Abstract:
A crossing frog includes: a cradle assembly which includes a movable point fitting component which has two projection elements which are mutually spaced-apart, a movable point which is mounted in the cradle assembly and fitted in the fitting component, spacer components which are interposed between the projection elements and the movable point, and accommodation for removably fixing the movable point in the fitting component. The spacer components are fixed to the projection elements in a removable manner by the accommodation for removable fixing so that it is possible to remove the point in a vertical direction relative to the cradle assembly.

Description:
FIELD OF INVENTION 
   The present invention relates to a movable point crossing frog for a rail track, comprising:
         a cradle assembly which comprises a movable point fitting component which has two projection elements which are mutually spaced-apart,   a movable point which is mounted in the cradle assembly and fitted in the fitting component,   spacer components which are interposed between the projection elements and the movable point, and   means for removably fixing the movable point in the fitting component.       

   BACKGROUND 
   Generally, the design of known crossing frogs does not allow the movable point to be removed and replaced on the track (in situ) when it is worn or damaged. 
   For example, the crossing frogs described in patent FR 2 788 535 comprise spacers which are formed in one piece with the projection elements. Removing the movable point from the fish-plate chamber can thus be carried out, for crossing frogs of this type, only in the main direction of the track, that is to say, axially. This removal requires the fitting component to be removed beforehand, fixedly joined to the movable point, the removal of the movable point then being carried in the workshop and not in situ, which requires the worn or damaged frog to be removed and replaced with a replacement part of the same type. 
   A maintenance operation of this type not only involves very high cost, but also the track being closed for a very long period of time. 
   The object of the invention is to overcome this disadvantage and to make it possible to carry out a maintenance operation of this type in situ in order to very significantly reduce the duration and the cost of the maintenance operation. 
   SUMMARY OF INVENTION 
   To this end, the invention relates to a crossing frog of the above-mentioned type, in which the spacer components are fixed to the projection elements in a removable manner by the means for removable fixing, so that it is possible to vertically remove the point relative to the cradle assembly. 
   According to optional features of the invention:
         the means for removable fixing comprise assembly elements which each have a threaded transverse shank which is fastened to the two projection elements and which, in cross-section, extends through the projection elements, the spacers and the movable point;   the assembly elements each have a bush assembly in which the threaded shank is mounted, the bush assembly extending at least partially, in cross-section, through the projection elements, the spacers and the movable point;   the crossing frog comprises, for each spacer component, at least one security shim which is fixed to a projection element in a removable manner, for example, by means of screwing, in abutment against an upper face of the spacer component so as to limit the vertical displacement of the point;   the cradle assembly comprises   a cradle at the side of the point end,   the fitting component at the side of the projection end, and   two intermediate elements which connect the cradle to the two projection elements, respectively, and   the fitting component has a support plate which extends between the two projection elements and which supports the movable point.       

   According to a first embodiment of the invention:
         the support plate is produced in one piece with the two projection elements;   the fitting component is constituted by a unitary projection component, in particular cast from steel or special cast iron; and   the projection component is assembled on the two intermediate elements by means of welding or by means of adhesively-bonded joints.       

   According to a second embodiment of the invention:
         the support plate is a separate component from the two projection elements; and   the two projection elements are produced by processing the two intermediate elements.       

   
     BRIEF DESCRIPTION OF DRAWINGS 
     Embodiments of the invention will be described in greater detail below with reference to the appended drawings, in which: 
       FIG. 1  is a schematic plan view of a crossing frog according to the invention, positioned on a track; 
       FIG. 2  is a partial plan view of a crossing frog according to a first embodiment of the invention; 
       FIG. 3  is an enlarged section, taken in plane  3 - 3 , of the crossing frog of  FIG. 2 ; 
       FIG. 4  is a view similar to  FIG. 2  of a crossing frog according to a second embodiment of the invention; and 
       FIG. 5  is an enlarged section, taken in plane  5 - 5 , of the crossing frog of  FIG. 4 . 
   

