GB2094377A - Railway track pads - Google Patents

Abstract

A base pad for location between the underside of a railway rail and a foundation, e.g. a sleeper, is provided with means such as edge recesses 1 for locating and holding the pad in a position of use and with two rows of apertures therein, the apertures in one row being opposite those in the other, and the spacing of the apertures in the rows being the same so that the pad can be used in conjunction with a packing pad having a similar pattern of apertures and studs thereon, the arrangement being such that the studs of the packing pad can be located in apertures of the base pad and yet leave sufficient apertures exposed so that a further packing pad can be superimposed therewith with its studs located in apertures in the first- mentioned packing pad. <IMAGE>

Description

SPECIFICATION Railway track pads This invention relates to railway track pads.

It is known to locate rubber or plastics pads between the underside of a railway rail and a foundation, for example, a wooden, concrete or steel sleeper or paved concrete slab track on which the rail stands, to prevent vibration being transmitted from the rail to the foundation, thereby causing damage and wear, to provide the necessary electrical insulation if the rails are to be used to carry electric current for signalling circuits and also to compensate for unevenness of the upper surfaces of the foundation.

Although the pads can be in the form of simple rectangular pads of material approximately 5 mm thick, it is preferred nowadays to provide pad locating means along two side faces of the pad so that the pad must be correctly located and cannot vibrate loose from its position of use. Such a pad is disclosed in U.K. Patent Specification No. 1397032.

Two of the most advantageous uses of railway track pads are to offset wear, either on the upper surface of the foundation, e.g. the sleepers or paved concrete slab track, or where the ballast in which the foundation is normally laid becomes dispersed or loosened between the support or bearing area allowing one portion of the foundation, e.g. a particular sleeper, to sink relative to the adjacent portions.

For whatever reason a concrete sleeper becomes abraided at the rail seating, and to overcome this problem, a pad, or more usually several pads, stacked one upon another, are placed between the underside of the rail and the foundation to pack up the rail and restore the correct tension in the rail fastening.

Whilst it is relatively simple to locate several plain rectangular pads beneath the rail in this manner, unfortunately one or more of such pads tends sooner or later to become displaced since there is no means of positively locating and retaining them in position and the pads as disclosed in U.K. Patent Specification No. 1 397032 cannot be used for packing purposes in respect of abraided sleepers because of the presence of the locating ears. If it is necessary to use them for packing purposes, the ears on either side of each locating recess have first to be removed which is a difficult and time-consuming exercise.

The present invention has been evolved so that one or more packing pads may be used with a modified version of the type of pads disclosed in Specification No. 1397032 but is not so limited and can apply to any type of railway track pad.

According to the present invention, we provide a base pad for location between the underside of a railway rail and a foundation, e.g. a sleeper on which the rail stands, the pad being provided with means for locating and holding it in a position of use, and with at least two spaced apart apertures therein, to receive at least one complementary stud projecting from the surface of a similar packing pad when the latter is located in superimposed relationship with said pad.

The pad may have four or more apertures therein arranged in two spaced rows, but there are preferably three apertures in each row, the apertures being equally spaced in each row and those in one row being opposite those in the other row.

Also according to the present invention, we provide a packing pad for use with the base pad described above, the packing pad having at least one stud projecting from its surface and engageable in a respective complementary aperture in the surface of the pad described above, and having at least one aperture therein to receive the stud of an identical packing pad (when the latter is turned over and placed over the pad).

The packing pad may have one aperture and one stud in one row and one stud and one aperture in the other row, with the spacing between stud and aperture in each row being the same, and the stud in one row opposite the aperture in the other, and vice versa.

Also according to the present invention, we provide a set of pads for location between the underside of a railway rail and a foundation on which the rail stands comprising a base pad which is normally used on its own and located between the rail and foundation and has at least two spaced apart apertures therein, and one or more similar packing pads for location between the base pad and the foundation, the packing pad having one aperture therein and one stud projecting from one face thereof, the location of the spacing between the stud and aperture being identical to the location and spacing of the apertures in the base pad.

Preferably, however, the or each packing pad is provided with two apertures and a stud in one row with the stud located mid-way between the two apertures, and, in a second row, spaced from the first row by an amount similar to the spacing of the stud from the apertures in that row, with two studs and an aperture, with the latter located mid-way between the studs, and spaced therefrom by the same amount as the spacing of the stud and apertures in the first row, an aperture in one row being opposite a stud in the other row.

It will thus be appreciated that one or more packing pads (the second and subsequent ones have to be reversed relative to the previous one) can be used in conjunction with the base pad above or below the latter between a railway rail and a foundation to pack the space there-between when the foundation or rail has been worn as a result of passage of trains over the rail, to pack up the rail to the correct level and restore the correct tension in the rail fastening.

The invention also extends to a method of packing the space between the underside of a railway rail and a foundation for the rail using a base pad and optionally one or more packing pads as described herein.

A preferred embodiment of the present invention is now described by way of example with reference to the accompanying drawings, in which: FIGURE 1 is a plan view of a base pad; FIGURE 2 is a plan view of a packing pad; FIGURE 3 is a section on the line B-B of Figure 2, and FIGURE 4 is a section on the line A-A of Figure 2.

Referring to the drawings, the pad B shown in Figure 1 is a modified version of the general type of pad disclosed in U.K. Patent Specification No. 1397032 and which is nowadays located between the bottom of a railway rail and a foundation upon which the rail stands.

