US20090261177A1

US20090261177A1 - Railway rail pad

Info

Publication number: US20090261177A1
Application number: US12/279,397
Authority: US
Inventors: Robert John Hamilton; Stephen John Cox; John Phillip Porrill; Martin Somerset; Paul Hewlett; Christopher Gardner
Original assignee: Pandrol Ltd
Current assignee: Pandrol Ltd
Priority date: 2006-02-21
Filing date: 2007-02-21
Publication date: 2009-10-22
Also published as: WO2007096616A1; AU2007217195B2; BRPI0706821A2; ES2441265T3; ATE470756T1; ZA200806940B; CA2642109C; PT1987200E; US20090045265A1; CN101389811B; KR20080098669A; KR101392930B1; WO2007096621A1; DK1987201T3; EP1987199B1; ZA200806904B; AU2007217198A1; EG25588A; AU2007217195A1; WO2007096620A1

Abstract

A rail pad is disclosed having two upstanding portions, integrally formed with the rail seat portion along opposite edges thereof, so as to extend along only a central part of the edge. Preferably, the upstanding portions are attached to the rail seat portion in such a manner as to be readily detachable therefrom.

Description

The present invention relates to a railway rail pad.
In the documents WO93/12294, WO93/12295 and WO93/12296, the present applicants disclosed a railway rail fastening system in which a rail fastening clip is driven laterally onto the rail and can be held in a clip anchoring device (shoulder) in a “pre-assembly” or “parked” position in which the toe portion of the clip does not bear on the rail. This enables railway sleepers to be preloaded at the factory with clips which are held in the pre-assembly position such that when the sleepers are delivered to site the clips can simply be driven home once the rail is in place. In addition, when maintenance of the rail or sidepost insulators (which lie between the rail and the shoulder) is subsequently required, the clip can be driven off the rail back into the pre-assembly position, or further into an “insulator-change position” in which the clip does not overlie the sidepost insulator, so complete withdrawal of the clip from the shoulder is not necessary. Such clips are sometimes known as “switch-on/switch-off” clips. Such a fastening system has proved to be very successful, but the applicant is desirous of making improvements to some aspects of its manufacture and use.
Rail fastening assemblies as described in the applicant's patent applications WO93/12294, WO93/12295 and WO93/12296 have a rail pad which underlies the foot of the rail, providing cushioning and electrical insulation, and electrical “sidepost” insulators which are located between the rail foot and the front face of an adjacent shoulder. Although once installed on a sleeper in the factory or in track the sidepost insulators are held in place by the rail clip, the installation process is comparatively difficult and costly.
According to a first aspect of the present invention there is provided a rail pad for use beneath a railway rail in a rail fastening assembly as cushioning and/or electrical insulation, the pad having a major face providing a rail seat portion on which the foot of the railway rail sits when the rail pad is in use, wherein the rail pad further comprises two upstanding portions, integrally formed with the rail seat portion along opposite edges thereof, so as to extend along only a central part of the edge.
The upstanding portions are preferably made of electrically-insulating material and are shaped and arranged so as to form insulation members for electrically insulating the rail foot from rail clip anchoring devices located one on either side of the rail when the pad is in use.
By forming the pad and side post insulators as one part, rather than two separate insulators and a pad, the unit can be produced more cheaply that the three separate parts. Because it is one part, it is also easier to fit than three separate parts—both in the sleeper factory and in the field. In addition, because the sidepost insulator members and rail seat portion are formed as one part, the rail pad will contribute to good overall electrical resistance of the assembly. In particular, by making a good seal between the insulator members and the rail seat portion, electrical insulation can be improved, as compared to having separate pad and insulator parts, because there is no path for moisture to be drawn through.
Desirably, the insulation members are formed of a material having greater resilience to damage than the rail seat portion of the pad, since these portions are subject to much higher pressure than the rail seat portion, due to the lateral loads which are transmitted through them to the shoulder. For example, the insulation members may be made of nylon and the rail seat portion of EVA.
It will, however, probably be necessary to replace worn sidepost insulators in track before the rail seat portion is due for replacement and accordingly, in order to avoid having to unclip the rail and jack the rail up in order to remove the rail pad, the upstanding portions are preferably attached to the rail seat portion in such a manner as to be readily detachable therefrom. The upstanding portions desirably mechanically interlock with the said rail seat portion.
Thus, in this preferred embodiment of the pad, the pad is such that the side post elements can be torn away from the rail seat portion after the pad is installed in track, thereby eliminating the need to jack the rail and the cost of replacing the rail seat portion of the pad. The new replacement parts would be separate individual side post insulators, that would not need to connect to the rail seat portion of the pad. It would not be a problem if one or both of the insulator members became detached from the rail seat portion in service, through wear or mechanical action rather than through deliberate action, as once in place the rail seat portion and insulating members of the pad can function separately, as in the prior art.
In use, the load has to go straight through the insulators into the shoulder, so the insulators must be hard up against the shoulders with no clearance. However, the actual positions of the shoulders will vary due to the tolerance on sleeper manufacture and it is obviously undesirable to provide a number of rail pads of different widths. Accordingly, in a preferred embodiment of the pad, the width of the said rail seat portion can conform to a range of rail seat widths. Preferably, this is achieved by providing the rail seat region of the pad with a concertinaed section which can be stretched or squeezed between a minimum width and a maximum width, so as to adjust the overall width of the rail seat portion. Thus, the pad is sized to fit a maximum railseat, and would be a ‘squash fit’ into a narrower railseat.
According to a second aspect of the present invention there is provided a railway rail fastening assembly comprising two railway rail fastening clips, two anchoring devices for retaining respective ones of the rail fastening clips when installed therein and a rail pad embodying the first aspect of the present invention, located between the two anchoring devices, wherein each insulation member of the pad is formed with a shelf which extends over a portion of that anchoring device which is adjacent thereto, the shelf being overlain by the rail clip installed in the anchoring device when the clip is in a pre-assembly position in which the clip does not overlie the rail seat portion of the pad. Thus, the pad is held in place by the clip.

