WO2011094825A1

WO2011094825A1 - Electric insulation for a vibration isolator with an elastic boot for continuously supported rails

Info

Publication number: WO2011094825A1
Application number: PCT/BE2011/000005
Authority: WO
Inventors: Patrick Carels
Original assignee: Cdm N.V.
Priority date: 2010-02-03
Filing date: 2011-02-03
Publication date: 2011-08-11
Also published as: BE1019172A5; EP2531653A1; EP2531653B1; HUE028980T2

Abstract

Vibration isolator with an elastic boot for continuously supported rails which are embedded in a railway bed, whereby the rails have a rail head (4) and a rail foot (5) which are mutually connected by means of a rail body (6), whereby the elastic boot extends in the longitudinal direction of the rail over practically the full length of the rail, fits closely to the rail and envelops it practically entirely, leaving at least a top side (24) of the rail head (4) accessible, such that a railway vehicle can move over the latter, whereby an electrically insulating layer (20) is provided between the elastic boot and the rail which practically entirely envelops the full length of the rail and only extends up to a distance from the rail head (4).

Description

Electric insulation for a vibration isolator with an elastic boot for continuously supported rails

The invention concerns a vibration isolator with an elastic boot for continuously supported rails which are embedded in a railway bed, whereby the rails have a rail head and a rail foot which are connected by means of a rail body with two sides having each a lateral cavity extending over the full length of the rail between the rail head and the rail foot.

The elastic boot fits closely to the rail and extends over practically the full length of the rail. It envelops the rail almost entirely, leaving the top side of the rail head accessible, such that a railway vehicle can move over it.

Thus, the elastic boot may consist of preferably at least three parts, namely a first and a second part which mainly extend in the lateral cavities on either side of the rail body and a third part which mainly extends under the rail foot. Further, this third part also fits closely to the first and second part of the boot.

The elastic boot is sufficiently rigid, making sure that the rail can rest on it and is kept in place in a groove in the railway bed, which is preferably made of concrete. Thus, the rail is clamped in this groove by the elastic boot and, preferably, no additional fastening means are thereby required for fixing the rails to the railway bed.

According to the present state of the art, such elastic boots are clamped against the rail, after which the latter is embedded in a concrete railway bed. Alternatively, these boots are glued to one another and/or to the rails by means of adhesive. Possibly, the elastic boot may also be formed by casting the elastic material in a mould round the rail.

Patents DE4004208, DE4344815 and EP0854234 describe a boot which is mainly formed of three elastic parts which are fixed to the rail by means of additional fastening means.

European patent EP1807569 also describes such a boot which is formed of three parts being clamped to the rail by means of additional external clamping means, after which this rail is embedded in concrete together with the boot. Further, this patent describes a method for installing and embedding a rail in a railway bed at a railway site. The rails which are enveloped by an elastic boot are hereby put in a correct position in relation to one another by means of installation bridges over the railway to be installed. To this end, the rails with the elastic boot are clamped under the rail head by means of claws via the flanks of the boot and suspended under the installation bridges. It is also possible for these enveloped rails to be supported via the rail foot. The railway bed is subsequently provided round the enveloped rails. Hereby must be borne in mind that the claws will have to be removed so as to be able to also provide material from the railway bed against the flanks of the boot where said claws are situated.

For electrified tracks it is also important to electrically insulate these tracks sufficiently from the railway bed to prevent any possible leakage currents and/or to sufficiently insulate the adjacent rails from one another in case these rails are used for example for signalling purposes. Said signalling may for example include the detection of a railway vehicle being present. Recently, there has been a clear evolution towards imposing technical specifications regarding the electric insulation of the rail. These specifications provide for significantly higher electrical resistance values than has hitherto been customary. Whereas 0.4 Ohm/km was customary a few years ago, values of 2 to 10 Ohm/km are required now. Thus, although these existing elastic boots also have electrically insulating qualities, major leakage currents still occur. This may also be due to a bad or inaccurate installation or to moisture seeping in.

Existing elastic boots are disadvantageous in that, when embedding the rails which are covered with said boots, one must bear the clamping means in mind, since they must be either removed during the embedding in concrete or they must be embedded in the concrete together with the rail and the boot. These clamping means may also cause electric leakage currents.

