Patent Publication Number: US-6986470-B2

Title: Rail mount

Description:
CROSS REFERENCE TO RELATED APPLICATION 
   This application is related to the provisional application No. 60/420,588 filed 23 Oct. 2002 and claims the benefit thereof under 35 USC 120. 

   FIELD OF THE INVENTION 
   The present application relates to a rail mount having a compression base plate and, more particularly, to an improved rail mount assembly in which the base plate is an elastomeric body bonded to a frame and to a top plate carrying the rail. 
   BACKGROUND OF THE INVENTION 
   In earlier configurations of rail mounting assemblies having an elastomeric body under compression, a metal frame and a top plate, there have been problems in the development of stress and strain in the elastomer which have resulted in tearing or separation of the elastomer and reduced life. 
   OBJECTS OF THE INVENTION 
   It is the principal object of the present invention to provide an improved rail mount with increased life and enhanced performance. 
   Another object of the invention is to provide a track fastener which can be accommodated to various load requirements and is more versatile and effective than earlier track fasteners. 
   SUMMARY OF THE INVENTION 
   These objects are achieved, in accordance with the invention in a track fastener which comprises:
         a generally rectangular top plate formed with a central rail receiving surface on a top of the top plate flanked at opposite ends of the receiving surface by eyes adapted to receive e-clips for securing a rail to the rail mount on the receiving surface, the top plate having a planar bottom surface, the receiving surface being canted with respect to a plane of the bottom surface, the top plate having upwardly extending ribs over a full width of the top plate at opposite ends thereof, each rib having an outer flank perpendicular to the plane, an inner flank inclined at an angle of substantially 30° to 60° to a vertical, and a rounded junction between the flanks;   a frame having a rectangular opening receiving the top plate with all-around clearance, the frame having a bottom surface spaced below the bottom surface of the plate and defining a cavity underlying the plate and communicating with the all-around clearance, the frame being further formed with hoods at opposite ends thereof reaching inwardly over the ribs and spaced above the ribs, and with four outwardly extending lugs located respectively along opposite longitudinal sides of the frame at each end thereof, the lugs being formed with openings enabling the passage of anchor bolts for securing the rail mount to a support; and   a body of elastomer bonded to both the top plate and the frame at all surfaces of the top plate and the frame contacted by the body of elastomer, the body of elastomer filling the cavity and the clearance and having a bottom formed with spaced apart pads of the elastomer and bearing load against the support varying as a train rides over the rail, the elastomer filling gaps between the hoods and the ribs and extending downwardly along the inner flanks. The inner flank angle may be 45°±7° in a preferred embodiment of the invention.       

   According to a feature of the invention, the pads are elongated in a direction perpendicular to a longitudinal axis of the rail mount, are of generally oval configuration and are arranged in a plurality of rows, preferably two, parallel to this axis. In particular, each of the pads may extend over at least ⅓ of the width of the body of elastomer which forms the bottom of the body and is juxtaposed with the support surface. 
   The elastomer is selected from the group which consists of natural rubber, synthetic rubber, mixtures of natural and synthetic rubber and silicone rubber and synthetic resins. 
   It has been found to be of considerable advantage for the hoods to have curved inner surfaces juxtaposed with the ribs but with radii of curvature of at least 5 mm. In earlier systems in which hoods were provided above a top plate, they had substantially smaller internal radii of curvature. 
   The elastomer on the inner flanks should taper in thickness downwardly to the top surface of the top plate and should have an outer concave face. The elastomer should also reach over the upper surface of the hood down to a ledge of the frame. 
   Each of the inner flanks also terminates at the top surface of the top plate and the receiving surface should have its lowest point above the top surface. The receiving surface should have a cant or tilt to the horizontal of a ratio of about 1:20. 
   The system of the invention has a number of significant advantages over earlier track fastener designs. Firstly, the track fastener of the invention can have vertical and/or lateral stiffness which can be tuned to the various requirements of the track fastener since the pads engage the support surface below the track fastener at different times during deflection caused by the passage of a train. As the track fastener senses increased axial loads from a passing train there is a corresponding increase in deflection of the elastomer body which causes a greater number of the pads to become supporting and as the number of pads which become supporting increases and the pads come under compression, the stiffness increases. The track fastener is thus particularly beneficial for tracks serving mixed axle loads, e.g. vehicles which are fully located or unloaded and commuter or freight or return traffic. 
   The track fastener of the invention also is effective in case of deterioration of the elastomer bond since the frame safely restrains lateral, longitudinal and uplift movements of the top plate. 
   The fact that four anchor bolts are used likewise provides excellent security and distribution of hold down forces. 
   All of the forces and vibrations reaching the frame are buffered by the elastomer body and anchor bolt failure is reduced. Since the receiving surface is located above the top plane or surface of the top plate, the rail cannot contact or abrade the top surface of the elastomer. 
   The system can allow vertical and lateral stiffness characteristics to be changed at a minimum cost by simply altering the characteristics of the elastomer. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
     The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the accompanying drawing in which: 
       FIG. 1  is a plan view of the assembly; 
       FIG. 2  is a section taken along the line II—II of  FIG. 1   
       FIG. 3  is a section taken along the line III—III of  FIG. 1 ; 
       FIG. 4  is a bottom plan view of the assembly; 
       FIG. 5  is a section taken along the line V—V of  FIG. 4 ; 
       FIG. 6  is a top plan view of the frame member; 
       FIG. 7  is a section along the line VII—VII of  FIG. 6 ; 
     FIG.  8 . is a section along the line VIII—VIII of  FIG. 6 ; 
       FIG. 9  is a section along the line IX—IX of  FIG. 6 ; 
       FIG. 10  is a plan view of the top plate; 
       FIG. 11  is a side elevational view of the top plate; 
       FIG. 12  is a section along the line XII—XII of  FIG. 10 ; 
       FIG. 13  is a section along the line XIII—XIII of  FIG. 10 ; 
       FIG. 14  is a detail XIV of  FIG. 11 ; 
       FIG. 15  is an enlarged cross sectional view of a portion of the assembly; and 
       FIG. 16  is a plan view of the track fastener showing a rail attached to the track. 
   

