WO2016027059A1

WO2016027059A1 - Assemblies comprising a railway rail side post insulator and railway rail clip anchoring device for use therewith

Info

Publication number: WO2016027059A1
Application number: PCT/GB2015/052146
Authority: WO
Inventors: Stephen John Cox
Original assignee: Pandrol Limited
Priority date: 2014-08-18
Filing date: 2015-07-24
Publication date: 2016-02-25
Also published as: CN106574448A; GB201414595D0; RU2017108803A; AU2015305007A1; EP3183389B1; RU2691466C2; CN106574448B; AU2015305007B2; EP3183389A1; DK3183389T3; BR112017003132A2; RU2017108803A3

Abstract

In an assembly comprising a first railway rail side post insulator and a railway rail clip anchoring device (3), for retaining a resilient railway rail fastening clip (6), which device (3) is configured to support the first railway rail side post insulator (1'), the first railway rail side post insulator (1') is configured to provide an electrically-insulating load bearing face (10') between an upright side face (21 A) of a foot (21) of a railway rail (2) and upright load bearing faces (301, 302, 303, 304) of a railway rail clip anchoring device (3) located adjacent to the rail foot (21), the electrically-insulating load bearing face (10') being provided by an outer face of a wall (100') of the insulator. The insulator further comprises a member (110'), joined to an inner face (12') of the wall (100'), which member (110') has a top surface (11') which extends in a substantially perpendicular direction with respect to the load bearing face (10') to a depth (do) from the inner face of the wall (100') which is greater than or substantially equal to a depth (d_w) of the wall in the said direction. The railway rail clip anchoring device (3) has upright load bearing faces (301, 302, 303, 304), comprising front wall faces (301, 303, 304) configured for location adjacent to the rail foot (21), and an upper central face (302) which is offset from the front wall faces (301, 303, 304) by an offset distance (D) which is between a tenth and a half of the depth (D₀) of the anchoring device (3) in a direction substantially perpendicular to the front wall faces (301, 303, 304), and an upwardly-facing surface (31) of the anchoring device (3) which extends from the upper central face (302) to provide a shelf portion (31) for receiving part (43) of the first railway rail side post insulator (1').

Description

ASSEMBLIES COMPRISING A RAILWAY RAIL SIDE POST INSULATOR AND

RAILWAY RAIL CLIP ANCHORING DEVICE FOR USE THEREWITH

The present invention relates to assemblies comprising a railway rail side post insulator and a railway rail clip anchoring device for use therewith.

Railway rail fastening assemblies which employ resilient rail fastening clips to secure the rail comprise, in addition to rail fastening clips bearing down on each side of a foot of a railway rail, some sort of railway rail clip anchoring device for retaining each rail fastening clip. Some rail fastening clips are driven onto the rail in a direction parallel to the longitudinal axis of the rail, and some are driven laterally onto the rail. Some laterally-driven clips can be held within the anchoring device in a position in which they do not bear on the rail, for example so as to allow the rail fastening assembly to be pre- assembled on the sleeper before delivery to site or to allow side post electrical insulators, carried by the anchoring device, to be replaced when worn. Such clips and anchoring devices are disclosed, for example, in EP0619852 and EP0619851 , and EP1987199 and EP1987198.

To allow for different track gauges and heights on non-ballasted track, it is desirable to provide for lateral and/or vertical adjustment in the rail fastening assembly. In a rail fastening assembly as mentioned above, in which a side post insulator is located by the anchoring device in the space between the side of the rail foot and the front wall of the anchoring device, lateral adjustability can be provided by changing out side post insulators of different depths. A standard system that provides no lateral adjustability would use, say, 8 mm side posts on both sides of the rail. To provide the maximum feasible lateral adjustment of about +/- 5 mm per rail seat, the spacing between the anchoring devices on either side of the rail seat is increased such that 13 mm side posts are used on each side. It is possible to swap these out in combinations up to 18 mm and down to 8 mm, such that each combination used adds up to a constant 26 mm. To provide lateral adjustment of +/- 5 mm in steps of 1 mm, 11 different side post depths are required.