The invention aims to remedy these disadvantages by proposing a vibration isolator and a method making it possible to provide a vibration-isolating elastic boot in a simple manner on the rails and to subsequently embed them in concrete without any adhesives being required or without any separate clamping means having to be provided and/or removed. The boot can hereby be simply provided on the site where the railway is being installed. Moreover, the proposed vibration isolator makes it possible to restrict electric leakage currents.

To this aim, a continuous electrically insulating layer is provided between the elastic boot and the rail which only extends over the rail foot up to a distance from the rail head over the full length of the rail, as specified in the appended claims.

Practically, the electrically insulating layer is provided between the elastic boot and the rail, whereby this rail entirely covers the bottom side of the rail foot and extends over the full length of the rail up to a least the top side of the rail foot and preferably up to the rail body, and whereby said layer leaves the rail head entirely uncovered.

The electrically insulating layer preferably only extends over the rail foot.

Thanks to the electrically insulating layer, a required electrical resistance amounting to at least 2 to 10 Ohm/km can be obtained.

The electrically insulating layer is preferably made of a material that electrically insulates better than the material out of which the elastic boot is made. Thus, it can be made for example of PP, rubber, PVC and/or XLPE.

Advantageously, the electrically insulating layer has a thickness which is smaller than the thickness of the elastic boot.

In a very advantageous manner, the elastic boot of the vibration isolator according to the invention is designed such that it is formed of at least three parts, whereby the third part is fixed to the first part by means of a tongue and groove joint, and such that the first part is clamped between the rail and this third part so as to fix the elastic boot to the rail. Advantageously, the third part is hereby further provided with a standing wall extending past the rail foot and which connects to a flank of the first part, such that said tongue and groove joint connects the standing wall to the first part. The tongue and groove joint may hereby consist of at least one rib and a corresponding recess in which this rib fits, whereby they extend over practically the full length of the elastic boot. This rib and the corresponding recess co-operate in order to fix the third part to the first part. The tongue and groove joint is preferably elastically deformable, for example as said rib and recess are elastically deformable.

The invention also concerns a method for covering a rail, whereby an electrically insulating layer is provided onto the rail, such that said layer connects to the rail and envelops the rail foot almost entirely over the full length of the rail, thereby leaving the rail head free, and whereby an elastic boot is subsequently provided round the rail and the electrically insulating layer, such that the elastic boot extends in the direction of the rail over practically the full length of the rail, fits closely to the rail with the electrically insulating layer and covers it almost entirely, thereby leaving at least a top side of the rail head uncovered, such that a railway vehicle can move over the latter.

Other particularities and advantages of the invention will become clear from the following description of a practical embodiment of the method and device according to the invention; this description is given as an example only and does not restrict the scope of the claimed protection in any way; the figures of reference used hereafter refer to the accompanying drawings.

Figure 1 is a schematic representation of a cross section of a rail enveloped with an electrically insulating layer and an elastic boot according to a first embodiment of the invention.

Figure 2 is a schematic exploded view of a cross section of a rail with an electrically insulating layer and an elastic boot according to a first embodiment of the invention as in figure 1.

Figure 3 is a schematic representation of a cross section of a rail enveloped with an electrically insulating layer and an elastic boot according to a second embodiment of the invention.

Figure 4 is a schematic representation of a cross section of a rail enveloped with an electrically insulating layer and an elastic boot according to a third embodiment of the invention. Figure 5 is a schematic representation of a cross section of a rail enveloped with an electrically insulating layer and an elastic boot according to a fourth embodiment of the invention.

Figure 6 is a schematic representation of a cross section of a rail enveloped with an electrically insulating layer and an elastic boot according to a fifth embodiment of the invention.

Figure 7 is a schematic representation of a cross section of a rail enveloped with an elastic boot according to the first embodiment of the invention, whereby an additional electrically insulating layer is also provided.

Figure 8 is a schematic exploded view of a cross section of a rail and an elastic boot according to a first embodiment of the invention as in figure 7.

Figures 9 and 10 are schematic representations of a rail placed in a railway bed according to the invention by means of a bridge with claw means.

In the different figures, the same figures of reference refer to identical or analogous elements.

