Abstract:
An assembly for supporting a railroad rail on a tie includes an abrasion plate arranged to be positioned on a tie, and a pad disposed on the abrasion plate and adapted to receive the rail. The pad and plate have mating depressions and buttons arranged in complementary patterns that provides means of interlocking the two components to resist migration in both longitudinal and lateral directions. Preferably the depressions are larger than the buttons to allow some play. The two elements may be attached to each other prior to transportation by a combination of a projection on one and a capturing hole in the other. The projection may be a stake having an enlarged head. The plate may be secured to the tie by an epoxy and may have irregularities on the bottom to be gripped by the epoxy. A seal may also be provided around the supports for the rail clips to keep sand and other extraneous matter from the interface between the plate and the tie. The seal may be provided on the plate or the pad.

Description:
RELATED APPLICATIONS 
   This application claims priority to provisional application Ser. No. 60/430,560 filed Dec. 3, 2002 and incorporated herein by reference. 

   BACKGROUND OF THE INVENTION 
   1. Field of Invention 
   This invention pertains to a novel abrasion assembly, and more particularly, to a abrasion assembly formed of an abrasion plate resting on the railroad tie and a pad on the plate and supporting the rail. More specifically, means are provided to interlock the abrasion plate and the pad to resist being separated by the shifting of the rail laterally or longitudinally, and to lock the abrasion plate to the tie for shipping. Means are also provided to seal the underside of the plate from contaminate egress. 
   2. Description of the Prior Art 
   During the last decades, the old wooden ties used to support railroad rails were replaced by concrete ties and pads were provided between the rails and the concrete ties. These pads provided two functions: they acted as shock absorbers for the rails and they provided electrical insulation. This latter function is important for railroad systems in which the rails form a part of the electrical circuitry for either the motive power, signaling or control functions. Separate rail clips or other similar fasteners are used to clamp the rail to the ties. For example, commonly owned U.S. Pat. No. 5,110,046, incorporated herein by reference, discloses a two part abrasion assembly: an elastomeric pad and an abrasion plate resting on the tie. The abrasion plate was made of a heat treated high carbon steel. The abrasion plate was provided on its bottom surface with a layer of adhesive to secure it to the concrete tie. Other abrasion assemblies have been developed with an abrasion plate made of a plastic material. 
   However, problems still remain with abrasion assemblies. One problem is that, after excessive use, the concrete tie under the assembly gets worn and has to be repaired. A further problem is that over time rails tend to expand and contract longitudinally due to temperature changes, as a result of train movement and tie maintenance. This action tends to separate the two parts of the assembly. 
   OBJECTIVES AND SUMMARY OF THE INVENTION 
   It is an objective of the present invention to provide a method of repairing worn railroad ties. 
   A further objective is to provide an improved abrasion assembly supported on the ties, said abrasion assembly being constructed of two parts: an erosion plate disposed on the tile and a pad disposed on the plate and supporting the rail. 
   A further objective is to provide an improved two-part abrasion assembly with means to prevent, or at least resist, forces a pad disposed under the rail to resist separation between the two parts. 
   Other objectives and advantages of the inventions shall become apparent from the following description. 
   A known two-part abrasion assembly consists of a sandwich of two layers, namely, a metallic abrasion plate and a plastic rail pad. The components of such a abrasion assembly conventionally are pre-assembled before it is transported to the track site for installation on a new concrete sleeper. Each such sandwich is held together by fiberglass tape that is strapped around the two assembled components for the purpose of preventing them from coming apart during transit. Such a tape is, however, difficult and slow to apply so as to ensure that the abrasion assembly will not come apart inadvertently. 