Reference will now be made, by way of example, to the accompanying drawings in which:

FIG. 1 shows a rail pad embodying the first aspect of the present invention, in which FIG. 1A is a perspective view from above, FIG. 1B is a plan view from above and FIG. 1C is a cross-sectional view taken along the line C-C in FIG. 1B.

FIG. 2 shows an anchoring device for use with a rail pad embodying the first aspect of the present invention, FIG. 2A showing a perspective view from above, FIG. 2B showing a front view, FIG. 2C showing a part sectional view taken on the line Z-Z in FIG. 2B, FIG. 2D showing a rear view, FIG. 2E showing a side view, FIG. 2F showing a plan view from above, FIG. 2G showing a plan view from below and FIG. 2H showing a side view of another anchoring device embodying the first to fourth aspects of the present invention;

FIG. 3 shows a railway rail fastening clip for use with a rail pad embodying the first aspect of the present invention, FIG. 3A showing a plan view of the clip, FIG. 3B showing a side view of the clip when in its non-operative configuration and FIG. 3C showing a side view of the clip when in an operative configuration; and

FIG. 4 shows a railway rail fastening assembly embodying the second aspect of the present invention, in which FIGS. 4A and 4B show the assembly in a side view in which the clip is in a pre-assembly position with respect to the rail, FIG. 4B being a part cross-sectional view, FIGS. 4C and 4D show another side view of the assembly in which the clip is bearing on the rail, FIG. 4D being a part cross-sectional view, FIG. 4E shows a rear view of the assembly and FIG. 4F shows a perspective view of the assembly.