Vertical adjustments to the rail itself can be achieved by introducing shims of different thickness into the rail seat. For example, to provide +10 mm height adjustment in 1 mm steps, 1 , 2, 3 and 5 mm thick shims that could be added together to produce any combination up to 10 mm are employed. Each shim is made from a hard material such as steel or HDPE and is roughly the size and shape of a rail pad.

In a rail fastening assembly as mentioned above, in which a side post insulator is located by the anchoring device in the space between the side of the rail foot and the front wall of the anchoring device, the side post insulator leads straight across on the level from the anchoring device to the rail foot edge, so vertical adjustment of the rail fastening assembly itself is more complicated. To allow for vertical adjustment in such an assembly, it would be necessary to provide a range of rail fastening clips with different toe heights, coupled with a range of different side post insulators that lead up or down from the fixed-height anchoring device to the edge of the rail when this varies in height. So for each rail height, a different additional clip and a different additional side post insulator would be required. In practice, the height adjustment available by this method would be limited to, say, +10 mm of vertical adjustment.

For practical reasons (for example to avoid expense and complexity), however, it is not desirable to provide multiple different clip variants and multiple different side post insulators for each step of vertical adjustment. It is possible to reduce the number of variants required by making the steps in clip toe height and side post design coarser than the 1 mm steps in rail height adjustment. By permitting a small variation in clip toe load and a small differential step at the edge of the rail, it is possible to supply only 3 clip variants and 3 side post variants to cover the basic range, while maintaining an acceptable variation in toe load and an acceptable rail edge step and still providing a 10 mm rail height range. However, there would still be a problem, in that to provide all the combinations it would be necessary to provide 1 1 different side posts at each of 3 different heights, which gives 33 combinations. Each of these would have to be manufactured and it would be difficult to handle logistically, and difficult in practice to make the adjustments, because there would be so many different parts to deal with. According to an embodiment of a first aspect of the present invention there is provided an assembly comprising a first railway rail side post insulator and a railway rail clip anchoring device, for retaining a resilient railway rail fastening clip, which device is configured to support the first railway rail side post insulator, wherein: the first railway rail side post insulator is configured to provide an electrically-insulating load bearing face between an upright side face of a foot of a railway rail and upright load bearing faces of a railway rail clip anchoring device located adjacent to the rail foot, the electrically-insulating load bearing face being provided by an outer face of a wall of the insulator, and the insulator further comprising a member, joined to an inner face of the wall, which member has a top surface which extends in a substantially perpendicular direction with respect to the load bearing face to a depth from the inner face of the wall which is greater than or substantially equal to a depth of the wall in the said direction; and the railway rail clip anchoring device has upright load bearing faces, comprising front wall faces configured for location adjacent to the rail foot, and an upper central face which is offset from the front wall faces by an offset distance which is between a tenth and a half of the depth of the anchoring device in a direction substantially perpendicular to the front wall faces, and an upwardly-facing surface of the anchoring device which extends from the upper central face to provide a shelf portion for receiving part of the first railway rail side post insulator.

Lateral and/or vertical adjustment is usually only actually applied quite rarely.

Accordingly, the applicant proposes that an assembly embodying the present invention, which is simple and uses few components, would be provided as a "default" assembly which would be used most of the time. The intention would be for the first side post insulator of the assembly (the "default" side post insulator) to be installed at the outset so as to provide an 'as-built' adjustment position of +5 mm vertical and +0 mm lateral adjustment.

With a typical 8 mm "default" side post insulator, to provide for a maximum 5 mm vertical height adjustment would create a very steep ramp, either upwards or downwards, to the rail edge. A rail clip could not be driven over a ramp of this nature. However, in an embodiment of the present invention, a central section of the front wall of the anchoring device is offset. This, together with a modification to the

corresponding centre section of the first side post insulator to make it much thicker, allows the maximum ramp angle that the clip has to be driven up or down to be much reduced. For example, moving the central bearing face of the anchoring device backwards by 26 mm, changes the maximum ramp angle from 5/8 to 5/34.

