Rail pads

Abstract

 An elastomeric rail pad (1) of generally rectangular plan configuration the pad having an upper face (6) adapted to underlie the lower face of a rail, and a lower face (3) adapted to overlie a concrete rail foundation member characterised in that the pad incorporates between the upper and lower face a fabric reinforcement layer (4) extending throughout at least the majority of the rail pad when viewed in plan, the fabric layer having a warp (18) and a weft (17) generally transverse one to the other.

Description

[0001] This invention relates to rail pads. Such pads are interposed between the lower surface of a railway rail and a foundation member on which the rail stands and to which it is usually secured. The rail foundation member may be a concrete or steel sleeper extending across the railway track, or a slab or plate, for example, running along the length of the rail. The purpose of the rail pad is to protect the foundation member from impulsive and other loads from passing-rail traffic, to compensate for any uneveness in the foundation member, and, where the rail is electrical, to provide some electrical insulation between the rail and the foundation member. Such rail pads are, from the very nature of their working disposition, subject to considerable potentially damaging forces as railway traffic passes along the rails supported by the pads, and a recurrent common problem with such pads is the damage so caused, and the inevitable need for frequent replacement at substantial cost.

[0002] It is an object of the present invention to overcome or at least substantially reduce the above-mentioned problem, and additionally to provide a rail pad capable of providing good impact protection for the foundation member therebelow.

[0003] In accordance with the present invention there is provided an elastomeric rail pad of generally rectangular plan configuration, the pad having an upper face adapted to underlie the lower face of a rail, and a lower face adapted to overlie a concrete rail foundation member characterised in that the pad incorporates between the upper and lower face a fabric reinforcement layer extending throughout at least the majority of the rail pad when viewed in plan, the fabric layer having a warp and weft generally transverse one to the other.

[0004] The fabric is preferably a woven fabric.

[0005] The warp and weft of the fabric may lie generally parallel with respect to the sides of the generally rectangular plan configuration rail pad.

[0006] The fabric may be of any appropriate and convenient material, and thus may for example be of a manmade fibre such as nylon.

[0007] More than one layer of fabric may advantageously be incorporated in the body of the pad to increase the effect of the invention. Surprisingly we have found two layers to be much more effective than would be expected by simply doubling a single layer.

[0008] We have found that by means of the invention the layer of fabric reinforcement is most effective in increasing the resistance of the rail pad to displacement and/or distortion by forces imparted by the passing traffic on the overlying rail. Since this is a characteristically typical of damage caused to rail pads by passing traffic, this leads to a significant increase in the useful life of a pad.

[0009] The generally rectangular plan configuration of rail pads may have rectangular recesses (in plan view) along two opposed sides midway along those sides, thereby defining on each end of such recesses what can be termed "ear" portions of the pad which in use locate the pad with respect to the anchoring assembly thereof between the overlying rail and the underlying rail foundation member. In such a case, the fabric reinforcing layer may be extended into the wings, providing welcome additional stiffness thereto, which has a significant effect in practice in preventing movement of the pad from its required disposition between the rail and the rail support member.

[0010] The pad may be provided on at least one face, with a plurality of protrusions to improve the attenuation of the rail foundation member from forces exerted by the rail due to traffic passing thereacross.

[0011] In order that the invention may be more readily understood, one embodiment thereof will now be described by way of example with reference to the accompanying drawings in which:-

Figure 1 is an over plan view of a rail pad incorporating the invention;

Figure 2 is an under plan view of the pad of Figure 1;

Figure 3 is a section plan view showing a reinforced woven fabric layer therein;

Figure 4 is a elevational cross section through part of the pad of Figure 1; and

Figure 5 is a cross section through a variation of the pad of Figure 1.

[0012] Referring now to Figures 1 to 4, a rail pad 1 is shown. This may be formed of a highly resilient vulcanised natural rubber (between 55 and 75 percent rebound value), or other appropriate elastomeric material having the same characteristics, such as a plastics or synthetic rubber. Desirably, the pad will be of between 50 and 90 shore A hardness.

[0013] The upper surface 6 of the pad is provided with a plurality of studs 2 each having a domed outer surface. Such arrangement of studs has been found to increase the attenuation provided by the pad between the overlying rail and the underlying foundation member during use as a result of the passage of rail traffic.

