particularly relates to improvements in force handling in an arrangement where a wear plate specifically designed for convenient and removable installation in the pedestal opening of a railway side frame is used in order to prevent wear on the load bearing surface of the pedestal. 
     2. Brief Description of the Related Art 
     For the sake of brevity, the teachings and complete disclosures of previous U.S. Pat. Nos. 3,897,736 and 4,203,371 are incorporated herein by reference. In many cases, a bearing adapter is provided over the axle bearing, said adapter having a slightly arcuate top surface which bears directly against a corresponding downwardly facing surface in the pedestal opening of the side frame. This arcuate top surface provides the wheel and axle with a freely pivoting end condition to avoid binding loads on the roller bearing. In order to reduce wear on the pedestal, a wear plate is placed between the downwardly facing pedestal surface and the top surface of the bearing adapter. The wear plate may have side lips and may clip onto the pedestal. 
     In service, movement or frictional sliding may occur between the bearing adapter and the clip-on pedestal wear plate, which may cause damage to the clip-on pedestal wear plate, resulting in the need to replace the wear plate. This condition also may result in the loss of the freely pivoting end condition and may weaken the frame at a load-bearing location. Repair of the frame surface is both expensive and time-consuming, since the worn surface must be ground down to return it to a flat condition. The amount of grinding allowed, however, is limited by structural considerations; after the limit has been reached, the side frame casting is condemned. Replacing the clip-on wear plate is less expensive, but still costly, as it involves removing the railroad car from service and jacking the car so that the broken clip-on wear plates can be removed and replaced. 
     The plate working load and stress are defined as the frictional forces applied to the wear plate by the bearing adapter as a rail car in service shifts and moves about laterally. These frictional forces induce a tendency for lateral movement of the wear plate, and are opposed by the corresponding friction developed between the plate top and the pedestal roof surface. If this opposing frictional force is insufficient to resist this movement, additional bending load and stress are imposed on the side lips of the wear plate. The sensitivity to imbalance in these frictional forces, and hence the tendency to impose stress and load on the plate side lips, increases with heavily loaded rail cars such as coal cars. 
     The result of the total installation related tensile stresses in combination with stress related to bearing adapter friction can result in a significant shortening of the plate service life. In some cases, the total tensile stresses developed may reach the yield strength of the plate and thereby cause bending of the plate. In other more severe cases the ultimate strength of the plate may be reached causing cracking of the plate. 
     The problem of the frictional force load handling has been further complicated as of late because of recent frame painting practices. As environmental concerns have caused an effort to reduce volatile organic emissions from sources including paints, rail car frames are increasingly being painted with solvent-free and alternative solvent based paints. One of the disadvantages of these paints is that a resultant painted surface will have a significantly lower coefficient of friction as compared to a surface painted by older “traditional” paints; at times the new paint may even be thought of as acting as a sort of lubricant. This has the disadvantageous result of greatly reducing the frictional force between the plate top surface and the pedestal roof surface, thereby increasing the effective tensile stress in the plate. This has in turn resulted in an increased occurrence in wear plate bending and cracking. 
     Increasing the thickness of the plate would seem to offer a means to achieving increased plate strength sufficient to resist lateral movement and consequent failure. The benefits of increasing plate thickness, however, are limited. A practical limit on plate thickness exists as installation bending stresses caused as the side lips are forced apart during plate installation increase in direct proportion to the plate thickness. The difference between these installation bending stresses and the ultimate stress at which failure occurs determine the working capacity of the plate to resist movement. At some thickness a maximum plate working capacity is reached and further thickness increases actually decrease working capacity. 
     For the above stated reasons, an unresolved need exists for a pedestal wear plate or wear plate assembly with an improved ability to withstand tensile stresses and thereby enjoy a reduced occurrence of bending and cracking. 
     SUMMARY OF THE INVENTION 
     According to a preferred embodiment, a resilient pad for use in connection with a pedestal wear plate is provided. The pad prevents or minimizes the aforesaid problems associated with plate tensile stress bending and cracking, while not introducing any significant increase in required installation effort. The pad is configured to facilitate handling of the load forces and stresses, and preferably accomplishes this by substantially absorbing and distributing the stresses while increasing the friction between the clip-on wear plate and the pedestal roof. 
     According to preferred embodiments, the pad has a configuration that facilitates the distribution of force loads and prevents or minimizes the concentration of force loads at a particular location. 
