Patent Publication Number: US-6702192-B2

Title: Rail retaining device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation-in-part of application PCT/CA99/00966 filed Oct. 13, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to rail retaining devices for incorporation in a rail track. 
     BRIEF SUMMARY OF THE INVENTION 
     The invention provides a rail retaining device comprising a shoulder member for bearing on a lateral side of a rail flange, and providing a downwardly facing abutment surface, and a rail clip in the form of a bent rod symmetrical about a vertical plane for extending laterally of the rail and having an inner portion for bearing on an adjacent flange in an installed position, intermediate limb portions for bearing upwardly on the downwardly facing abutment surface, and an outer portion connected to each intermediate limb portion for extending outwardly from said abutment surface and curving laterally arcuately outwardly and downwardly toward a lower portion adapted to bear on a bearing surface, and wherein in said installed position there is a reaction between the intermediate limb portions and the downwardly forcing abutment surface flexing the intermediate limb portions resiliently downwardly. 
     The arrangement of the invention provides excellent stress distribution and avoids stress concentrations that can contribute to premature failure in known clips. Further, the clip is compliant and tolerant of dimensional variation in the components and is relatively easily to install, while providing a highly effective and durable rail retaining function. 
     Preferably, the lower portion of the clip is adapted to bear on a bearing surface at a region that is offset laterally inwardly from a centre of curvature of the outer portion. This further improves the stress distribution through the clip in service. 
     In a preferred form, the inner portion comprises an upwardly bowed portion adjacent the abutment surface that provides increased resistance to migration of the clip outwardly from its installed position as a result of impacts or vibration encountered in service. 
     Preferably, each lower portion of said outer portions inclines longitudinally with respect to said vertical plane, whereby squatting of the outer portion is facilitated during installation, rendering the clip particularly compliant and facilitating installation. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     Examples are described in more detail hereinafter, by way of example, with reference to the accompanying drawings. 
     FIGS. 1,  2  and  3  show side, top and isometric views of installed rail retaining devices in accordance with a first embodiment of the present invention. 
     FIG. 4 shows an isometric view of the clip employed in the arrangements of FIGS. 1 to  3 . 
     FIGS. 5,  6 ,  7  and  8  show top, isometric, side and front views of a second embodiment of a rail clip in accordance with the invention. 
     FIG. 9 (which appears on the same sheet as FIG. 4) shows an isometric view of a third embodiment of the rail clip. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings, wherein like reference numerals indicate like parts, FIGS. 1 to  3  show a fastening arrangement employing a steel tie  20 , electrically insulating cant plate  50  and hook-in field and gauge shoulder members  60  and  70 , respectively, these elements being generally as and installed as described in, applicant&#39;s published application WO 96/23107, which should be referred to for further details and the disclosure of which is incorporated herein by reference. 
     While the clips described herein are preferably employed with the above described shoulder members, it is contemplated they may be used with other shoulder members providing a downwardly facing abutment surface. 
     In the installed position, as seen in FIGS. 1 to  3 , clips  80  extend through openings  61  and  71  in the shoulder members  60  and  70 , respectively, and bear upwardly on a downwardly facing abutment surface provided on an upper side of the opening  61  or  71 , for example on surface  62  as shown in broken lines in FIG.  1 . An end portion  81  of the clip  80 , disposed laterally inwardly of the clip  80  with respect to a rail  30  bears on a rail flange  31  either directly, or, more usually, through an electrical insulator pad  90  interposed between the rail flange  31  on the one hand and the clip  80  and the shoulder  60  or  70  on the other. 
     A laterally outer end of the clip  80  engages on a bearing surface, for example a laterally outer extension  63  or  73  of the shoulder  60  or  70 . Preferably, the upper surface of the extensions  63  or  73 , as well as the lower side of the opening  61  or  71 , inclines upwardly laterally inwardly to provide an inclining ramp surface facilitating installation by guiding the clip  80  upwardly on to the upper side of the flange  31 . 
     Also visible in FIG. 1 are the hook-in leg portions  64  and  74  formed integrally with shoulders  60  and  70 , respectively, and that are passed through openings in the tie  20  and secure the shoulder portions  60  and  70 , to the tie  20  For details of the arrangement of the hook-in leg portions and of the openings in which they are received, reference should be made to WO 96/23107 referred to above. 