A studded rail pad 4 embodying the first aspect of the present invention will now be described with reference to FIGS. 1A to 1C. Rail pad 4 is made of electrically-insulating material and is substantially rectangular in outline, having a first major face 41 and a second major face 42 opposite to the first major face, the first major face 41 providing a rail seat portion 43 on which rows of studs 43 a are provided, the rail seat portion 43 providing cushioning between the underside of the rail foot and the underlying concrete sleeper. The rail seat portion 43 is also provided with a concertinaed section 43 b which extends across the rail seat portion 43 in a direction parallel to the axis of a rail when seated thereon, the concertinaed section serving to allow the pad to conform to rail seats of varying widths, within a certain range. The four corners of the rail pad constitute ears 44 between which there are defined two recesses 45 which receive respective shoulders 1, providing longitudinal location and creep resistance. Integrally formed with the rail seat portion 43 and the ears 44 are sidepost insulator portions 46 for insulating the rail from the shoulder 1, each insulating portion 46 projecting upwardly from the first major face 41 and having a substantially horizontal shelf 47 which extends away from the rail seat portion 43 such that, when the rail pad 4 is in position between two shoulders 1, the shelf 47 will extend over a portion of the shoulder 1 and will be overlain by the toe portion 34 of a clip 3 installed in the shoulder 1.
To minimize part cost and manufacturing time, the sidepost insulator portions 46, which may be formed of nylon, may be cored out, the cored-out parts of the insulator portions 46 being filled with the material forming the rail seat portion 43, for example EVA.
With reference to FIGS. 2A to 2G an anchoring device (shoulder) for use with a rail pad embodying the invention will now be described. The anchoring device 1 shown in FIGS. 2A to 2G comprises a head 1A from the underside of which downwardly project a stem part 1B and two spaced-part tangs 1C. The stem part 1B comprises a substantially Y-shaped stem 100, connected to the underside of the head 1A at the ends of upper arms 101 of the Y, and a bent part 102 at the other end of the Y for resisting withdrawal of the stem from the concrete in which it is embedded when it is in use. As shown in FIG. 2H, which shows another shoulder for use with a rail pad embodying the present invention, the underside of the shoulder 1 may be provided with one or more webs 1D connecting the stem 100 of the shoulder 1 to its head 1A, instead or in addition to the tangs 1C (not shown in FIG. 2H), for assisting in preventing the shoulder 1 tipping forward when a clip is driven into it.
The head 1A of the anchoring device 1 comprises two spaced-part walls 10, connected together at one end of the head 1A, at the bottom of the walls 10, by a connection portion 14. The top surface of the connection portion 14 is downwardly inclined and forms a ramp 140, while the front surface of the connection portion 14 forms the front face 12 of the shoulder 1. The end of the walls 10 at the front end of the head 1A are connected to the front face 12 of the shoulder by curved portions 13.
The walls 10 extend outwardly at their tops to provide respective clip-engaging surfaces 11 provided with two clip-engaging projections 110A, 110B, which project downwardly and are connected by means of a ramped surface 111 which inclines downwardly from the rear of the shoulder 1 to the front of the shoulder 1, for deflecting the leg of a railway rail fastening clip. The front face 12 of the shoulder 1 is provided with projections 120 for engaging with the sleeper mould so as to set the shoulder at the correct height in the mould before the concrete is introduced. The shoulder 1 has a rear face 15 opposite to the front face 12.
A railway rail fastening clip 3 for use with a rail pad embodying the first aspect of the present invention will now be described with reference to FIGS. 3A to 3C. The rail clip 3 is formed from a steel rod bent so as to have, proceeding from one end A of the rod to the other end B of the rod, firstly a straight first portion 31 forming one leg of the clip, then a bent second portion 32 which bends through more than 180°, then a third portion 33, then a fourth portion 34 which forms the toe portion of the clip and is bent through 180°, then a fifth portion 35 which mirrors the shape of the third portion 33, then a sixth portion 36 which mirrors the shape of the second portion 32 and finally a seventh portion 37 which forms the other leg of the clip. Thus, when viewed as seen in FIG. 3A, the clip may be considered to be substantially M-shaped. The free ends A, B, of the rod have a chamfer 37 a on the surface of the leg which is to be uppermost when the clip 3 is bearing on a rail for assisting in inserting the clip into the shoulder. Adjacent to the ends A, B, on the uppermost surface of the clip 3, the clip 3 is formed with detents 38 for cooperating with the projections 110A, 110B formed on the walls 10 of the shoulder 1 to retain the clip 3. The detents 38 are formed so as to have two oppositely-inclined spaced-apart faces defining respective pre-assembly and insulator-change positions relative to the shoulder 1.