The invention generally concerns a vibration isolator comprising an elastic boot for a rail embedded in a railway bed, whereby the top side of the rail head practically corresponds to the top side of the railway bed and whereby the rails are continuously supported by the elastic boot. In particular, the invention concerns an elastic boot for rails having a rail head and a rail foot which are mutually connected by means of a rail body having two sides with a lateral cavity on each side extending over the full length of the rail between the rail head and the rail foot. The elastic boot has been designed such that it envelops the rail practically entirely, thereby leaving the rail head accessible for a railway vehicle to move over the latter. Thus, the rail is entirely insulated in relation to the railway bed by the boot. Further, the elastic material of this boot is sufficiently rigid to continuously support the rail and to make sure, that the rail is kept in place in a groove in the railway bed while a railway vehicle moves over this rail. Such elastic materials are already known to the expert and they may consist for example of rubber or recycled rubber as described in European patents EP0854234 and EP 1807569.

A possible practical first embodiment of the vibration isolator according to the invention is schematically represented in figures 1 and 2.

This vibration isolator comprises an elastic boot which fits closely to the rail and extends over almost the full length of the rail. The boot may be built of several units extending in one another's prolongation according to the longitudinal direction of the rail. These units preferably have a length of 1 to 2 metres. Further, the boot practically entirely envelops the rail, thereby leaving the top side of the rail head 4 freely accessible, such that a railway vehicle can move over the latter.

According to this first embodiment of the invention, the boot is formed of at least three parts 1, 2 and 3 extending in the longitudinal direction of the rail.

A first part 1 extends in a first cavity 7 of a first lateral side of the rail whereas a second part 2 extends in a second cavity 7 of a second side of the rail.

These first and second parts 1 and 2 rest on the top side 10 of the rail foot 5 and are preferably at least partly clamped between the top side 10 of the rail foot 5 and the bottom side 11 of the rail head 4. Consequently, these first and second parts 1 and 2 at least partly fit closely onto the rail and at least partly fill the lateral cavities 7 between the rail foot 5 and the rail head 4. These first and second parts 1 and 2 each have a flank 18 and 19 which is turned away from the rail and practically parallel to the rail body 6.

A third part 3 of the elastic boot extends under the rail foot 5.

This third part 3 has a U-shaped cross section. If this third part 3 is put over the bottom side 12 of the rail foot, this part 3 will extend past the top side 10 of the rail foot 5. This third part 3 connects the first part 1 to the second part 2 and fits closely to the bottom side 12 of the rail foot 5, which rests on said third part 3. The third part 3 hereby also fits closely to the flanks 18 and 19 of the first part 1 and the second part 2 of the boot. According to this embodiment, the third part 3 at least partly overlaps the flanks 18 and 19. Preferably, these parts 1, 2 and 3 mutually fit in such a way that a watertight boot is obtained.

Said third part 3 preferably has a U-shaped cross section with a basis 15 and two standing walls 16 and 17 extending opposite one another. When this third part 3 is put over the bottom side 12 of the rail foot 5, the basis 15 will thus fit onto said bottom side 12, and the walls 16 and 17 will fit onto said first part 1 and said second part 2 respectively. Thus, the rail is put in the U-shaped part 3 together with the first and second part 1 and 2 of the boot.

The boot is hereby provided with tongue and groove joints with which the third part 3 is fixed to the first part 1 and also to the second part 2. To this end, the elastic boot is provided with at least one rib 8 and a corresponding notch 9 in which this rib 8 fits, such that the third part 3 is fixed to the standing flanks 18 and 19 of the first part 1 and the second part 2 respectively. This also makes it possible to obtain a watertight seal between said three parts 1, 2 and 3.

Preferably, the first part 1 and the second part 2 are provided with ribs 8, and the third part 3 is provided with two corresponding notches 9 in which these ribs 8 fit. These ribs 8 and notches 9 extend over the full length of the boot. In particular, said notches 9 are provided in the sides of the standing walls 16 and 17 turned towards one another, whereas said ribs 8 are situated in a corresponding position in the second and third part 2 and 3.

As a result, the third part 3 also clamps the first part 1 and the second part 2 between the third part 3 and the rail. Consequently, the elastic boot is also fixed to the rail as a result thereof.

A continuous electrically insulating layer 20 is provided between the elastic boot and the rail. This layer 20 covers the rail foot 5 almost entirely over the full length of the rail. The layer 20 hereby fits closely to the rail and the elastic boot.

In this embodiment, the electrically insulating layer 20 extends over only the rail foot 5, leaving the rail body 6 and the rail head 4 uncovered.