     FIG. 1  schematically illustrates a crossing frog  1  according to the invention, positioned on a track, in a state for use. 
   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   In the remainder of the description below, the crossing frog will be assumed to be in its horizontal position for use and all the terms relating to directions and positions should be understood in accordance with this orientation. 
   In particular, the terms “horizontal” and “vertical”, which may qualify specific components of the crossing frog, should be understood in accordance with a horizontal position for use of the crossing frog. 
   Furthermore, the terms “axial” and “transverse” should be understood relative to the general direction of the track. 
   With reference to the schematic view of  FIG. 1 , the crossing frog  1  substantially comprises a cradle assembly  3  which is fixed to the cross-pieces, and a movable point  5  which is mounted in the cradle assembly  3 . 
   The cradle assembly  3  is substantially constituted by a point cradle  11 , a fitting component  12 , and an intermediate component  13  which connects the fitting component  12  to the point cradle  11 . 
   At one point end, the cradle  11  has two regions  21 ,  22  which are arranged symmetrically at one side and the other of the vertical axial plane. 
   These regions  21 ,  22  have, in cross-section, respective forms which are symmetrical relative to the vertical axial plane of the cradle  11  and have a rail-like profile. 
   Two lengths  21 A,  22 A of rail are welded to the regions  21 ,  22  of the point end of the cradle  11 , respectively, each of these lengths having a rail-like profile identical to that of the corresponding end region  21 ,  22 . 
   In the same manner, the cradle  11  has, at the projection end thereof, two regions  23 ,  24  which are arranged symmetrically at one side and the other of the vertical axial plane, these regions  23 ,  24  having, in cross-section, respective forms which are symmetrical relative to this plane. 
   The intermediate portion  13  comprises two intermediate elements  33 ,  34  which each have a rolled rail-like profile or cast elements whose ends are identical to those of the corresponding region  23 ,  24 . 
   The fitting component  12  correspondingly comprises two projection elements  35 ,  36  whose profile ends correspond to those of the intermediate elements  33 ,  34  and extend the intermediate elements  33 ,  34 , respectively. 
   The cradle assembly  3  further comprises, generally as a plurality of assembled components, a base wall which extends horizontally between the profiles defined by the end regions  21 ,  22 ,  23 ,  24 , the intermediate elements  33 ,  34  and the projection elements  35 ,  36 . The movable point  5  rests on this base wall when it is mounted in the cradle assembly  3 . 
   The movable point  5  comprises a tapered free end region  41  (or point end) having a profile which is provided in order to ensure continuity of the guiding surface, selectively with one or other of the point regions  21 ,  22  of the cradle  11 , in accordance with the position of the point end  41 . 
   As will also be seen more clearly with reference to  FIGS. 3 and 5 , the movable point  5  comprises two rails  43 ,  44  having a special profile having a thick web  46  which has a mushroom-like member  47  and a reinforced runner  48 . These rails  43 ,  44  extend so as to converge towards the point end  41 , this being constituted at the end of one of the two rails. 
   The movable point  5  has a fitting section  49  which is fixed in the cradle assembly  3  by means which will be described below. 
     FIGS. 2 and 3  illustrate a first embodiment of the invention, in which the fitting component  12  is constituted by a unitary cradle. For example, this unitary cradle  12  is produced by means of casting from steel or special cast iron, and the projection elements  35 ,  36  thereof are assembled with the respective intermediate elements  33 ,  34  by means of welding or by means of adhesively-bonded joints. 
   As illustrated in  FIG. 2 , the cradle assembly  3  is fixed to cross-pieces  50  by means of fixing devices which are all generally designated  51  but which may be of a different type for each of the elements of the cradle assembly  3 , that is to say the cradle  11 , the fitting component  12 , and the intermediate component  13 . The invention does not relate to these fixing devices and they are therefore not described in greater detail. 
   As can be seen in  FIG. 3 , the unitary cradle  12  which forms a fitting component has a support plate  55  which forms a base wall, on which the runners  48  of the two rails  43 ,  44  which form the movable point rest. 
   The support plate  55  which is formed in one piece with the projection elements  35 ,  36  defines, with the projection elements  35 ,  36 , a generally U-shaped cross-section of the cradle  12 . The support plate  55  is extended laterally, externally relative to the projection elements  35 ,  36 , by means of outer rims  57  which allow it to be fixed to the cross-pieces  50  of the cradle  12  using the fixing devices  51 . 
   The two rails  43 ,  44  are mutually secured by means of a spacer  60  which conforms to the inner profile portions thereof and is supported thereon. 
   In order to ensure the fixing and securing of the movable point  5  in the region of the section  49  thereof in the cradle  12  (or fitting component), the crossing frog  1  comprises removable fixing and securing means  61 . 
   These means  61  comprise spacer components  63 , of which there are four in the example illustrated in  FIG. 2  and which are arranged in pairs facing each other each side of the movable point. 
   Each spacer component  63  has a generally parallelpipedal form which is axially elongate. The two spacer components  63  of the same pair are substantially symmetrical relative to the vertical axial plane and each secure one of the two rails  43 ,  44  on the corresponding projection element  35 ,  36 . 
   Each spacer component  63  is supported, by means of an outer lateral face, on an inner face of the corresponding projection element  35 ,  36  and, by means of an inner lateral face, on an outer side of the web  46  of the corresponding rail  43 ,  44 . 
   The spacers  63  have a shape which is suitable for co-operating, by means of complementary shape over the entire axial length of the spacer, with a portion of the outer profile of the respective rail  43 ,  44 , this portion comprising the upper surface of the runner  48 , the outer surface of the web  46 , as far as the transition surface between the web  46  and the mushroom-like member  47 . 
   Transverse holes  69 , for example, four per spacer, extend coaxially through the projection elements  35 ,  36 , the webs  46  of the rails  43 ,  44 , the spacer  60  and the spacer components  63 . These holes  69  are offset axially relative to each other in the example illustrated; they are illustrated by means of dot-dash lines in  FIG. 2 . 
   The fixing and securing means  61  comprise, for each hole  69 , a fastening bolt  70 . 
   The bolt  70  comprises a screw  71  whose head  72  is supported on an outer face of a projection element  36 , by means of washers  73 , and whose threaded shank  75  extends coaxially through the hole  69 . The bolt  70  further comprises a nut  77  which is fastened to the threaded end of the threaded shank  75  and which is supported on an outer face of the other projection element  35  by means of washers  79 . The fastening of the nut  77  on the screw  71  is secured by means of a brake nut  80 . 
   The fixing and securing means  61  further comprise a bush assembly which is arranged coaxially between the threaded shank  75  and the inner face of the hole  69 . This bush assembly comprises a central cylindrical sleeve  81  which is arranged in the hole of the spacer  60 , and two pins  83  (preferably of the Mecanindus® type). These pins  83  are each engaged in a section of the hole  69  formed in a projection element  35 ,  36 , a spacer component  61 , and a rail web  46 , at one side and the other of the central sleeve  81 . 
   Each bolt  70  defines, with the bush assembly  81 ,  83 , a removable assembly element which, when used, is fastened to the two projection elements  35 ,  36  by securing, in a transverse manner with no possibility of significant transverse play, the movable point  5  between the projection elements  35 ,  36  by means of the spacer components  63 . 
   The fixing and securing means  61  comprise, in the example illustrated, although this is optional, security shims  89  which are associated with each spacer component  63 . Each shim  89  is fixed in a removable manner, in this instance by means of screws  90 , to a respective projection element  35 ,  36 , in an upper portion of the projection element. The shim  89  protrudes towards the inner side of the cradle  12  and is supported, by means of a lower face, on an upper face of the corresponding spacer component  63 . 
   The shims  89  are provided in order to limit the vertical displacement of the spacer components  63  during actual use of the crossing frog, so as to reduce the vertical movements of the point  5  if one or more bolts  70  become(s) loose. 
   It should be understood that the movable point  5  may be removed vertically (in direction Z indicated in  FIG. 3 ) from the fitting position thereof, after removing the fixing and securing means  61 . 
   In order to remove the movable point  5  from the cradle assembly  3 , operators may proceed in situ in the following manner:
         releasing the ends of the rails  43 ,  44  by separating them from the conventional track;   removing the shims  89  by removing the screws  90 ;   removing the bolts  70  with their bush assembly  81 ,  83  (using appropriate means, such as hydraulic jacks);   vertically removing, in direction Z, the movable point  5  with the spacer components  63 .       