[0014] As can be seen from Figure 2, the underside 3 of the pad 1 is of a plain configuration.

[0015] Disposed within the pad is a layer of woven fabric. This extends through the great majority of the pad in plan apart from a peripheral portion 5 adjacent the edges thereof which effectively prevent ingress of moisture to the fabric layer.

[0016] As can be seen in Figure 3 at 7, the fabric is of a "square" woven nature, the weft 17 and warp 18 thereof lying parallel to respective sides 19 and 20 of the pad.

[0017] The material of the fabric layer 4 may be of nylon, but can be formed of other man made fibre such as a polyester, or can be a natural fabric material such as cotton. It is necessary that the fabric has good adhesion to the elastomeric material and whilst such good adhesion occurs naturally with some materials such as cotton, with other materials such as nylon, appropriate treatment, such as with resorcinol formaldehyde latex, can be carried out to ensure good adhesion of the fabric reinforcement so that in use there is no possibility of separation of the pad 1 into different layers which could otherwise lead to rapid destruction of the pad.

[0018] As can be seen, opposed sides of the pad are provided with recesses 8, 9 for engagement with the securing assembly for the overlying rail upon the underlying rail support (not shown), these recesses defining ears 10, 11 and 12, 13 at each end, and it is to be observed that the fabric reinforcement 4 extends fully into these ears, thereby providing significant stiffening to the ears, and increasing the resistance of the pad to any movement out of its required disposition within the securing assembly and under the rail and over the foundation member in use.

[0019] Typically, the pad is 190 mm square and of an overall thickness of 6.5 mm, whilst the recesses are typically of 84 mm in length. The upper surface of the reinforcing fabric layer 4 may be at least 1 mm above the under surface 3 of the pad 1, and at least 3 mm from the upper surface 6 of the pad.

[0020] Figure 5 illustrates a variation of the pad of Figures 1 to 4 in which two separate fabric 14, 15 reinforcing layers, both corresponding to the reinforcing fabric layers of Figures 1 to 4, are utilised in a pad 16. We have found that the use of two reinforcing layers is surprisingly effective in providing the advantages of the invention, and in this respect is significantly more effective than simply a doubling of the effect of a single layer.

[0021] By means of the invention particularly as illustrated, we have provided a reinforced rail pad where the resistance to displacement and/or distortion by forces imparted by trains passing over the overlying rail in use is most significantly increased, thereby increasing similarly the useful life of the rail pad.

[0022] It is to be understood that the foregoing is merely exemplary of rail pads in accordance with the invention and that modifications can readily be made thereto without departing from the true scope of the invention.

Claims

1. An elastomeric rail pad of generally rectangular plan configuration, the pad having an upper face adapted to underlie the lower face of a rail, and a lower face adapted to overlie a concrete rail foundation member characterised in that the pad incorporates between the upper and lower face a fabric reinforcement layer extending throughout at least the majority of the rail pad when viewed in plan, the fabric layer having a warp and a weft generally transverse one to the other.

2. The Rail Pad as claimed in claim 1 characterised in that the fabric is a woven fabric.

3. A Rail Pad as claimed in claim 1 or 2 characterised in that the warp and weft of the fabric lie generally parallel with respect to the sides of the generally rectangular plan configuration Rail Pad.

4. A Rail Pad as claimed in any one of the proceeding claims characterised in that the fabric is formed from a man-made fibre.

5. A Rail Pad as claimed in claim 4 characterised in that the fabric is formed of nylon.

6. A Rail pad as claimed in any one of the proceeding claims characterised in that pad has rectangular recesses (in plan view) disposed generally midway along two opposed sides, thereby defining on each end of such recesses wing portions of the pad which in use locate the pad with respect to the anchoring assembly thereof between the overlying rail and the underlying foundation member, characterised in that the fabric reinforcing layer extends into the wings providing stiffening thereto.

7. A Rail Pad as claimed in any one of the proceeding claims characterised in that a plurality of layers of fabric are incorporated, generally parallel one to another, within the body of the pad.

8. A rail pad as claimed in claim 7 wherein two layers of fabric are incorporated.

9. A Rail pad as claimed in any one of the proceeding claims characterised in that at least one face thereof is provided with a plurality of protrusions to improve the attenuation of the rail foundation member from forces exerted by the rail due to traffic passing there across.

Drawing