This layer 20 may be formed of several parts fitting closely to one another or at least overlapping one another. A second embodiment of the invention is represented in figure 3 and differs from the above-described first embodiment in that, in order to fix the third part 3 of the elastic boot to the first part 1 and the second part 2, ribs 8 are provided on this third part 3, whereas corresponding recesses 9 are provided in the first part 1 and the second part 2 of the boot. Preferably, these ribs 8 protrude over the top side 10 of the rail foot 5 when the third part 3 has been put on the bottom side 12 of the rail foot 5.

Further, in this second embodiment, the electrically insulating layer 20 extends over the rail foot 5 and at least partly also over the rail body 6 up to a distance from the rail head 4. As a consequence, the electrically insulating layer 20 leaves the real head 4 entirely free.

A third possible embodiment of the invention, represented in figure 4, differs from the above-described first embodiment in that the second and the third part 2 and 3 of the boot are formed as a whole. Consequently, these two parts 2 and 3 are permanently connected to one another. A recess 13 extending over almost the full length of the boot can be provided between the second 2 and the third part 3. As a result, the connection 14 between these parts 2 and 3 is easily elastically deformable, such that they can rotate in relation to one another. In order to connect the third part 3 to the first part 1 , the standing wall 16 is moved past the rail foot 5, against the flank 18 of the first part 1.

Further, in this third embodiment, the electrically insulating layer 20 extends over the rail foot 5 and at least partly also over the rail body 6 up to a distance from the rail head 4, as is the case in the second embodiment.

Fourth and fifth possible embodiments of the invention, represented in figures 5 and 6, mainly differ from the above-described second and third embodiment in that the third part 3 is provided over a rib 8 and the rail foot and has been designed such that the rib 8 as well as a far end 18 of the rail foot 5 fit in the notch 9. The third part 3 hereby extends over the top side 10 of the rail foot.

The third part 3 possibly comprises an elastic bottom, not represented in the figures, which fits onto the bottom side 12 of the rail foot 5 and which is selected as a function of the load of the rail to be provided and the required vibration isolation.

The elastic boot is formed such that its inside preferably fits almost entirely onto the rail. The outside of the elastic boot further fits onto the groove in the railway bed. This elastic boot prevents the rail from making any direct contact with the railway bed.

According to the invention, the rail is thus provided with an electrically insulating layer 20 applied round the rail foot 5 between the rail and the elastic boot, as is also represented in figures 7 and 8 for example. This insulating layer 20 extends over the full length of the rail from one side of the rail body 6, over the entire rail foot 5, up to the other side of the rail body 6. The electrically insulating layer can be made of materials known as such, such as PP, i.e. polypropylene, rubber, PVC, i.e. polyvinylchloride, XLPE, i.e. cross-linked polyethene, which provide a better electric insulation than the elastic material out of which parts 1, 2 and 3 of the boot are made. The thickness of this electrically insulating layer 20 is preferably smaller than the thickness of the elastic boot. In particular, this thickness is preferably smaller than the smallest thickness of the elastic boot. This thickness preferably amounts to 0.5 to 5 mm. The electrically insulating layer 20 may consist of a foil or a coating which is provided on the rail and/or on the inside of the elastic boot. According to an advantageous embodiment of the invention, the electrically insulating layer 20 is formed of a foil of polypropylene having a thickness of 0.5 to 2 mm and which preferably amounts to practically 1 mm. This additional electrically insulating layer 20 must not extend up to the rail head 4 to provide a sufficient electric insulation for the rail, together with the elastic boot. This layer 20 should only cover the rail foot 5 and possibly a part of the rail body 6. Thus, it is not necessary for this layer 20 to hereby also cover the bottom side 11 of the rail head 4.

The electrically insulating layer 20 helps to prevent any leakage currents which may occur in the rails enveloped by an elastic boot in embedded rails of for example electrified tram rails. Naturally, this electrically insulating layer 20 can be applied in all the above-described embodiments of the invention, but also in other existing elastic boots for continuously supported and/or embedded rails. Thus, this additional insulating layer 20 can also be applied to a rail whereby an elastic boot is cast round the rail. The electrically insulating layer 20 can be glued on the rail and/or it can be clamped between the rail and the elastic boot.

The invention also concerns a method for installing and embedding a rail on a railway site and for making a railway bed with embedded continuously supported rails.

The method makes it possible to put the rails in a correct position and to then cast the hardening of the railway bed round the rails up to practically the same height as the top side 24 of the rail head 4.

