GB2229213A

GB2229213A - Rail pad and method of upgrading railway track using such a pad

Info

Publication number: GB2229213A
Application number: GB9005892A
Authority: GB
Inventors: Geoffrey Gordon Leeves
Original assignee: Pandrol Ltd
Current assignee: Pandrol Ltd
Priority date: 1989-03-15
Filing date: 1990-03-15
Publication date: 1990-09-19
Anticipated expiration: 2010-03-15
Also published as: CA2012143A1; ATE92126T1; EP0388190B1; DE69002354D1; ES2043272T3; GB9005892D0; GB2229213B; GB8905917D0; EP0388190A1

Abstract

A pad which is suitable to be placed on a foundation for a railway rail and to have the rail standing on it, the pad being generally rectangular and comprising a web (1) from which, when the web (1) is lying horizontally, protuberances (2, 3) project upwardly but no protuberances project downwardly, is characterised in that there are tens of the protuberances (2, 3) in the form of studs, each of which, except possibly at the edges of the pad, is completely surrounded by a portion of the web (1) which is free from protuberances (2, 3), the studs having convexly rounded tips and all the studs, except possibly at the edges of the pad, being substantially identical and of circular cross-section. The pad is further characterised in that it has two ears (8) projecting laterally from each of two opposite edges of the pad to receive between them a part projecting upwardly from the rail foundation whereby the pad is prevented from moving along the rail. The pad is still further characterised in that it is no more than 6.5mm. thick. Preferably, the pad is no more than 6mm. thick, and is desirably about 5.5mm. thick. A method of upgrading a section of railway track using such a pad is also disclosed.

Description

1 RAIL PADS AND METHODS OF UPGRADING RAILWAY TRACK USING SUCH PADS

According to a first aspect of the present invention, there is provided a pad which is suitable to be placed on a foundation for a railway rail and to have the rail standing on it, the pad being generally rectangular and comprising a web from which, when the web is lying horizontally, protuberances project upwardly but no protuberances project downwardly, characterised in that there are tens of the protuberances in the form of studs, each of which, except possibly at the edges of the pad, is completely surrounded by a portion of the web which is free from protuberances, the studs having convexly rounded tips and all the studs, except possibly at the edges of the pad, being substantially identical and of circular cross-section and further characterised in that the pad has two ears projecting laterally from each of two opposite edges of the pad to receive between them a part projecting upwardly from the rail foundation whereby the pad is prevented from moving along the rail and still further characterised in that the pad is no more than 6.5mm. thick.

Preferably, a pad embodying the first aspect of the present invention is no more that 6mm. thick, and is desirably about 5.5mm. thick.

It is also preferable that in a pad embodying the first aspect of the present invention the studs are in parallel rows and in parallel columns inclined by an acute angle to the rows.

In a pad embodying the first aspect of the present invention it is desirable that, except at the edges of the pad, each stud is surrounded by six other studs none of which is at a distance from it greater than the thickness of the stud.

Preferably, in a pad embodying the first aspect of the present invention the studs at each of two opposite edges of the pad are wider, in a direction from one of said edges to the other, than the studs nearer the centre of the pad.

DE-1014139 discloses a pad which is suitable to be placed on a foundation for a railway rail and to have the rail standing on it, the pad being generally rectangular and comprising a web from which, when the web is lying in a particular orientation, protuberances project upwardly but no protuberances project downwardly. However, the protuberances on the pad disclosed in DE-1014139 are very few and they are large and widely spaced apart and are joined together by cross-pieces which undesirably limit the flexibility of the pad.

According to a second aspect of the present invention, there is provided a method of upgrading a section of railway track in which a rail stands on a first pad which lies on a foundation, in which method the pad is replaced by a second pad embodying the first aspect of the present invention and of substantially the same thickness, when compressed, as is the first pad, when compressed, or no more than about lmm. thicker.

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

Figure 1 shows a plan view of a rail pad embodying the first aspect of the present invention; Figure 2 shows a side view of the rail pad when viewed as indicated by the arrow II in Figure 1; and Figure 3 shows a sectional view on a larger scale of part of the rail pad when viewed as indicated by the arrow II in Figure 1.

