Title of Invention

RAIL PADS

Abstract

The invention provides an elastomeric rail pad 1 of generally rectangular plan configuration, the pad having an upper face 2 adapted to underlie the lower face of a rail, and a lower face adapted to overly a concrete rail foundation member characterised in that the pad includes a reinforcement means 13 which is generally parallel to its mean plane and extends at least between dispositions associated with generally opposing corners of the generally rectangular pad, said reinforcing means having a tensile strength such as to resist, in use of the pad, forces from traffic passing across the rail disposed thereabove otherwise tending to stretch the pad in the mean plane thereof.

Full Text

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, for example, 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 unevenness in the foundation member; and, where the rail is electrical, to provide electrical insulation between the rail and the foundation member. Such rail pads were from their working disposition, subject to considerable potentially damaging forces as railway traffic passes along the rail supported by the pads, and the recurrent common problem with such pads was the damage so caused, and the inevitable need for frequent replacement at substantial cost. To alleviate this problem it has been established that the provision of an elastomeric rail pad of generally rectangular plan configuration having an upper surface adapted to underlie the lower face of a rail, and a lower face adapted to overly a concrete rail foundation member in which the pad is studded on the upper side (underlying the rail) will substantially improve the attenuation of the rail foundation member from forces exerted by the rail due to traffic passing thereacross. Whilst such an arrangement has been singularly effective in reducing damaging forces upon the pad and the foundation member therebelow, particularly when the foundation member or sleeper contains recesses or pockets to contain and position the pads under the rail. In this purpose-built assembly, pads are able to withstand high vertical and side loading whilst providing shock attenuation and minimising track damage with no possibility of extrusion caused by side loading. The improved behaviour resulting from the use of rail pads in flat sleeper assemblies can be outweighed by the tendency of pads to be extruded and "lost" from under track by high side forces, this condition having particular effect when trains are negotiating bends in the track and when high axle loads are present. It is especially to these conditions of track where sleepers do not have containment pockets for pads and also where high slide loads are present that the present invention is directed, and it is an object of the present invention to overcome or at least substantially reduce the problems identified above. In accordance with the 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 overly a concrete rail foundation member characterised in that the pad includes reinforcement means which is generally parallel to its mean plane, and extending at least between dispositions associated with generally opposing corners of the generally rectangular pad, said reinforcing means having a tensile strength such as to resist, in use of the pad, forces from traffic passing across the rail disposed thereabove otherwise tending to stretch the pad in the mean plane thereof. 3 The reinforcing means can be associated with the lower or upper faces of the pad, or elsewhere, but in one preferred embodiment may be associated with the lower face of the pad. The reinforcing means may be of a sufficient tensile strength plastic, such as nylon, or a metal such as steel, and may be disposed within the pad by forming the pad about such reinforcement, or may comprise a member attached to, for example, the base of the pad. The reinforcement means may comprise a member of any appropriate configuration to achieve the desired result hereinabove specified, and in one embodiment may be in the form of a cruciform extending between corners of the generally rectangular pad. The pad can have smooth lower and/or upper surfaces, or the upper and optionally the lower surface can have an array of grooves, ridges, studs or other protrusions or recesses for the purpose of improving the cushioning properties of the pad. The pad, in a preferred embodiment, may be of a single sided nature in that a plurality of protrusions to improve the attenuation of the rail foundation member may be disposed solely on the upper face of the pad. In this case, the reinforcement means may be attached, by rivets for example, to the lower, flat, face of the pad. In other embodiments the reinforcing means may be disposed within the pad which then may be again of a single upper face protrusion laden pad, or may be both upper and lower protrusion laden. The generally rectangular plan configuration of the rail pad 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 this case the reinforcing means may be configured such as to extend into the wings, thereby providing stiffness thereto, with significant affecting practice and preventive movement of the pad from its required disposition between the rail and rail support member. Accordingly the present invention also provides a method of protecting a foundation member for a railway rail from impulsive and other load from rail traffic passing over the rail, which method comprises: formmg an elastomeric rail pad to have a substantially rectangular plan configuration; providing the elastomeric rail pad with; an upper face adapted to underlie the lower face of a rail; a lower face adapted to overlie a concrete rail foundation member; a reinforcement means which is generally parallel to a mean plane of the pad, the reinforcement means extending at least between dispositions associated with generally opposing comers of the pad, said reinforcement means having a tensile stress such as to resist forces traffic passing across the rail disposed thereabove otherwise tending to stretch the pad in the mean plane thereof; and positioning the elastomeric rail pad between the foundation member and the railway rail. 