   Briefly, in order to eliminate the use of fiberglass tape and instead thereof to afford an easier and more economical attachment arrangement for the plastic abrasion plate and the rail pad of the 2-part abrasion assembly of the present invention, it is contemplated to utilize a “heat stake” feature. The basic design of this feature is a protruding plastic post which is provided on one of the components of the assembly and is dimensioned to fit through a corresponding hole in the other component. In the preferred form of the present invention, since the rail pad rests on the abrasion plate, the post which constitutes the “heat stake” is provided on and as a part of the abrasion plate and the hole is formed in the rail pad (but the arrangement could just as well be the reverse), such that in the assembled state an end portion of the post extends from the hole. When it is desired to attach the two components to each other, the protruding end of the post is pressed with a hot surface, for example, such as the tip of a soldering iron. The hot surface serves to melt the protruding end region of the post to a width greater than that of the hole, by virtue of which the post is prevented from being withdrawn from the hole and the two components are permanently attached to each other. Each paired abrasion plate and rail pad may, of course, be provided with more than one post and one hole, as the case may be. 
   A unique feature of the “heat stake” of the present invention is the large amount of clearance incorporated into the post and hole fit. It would be understandable if one were to desire to smash the melted post into the hole so as to form them into a single joint held tightly together; that, however, would be a mistake. The rail pad and the abrasion plate should not be assembled tightly together because the rail pad must be free to locate itself around the sidepost insulator. Therefore, the “heat stake” of the present invention is so implemented that there will be a large annular clearance between the post and the hole. The post-melting process will be carefully controlled so that a “mushroom” head is formed on the protruding end region of the post which will block any withdrawal of the post through the hole but will not hinder the rail pad and the abrasion plate from moving freely in relationship to each other within the constraints of the annular clearance between the post and the hole. 
   Another problem addressed by the present invention relates to insufficient longitudinal restraint of the rail. A contributing factor to low longitudinal restraint was thought to be the lack of a positive mechanical lock between the abrasion plate and the rail pad. It will be understood that as the rail moves longitudinally under operational, environmental or maintenance conditions, it tries to drag the rail pad along. The corresponding movement of the rail pad had previously been restrained by a combination of arrangements, such as protruding ears that fit around the shoulders, rectangular upstands that engage the side post insulator, and surface finish modifiers designed into the rail abrasion assembly. 
   The interlocking mechanism of the present invention consists of a pattern of male protrusions on the top face of the abrasion plate and a corresponding pattern of female recesses or depressions on the bottom face of the rail pad. The interlocking features are designed with clearance at initial assembly and positioning. This allows the rail pad and the abrasion plate to take up their corresponding positions in the rail seat region with respect to the differing positions of the shoulders and the side post insulators. 
   The present interlocking feature also affords an additional method of restraining the abrasion plate. As the pad moves longitudinally relative to the abrasion plate, the clearance between the male protrusions and the female depressions is decreased until contact occurs. The multiple points of contact positively lock the abrasion plate and the rail pad together, thereby increasing longitudinal restraint. 
   The present invention also provides another solution to the problem of reducing the ingress of sand and small debris into the interface space between the abrasion plate and the rail seat area of the concrete sleeper. This solution was based on the consideration that the small gap between each side of the abrasion plate and the respective proximate cast shoulder acts as a pocket to trap abrasive contaminates that would eventually find their way under the abrasion plate. These particles trapped between the two surfaces would add to abrasive wear of both the concrete sleeper at the rail seat and the overlying abrasion plate. 