     According to a preferred embodiment, the pad comprises a face with a substantially flat surface that engages the pedestal wear plate and has a bulged opposite face. Retaining elements preferably are provided to facilitate holding of the pad on the wear plate. According to one embodiment, two lips at opposite ends of the pad running perpendicular to the pad&#39;s length, as well as two extensions on either side of the pad running parallel to the pad&#39;s length, hold the pad in a preferred location, centered on the clip-on wear plate. 
     According to a preferred embodiment, the force handling structures include two bulges, which preferably are dome-shaped, and act to distribute downward force loads and horizontally spread these loads out over the surface of the clip-on wear plate. 
     According to one embodiment, the force handling structures are provided on both sides of the pad. According to another embodiment, one side of the pad has a substantially flat surface and the other side of the pad has a surface that contains bulged regions. 
     It is an object of the invention to provide a pad that provides a more evenly distributed force load relative to the wear plate so as to avoid concentration of force loads in a particular location on the wear plate. 
     It is another object of the present invention to provide a pad that reduces or eliminates point loading associated with the poor surface finish of the cast pedestal roof, where the surface finishes are associated with lower coefficients of friction. 
     It is an object of the invention to extend the life of a resilient pedestal wear plate by changing the load bearing and friction characteristics to offer improved capacity to withstand tensile stresses, while not significantly increasing required installation effort. 
     According to an alternate embodiment, a pad is provided and is configured for disposition between a bearing adapter and a pedestal surface to facilitate the handling of force loads. The alternate embodiment preferably is constructed with one or more features to facilitate alignment of the pad with the bearing adapter surface. According to some embodiments, the pad may be installed between the bearing adapter and the pedestal roof surface (such as the flat surface in a pedestal opening), with the lower surface of the pad engaging the bearing adapter and the upper surface of the pad engaging the pedestal roof surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top plan view of a first embodiment of a pad according to the invention. 
         FIG. 2  is a right side elevation view of the pad of  FIG. 1 . 
         FIG. 3  is a perspective view of the pad of  FIG. 1 . 
         FIG. 4  is a top plan view of a second embodiment of a pad according to the invention. 
         FIG. 5  is a right side elevation view of the second embodiment of the pad shown in  FIG. 4 . 
         FIG. 6  is a perspective view of the pad of  FIG. 4 . 
         FIG. 7  is a right side elevation view of a third embodiment of a pad according to the invention. 
         FIG. 8  is a perspective view of the third embodiment of the pad shown in  FIG. 7 . 
         FIG. 9  is an exploded view of an example of a side frame and axle of a railway truck, with a portion of the frame being shown in a cut away view to expose the wear plate. 
         FIG. 10  is a side elevation view of the side frame and axle assembly of  FIG. 9 , shown with the components, including the pad of  FIG. 1 , installed in an assembled condition. 
         FIG. 11  is a sectional view of the frame and axle assembly of  FIG. 10 , with the bearing adapter, wear plate, pad and pedestal shown in a sectional view taken through the line  11 - 11  of  FIG. 10 . 
         FIG. 12  is a right side elevation view showing an alternate installation of a pad according to the invention shown in use with a wear plate, where a first pad is provided on one side of the wear plate and a second pad is provided on the other side of the wear plate. 
         FIG. 13  is a perspective view of a fourth embodiment of a pad according to the invention. 
         FIG. 14  is a right side elevation view of the fourth embodiment of the pad shown in  FIG. 13 . 