   After replacing the damaged movable point, the movable point is reassembled in reverse order which it is not necessary to set out in detail. 
   The second embodiment of the invention illustrated in  FIGS. 4 and 5  differs from the first embodiment described above only in that the fitting component  12  is not defined by a unitary cradle. 
   In this embodiment, the support plate  155  is a separate component from the two projection elements  35 ,  36  which are obtained by processing the respective intermediate elements  33 ,  34 . The support plate  155  is preferably produced from a different material from that of the projection elements  35 ,  36  and is fixed to the support independently thereof. 
   It should be noted in particular that the spacer components  63  and the means  61  for fixing and securing the movable point in the fitting component  12  are, in all respects, similar or identical to those described in the first embodiment. They will therefore not be described again. 
   It should be noted that the cradle  11  is preferably produced by means of casting techniques and cast from alloyed steel, in particular from cast manganese steel which is hyper-quenched and, optionally, pre-hardened. It is processed over all the rolling, contact, sliding or connection surfaces. 
   The two rail lengths  21 A,  22 A which form part of the crossing frog are rail profiles of rolled carbon steel or lightly alloyed steel and are connected to the cradle  11  by means of welding, optionally using inserts. 
   The intermediate elements  33 ,  34  are preferably produced in the form of a rail or from cast carbon steel or lightly alloyed steel which has a mechanical strength similar to that of the rails, and which allows them to be welded to the cradle  11 , optionally using an insert.