In one embodiment the offset distance is between a quarter and a half of the depth of the anchoring device, for example between a quarter and a third of the depth of the anchoring device. In the first sidepost insulator, the depth of the top surface of the member from the wall is desirably substantially twice the depth of the wall. Preferably the height of the member, from its top surface to a bottom surface of the member, is substantially the same as the height of the wall.

In order to accommodate lateral and/or vertical adjustments outside the range provided by the first "default" side post insulator of the "default" assembly, an assembly embodying the present invention preferably further comprises a kit of parts comprising a first plurality of first side post insulator portions and a second plurality of second side post insulator portions, wherein: any one of the first side post insulator portions is interlockable with any one of the second side post insulator portions so as to form a second railway rail side post insulator, for providing electrical insulation between the side face of the foot of the railway rail and the load bearing faces of the railway rail clip anchoring device adjacent to the rail foot, in place of the first railway rail side post insulator; the first side post insulator portions of the first plurality each have an outer load bearing side face and differ from one another in maximum depth, as measured in a direction substantially perpendicular to a plane in which the outer load bearing side face of the first side post insulator portion extends; and the second side post insulator portions of the second plurality each have an outer load bearing side face and differ from one another in thickness, as measured at the outer load bearing side face of the second side post insulator portion.

The number of first side post insulator portions in the first plurality need not be, and preferably is not, the same as the number of second side post insulator portions in the second plurality. In a preferred embodiment, there are eleven first side post insulator portions in the first plurality and only three second side post insulator portions in the second plurality.

By splitting a side post insulator into first and second interconnectable side post insulator portions, and providing a set of first side post insulator portions of different depths, each of which is interconnectable with each of a set of second side post insulators of different thicknesses, it is possible to reduce the overall number of insulator components required in order to provide both vertical and lateral adjustment over a desired range. For example, 1 1 different first side post insulator portions can provide the different lateral adjustment positions required, whereas 3 different second side post insulator portions can provide the different vertical adjustment combinations required. The two elements when clipped together provide all of the required 33 combinations, but there are only (11 + 3 =) 14 different parts, which is not much more than the 11 required to provide for lateral adjustment only. Different colour coding may be used to ensure that the correct combinations of clip and vertical adjustment element are used together, and colour coding may also be used to ensure that the correct combinations of lateral adjustment parts are used. In this way, immediate visual feedback may also be provided as to where the track has been adjusted and by how much when the track is inspected. The first side post insulator portion may be shaped so as to provide: an upper inner load bearing side face and a lower inner load bearing side face for positioning against respective upright load bearing faces of the railway rail clip anchoring device; a bottom face for positioning on a shelf portion of the anchoring device; the outer load bearing side face for positioning adjacent to the upright side face of the rail foot; and a top surface portion shaped for mating engagement with the second side post insulator portion.

The second side post insulator portion may be shaped so as to provide: the outer load bearing side face for positioning adjacent to the upright side face of the rail foot; and a bottom surface shaped for mating engagement with the first side post insulator portion.

One of the first and second side post insulator portions may be provided with one or more protrusions and the other of the first and second side post insulator portions may be provided with one or more corresponding apertures for engaging the respective protrusions. For example, a side of an aperture may be provided with an internal ledge or similar structure, in which case a protrusion may be provided with a barb (e.g. at its end) such that when the barb on the protrusion is pushed past the ledge, the barb engages the ledge to prevent withdrawal of the protrusion from the aperture. The second side post insulator portion may have a top surface which is shaped such that it is inclined upwardly or downwardly from the outer load bearing side face of the second side post insulator portion. Thus, when such a second side post insulator portion is interlocked with a first side post insulator portion, the upper surface of the railway rail side post insulator so formed is shaped as an upwardly-inclined or downwardly-inclined ramp. A side post insulator which is used as the "default" side post insulator in the so-called "standard" assembly which embodies the present invention is preferably a one-part insulator, but could be for example a two-part insulator as described above. In a preferred embodiment the anchoring device of the assembly is configured to retain a resilient railway rail fastening clip of a type which is driven laterally onto a railway rail, such as (but not limited to) a clip disclosed in EP0619852 or EP1987199.