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 a top plan view of a rail pad to which the invention can be applied; Figure 2 is a schematic side view of the rail pad of Figure 2; Figure 3 shows the forces applicable upon a rail which affect a pad disposed therebelow; Figure 4 shows the resultant stress and stretching of a pad disposed between a rail and a rail support member; Figure 5 shows an underview of a pad incorporating the invention; Figure 6 shows in more detail the reinforcing member illustrated in Figure 5; Figure 7 shows in cross section a configuration of one of the bores within the reinforcing member of Figure 6. Figure 8 is a plan view of a rail pad according to a second embodiment of the invention; Figure 9 is a sectional elevation along line l-l in Figure 8; Figure 10 is a plan view of a rail pad according to a third embodiment of the invention: and Figure 11 is a sectional elevation along line 11-11 of Figure 10. Referring now to Figure 1 and 2 a rail pad 1 is shown. This is formed of highly resilient vulcanised natural rubber (between 55% and 75% rebound value) or other appropriate elastomeric material having the same characteristics such as a plastics or synthetic rubber. Desirably the material from which the pad is formed will have an IRHD hardness of between 50 and 90. The upper surface 2 of the pad is provided with a plurality of studs 3 each having a domed outer surface 4. 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. As can clearly be seen from Figure 2 the under side 5 of the pad is of plane configuration. Figure 3 illustrates the vertical (8) and transverse (9) forces, very schematically, acting upon a rail 6 when a wheel 7 of rail traffic passing thereabove acts upon the rail. As can be seen in Figure 4 this result in stresses 10 upon a rail pad 1 disposed between the rail 6 and a rail support member (not shown), the axis of the rail being along the line 11, and the upstream/downstream direction being as shown by arrow 12 parallel to axis 11. It will be seen that the affect of the forces by traffic on the rail stretch and attenuate the rail pad 1 such as to deform the same and reduce its effectiveness. 6 Figure 5 illustrates schematically from below the underside of the rail pad 1 of Figures 1 and 2 the attachment of a nylon cross-shaped member 13 which in practice is arranged to ensure, because of its relatively high tensile strength compared to that of the pad, that the stretching of the pad is very strictly limited compared to the situation illustrated in Figure 4. It will be seen that the cross-shaped support member 13 has apertures 1 5 at the ends of its arms 14, by means of which rivets or the like may attach the nylon reinforcement cross 13 to the base of the pad 1, which thereby holds the pad in place. Figure 6 is a somewhat more detailed plan illustration (still schematic) of the reinforcement member 13 illustrated in Figure 5. In addition to the end most apertures 15 at the ends of the limbs 14, a plurality of further apertures 16 (which can be of various shapes in addition to the shapes illustrated) are shown disposed along the arms of the reinforcement member 13. These apertures receive, without protrusion therebelow, securement rivets (not shown) to the rail pad to which they must be attached. By appropriate securement through several or all of the apertures in the limbs, a very secure engagement between the reinforcing member 13 and the pad 1 disposed thereabove can be obtained as is necessary in the circumstances. By means of the invention, particularly as hereinabove illustrated, we have provided a reinforced rail pad where the resistance to displacement and/or distortion by forces from traffic passing thereover in use is most significantly increased, thereby increasing the useful life and the effectiveness of the rail pad concerned. The reinforced rail pad of the present invention is able to provide a stable (non-extrudable) replacement for the multiplicity of existing pads which are in use in the United Kingdom and elsewhere. This enables a truly resilient pad with real and meaningful shock attenuation properties to be used. This enables a relatively inexpensive method of uprating track, whic is advantageous in ail track without pocl Amongst other things it is especially beneficial for high axle load use and especially where tight bends are involved. This is often encountered outside the United Kingdom and on private lines such as ore carrying trains etc. In addition, pads according to the invention could be used on light rail and tramways. The rail pad illustrated in Figures 5 to 7 represents one preferred embodiment of the invention in that the arrangement of studs on the upper surface has been found to be particularly effective in cushioning the railway sleeper or other foundation member from the impulsive forces of rail traffic passing thereover. However, instead of having a plurality of stud-like protrusions on the upper surface thereof, the rail pad can have smooth upper and lower surfaces, or a grooved upper (and optionally lower) surface, and embodiments illustrating such arrangements are shown in Figures 8 to 11. In the rail pad of Figures 8 and 9, both the upper surface 102 and lower surface 105 of pad 101 are smooth, and a cruciform polyamide reinforcing member 113 is secured to the lower surface 105 by means of rivets 122. In the rail pad of Figures 10 and 11, the lower surface 205 of pad 201 is smooth but across the upper surface 202 extends an array of parallel grooves 220. A cruciform reinforcing member similar to that of the embodiments of Figures 5 to 9 is secured to the lower surface 205 by means of rivets 222. Although, in this embodiment, the lower surface 205 is shown as being smooth, it could if desired be provided with grooves similar to those found in the upper surface 202. 