Although not shown in FIGS. 3A to 3C, but seen from FIGS. 4A to 4F, the toe portion 34 of the clip 3 when in use normally carries a toe insulator 34 a for insulating the clip 3 from the rail. The toe insulator 34 a also extends over parts of the third and fifth portions, 33, 35 of the clip 3. In order to reduce the likelihood that the toe insulator 34 a may be removed unintentionally from the clip 3, those portions of the toe portion 34 and third and fifth portions 33, 35 which come into contact with the toe insulator 34 a when it is located on the clip 3 may be left free of the coating which is generally applied to the remainder of the clip.
When the clip 3 is in its non-operative configuration, i.e. a non-stressed configuration in which the clip is not in use, the longitudinal axes of all parts of the clip lie substantially in the same plane P, that is the clip is flat.
As shown in FIG. 3C, when the clip 3 is deflected into an operative configuration, by driving the clip into a shoulder 1, the legs 31, 37 of the clip 3 are driven downwards out of the first plane P into a second plane Q and the third, fourth and fifth portions 33, 34, 35 of the clip 3 are deflected upwardly out of the plane P into a third plane R, the planes P, Q, R being non-parallel.
Compared to the applicant's prior art switch-on/switch-off clip, the above-described clip may be made from 14 mm diameter bar instead of 15 mm. In addition, the clip is smaller in plan view, both shorter by about 10 mm and narrower by about 10 mm. The clip may be rolled around smaller radius formers to make the arches of the clip, in particular at the toe of the clip, as a consequence of which, and the smaller diameter, the clip may be significantly lighter. It also operates at a slightly higher stress level. The clip may be initially produced with some profile and then cold-set so that it returns to a flat shape (i.e. over-pressed when cold such that it yields and takes on some permanent deformation).
A railway rail fastening assembly employing the elements described above will now be described with reference to FIGS. 4A to 4F. The railway rail fastening assembly of FIGS. 4A to 4F, for fastening a railway rail 5, comprises a shoulder 1, a rail fastening clip 3, a sealing plate 2 and a rail pad 4 embodying the first aspect of the present invention. It will be appreciated that, although not shown in FIGS. 4A to 4F, when in use the rail is fastened on both sides of the rail head by such an assembly and that the stem 1B and tangs 1C are embedded in the concrete sleeper 6. The sealing plate 2 is also embedded in the concrete sleeper 6, such that the top face of sealing plate 2 is flush with the upper surface of the sleeper 6. As shown in FIGS. 4A/4B the clip 3 may be driven into the shoulder 1 by introducing the chamfered free ends A, B of the clip legs 31, 37 into the gaps between the top surfaces 25 a of the clip seat projections 25 on the sealing plate 2 and the first projection 110A on the outer surface of the walls 10 of the shoulder 1, and inserting the toe portion 34 of the clip 3, bearing a toe insulator 34 a, into the space between the inner surfaces of the walls 10 of the shoulder 1, such that the toe 34 of the clip 3, through the toe insulator 34 a, bears on the ramp 140 of the shoulder 1 and the projections 110A are located within the detents 38 in the clip legs 31, 37, with the projection 110A contacting the rear face of the detent 38. This position is known as the “pre-assembly” or “parked” position, in which the clip does not bear on the rail 5, but overlies the shelf 47 of the side post insulator portion 46 of pad 4. Downwardly-facing parts of the legs 31, 37 rest on the top surfaces 25 a of the clip seat projections 25.
As shown in FIGS. 4C and 4D, the clip 3 can be driven from the pre-assembly position (first operative position) into a second operative position in which the toe portion 34 of the clip 3 bears on the foot of the rail 5, the second projections 110B on the walls 10 engage the detents 38 of legs 31, 37 of the clip 3 and the second and sixth portions 32, 36 (heel portions) of the clip 3 bear on the top surfaces 25 a of the clip seat projections 25. The clip overlies the shelf 47 of the side post insulator portion 46 of the rail pad 4. The clip can be withdrawn from this position back into the pre-assembly position, if required in order to remove or work on the rail, or further back into the “insulator-change” position in which the front face of the detent 38 contacts the projection 110A and the clip 3 does not overlie the shelf 47 of the sidepost insulator portion 46 of pad 4.
As the clip 3 is installed, the toe 34 of the clip 3 is driven upwards by the ramp 140 in the centre of the shoulder 1, and the legs 31, 37 are driven down, thereby splitting the clip open. This makes it possible to make the assembly a little lower than would otherwise be possible.