   SPECIFIC DESCRIPTION 
   As can be seen from  FIGS. 1-5 , the compression base plate assembly comprises an outer frame  10  having outwardly extending lugs  11  through which bolts can pass and which has a toothed portion  12  surrounding the slot  13  through which the bolt passes. The toothed portion is shown in section in FIG.  9 . 
   The frame receives a body  1  of an elastomer (e.g. rubber neoprene) which is bonded (e.g. vulcanized) to the frame  10  and to the top plate  15 . 
   The frame  10  (see especially FIGS.  6 - 9 ), has a pair of hoods  16  and  17  overhanging an opening  18  in the frame. The opening  18  is rectangular as can be seen from FIG.  6 . 
   The top plate  15  can have an inclined platform  20  upon which the base of a rail can rest and tubular bosses or bushes  21  flanking the platform to receive fastening elements for securing the rail in place. The top plate  15  is of rectangular configuration and has ridges  22  and  23  at its ends, adapted to lie below the inner extremities of the hoods  16  and  17  (see especially FIGS.  2  and  5 ). The ribs  22  and  23  are radiused along their tops  24  and bases  25  where the ribs merge into the upper surface  26  of the top plate which is generally planar. The hoods  16  and  17  have radiused edges  27  and radiused inner faces  28  as can be seen from FIG.  15 . 
   The elastomeric body  14  forms a base plate  29  having grooves  30  ( FIG. 15 ) separating islands  31  with which the base plate rests upon a support surface. In addition, the body  14  comprises elastomeric framing parts  32  integral with the elastomeric base plate and rising along the edges of the top plate  15  (see especially  FIGS. 2 and 15 ) and along the inner wall  33  defining the opening  18  in the frame  10 . 
   The frame portions  32  of the elastomer passes over the ridges  24  into the arcuate portion  25  and terminates just short of a vertical wall  34  of the central portion  35  of the top plate. The elastomeric material also overhangs the hood  16  or  17 , reaching outwardly over the outer surface  37  thereof to terminate at  38  at a ledge of the frame just short of the outer periphery of the frame. As noted, the elastomeric material is vulcanized or bonded to both the top plate  15  and the frame  10  at the surfaces at which the elastomer is in contact with them. The surface  40  of the elastomer between the hood and the bottom  41  of the channel between the rib  22  and  23  and the central portion  35  is of a concave and inclined contour. With this configuration of the elastomer and the rib and hood parts as described, stress and strain in the elastomer with cyclically reversing loads is effectively countered to prevent damage to the elastomer. The underside hood radius of the invention has been increased significantly over that commonly provided (up to 5 mm), resulting in a reduction of bond stress. The downward and inward inclination of the elastomer at the upper surface of the top plate likewise enables the mount to better survive cyclic oscillating loads reversing from tension to compression. 
   In  FIG. 16 , a rail  50  is shown to be secured to the top plate  15  by e-clips  51  engaged in the tubular bosses  21  and having ends  52  bearing on the flanges  53  of the rail. The e-clips can be welded to the rail. 
   The track fastener is shown in  FIG. 16  to be held onto the support surface  54  by bolts  55  having oval washers  56  bearing upon the serrated margins  12  surrounding the slots  13  through which the respective bolts pass.