         FIG. 15  is a right side elevation view of a fifth embodiment of a pad according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIGS. 1-3 , a preferred embodiment of a pad  10  for a wear plate is shown having a main body  11  with an upper surface  12  and lower surface  14 . According to a preferred embodiment, the lower surface  14  is configured as a substantially planar surface. Preferably, the upper surface  12  is provided having force handling means comprising a force handling configuration. According to a preferred embodiment, the force handling means is illustrated comprising raised portions  15   a ,  15   b  of the surface  12 . The raised portions  15   a ,  15   b  preferably are bulged and are disposed transversely on the pad  10  in a spaced apart relation to each other. As illustrated in  FIGS. 1-3 , the pad  10  has a spacing portion  13 , with the raised portions  15   a ,  15   b  being provided on opposite sides of the spacing portion  13 . The pad  10  preferably includes a feature for holding and aligning the pad  10  in an appropriate location for installation. Holding means for facilitating holding and aligning of the pad  10  is illustrated comprising the centering wings or extended portions  17   a ,  17   b  disposed protruding outwardly from the pad  10  on opposite lateral sides thereof. In addition, the holding means preferably includes holding elements, such as, for example, the lips  16   a ,  16   b , which are shown transversely disposed on each&#39;end of the pad  10 . The lips  16   a ,  16   b  are provided at each pad end and run perpendicular to the pad&#39;s length at opposite ends of the pad. The extended portions  17   a ,  17   b , preferably are disposed on each lateral side of the pad  10 , parallel to the pad&#39;s length, to hold the pad in a centered position when installed on a clip-on wear plate. Preferably, the pad  10  is constructed having dimensions that conform to the wear plate in which the pad  10  is to be installed. The lips  16   a ,  16   b  preferably, are disposed at each end of the pad  10  so that the lips  16   a ,  16   b  may engage an edge of a wear plate when installed. This facilitates aligning the pad  10  relative to a wear plate, as well as maintaining the pad  10  in an aligned position during installation of other components, or, for example, when lowering a jacked truck back to its original position. Although illustrated as a continuous portion, the lips  16   a ,  16   b  may be provided as one or more segmented portions, including, for example, a pair of segments on each opposite edge of the pad  10 . 
     Preferably, the raised portions  15   a ,  15   b  are configured as two dome shaped bulges which, when encountering the force from the frame  510  or pedestal  511  (see  FIGS. 9-11 ) act to distribute the downward force, and, preferably, to evenly spread the force out on the surface of the clip-on wear plate  525 . The pad  10  also eliminates or minimizes the point loading associated with the poor surface finishes that may be present on the cast pedestal roof. 
       FIGS. 4-6  illustrate a pad  110  constructed according to a second preferred embodiment of the invention. Referring to the side elevation view of  FIG. 5 , the pad  110  preferably has a substantially flat base  114  and top surface  112  to provide for a more uniform and integral fit to the clip-on wear plate and roof liner. In this embodiment, the pad  110  is constructed to be substantially as wide as the clip-on wear plate, and the extended portions  17   a ,  17   b  on the pad  10  of  FIGS. 1-3 , are not provided. The second embodiment of the pad  110  is also shown with locking lips  116   a ,  116   b  running perpendicular to the length of the pad  110  and being transversely disposed at each end of the pad  110 . 
     Referring to  FIGS. 7-8 , a third preferred embodiment of a pad  210  constructed according to the invention is illustrated. Referring to the side elevation view of  FIG. 7 , the pad  210  is shown having a main body  211  that is preferably substantially flat with a first pair of bulges  214   a ,  214   b  protruding upward from the main body  211 , and a second pair of bulges  215   a ,  215   b  protruding downward from the main body  211 . The pad  210  in this alternate embodiment has centering wings  217   a ,  217   b  as well as locking lips  216   a ,  216   b  to hold the pad  210  in the center of a clip-on wear plate. 
     Preferably, the pads  10 ,  110 ,  210  are constructed from a suitable elastomeric material that is durable and resilient. Preferred materials from which the pads  10 ,  110 ,  210  may be made include natural and synthetic rubbers, polyurethanes, urethanes, elastomers, co-elastomers, thermoplastic elastomers (TPE), copolyester elastomers (COPE) and other suitable materials. Preferably, the durometer of the pad is from about 58 A to 75 D, and more preferably from about 70 A to 75 D, or from about 90 A to 58 D. Although the pads  10 ,  110 ,  210  shown and described herein preferably may be constructed having a thickness suitable to handle the force loads that are anticipated being received from the truck and associated rail cars and the car loads, it has been found that preferred pad thicknesses may range from between about 1/32″ and 4/7″. The pads shown and described herein may be constructed from a one-piece component, or alternately, the pads may be constructed from one or more components. For example, in some instances it may be advantageous to utilize a two-part pad, where, for example, the locking lips  16   a ,  16   b ,  116   a ,  116   b ,  216   a ,  216   b , and centering arms,  17   a ,  17   b ,  217   a ,  217   b  are made from lower cost tougher plastic or metal. The pad  10 ,  110 ,  210  may be constructed by molding, casting, extruding, or other suitable production technique. 