The pad illustrated in the drawings consists of a single moulding of polyurethane and is generally rectangular as seen in plan view. It consists of a generally rectangular web 1 2.5mm. thick having many protuberances in the form of studs 2 of circular cross-section and studs 3 of elongate cross- section on one face 4 of the web. On the opposite face 5 of the web there are no protuberances and no recesses. The distance from the face 5 to the tips of the studs 2 and 3 is 5.5mm..

The studs 2 have a diameter of 9.75mm. at their tips and a slightly larger diameter at their roots because their flanks are inclined by an angle X of about 5 0 to the normal 6 to the web. The tips of the studs 2 are convex with a radius of 24mm.. The studs 3 have a flat area 3A at their tips and a convexly curved area 3B at the sides of their tips nearer the centre of the pad. The studs 2 are arranged in columns which are vertical in Figure 1 and in rows which are inclined by an acute angle Y to the columns. There are eight columns each with eleven studs 2 and one stud 3 at each end of the column and, between those columns, seven columns each consisting of twelve studs 2. The pitches of the studs 2 in the columns are llmm. and the columns themselves have a pitch of 12.7mm., measured perpendicularly to the columns. Where two studs 2 or one stud 2 and one stud 3 in any one column have their roots adjoining one another there is a radius R of 0.55mm..

At each of two opposite edges of the web there is a region 7 where the web thickness is 4mm. and from each region 7 there project two ears 8 of the same thickness as the region 7, the intention being that a clip-retaining member for a so-called P-R clip or an e-clip is to lie partly between each two adjacent ears 8 whereby any tendency for the pad to move along the rail is opposed.

A pad embodying the first aspect of the present invention can isolate the rail foundation from approximately 40% of a 40kHz vibratory force applied to the overlying rail.

It should be noted that, although the pad described with reference to the Figures is made of polyurethane, a pad embodying the first aspect of the present invention could be made of any other suitably robust or hardened material, such as polyester, polyethylene or rubber.

In some circumstances it may be desirable to secure the face 5 of the web, by a suitable adhesive, to a rail seat on a concrete rail foundation, for example a sleeper consisting of a concrete beam upon which two rails rest, or a block upon which only one rail rests and forming part of a sleeper comprising two blocks joined together by a steel tie-bar, or a long slab of concrete extending along the railway track. One of the reasons why it may be desirable to secure the pad by an adhesive is that this prevents sand, which is applied to the running surfaces of the rail, from penetrating between the pad and the concrete sleeper, where it can cause abrasion of both the pad and the sleeper.

it is also possible to secure the illustrated pad by an adhesive to a steel railway sleeper. Furthermore an entirely different pad, but having protuberances ' and/or recesses on its upper face, but not on its lower face, may also have its lower face secured by an adhesive to a concrete or steel rail foundation.

Pads according to the first aspect of the present invention are preferably employed in methods embodying the second aspect of the present invention, as will now be described.

In some circumstances, it is desirable to upgrade a section of railway track, so as to allow that section to withstand heavier loads, for example because of the wish to use heavier railway vehicles and/or vehicles t c; 1 travelling at faster speeds.

According to the second aspect of the present invention, firstly the means fastening the rail to the foundation are released. Typically, the rail fastening 5 means comprise rail clips, such as a P-R clip or an e- clip, and to release the rail from retention by such clips the clips are extracted from respective clip-retaining members embedded in, or otherwise attached to, the rail foundation.

When the rail has been released, the rail pad that had been lying between it and the rail foundation is removed and is replaced by a pad, embodying the first aspect of the present invention, which is of substantially the same thickness, when compressed, as the pad that it is replacing, when that pad is compressed, or no more than about lmm. thicker. Since pads embodying the first aspect of the present invention have protuberances on only one face, it is possible to manufacture a pad which better isolates the foundation from dynamic forces than the pad which it is to replace, but is at the same time not substantially thicker than that pad. By replacing the first pad by such a pad, it is possible to re-use the rail clins. which were previously extracted so as to release the rail, to secure the rail once again to the rail foundation, without the distortion of the clips on driving them into position being so great that they exert too high a force on the rail.