Claims

1-12. (canceled)

13. A rail pad for use beneath a railway rail in a rail fastening assembly as cushioning and/or electrical insulation, the pad having a major face providing a rail seat portion on which the foot of the railway rail sits when the rail pad is in use, characterised in that the rail pad further comprises two upstanding portions, integrally formed with the said rail seat portion along opposite edges thereof, so as to extend along only a central part of the edge.

14. A rail pad as claimed in claim 13, wherein the said upstanding portions are made of electrically-insulating material and are shaped and arranged so as to form insulation members for electrically insulating the rail foot from rail clip anchoring devices located one on either side of the rail when the pad is in use.

15. A rail pad as claimed in claim 14, wherein the insulation members are formed of a material having greater resilience to damage than the rail seat portion of the pad.

16. A rail pad as claimed in claim 13 wherein the upstanding portions are attached to the rail seat portion in such a manner as to be readily detachable therefrom.

17. A rail pad as claimed in claim 16, wherein the said upstanding portions mechanically interlock with the said rail seat portion.

18. A rail pad as claimed in claim 13, wherein the width of the said rail seat portion can conform to a range of rail seat widths.

19. A rail pad as claimed in claim 18, wherein the rail seat portion of the pad has a concertinaed section which can be stretched or squeezed between a minimum width and a maximum width, so as to adjust the overall width of the rail seat portion.

20. A railway rail fastening assembly comprising two railway rail fastening clips, two anchoring devices for retaining respective ones of the rail fastening clips when installed therein and a rail pad as claimed in claim 1 or 6, located between the two anchoring devices, wherein each insulation member of the pad is formed with a shelf which extends over a portion of that anchoring device which is adjacent thereto, the shelf being overlain by the rail clip installed in the anchoring device when the clip is in a pre-assembly position in which the clip does not overlie the rail seat portion of the pad.

21. An assembly as claimed in claim 20, wherein each of the clips is such that it can be deflected from a non-operative configuration to at least one operative configuration in which a toe portion of the clip bears on a railway rail, the clip being made from a rod of resilient material shaped so as to have, proceeding from one end A of the rod to the other end B of the rod, firstly a substantially straight first portion, then a substantially bent second portion, then a third portion, then a fourth portion which is substantially U-shaped and forms the toe portion of the clip, then a fifth portion, then a substantially bent sixth portion, and finally a substantially straight seventh portion, the first and seventh portions of the clip forming leg portions, the longitudinal axes of which lie substantially in a first plane when the clip is in its non-operative configuration and, when the clip is viewed in a direction perpendicular to the said first plane, the third and fifth portions appear to lie between the first and seventh portions, wherein, when the clip is in its non-operative configuration, the longitudinal axes of the second, third, fourth, fifth and sixth portions also lie substantially in the said first plane, and, when the clip is in the said at least one operative configuration, the longitudinal axes of the third, fourth and fifth portions lie substantially in a second plane and the longitudinal axes of the first and seventh portions lie substantially in a third plane, the second and third planes being non-parallel to one another.

22. An assembly as claimed in claim 20, wherein each of the said anchoring devices comprises two interconnected spaced-apart walls, between which a portion of the clip to be retained is held when the anchoring device is in use, and clip-engaging means, supported by the walls, for engaging a portion of the rail fastening clip to be retained, wherein the device does not have any feature or surface which engages the surface of that clip portion which faces downwardly when the clip is in use.

23. An assembly as claimed in claim 22, wherein the clip-engaging means define contact regions at which the device engages the rail clip to be retained when the clip bears on a railway rail, the device not engaging the clip at any other region of the device when the clip is bearing on the rail in normal operation, such that none of the said contact regions of the device can be seen when the anchoring device is viewed from above when in its operative orientation in which it will be used when adjacent to a railway rail and all of the said contact regions of the device can be seen when the anchoring device is viewed from below when in the said operative orientation.

24. An assembly as claimed in claim 23, wherein, when the device is in use, all the said contact regions of the device lie substantially at the same horizontal distance from the edge of the rail foot when measured perpendicularly to the axis of the rail and in the plane of the rail foot.

25. A rail pad as claimed in claim 14 wherein the upstanding portions are attached to the rail seat portion in such a manner as to be readily detachable therefrom.

26. A rail pad as claimed in claim 15 wherein the upstanding portions are attached to the rail seat portion in such a manner as to be readily detachable therefrom.