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. WE CLAIM 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 overly a concrete rail foundation member characterized in that the pad has a reinforcement means which is generally parallel to its mean plane and extends at least between dispositions associated with generally opposing corners of the generally rectangular pad, said reinforcing means having a tensile strength such as to resist, forces from traffic passing across the rail disposed thereabove otherwise tending to stretch the pad in the mean plane thereof 2. The elastomeric rail pad as claimed in claim 1 wherein the reinforcing mean is associated with the lower face of the pad or the upper face of the pad. 3. The elastomeric rail pad as claimed in claim 1 wherein the reinforcing means is associated with the lower face of the pad. 4. The elastomeric rail pad as claimed in claim 3 wherein the reinforcing means comprises a member attached to the base of the pad. 5. The elastomeric rail pad as claimed in claim 4 wherein the reinforcing member has a plurality of apertures disposed over its area, which apertures in use serve to grip elatomeric material of the rail pad. 6. The elastomeric rail pad as claimed in claim 1 wherein the reinforcing means is disposed within the pad by forming the pad thereabout. 7. The elastomeric rail pad as claimed in any one of the preceding claims wherein the reinforcing means is formed from a plastics material . The elastomeric rail pad as claimed in claim 7 wherein the plastics material is a »olyamide. . The elastomeric rail pad as claimed in claim 8 wherein the polyaamide is lylon. 0. The elastomeric rail pad as claimed in any one of the preceding claims wherein the reinforcing means is formed from steel. II. The elastomeric rail pad as claimed in any one of the preceding claims wherein the reinforcing means is in the form of cruciform extending between comers of the generally rectangular pad. 12. The elastomeric rail pad as claimed in any one of the preceding claims having on the upper surface thereof, but not on the lower surface thereof, a plurality of protrusions to improve the attenuation of the rail foundation member. 13. The elastomeric rail pad as claimed in claim 12 wherein the reinforcing means is attached to the lower, flat, surface of the pad. 14. The elastomeric rail pad as claimed in claim 13 wherein the reinforcing means is attached to the lower surface by means of rivets. 15. The elastomeric rail pad as claimed any one of the preceding claims wherein the reinforcing means is disposed within the pad, and either (i) the upper surface but not the lower surface have protrusions thereon, or (ii) both the upper and lower surfaces have protrusions thereon. 16. An elastomeric rail pad as claimed in any one of the preceding claims wherein the generally rectangular plan configuration of the rail pad may has rectangular recesses (in plan view) along two opposed sides midway along those sides, thereby defining ear portions of the pad on each end of such recesses, which ear portions in use locate the pad with respect to the anchoring assembly thereof between the overlying rail and the underlying rail foundation member. 17. The elastomeric rail pad as claimed in claim 16 wherein the reinforcing means is configured such as to extend into the ear portions. 18. The elastomeric rail pad as claimed in any one of the preceding claims wherein the pad is formed of an elastomeric material having from 50 to 90 shore hardness. 19. A method of protecting a foundation member for a railway rail from impulsive and other load from rail traffic passing over the rail, which method comprises: forming an elastomeric rail pad to have a substantially rectangular plan configuration; providing the elastomeric rail pad with; an upper face adapted to underlie the lower face of a rail; a lower face adapted to overlie a concrete rail foundation member; a reinforcement means which is generally parallel to a mean plane of the pad, the reinforcement means extending at least between dispositions associated with generally opposing corners of the pad, said reinforcement means having a tensile stress such as to resist forces traffic passing across the rail disposed thereabove otherwise tending to stretch the pad in the mean plane thereof; and positioning the elastomeric rail pad between the foundation member and the railway rail. 20. A reinforced elastomeric rail pad substantially as herein described herein with reference to Figures 5 to 11 of the accompanying drawings. 21. A method of protecting a foundation member for a railway rail from impulsive and other load from rail traffic passing over the rail substantially as herein described with reference to the accompanying drawings.

Documents:

123-mas-98 abstract.pdf

123-mas-98 assignment.pdf

123-mas-98 claims-duplicate.pdf

123-mas-98 claims.pdf

123-mas-98 correspondence-others.pdf

123-mas-98 correspondence-po.pdf

123-mas-98 description (complete)-duplicate.pdf

123-mas-98 description (complete).pdf

123-mas-98 form-19.pdf

123-mas-98 form-2.pdf

123-mas-98 form-26.pdf

123-mas-98 form-4.pdf

123-mas-98 form-6.pdf

123-mas-98 others.pdf