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

Figure 1A shows a side view, Figure 1 B shows a partial plan view, and Figure 1 C shows a cross-sectional side view of a first assembly embodying the present invention, designed for a track gauge of 1435mm, comprising first railway rail side post insulators;

Figure 1 D shows a cross-sectional side view of a second assembly embodying the present invention, designed for a maximum track gauge of 1445mm, comprising second railway rail side post insulators; Figure 1 E shows a cross-sectional side view of a third assembly embodying the present invention, designed for a minimum track gauge of 1425mm, comprising second railway rail side post insulators;

Figure 2 shows a perspective view of an anchoring device for use in an assembly embodying the present invention;

Figures 3A and 3B show respective top perspective and bottom perspective views of a first railway rail side post insulator for use in an assembly embodying the the present invention;

Figures 4A and 4B show respective front perspective and rear perspective views from above, and Figure 4C shows a perspective view from below, of a first portion of a second railway rail side post insulator for use in an assembly embodying the present invention, as shown on the lefthand side of Figure 1 D and the righthand side of Figure 1 E; Figures 4D and 4E show respective front perspective and rear perspective views from above, and Figure 4F shows a perspective view from below, of an alternative first portion of a second railway rail side post insulator for use in an assembly embodying the present invention, as shown on the righthand side of Figure 1 D and the lefthand side of Figure 1 E;

Figures 5A and 5D show respective front perspective and rear perspective views from above, and Figure 5G shows a perspective view from below, of a second portion of a second railway rail side post insulator for use in an assembly embodying the present invention, as shown in Figure 1 D;

Figures 5B and 5E show respective front perspective and rear perspective views from above, and Figure 5H shows a perspective view from below, of an alternative second portion of a second railway rail side post insulator for use in an assembly embodying the present invention; and

Figures 5C and 5F show respective front perspective and rear perspective views from above, and Figure 5I shows a perspective view from below, of another alternative second portion of a second railway rail side post insulator for use in an assembly embodying the present invention, as shown in Figure 1 E.

Each of the first, second and third railway rail fastening assemblies shown in Figures 1 A to 1 E comprises a pair of railway rail clip anchoring devices 3 for retaining respective resilient rail fastening clips 6 (or 6' or 6") of a type which are driven laterally onto a foot 21 of a railway rail 2. The front of each anchoring device 3, adjacent to the side 21 A of the rail foot 21 , supports a first side post insulator 1 ' or a second side post insulator 1 configured to provide an electrically-insulating load bearing face 10' (or 10) between the upright side face 21 A of the rail foot 21 and upright load bearing faces 301 , 302, 303, 304 of the anchoring device 3. The rail 2 is supported on a rail foundation (in this case a concrete sleeper) 7 via a rail pad 8 and, in some cases (except Figure 1 C), at least one shim 9.

The illustrated assemblies are designed to allow for vertical adjustment of the track height and lateral adjustment of the track gauge. In this example, the anchoring device is 5 mm taller than a "standard" version, and a 5 mm shim is supplied as part of the default assembly, but further shims of different heights and different variants of the side post insulators 1 ', 1 and the rail clips 6, 6", 6" are employed to allow a +/- 5 mm vertical adjustment from this. In particular, as shown in Figures 1A to 1 C, a default assembly will employ a "standard" clip 6 and an 'on the level' first (default) side post insulator 1 ', and the same clip 6 and first side post insulator 1 ' would be used for adjustments of +1 mm and -1 mm relative to this. A first modified clip 6' with a +3.5 mm relative toe height and a second side post insulator 1 of a type with a ramp up are provided to cover +2 mm to +5 mm adjustment (see the assembly of Figure 1 E, which has components providing a +5mm height adjustment and a -10mm gauge adjustment compared with that of Figure 1A), and a second modified clip 6" with a -3.5 mm relative toe height and another second side post insulator 1 of a type with a ramp down are provided for -2 mm to -5 mm adjustment (see the assembly of Figure 1 D which has components providing a -5mm height adjustment and a +10mm gauge adjustment compared with that of Figure 1A). Figure 2 shows the anchoring device 3 in more detail. The anchoring device 3 has upright load bearing faces 301 , 302, 303, 304, comprising front wall faces 301 , 303, 304 configured for location adjacent to the rail foot 21 , and an upper central face 302 which is offset from the front wall faces 301 , 303, 304 by an offset distance D. In this embodiment D is approximately 30% of the depth Do of the anchoring device 3 in a direction substantially perpendicular to the front wall faces 301 , 303, 304, but could be anything between a tenth and a half of the depth D₀ of the anchoring device 3. The anchoring device 3 has an upwardly-facing surface 31 which extends from the upper central face 302 to provide a shelf portion 31 of depth D for receiving part, 1 10' or 43, of a railway rail side post insulator 1 ' or 1.