     The present invention thereby offers a practical and effective solution to the serious tensile stress related plate bending and breaking problems experienced by clip-on pedestal wear plates. An exemplary environment is illustrated in  FIGS. 9-11 , where a fragmentary portion of a pedestal  511  and frame  510  of a rail car truck is shown. The frame  510 , although shown in part is generally part of a railway truck, which are commercially known in the industry to include a pair of spaced apart side frames supported on wheel and axle assemblies, with a bolster connected between the side frames for supporting the rail car body.  FIG. 9  illustrates one end of a side frame  510  terminating in the pedestal  511  in the form of a downwardly open pedestal jaw  512   a ,  512   b  engaged over the axle  513  on which the car wheels  514  ( FIG. 10 ) are mounted. As shown in  FIGS. 9-11 , a roller bearing  515  is carried on the axle  513  near the end thereof, and a bearing adapter  516  is provided between the top portion of the bearing  515  and the internal surfaces  517  of the pedestal  511 . The downwardly facing surface  518  of the adapter  516  is curved to correspond to the cylindrical outer race of the bearing  515 , and the upper portion of the adapter comprises a top slightly convex surface which normally bears against a downwardly facing flat surface  517  in the pedestal opening. A pedestal wear plate  525 , or wear liner as it is sometimes referred to, is shown between the pedestal roof and the bearing  516 . In the illustration, the pedestal wear plate  525  is a clip-on pedestal wear plate  525  having upward side lips  526 ,  527  that clamp the plate  525  on the pedestal  511 . Side surfaces  519  are provided on the adapter  516  in engagement with corresponding surfaces  520  in the pedestal opening  522 . Thus, the upper portion of the adapter  516  is generally rectangular so as to be received in the rectangular pedestal opening  522  or roof, although the adapter corners are omitted or cut away to prevent galling of the corners in the pedestal opening. Although only a single side of the rail car truck pedestal is shown in partial view, preferably, similar to the left side shown, there is a pedestal at the right side of the side frame that is similar to the pedestal shown. According to a preferred installation configuration, the pads  10 ,  110 ,  210  shown and described herein are designed to be placed on the pedestal facing surface  528  of the wear plate  525 . The pad  10  is shown installed on the wear plate  525 . In the example illustrated, the adapter  516  includes a pair of raised surfaces  529 , and the raised portions  15   a ,  15   b  are provided over the raised surfaces  529 . 
     Referring to  FIG. 12 , an alternate embodiment of a pad configuration  310  for a wear plate is shown in an alternate installation configuration. The pad installation is illustrated including a first pad  310   a , that may comprise a pad such as those pads  10 ,  110 ,  210 , shown and described herein, and a second pad  310   b  that also may comprise a pad, such as those pads  10 ,  110 ,  210 , shown and described herein. In the embodiment illustrated in  FIG. 12 , the first pad  310   a  is shown configured like the pad  10 , and has locking lip segments  316   a  (only one being shown) and tab portions  317   a ,  317   b . The second pad  310   b , which preferably may be a second one of any of those pads  10 ,  110  and  210  shown and described herein, is shown in  FIG. 12 , according to a preferred embodiment, having a configuration like the pad  110 . The dimensions of the lower pad  310   b  may be provided to correspond with an adapter with which the pad  310   b  is used, such as the adapter  516  (shown in  FIGS. 9-11 ), and may provide locking lips not shown (that are similar to those  316  of the upper pad  310   a ). The pads  310   a ,  310   b , according to preferred embodiments, may be constructed from material that is the same as that described herein in connection with the pads  10 ,  110 , and  210 . The first pad  310   a , when installed in a pedestal  511  with a wear plate  525 , engages the upper surface  528  of the wear plate  525  and engages the downwardly facing pedestal surface, such as, for example, the flat surface  517  in the pedestal opening (see e.g.,  FIGS. 9-11  where a pedestal  511  is illustrated). The second pad  310   b  is designed for disposition between the wear plate lower surface  530  and the upper surface of a bearing adapter, such as, for example, the adapter  516  illustrated in  FIGS. 9-11 . 