Since pads used in railway track to which methods embodying the second aspect of the present invention may be applied are generally 4.5mm. to 6.5mm. thick, and are typically 5.5mm. in overall thickness, when compressed, pads embodying the first aspect of the present invention are, when compressed, no more than 6.5mm. thick, are preferably no more than 6mm. thick, and are desirably about 5.5mm. thick.

Claims

CLAIMS:

1. A pad which is suitable to be placed on a foundation for a railway rail and to have the rail standing on it, the pad being generally rectangular and comprising a web from which, when the web is lying horizontally, protuberances project upwardly but no protuberances project downwardly, characterised in that there are tens of the protuberances in the form of studs, each of which, except possibly at the edges of the pad, is completely surrounded by a portion of the web which is free from protuberances, the studs having convexly rounded tips and all the studs, except possibly at the edges of the pad, being substantially identical and of circular cross-section and further characterised in that the pad has two ears projecting laterally from each of two opposite edges of the pad to receive between them a part projecting upwardly from the rail foundation whereby the pad is prevented from moving along the rail and still further characterised in that the pad is no more than 6.5mm. thick.

2. A pad according to claim 1, wherein the pad is no more than 6mm. thick.

3. A pad according to claim 1 or 2, wherein the pad is about 5.5mm. thick.

4. A pad according to any preceding claimf in which the studs are in parallel rows and in parallel columns inclined by an acute angle to the rows.

5. A pad according to any preceding claim, in which, except at the edges of the pad, each stud is surrounded by six other studs none of which is at a distance from it greater than the thickness of the stud.

6. A pad according to any preceding claim in which the studs at each of two opposite edges of the pad are wider, in a direction from one of said edges to the other, than the studs nearer the centre of the pad.

1 1.

7. A pad substantially as hereinbefore described with reference to the accompanying drawings.

8. A method of upgrading a section of railway track in which a rail stands on a first pad which lies on a foundation, in which method the pad is-replaced by a second pad according to any preceding claim and of substantially the same thickness, when compressed, as is the first pad, when compressed, or no more than about lmm. thicker.

9. A method of upgrading a section of railway track in which a rail stands on a first pad which lies on a foundation, in which method the first pad is replaced by a second pad having protuberances on only one face thereof.

k Published 1990 at The PatentOffice. State House. 6671 High Holborn. London WC1R4TP.Purther copies maybe obtained from The Patent Office Wes Branch, St Mary Cray. OrpIngton. Kent BRS 3RD. Printed by Multiplex twechluques ltd, St Mary Cray. Kent, Con. V87

Amendments to the claims have been filed as follows A pad which is suitable to be placed on a foundation for a railway rail and to have the rail standing on it, the pad being generally rectangular and comprising a web from which, when the web is lying horizontally, protuberances project upwardly but no protuberances project downwardly, characterised in that there are tens of the protuberances in the form of studs, each of which, except possibly at the edges of the pad, is completely surrounded by a portion of the web which is free from protuberances, the studs having convexly rounded tips and all the studs, except possibly at the edges of the pad, being substantially identical and of circular cross-section and further characterised in that the pad has two ears projecting laterally from each of two opposite edges of the pad to receive between them a part projecting upwardly from the rail foundation whereby the pad is prevented from moving along the rail and still further characterised in that the pad is no more than 6.5mm. thick when the rail, secured to the foundation, is standing on it.

2. A pad according to claim 1, wherein the pad is no more than 6mm. thick.

3. A pad according to claim 1 or 2, wherein the pad is about 5.5mm. thick.

4. A pad according to any preceding claim, in which the studs are in parallel rows and in parallel columns inclined by an acute angle to the rows.

1 9 7. A pad substantially as hereinbefore described with reference to the accompanying drawings.

8. A method of upgrading a section of railway track in which a rail stands on a first pad which lies on a foundation, in which method the pad is replaced by a second pad according to any preceding claim and of substantially the same thickness, when compressed, as is the first pad, when compressed, or no more than about lmm. thicker.