   The mentioned additional solution to this problem is the provision of a positive interference fit from the abrasion plate to the cast shoulders. The dimensional tolerances of the cast shoulders, or sleeves, the dimensional tolerances of the positioning of the cast shoulders on the sleeper, and the dimensional tolerances of the abrasion plate all combine to effectively preclude the achievement of a close precise fit between the abrasion plate and the cast shoulders. Instead of a manufactured close fit, therefore, the solution contemplated by the present invention is to have a thin, flexible protrusion or lip added to each side of the abrasion plate adjacent to the proximate cast shoulder. The lips are designed to interfere with the respective shoulders to the extent of about 0.015″. As the abrasion plate is slipped onto the rail seat and between the shoulders, these thin lips abut against the shoulders and deflect to precisely cover the gaps between the sides of the abrasion plate and the respective shoulders, thereby to seal out the contaminates. The interference fit between these lips and the shoulders also serves to lock the assembly onto the tie for shipping purposes thereby making double sided tape or adhesives to attach the assembly to the tie unnecessary. This arrangement is useful when ties and, the rail clip retaining shoulders or sleeves, and abrasion assembly or assembled in one location and then shipped together to the field. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
       FIG. 1  shows an isometric view of a rail supported by a abrasion assembly and a concrete tie in accordance with this invention; 
       FIG. 2  shows an isometric exploded view of the two parts making up the abrasion assembly; 
       FIG. 3  shows the two parts of the abrasion assembly permanently joined together; 
       FIGS. 4A and 4B  shows a partial cross sectional view of abrasion assembly in the storage/transport and installed configuration respectively with details of the stakes and their distorted heads, taken along lines  4 — 4 in  FIG. 3 ; 
       FIG. 5  shows an enlarged cross sectional view of the interface between the plate and the pad; 
       FIG. 6  shows an alternate embodiment wherein the plate and the pad have matching depressions and protrusions with no substantial clearance; 
       FIG. 7  shows an alternate embodiment wherein the plate is provided with depressions and the pad is provided with matching protrusions; 
       FIG. 8  shows a details of a sealing lip between the plate and the sidewalls of a sleeve; 
       FIG. 9  shows a plan view of an alternate embodiment of the plate; 
       FIG. 10  shows a side elevational view of the plate of  FIG. 9 ; 
       FIG. 11  shows an isometric view of the plate of  FIGS. 9 and 10  with a juxtaposed pad, during assembly; and 
       FIG. 12  shows an isometric view of the completed abrasion assembly of  FIG. 11 ; and 
       FIG. 13  shows a side elevational view of the abrasion assembly of  FIG. 12 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  shows a standard rail  10  with a web  12  and a flange  14  and is supported on a concrete tie  20  by a two-part abrasion assembly  30 . A sleeve  16  is attached to an anchor (not shown) that is imbedded in the tie  20 . The sleeve  16  engages and supports a steel clip  18 . Other clip supports may be used as well. The clip presses down on a wedge  22  which pushes down on the flange  14 . In this manner, the abrasion assembly  30  is sandwiched between the rail flange  14  and the tie  20 . The abrasion assembly includes an erosion plate  32  and a pad  34  described in more details below, 
   As mentioned above, one problem with existing assemblies and ties is that, over time, the surface of the tie  20  disposed under the abrasion assembly  30  is worn away by sand, and other foreign matter, causing a large indentation. Because of this indentation, the abrasion assembly becomes loose and is no longer able to perform its function properly. 
   According to this invention, this condition is repaired as follows. First, the clips  18  are removed from the sleeve  16  and are disengaged from the wedges  22  to free the rail  10 . This process is termed declipping in the art. Next, the rail  10  is raised and then the old abrasion assembly is removed from underneath the tie  20 . Next, a suitable epoxy mixture  25  is applied to the top surface  23  of the tie  20  in the region of the worn surface and a new abrasion assembly  30  is immediately placed onto the still semi-liquid epoxy mixture  25  covering the surface  23 , Soon afterward, the rail  10  is lowered back onto the abrasion assembly  30  and the uncured epoxy  25 . Under the load of the rail  10 , the uncured epoxy mixture  25  is squished out to fill in, and subsequently to cure with an irregular undersurface filling the worn portion of surface  23 . The top portion of epoxy  25  is cured to form a planar upper surface laying flat against the underside of the abrasion assembly  30 , and more particularly to the lower surface  33  of the abrasion plate  32 . The cured epoxy forms a filler which has just the right shape to fill in the irregular gap between the bottom surface of the erosion plate  32  and the worn top surface  23 , and form a physical lock between the abrasion plate and the tie. 