As shown in Figures 3A and 3B, the electrically-insulating load bearing face 10' of the one-part first railway rail side post insulator 1 ' is provided by an outer face of a wall 100' of the insulator V. Unlike prior art side post insulators, the insulator 1 ' further comprises a member 1 10', joined to an inner face 12' of the wall 100', which has a top surface 1 1 ' which extends in a substantially perpendicular direction with respect to the load bearing face 10' to a depth do from the inner face of the wall 100' which is greater than or substantially equal to the depth d_w of the wall 100' in the said direction. In this embodiment the depth do of the top surface from the inner face 12' of the wall 00' is approximately twice the depth d_w of the wall 100', but the value of depth do is dependent upon depth D of the anchoring device shelf 31. For example, where D is 26mm, in the illustrated embodiment do + d_w is 39mm, d_w is 13mm, so do is 26mm, but, like D, do could vary, for example in the range 10mm to 63mm. In the embodiment of Figures 3A and 3B, the member 1 10' has a thickness h which is substantially the same as the thickness h_w of the wall 100'. A bottom face 15' of the member 1 10' and the base of the wall 100' are provided with rebates 105', so as to lower the overall weight and material of the first side post insulator 1 '.

In order to allow for vertical and lateral adjustments, in the non-default versions of the assembly a type of two-part second railway rail side post insulator 1 is employed, as shown in Figures 1 D and 1 E. In this case the electrically-insulating load bearing face 10 of the second side post insulator 1 is provided by respective outer load bearing side faces 40, 50 of first and second separately-formed, interlockable side post insulator portions 4, 5.

It is intended that a first plurality of first side post insulator portions 4 and a second plurality of second side post insulator portions 5 would be available, where any one of the first side post insulator portions 4 is interlockable with any one of the second side post insulator portions 5 so as to form the second railway rail side post insulator 1 , the first side post insulator portions 4 differing from one another in maximum depth d-i , d2, as measured in a direction substantially perpendicular to a plane in which the outer load bearing side face 40 extends, and the second side post insulator portions 5 differing from one another in thickness to, ti , t.2, as measured at the outer load bearing side face 50.

In one preferred embodiment, eleven first side post insulator portions 4 and three second side post insulator portions 5 would be provided, together with the "default" one-part first side post insulator V. A first one 4i of such first side post insulator portions 4, designed for the maximum gauge, is shown on the left of Figure 1 D and the right of Figure 1 E, and, in more detail, in Figures 4A to 4C. A second one Az of such first side post insulator portions 4, designed for the minimum gauge, is shown on the right of Figure 1 D and the left of Figure 1 E, and, in more detail, in Figures 4D to 4F. Although only two are illustrated here, as discussed above a number of further first side post insulator portions of intermediate sizes would also be provided.

In each case the first side post insulator portion 4 (4-j , 42) is shaped so as to provide: an upper inner load bearing side face 41 and a lower inner load bearing side face 42 for positioning against respective upright load bearing faces 302, 304 of the railway rail clip anchoring device 3; a bottom face 43 for positioning on the shelf portion 31 of the anchoring device 3; the outer load bearing side face 40; back wall 45; top surface portions 44A, 44B shaped for mating engagement with the second side post insulator portion 5; and left and right side portions 47. The underside of the first side post insulator portion is also provided with rebates 46 to save material and hence weight.

A first one 5i of such second side post insulator portions 5 is shown in Figure 1 D and, in more detail, in Figures 5A, 5D and 5G. A second one 52 of such second side post insulator portions 5 is shown in Figures 5B, 5E and 5H. A third one 53 of such second side post insulator portions 5 is shown in Figure 1E and, in more detail, in Figures 5C, 5F and 5I.