The invention also concerns a method for installing and embedding a rail on a railway site and for producing a railway bed with embedded continuously supported rails.

The method makes it possible to put the rails in a correct position and to subsequently cast the hardening of the railway bed round the rails up to practically the same height as the top side 24 of the rail head 4.

With the method according to the invention, an electrically insulating layer 20 is provided on the rail, such that this layer 20 fits on the rail and hereby practically entirely covers the rail foot 5 over the full length of the rail. The rail head 4 is hereby left uncovered. Next, an elastic boot is provided round the rail and the electrically insulating layer 20, such that the elastic boot extends in the longitudinal direction of the rail over practically the full length of the rail, fits closely to the rail with the electrically insulating layer 20 and covers it almost entirely, thereby leaving at least a top side 24 of the rail head 4 uncovered, such that a railway vehicle can move over the latter.

It is hereby also possible to cast the elastic boot round the rail. With a possible method according to the invention, in a first step, uncovered rails are suspended via the rail head 4 over a foundation by means of an installation bridge 22 with claw means 21 , such that the rail body 6 and the rail foot 5 are easily accessible, as is also represented in figures 9 and 10. The rail is hereby put in its required position on the site. It is hereby made sure that the top sides of connecting rails are situated in one and the same plane, or in other words, that successive connecting rails are aligned. Further, it is also made sure that the distance up to an adjacent rail and the height in relation to this adjacent rail is correct, such that together they form the tracks of a railway. Consequently, the rail is also aligned in relation to an adjacent rail.

In a second step, the electrically insulating layer 20 is provided and, subsequently, a first part 1 of the elastic boot is provided in a first lateral cavity 7 of the rail. Further, in an analogous manner, a second part 2 of the elastic boot is provided in a second lateral cavity 7 on the other side of the rail. The first part 1 and the second part 2 hereby extend on either side of the rail over preferably almost the full length of this rail. Preferably, these first and second parts 1 and 2 also fill the lateral cavities 7 entirely and they rest on the top side 10 of the rail foot 5.

Possibly, according to this method, also the electrically insulating layer 20, the first and second parts 1 and 2 can be provided before the rail is suspended to the installation bridge 22.

In a third step, a third part 3 of the elastic boot is put over the bottom side 12 of the rail foot 5, such that this third part 3 at least partly clamps the first and the second part 1 and 2. To this end, the third part 3 is provided with two standing walls 16 and 17 which fit onto the flanks 18 and 19 of the first and the second part 1 and 2. As the third part 3 clamps the first and second parts 1 and 2 together with the rail foot 5, these parts 1 , 2 and 3 are fixed to the rail. Preferably, in this manner, the elastic boot is fixed to the rail without any additional adhesives or clamps being required. . ;

Possibly, the boot is formed of several analogous units provided in an analogous way in one another's prolongation round the rail. These units thus each consist of an analogous first, second and third part 1 , 2 and 3. Thus, practically the full length of the rail is covered with the boot. Preferably, the units and/or parts which are situated in one another's prolongation overlap at least partly, such that the seam between these units and/or parts is practically entirely sealed. To this end, the far ends of said parts 1 , 2 and 3 are mitred, for example, or they have what is called a tongue and groove joint, such that successive units connect in a fitting manner without any gaps.

In a fourth step, material from the railway bed is provided round the rail enveloped by the elastic boot. This material may be concrete, for example, forming a groove after having hardened in which the covered rail is fixed. Material from the railway bed is hereby preferably provided until the top side of the railway bed reaches practically the same height as the top side 24 of the rail head 4.

With this method according to the invention, the third part 3 is fixed to the first and second parts 1 and 2 as a rib 8 of the first part 1 and a rib 8 of the second part 2 are each provided in a corresponding notch 9 of the third part 3. When this third part 3 is provided, it will be elastically deformed and put over the first and second parts 1 and 2, such that the ribs 8 snap in the notches 9. The third part 3 thus meshes in the first and second parts 1 and 2, such that these three parts 1 , 2 and 3 cover the rail entirely under the rail head 4.

According to a very advantageous method of the invention, the rail is practically only being held on the top side 24 of the rail head 4 in the first step, such that the lateral sides and the bottom side of the rail head 4 remain freely accessible, as well as the rail body 6 and the rail foot 5, as represented in figures 9 and 10. Thus, the rail is only being held on a part of the rail head 4 that should remain accessible once the rail is installed in order to allow railway vehicles to move over the latter.