   Some commercially available materials that may be used is an epoxy available form R-Solutions of Denver, Colo. under the name of Concrete Tie Epoxy, but other materials may be suitable as well. 
   Details of several embodiments of the improved abrasion assembly  30  are now described in conjunction with  FIGS. 2–9 . It should be understood that abrasion assembly  30  can be applied on a tie with or without a worn surface  23 . The abrasion plate  32  is made of a high impact plastic material such as polypropylene and has a generally H-shaped outline with a flat portion  40  and may incorporate two transversal sides  42  and  44  (the terms transversal and longitudinal are used herein with reference the longitudinal axis of rail  10 ). 
   The flat section  40  is formed with two rectangular cutouts  46  and  48  designed to wrap around the sleeves  16 , as seen in  FIG. 1 . The side  42  is formed with a flat portion  52  and a slanted portion  50 . The slanted portion  50  is designed to match the slanted wall  26  of the tie. The side  44  has the same shape and size as the portion  42 . The distance between the two sides  42  and  44  is selected so that the erosion plate  32  seats completely on the tie  20  with the flat section  40  and flat portions  52  are in substantially continuous contact with the top surface  23  (when the surface is not worn) with the slanted portions  50  being in substantial contact with the slanted walls  26 . Alternatively, the slanted portions may be dimensioned to form a slight clearance with the slanted walls  26 . 
   The sides  44  are provided with three standoff posts  54 . While the remainder of the abrasion plate  32  is solid, these standoff posts  54  are hollow to save weight and material. The tops of the posts may be formed with buttons  56 . As seen in  FIG. 1 , the buttons have the same thickness as the pad  34 . The buttons  56  may be omitted. 
   The flat section  40  is formed with a pattern of protrusions  58  on its top surface  60  which shall be discussed in more detail below. At the four corners of top surface  60 , the flat section  40  is also provided with coupling stalks  62 . As shown in  FIG. 4A , each stalk terminates with a mushroom shaped head  64 . 
   At the interface between the flat section  40  and the transversal sides  42 ,  44  a shoulder  66  is formed by making the transversal sides  42 ,  44  thicker than the section  40 . This shoulder provides an additional means of increasing the longitudinal restraint and securing the rail pad to the abrasion plate such that pad extrusion and deformation decreases. 
   The rail pad  34  is now described in conjunction with  FIGS. 2 ,  3 ,  4 A and  4 B. It has a generally H-shaped body having a substantially uniform thickness. As with abrasion plate  32 , the pad  34  has two cutouts  72 ,  74  placed substantially in the same position as the cutouts  46 ,  48  so that when the plate  32  and  34  are coupled to each other, these cutouts partially surround the sleeves  26 . 
   At its four corners, the pad  34  has four generally square bosses  76  extending upwardly. The transversal distance W between the bosses  76  is equal to or slightly wider than the width of the rail  10 . The longitudinal distance L between the bosses is slightly larger then the longitudinal length of wedge  22 . 
   In addition, the pad  34  has four holes  78 , each hole matching the position of a respective coupling stalk  62 , a first set of circular dimples  80  on its top surface and a second set of circular dimples  82  on its bottom surface. The two sets of dimples  80 ,  82  have the same size dimples but the dimples  80  are laterally offset and do not fall exactly the top dimples  80 . The dimples need not be circular but could have other shapes as well. 
   As mentioned above, conventionally a rail pad and the corresponding abrasion plate are taped together and therefore difficult to separate in the field. The storage/transport configuration is shown in  FIG. 4A . In this configuration, as the name implies, the pad and the plate are kept together so that they can be stored or transported. The plate  32  and pad  34  are manufactured separately (e.g., by molding), with the stalks  62  being formed without the mushroom head  64 . Once these elements are completed, the pad is superimposed over the pad  32  and they are pressed together causing the tips of the stalks  62  to enter through holes  78  on the pad  32 . The tips are then deformed into heads  64  using a hot cup-shaped element. The heads  64  have a larger diameter than the holes  78  so that, once the heads are formed, the stalks  62  are captured, and the pad is coupled to and cannot be separated from the plate without breaking the stalks (See  FIG. 4A ). Preferably, the head  64  is offset slightly vertically from the pad, and the holes  78  are larger then the diameter of the stalks  62 . These features allow some movement between the pad and the plate that is beneficial while the abrasion assembly is installed. 