In each case the second side post insulator portion 5 is shaped so as to provide the outer load bearing side face 50 for positioning adjacent to the upright side face 21 A of the rail foot 21 , and a bottom surface 51 , shaped for mating engagement with the first side post insulator portion 4, which has weight-saving rebates 53.

Second side post insulator portion 5i has a thickness t-i at outer load bearing face 50, which is the smallest thickness of the three, and provides a downward ramp. Second side post insulator portion 52 has a thickness t.2 at outer load bearing face 50, which is the middle thickness of the three, and provides a flat upper surface. Second side post insulator portion 53 has a thickness t3 at outer load bearing face 50, which is the largest thickness of the three, and provides a upward ramp.

The bottom surface 51 of each second side post insulator portion 5 is provided with three protrusions 521 , 522, 523, and the top surface 44 of each first side post insulator portion 4 is provided with three corresponding apertures 441 , 442, 443 for engaging the respective protrusions 521 , 522, 523. Respective inner walls of outermost apertures 441 and 443 are provided with internal ledges 441 A, 443A, and each corresponding protrusion 521 and 523 is provided with a barb 521A, 523A at its end, such that when the barb on the protrusion is pushed past the ledge, the barb engages the ledge to prevent withdrawal of the protrusion from the aperture. To ensure the parts are interlocked in the correct orientation, an edge of the innermost aperture 442 is shaped with a recess 442A for receiving a corresponding portion 522 A extending from the innermost protrusion 522.

As mentioned above, the second side post insulator portions 5i and 53 have respective top surfaces 52 which are shaped so as to be inclined upwardly or downwardly from the outer load bearing side face 50 of the second side post insulator portion 5. Thus, when such a second side post insulator portion 5 is interlocked with a first side post insulator portion 4, the upper surface of the second railway rail side post insulator 1 so formed is shaped as an upwardly-inclined or downwardly-inclined ramp.

Examples of the thicknesses of insulators and shims which can be used to achieve respective desired lateral gauge and height adjustments are shown in the following tables, Table 1 and Table 2. Table 1

Lateral Gauge Adjustment Field Side Insulator Gauge Side Insulator (mm) per rail seat Thickness (mm) Thickness (mm)

+5 8 18

+4 9 17

+3 10 16

+2 1 1 15

+1 12 14

0 13 13

-1 14 12

-2 15 1 1

-3 16 10

-4 17 9

-5 18 8 Table 2

Verticai Height Adjustment (mm) per rail Shim stack thickness seat

+5 10 (5+5)

+4 9 (5+4)

+3 8 (5+3)

+2 7 (5+2)

+ 1 6 (5+1 )

0 5

-1 4

-2 3

-3 2

-4 1

-5 -

Claims

1 An assembly comprising a first railway rail side post insulator (1 ') and a railway rail clip anchoring device (3), for retaining a resilient railway rail fastening clip (6), which device (3) is configured to support the first railway rail side post insulator (1 '), wherein: the first railway rail side post insulator (1 ') is configured to provide an electrically- insulating load bearing face (10') between an upright side face (21A) of a foot (21 ) of a railway rail (2) and upright load bearing faces (301 , 302, 303, 304) of a railway rail clip anchoring device (3) located adjacent to the rail foot (21 ), the electrically-insulating load bearing face (10') being provided by an outer face of a wall (100") of the insulator, and the insulator further comprising a member (1 10'), joined to an inner face (12') of the wall (100'), which member (1 10') has a top surface (1 1 ') which extends in a

substantially perpendicular direction with respect to the load bearing face (10') to a depth (do) from the inner face of the wall (100') which is greater than or substantially equal to a depth (d_w) of the wall in the said direction; and

the railway rail clip anchoring device (3) has upright load bearing faces (301 , 302, 303, 304), comprising front wall faces (301 , 303, 304) configured for location adjacent to the rail foot (21 ), and an upper central face (302) which is offset from the front wall faces (301 , 303, 304) by an offset distance (D) which is between a tenth and a half of the depth (Do) of the anchoring device (3) in a direction substantially perpendicular to the front wall faces (301 , 303, 304), and an upwardly-facing surface (31 ) of the anchoring device (3) which extends from the upper central face (302) to provide a shelf portion (31 ) for receiving part (43) of the first railway rail side post insulator (1 ').