This is made possible by suspending the rail on one or several magnets 21 which are placed above the railway to be made by means of installation bridges 22. The installation bridge 22 is provided with adjusting means to put the rail in the correct position in relation to the foundation. To this end, the magnet 21 is placed at the required height and distance from an adjacent rail by means of the bridge 22. Further, the magnet 21 is directed such that the rail is situated in a correct position. The rails are thus aligned in relation to one another, such that they can form a railway. According to a possible embodiment of the invention, the magnet has a flat surface which can attract the almost flat top side 24 of the rail head 4 and can seize it.

This method makes it possible, for example, to easily suspend an uncovered rail under a bridge 22 and to cover it with the boot according to the invention. Thus, the first and second parts 1 and 2 of the boot can be provided in the lateral cavities 7 of the rail in an unhindered manner, after which the third part 3 is pushed over the rail foot 5 and is snapped in the flanks 18 and 19 of the first and second parts by means of a tongue and groove joint.

Possibly, by means of this method according to the invention, also non-elastic material can be cast round a rail which is provided with an electrically insulating layer 20, such that this material covers the rail almost entirely up to the top side of the rail head 4.

This method also makes it possible to easily cover the rail with an electrically insulating layer 20 by providing a coating or a foil while it is hanging under a bridge 22, before providing an elastic boot.

Further, this method also makes it possible to easily provide a hardening for the railway bed such as concrete between the rails without having to account for any contact points between the rails of the elastic boot and the claw means which maintain the rail in its correct position. Indeed, these claw means only extend above the railway bed. As soon as the rails have been definitively aligned, concrete will be cast round the covered rails to this end, for example. As soon as the hardening 23 of the railway bed has been provided, the installation bridge 22 with the magnets 21 can be easily removed.

Magnets which are appropriate to be used for these claw means are known as such. Permanent or electric magnets can be used, for example. These magnets must attract sufficiently to provide for a sufficient bearing power to hold the rail, possibly together with the elastic boot. Several magnets could be used hereby, distributed over the length of a rail. Thus, for example, magnets with a bearing power of some 1 ,000 kilos could be used.

Thus, also an electrically insulating layer 20 can be easily provided according to the above-described methods, before providing the elastic boot. This layer 20 is preferably provided round the rail foot 5 and against a part of the rail body 6. It is not required hereby to provide the layer 20 close round the rail head 4.

The electrically insulating layer 20 and the elastic boot are preferably provided close to the rail, such that any moisture seeping in is prevented. Possibly, the elastic boot can hereby press the electrically insulating layer 20 against the rail.

Naturally, the invention is not restricted to the method described above and to the devices represented in the accompanying drawings. Thus, for example, the boot can also be provided with clamping means extending over the full length of the boot and making it possible to clamp the rail with the boot in the groove, and which, after these clamping means have been removed, make it possible to remove the rail with the boot from the groove without damaging the boot or the railway bedding.

Possibly, the contact surface between the different parts 1 , 2 and 3 may also be uneven, in particular at the tongue and groove joint, creating a greater shear resistance at the contact surfaces between the different parts 1 , 2 and 3.

Possibly, the electrically insulating layer (20) may also extend over at least a part of the rail head (4). However, a sufficient electric insulation can already be obtained when this electrically insulating layer (20) only extends over the rail foot (5) and possibly the rail body (6).

Thus, with a method according to the invention, the rails can be put in a correct position either before these rails are covered with the boot or after the boot has been provided round the rail.

Claims

1. Vibration isolator with an elastic boot for continuously supported rails which are embedded in a railway bed,

whereby the rails have a rail head (4) and a rail foot (5) which are mutually connected by means of a rail body (6) and have a lateral cavity (7) on either side extending over the full length of the rail between the rail head (4) and the rail foot (5),

whereby the elastic boot extends, in the longitudinal direction of the rail over practically the full length of the rail, fits closely to the rail and envelops it practically entirely, leaving at least a top side (24) of the rail head (4) accessible, such that a railway vehicle can move over the latter,

characterised in that a continuous electrically insulating layer (20) is provided between the elastic boot and the rail which practically entirely envelops the full length of the rail and only extends up to a distance from the rail head (4).