   In an alternate embodiment, the stalks  62  and holes  78  have matching dimensions and do not allow any movement between the plate and the pad. In this embodiment, the stalk can be formed with a head  64 B that is closer to the surface of the pad is collapsed around the mouth of the respective holes  78 , as shown in  FIG. 4B . 
   Referring now to  FIG. 5 , in one embodiment of the invention, the abrasion plate  32  is formed with a plurality of depressions  57  on its bottom surface and a plurality of protrusions  58  on its top surface. The protrusions on the bottom surface trap some of the epoxy mixture  25  and further increase the adhesion between the surface of the tie  12  and the abrasion plate  32 . 
   The rail pad  34  is formed with a plurality of circular depressions  80  on the top surface and a plurality of depressions  82  on the bottom surface. The purpose of depressions  80  is to enable modification of the rail pad spring rate, and its damping characteristics. The depressions  82  are arranged to receive the protrusions  58  as shown. Preferably, the depressions  82  are slightly larger than the protrusions so that before the plate  32  and pad  34  are locked into their final positions, they can be shifted around slightly to accommodate various dimensional tolerances. Importantly, even after the plate and pad are in the installed configuration, if the abrasion assembly is installed, the rail  10  is lowered onto the pad  34  so that it is positioned and captured between the bosses  76 . Next, the rail  10  is secured to the tie  20  and abrasion assembly  20  by pins  18  and wedges  22 . The wedges are also captured between the bosses  76 . The sleeves  16  are captured between the cutouts  46 ,  48 ,  72  and  74 . 
   Any slight movement of the rail relative to the abrasion assembly or tie, either longitudinally or transversely, causes the pad  34  to shift in the respective direction slightly, until the edges of the depressions  82  contact the edges of protrusions  58 , as shown in phantom in  FIG. 5 . 
   In other embodiments of the invention, each of the protrusions  58  can be converted into depressions, and each of the depressions can be converted into protrusions (as shown in  FIG. 6 ) to obtain the same result. In another embodiment, shown in  FIG.7 , the pad and plate have matching protrusions and dimples with virtually no clearance therebetween. 
   As discussed above, one pernicious problem with abrasion assemblies has been that sand and other foreign particles get lodged between the plate and the tie and eventually cause indentations in one or both which may compromise the fastening function. It is believed that one source that allows ingress of sand is the spacing between the sleeve  16  (and the supporting anchor-both of which are made of cast ductile iron with relatively large tolerances) and the plate  32 . The interface between the sleeve  16  and plate  32  occurs at the periphery of the cut outs  46 ,  48 . Therefore, in one embodiment of the invention, the plate  32  is provided around the cutouts with a thin lip  88 . The lip  88  is thin enough so that it is flexible, and can be deflected upwardly with respect to the plane of plate  32 . Moreover, the thin lip  88  defines a space that is somewhat smaller than the dimensions of the sleeve  16  and its anchor. Therefore, when the plate  32  is installed in tie  20  and over the sleeve  16 , lip  88  is bent upwards, all around each cutout so that its tip bears against the sidewalls or shoulders  89  of the sleeve  16  as shown in  FIG. 8  thereby forming a seal around the sleeve  16 . This seal insures that sand and other foreign matter is kept away from the interface between the plate  32  and tie  12 . In other words, the lip  88  forms an interference fit with the shoulders  89 . The width of this lip  88  may be in the order of about 0.020″ high (or thick) and may be about 3/16″ wide while the plate adjacent to the lip is about 3/16″ thick. 