2. An assembly as claimed in claim 1 , wherein a height (h) of the member (1 10'), from its top surface (1 ') to a bottom surface (15') of the member (1 10'), is

approximately the same as a height (h_w) of the wall (100').

3. An assembly as claimed in claim 1 or 2, wherein the first railway rail side post insulator (1 ') is a one-part insulator.

4. An assembly as claimed in claim 1 , 2 or 3, wherein the depth (do) of the top surface is approximately twice the depth (d_w) of the wall.

5. An assembly as claimed in any preceding claim, wherein the offset distance (D) is between a quarter and a half of the depth (D₀) of the anchoring device (3).

6. An assembly as claimed in claim 5, wherein the offset distance (D) is between a quarter and a third of the depth (D₀) of the anchoring device (3).

7. An assembly as claimed in any preceding claim, wherein the device (3) is configured to retain a resilient railway rail fastening clip (6) of a type which is driven laterally onto a railway rail (2).

8. An assembly as claimed in any preceding claim, further comprising a kit of parts comprising a first plurality of first side post insulator portions (4) and a second plurality of second side post insulator portions (5), wherein:

any one of the first side post insulator portions (4) is interlockable with any one of the second side post insulator portions (5) so as to form a second railway rail side post insulator (1 ), for providing electrical insulation between the side face (21 A) of the foot (21 ) of the railway rail (2) and the load bearing faces (301 , 302, 303, 304) of the railway rail clip anchoring device (3) adjacent to the rail foot (21 ), in place of the first railway rail side post insulator (1 ');

the first side post insulator portions (4) of the first plurality each have an outer load bearing side face (40) and differ from one another in maximum depth (d-| , d2), as measured in a direction substantially perpendicular to a plane in which the outer load bearing side face (40) of the first side post insulator portion (4) extends; and

the second side post insulator portions (5) of the second plurality each have an outer load bearing side face (50) and differ from one another in thickness (to, t-i, t.2), as measured at the outer load bearing side face (50) of the second side post insulator portion (5),

9. An assembly as claimed in claim 8, wherein the number of first side post insulator portions (4) in the first plurality differs from the number of second side post insulator portions (5) in the second plurality.

10. An assembly as claimed in claim 9, wherein there are eleven first side post insulator portions (4) in the first plurality and three second side post insulator portions

(5) in the second plurality.

1 1. An assembly as claimed in any one of claims 8 to 10, wherein the first side post insulator portion (4) is shaped so as to provide: an upper inner load bearing side face (41 ) and a lower inner load bearing side face (42) for positioning against respective upright load bearing faces (302, 304) of the railway rail clip anchoring device (3); a bottom face (43) for positioning on the shelf portion (31 ) of the anchoring device (3); the outer load bearing side face (40) for positioning adjacent to the upright side face (21 A) of the rail foot (21 ); and a top surface portion shaped (44) for mating engagement with the second side post insulator portion (5).

12. An assembly as claimed in any one of claims 8 to 1 1 , wherein the second side post insulator portion (5) is shaped so as to provide: the outer load bearing side face (50) for positioning adjacent to the upright side face (21 A) of the rail foot (21 ); and a bottom surface (51 ) shaped for mating engagement with the first side post insulator portion (4).

13. An assembly as claimed in any one of claims 8 to 12, wherein one (5) of the first and second side post insulator portions (4, 5) is provided with one or more protrusions (521 , 522, 523) and the other (4) of the first and second side post insulator portions (4, 5) is provided with one or more corresponding apertures (441 , 442, 443) for engaging the respective protrusions (521 , 522, 523).

14. An assembly as claimed in any one of claims 8 to 13, wherein the second side post insulator portion (5) has a top surface (52) and is shaped such that the top surface (52) is inclined upwardly or downwardly from the outer load bearing side face (50) of the second side post insulator portion (5).