     As seen in more detail in FIG. 4, the clip  80  is of bent rod form. This bent rod clip  80  has an advantage over similar plate form clips that it is not subject to failure by delamination. The clip  80  is symmetrical about a vertical plane  82 , indicated in FIG. 2, extending laterally of the rail  30 , with the inner portion  81  for bearing on the rail flange, intermediate limb portions  83  for engaging upwardly on the downwardly facing abutment surface such as surface  62 , and an outer portion  84  curving laterally arcuately outwardly and downwardly and for bearing on a bearing surface such as an upper surface  66  of the extension  62  or  72 . 
     In the installed condition, as seen in FIGS. 1 to  3 , the downwardly facing abutment surface, for example surface  62 , engages the intermediate portions  83  of the clip  80  and the downward reaction with the surface  62  flexes the portions  83  downwardly with respect to the inner and outer portions  81  and  84 . There is therefore corresponding upward reaction at the inner and outer portion  81  and  84 . The reaction at the inner portion  81  applies a toe load to the flange  31  while the outer portion  84  tends to flex resulting in compression of the outer portion. 
     It has been formed that this arrangement results in surprisingly excellent stress distribution and avoids stress concentrations that would tend to lead to premature failure of the clip. It is believed that the stress distribution results from the stress reversals that occur through the length of the clip  80 . That is to say at the inner and outer portions  81  and  84  there are upward reactions on the clip  80  while in the intermediate portion  83  there is a downward reaction acting on the clip. The stress distribution is further improved by having the lower portion of the outer portions  84  bear on the bearing surface  63  along a substantial part of their length, as best seen in FIG. 1, at a region that is offset laterally inwardly from the centre of curvature of the outer portion  84 . 
     In preferred form, the inner portion  81  of the clip  80  includes upwardly bowed portions  86  that reacts with the surface  62  to provide a reaction having an inwardly directed component of force on uplift of the rail flange  31 , so that vertical vibration or oscillation of the flange  31  creates forces tending to resist migration of the clip  80  outwardly from the shoulder  60  or  70 . Desirably, in the non-compressed or free, non-installed condition of the clip  80  as best seen in FIG. 7, a sloping side of the upwardly bowed portion  86  at its side adjacent the surface  63 , defines with the lower side of the lower portion  107  (or a line S drawn tangential to the lowermost portion thereof) a positive angle θ. That is, lines T and S intersect at a point laterally outwardly of portion at an angle greater than 0° and less than 90°, preferably about 10° to 30°, more preferably about 15° to about 25°, and still more preferably about 20°. 
     In the preferred form, each lower portion  84 , as best seen in FIG. 2 inclines longitudinally with respect to the vertical plane  82 , so that during installation, when the clip  80  is driven inwardly through the opening  61  or  71 , the portions  84  can twist sideways relative to the remainder of the clip  80 , so that the lower outer portion of the clip  80  compresses or squats. This renders the clip  80  particularly compliant and easy to install. In the example illustrated in FIGS. 1 to  4 , the portions  84  are toed inwardly. Once installed, the clip  80  of FIGS. 1 to  4  resists rail uplift since squatting is limited by the portions  84  approaching and touching one is another. 
     In a preferred form of clip  100 , shown in FIGS. 5 to  8  the lower portions  107  are toed outwardly. This arrangement provides a wider footprint and greater stability for the clip during installation, and reduces any tendency for the clip to spring outwardly from the shoulder when driven inwardly relative to the shoulder. The clip  100  is otherwise similar to that described above with reference to FIGS. 1 to  4 . Clip  100  may be used with shoulders having extensions such as extensions  63 , having anti-squat side wall members, such as raised walls  108  as seen in FIG. 3, disposed longitudinally outwardly from lower portions  107 . The walls  108  limit outward movement of portions  107  and limit the extent of squatting when uplift of the flange  31  occurs. 
     Clip  110  shown in FIG. 9 is similar to clips  100  except extensions of lower portion  84  or end portions  108  extend upwardly and abut the outer side of the shoulder and extend above the upper edge of the shoulder such as shoulder  60  in the installed position. The exposed upper ends of the portion  108  may be engaged by tools to facilitate removal of the clips when desired. 
     In use the clips  80 ,  100  and  110  may be installed by laying their inner ends  81  loosely in the openings  61  or  71  and driving the clips inwardly with an inwardly directed force applied to the end of the outer portions until the upwardly bowed portion snaps past downwardly facing abutment surface such as surface  62  as the inner end portion  81  rides up the flange  31  or pre-installed insulator  90 , and the intermediate portion  83  is flexed resiliently downwardly.