   Advantageously, because there is an interference fit provided between the abrasion assembly  30  and the clip sleeve  16 , it is now possible to assemble in a warehouse a tie with clips sleeves embedded therein and an abrasion assembly disposed between the clip sleeves  16 , and then ship these parts together to the installation site. 
   The abrasion assembly discussed so far is preferably used for existing installations, especially where the tie has been worn away, as discussed above.  FIGS. 9–12  show another embodiment of the invention, which is suitable primarily for new installations. However, either embodiment could be used for new and existing installations. 
   Referring now to  FIG. 9 , plate  132  is made of a high impact plastic material such as polypropylene, and has a generally H-shaped outline with a flat recessed portion  140  and two transversal ridges  142  and  144 , which are tapered in width to match the shape of standard railroad ties. 
   The flat section  140  is formed with two rectangular cutouts  146  and  148  performing the same functions as the cutouts  46 ,  48  in  FIG. 1 . 
   The flat section  140  is formed with a pattern of protrusions  158  on its top surface  160 . The bottom surface of the plate  132  can be made with indentations in the same manner as plate  32 , or alternatively, the plate  132  is made with a flat bottom surface, as shown in  FIG. 10 . At its four corners, section  140  is also provided with coupling stalks  164 . The flat section  140  is formed with transversal ridges  142 ,  144 , as an additional method of increasing longitudinal restraint and securing the rail pad to the abrasion plate such that pad extrusion is decreased. 
   Once the plate  132  and pad  134  are formed using standard molding techniques, the pad  134  is placed over the plate with the stalks  164  extending through the holes in the pad  134  as shown in  FIG. 11 . The tips of the stalks  164  are then rounded or otherwise deformed to thereby interlock the plate  132  and pad  134  as shown in  FIGS. 12 and 13 . The pad and plate now form an abrasion assembly that can be stored and shipped efficiently to the railroad installation site. Alternatively, since the plate  132  is also formed with sealing lips (not shown), the abrasion assembly of  FIGS. 12 and 13  can also be inserted between the shoulders of two sleeves on a tie prior to shipping. 
     FIGS. 14A and 14B  show an alternate embodiment of a rail pad. This rail pad  234  may mounted on and together with a standard abrasion plate (not shown). The pag has four bosses  276  and a plurality of transversal indentations  290 . Along its sides, the pad  234  has two indentations  272 ,  274  sized to fit around respective sleeves  16  (shown in  FIG. 1 ) or other similar clip support members. Importantly, as best seen in  FIG. 14B , the indentations  272 ,  274  are provided with respective peripheral sealing lips  288 . These lips seal the tie under the pad  234  (and the abrasion plate) from sand and other impurities, in a manner similar to the lips  88  discussed above. Similar lips may also be provided on pads  34  and  134 . The lips on the pads may be about 3/16″ wide and about 0.050″ thick while the lad itself is about ¼″ thick. 
   To summarize, a novel abrasion assembly is disclosed that includes means of securing the abrasion assembly to a concrete tie, securing and coupling the parts of  234  the abrasion assembly together, sealing the abrasion assembly around the sleeves holding the pins, securing the rail to the abrasion assembly, and securing and coupling the abrasion assembly to a tie in a factory or assembly line prior to shipping. These means include the use of epoxy mixture between the plate and the tie, the provision of protrusions or indentations on the bottom surface of the plate, provision of side portions on the plate positioned over the respective inclined walls of the tie, the provision of matting protrusions and dimples or depressions at the interface between the plate and the pad, the provisions of the stakes on the plate and the matching holes in the pad, provision of the heads on the stakes, provision of the bosses on the pad that capture both the rail and the wedges, provision of a sealing lip around critical areas of the sleeve, etc. 
   While the invention has been described with reference to several particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles of the invention. Accordingly, the embodiments described in particular should be considered as exemplary, not limiting, with respect to the following claims.