2. Vibration isolator according to claim 1, whereby the electrically insulating layer leaves the rail head (4) entirely free.

3. Vibration isolator according to claim 1 or 2, whereby the electrically insulating layer (20) covers the bottom side (12) of the rail foot (5) entirely and extends over the full length of the rail up to at least the top side (10) of the rail foot (5) and, preferably, up to the rail body (6), and whereby this layer (20) leaves the rail head (4) entirely free.

4. Vibration isolator according to any one of the preceding claims, whereby the electrically insulating layer (20) only extends over the rail foot (5) and encloses the latter almost entirely.

5. Vibration isolator according to any one of the preceding claims, whereby the electrically insulating layer (20) is made of a material which electrically insulates better than the material out of which the elastic boot is made.

6. Vibration isolator according to any one of the preceding claims, whereby the electrically insulating layer (20) has a thickness which is smaller than the thickness of the elastic boot.

7. Vibration isolator according to any one of the preceding claims, whereby the electrically insulating layer (20) has a thickness between 0.5 to 5 mm, preferably of some 1 mm.

8. Vibration isolator according to any one of the preceding claims, whereby the electrically insulating layer (20) is made of polypropylene PP, rubber, polyvinylchloride PVC and/or crosslinked polyethene XLPE.

9. Vibration isolator according to any one of the preceding claims, whereby the elastic boot comprises a first part (1) and a second part (2) which each extend in a lateral cavity (7) of the rail in the longitudinal direction of the latter and whereby this boot comprises a third part (3) extending under the rail foot (5) of the rail in the longitudinal direction thereof, whereby the third part (3) is further fixed to the first part (1) by means of a tongue and groove joint and the first part (1) is clamped between the rail and this third part (3), as a result of which the elastic boot is fixed to the rail.

10. Vibration isolator according to any one of the preceding claims, whereby the third part (3) has a standing wall (16) which extends past the rail foot (5) and which fits onto a flank (18) of the first part (1), such that said tongue and groove joint connects the standing wall (16) to the first part (1).

11. Vibration isolator according to any one of the preceding claims, whereby said tongue and groove joint consists of a rib (8) and a corresponding recess (9) extending over practically the full length of the elastic boot.

12. Vibration isolator according to claim 8, whereby the third part (3) is provided with two recesses (9) extending over the full length of this third part (3) and whereby the first part (1) and the second part (2) are each provided with a rib (8) extending over the full length of these parts (1, 2) and which each fit in a recess (9) of the third part (3), whereby this third part (3) clamps the first and the second part (1, 2) between the third part (3) and the rail.

13. Vibration isolator according to any one of the preceding claims, whereby the second part (2) and the third part (3) form a physical whole and are thus permanently connected to one another.

14. Vibration isolator according to any one of the preceding claims, whereby said tongue and groove joint is elastically deformable.

15. Vibration isolator according to any one of the preceding claims, whereby said tongue and groove joint extends between the first part (1) and the third part (3) between the rail head (4) and the rail foot (5) when the elastic boot envelops the rail.

16. Method for manufacturing a rail with a vibration isolator for a railway bed with an embedded continuously supported rail with a rail head (4) and a rail foot (5) which are connected by means of a rail body (6) and having a lateral cavity (7) on either side extending over the full length of the rail between the rail head (4) and the rail foot (5), whereby

- an electrically insulating layer (20) is provided on the rail, such that this layer (20) fits onto the rail and envelops the rail foot (5) practically entirely over the full length of the rail, thereby leaving the rail head (4) free, and subsequently

- an elastic boot is provided round the rail and the electrically insulating layer (20), such that the elastic boot extends in the longitudinal direction of the rail over practically the full length of the rail, fits closely onto the rail with the electrically insulating layer (20) and envelops it practically entirely, thereby leaving at least a top side (24) of the rail head (4) free, such that a railway vehicle can move over the latter.

17. Method according to claim 16, whereby an electrically insulating layer (20) is provided on the rail having a thickness which is smaller than the thickness of the elastic boot.

18. Method for manufacturing a railway bed with an embedded continuously supported rail provided with a vibration isolator as in one of the preceding claims, whereby a rail is covered with an electrically insulating layer (20) and an elastic boot and whereby the rail is suspended via the rail head (4), after which material from the railway bed (23) is provided round the covered rail and this material hardens, and a groove is formed in which the rail is fixed together with the elastic boot.