     According to an alternate configuration, the second pad  310   b  is provided and installed between the wear plate  525  and the adapter  516 , and the wear plate upper surface  528  is permitted to carry the pedestal  511  directly thereon. According to another alternate installation configuration, a pad, such as those pads  10 ,  110 , and  210  shown and described herein, is positioned between the bearing adapter  516  and the downwardly facing flat surface  517  in the pedestal opening so that the flat surface  517  engages a surface on one side of the pad and the upper portion of the bearing adapter  516  engages the surface on the other side of the pad. The pad  10 ,  110 ,  210  facilitates the force handling by handling force loads received through the pedestal  511 . In  FIGS. 13 and 14 , an alternate embodiment of a pad  410  is illustrated having a preferred configuration for placement between a bearing adapter  516  and the downwardly facing flat surface  517  of the pedestal  511  (as illustrated in connection with the pad  310  in  FIGS. 9-11 ). The pad  41 . 0  preferably is configured for disposition on a bearing adapter, such as, for example the bearing adapter  516  shown in  FIGS. 9-11 . The pad  410  has an upper surface  412  and a lower surface  414 . The upper surface  412  preferably has force handling means for handling force loads. According to a preferred construction, a plurality of force handling means is illustrated comprising raised portions  415  of the upper surface  412 . The raised portions  415  preferably are bulged and are disposed transversely on the pad  410  in a spaced apart relation to each other. According to a preferred embodiment, the pad  410  preferably is configured with a lower surface  414  having one or more corresponding surface features that preferably align with a bearing adapter, such as, for example, the bearing adapter  516  illustrated herein. An alignment feature is illustrated comprising a centering tab  417  that is transversely disposed relative to the length of the pad  410 . The pad  410  includes a first end  418  and a second end  419 . Locking lips  416   a ,  416   b  are provided at the ends of the pad  410 . A second set of lips, the second lips  426   a ,  426   b , are provided on the pad  410 . According to a preferred construction, the second lips  426   a ,  426   b  protrude downwardly from the pad body  411  and are disposed relatively inward from the first lips  416   a ,  416   b  in relation to the length of the pad  410  and the pad ends  418 ,  419 . Although a plurality of raised portions  415  are illustrated, the pad  410  may be constructed with a number of raised portions greater or lesser than those shown in  FIGS. 13 and 14 . The pad  410  may be utilized in an installation where the pedestal roof or upper surface  517  engages with the upper surface  412  of the pad  410 . The lower surface  414  may engage the upper surface of a bearing adapter  516 . According to a preferred embodiment, the central portion  417  may be constructed for disposition on the bearing adapter, such as, for example, the installation between the raised surface portions  529  of the bearing adapter  516  illustrated in  FIGS. 9-11 . Although the central portion  417  and the first locking lips  416   a ,  416   b  and second lips  417   a ,  417   b  are illustrated in a preferred arrangement, the first and/or second lips may be provided having different configurations and numbers that aid in aligning and positioning the pad  410  relative to a bearing adapter and/or pedestal. 
       FIG. 15  shows an alternate embodiment of a pad  610  having a main body  611  with an upper surface  612  and lower surface  614 , where the upper surface  12  is configured as a substantially planar surface, and where the lower surface  614  is provided having force handling means comprising a force handling configuration similar to those shown and described herein, such as, for example, raised portions  615   a ,  615   b  (similar to those raised portions  15   a ,  15   b  shown in  FIG. 2 ). The raised portions  615   a ,  615   b  preferably are bulged and are disposed transversely on the pad  610  in a spaced apart relation to each other. The pad  610  may be constructed similar to the pad  10  shown and described in connection with  FIGS. 1-3 . The pad  610  may be used in installations similar to those pads shown and described herein, including, for example, on top of the pedestal wear plate  525 , or below the pedestal wear plate  525 , or with another pad (as in  FIG. 11 ) that is placed above or below the pedestal wear plate  525 ; or without a pedestal wear plate, where the pad is placed on the top of the adapter  516 . 
     While preferred embodiments and example configurations have been shown and described, it is to be understood that various further modifications and additional configurations will be apparent to those skilled in the art. Other embodiments of the invention, for example, may comprise more or fewer bulges on the top face and/or bottom face. Although locking lips  16 ,  116  and  216  are illustrated along the edge of the pad  19 ,  110 ,  210 , respectively, the locking lips may be configured as one or more segments or elements, such as, for example, the locking segments  316  shown in  FIG. 12 . Further, although the locking lips and extended portions are illustrated in preferred embodiments having preferred arrangements, different configurations and numbers of locking lips and/or extended portions may be provided. In addition, the pads shown and described herein may be made having a dimension suitable for the size of the pedestal, adapter and/or other components that the pad is to be used with. According to some embodiments; the pad may have a thickness ranging from about 1/32″ to 4/7″, and more preferably, according to some embodiments, from about 1/16″ to ⅓″. It is intended that the specific embodiments and configurations disclosed are illustrative of the preferred and best modes for practicing the invention, and should not be interpreted as limitations on the scope of the invention as defined by the appended claims.