The pad is of generally rectangular configuration and has a substantially rectangular recess 1 located centrally along each of two opposite sides of the pad and by means of which the pad is located on the sleeper between a pair of spaced anchoring members on the sleeper. The pad has the traditional chamfered upper edges 3 along its other two parallel sides and in accordance with the present invention, six apertures 5, 7, 9, 11, 13 and 1 5. The apertures 5, 7 and 9 are located in one row with the aperture 7 mid-way between the apertures 5 and 9, and the apertures 11, 13 and 1 5 are located in a second row parallel to the first row but spaced therefrom, the aperture 13 being located mid-way between the apertures 11 and 15 and the spacing between the apertures in one row being identical to that between the apertures in the second row. Furthermore, each row is spaced inwardly from its adjacent parallel side edge of the pad by a similar amount.

This pad can be used in the traditional manner as described in the said U.K. Patent Specification No.1397032.

The pad of Figure 1 comprises a base pad B and is desired for use with one or more packing pads P, the subject of Figures 2-4. The packing pads have a width which is no greater than and normally less than, the width of the foot of a railway rail for which it is to be used. The length of the packing pads P is substantially the same as that of the base pad B. In each packing pad P three apertures 5, 9 and 13 are provided at locations which correspond with the locations of the identical apertures in the base pad B, but the apertures 7, 11 and 1 5 are replaced by upstanding studs 17, 21 and 25 each of which has a chamfered periphery 1 9.The diameter of the studs is such that they form a close fit within the apertures 7, 11 and 1 5 or, as will hereinaafter be explained, the apertures 1 3, 5 and 9 in the base pad B.

Normally, a base pad B will always be provided between the underside of a rail and its foundation.

If the foundation or rail becomes worn with the result that on passage of a train over the rail above the pad the rail will bounce up and down, it is a very simple matter for the permanent way staff to pack the resultant gap by replacing the old pad with an assembly consisting of base pad and one or more packing pads P. The fastening holding the rail to the foundation can be removed together with the old pad whereupon the extent of wear to the foundation and/or the rail would be measured. A suitable assembly consisting of one base pad B together with one or more packing pads P would then be assembled with the packing pads P placed above or below the base pad B as appropriate. The assembly would then be placed between the underside of the rail and the foundation and the rail fastening replaced.

Alternatively, in the event of wear occurring at any time after a single base pad B has been used, the clips holding the rail to the foundation would be removed and the rail raised slightly, whereupon a pad P could be slipped between the underneath of the rail and the pad B or between the pad B and the foundation and located in position by the three studs 17, 21 and 25 which are arranged facing upwards or downwards as appropriate being located in the apertures 7, 11 and 1 5 (or 13, 3 and 9 if the pad is turned 1800).

If, however, one packing pad is not sufficient to fill the space below base pad B, a second pad P can be inserted below the first pad P and since the lower face of the first pad P will present three downward facing apertures 5, 13 and 9, the studs 17, 21 and 25 in the second pad P can be located in these apertures. What is more, if a further packing pad is required, this again can be placed under the second pad P and located in position by means of its studs engaging in the apertures 1 3, 5 and 9 of the second pad. Once the required number of packing pads have been located in position, the clips holding down the rail can be re-inserted. It will thus be appreciated that the base pad B being located between the anchoring members on the sleeper also holds the packing pads in position and will always be to within 1 mm of the correct height (see Table). What is more, the rail does not have to be lifted above the level of the anchoring devices to enable a packing pad to be placed in position.

In the event of it being established that there is a loss of tension in the rail fastening which cannot be adjusted within the fastening itself, the tension may be improved or even fully restored by the insertion of one or more packing pads P between the rail and the base pad B as described above.

If in addition to the loss of tension in the fastening, there is also wear to either rail or foundation, then the measured total wear would be increased to allow for the loss of tension.

If wear on the foot of the rail itself exceeds 3 mm, it is not normally acceptable to leave the rail in position; therefore, not more than one packing pad P should ever be necessary between the rail and base pad B to solve this problem.

It will be appreciated that the invention is applicable to pads having different outlines from that of the base pad B shown in Figure 1. Furthermore, the particular arrangement and number of apertures in the base pad and studs and apertures in the packing pads can be changed from that illustrated. It is important, however, that the patterns of apertures in the base pad and studs and apertures in the packing pads match. A particular advantage of the illustrated construction is that the packing pads are located against lengthwise and lateral movement by spaced rows of co-operating studs and apertures with the result that shear forces resulting from a packing pad attempting to move relative to a base pad or another packing pad are kept to a minimum and not concentrated on a particular line through the pad.

The pads in accordance with the present invention may have any desired thickness, preferably in the range of about 3-1 0 mm and the height of the studs is no greater than the thickness of the pads.

The pads are preferably 3 mm thick (see Table) and made of a natural or synthetic rubber or a plastics material. It is of course important that the pads are durable and can withstand sunlight and chemicals which may be dropped on them from passing trains.

TABLE Number of Clip tension Total wear packing pads P +or- 1 mm nil -1 2mm 1 +1 3 mm 1 correct 4 mm 1 -1 5 mum 2 +1 6 mm 2 correct 7 mm 2 -1 8mm 3 +1 9 mm 3 correct etc.. ..

Claims (11)

1. A base pad for location between the underside of a railway rail and a foundation, said pad being provided with means for locating and holding it in a position of use, and with at least two spaced apart apertures in one row being opposite those in the other row and the apertures being equally spaced in packing pad when the latter is located in superimposed relationship with said pad.

2. A base pad according to claim 1 wherein the pad has at least four apertures therein.

3. A pad according to claim 1 or 2 wherein there are two rows of three apertures in the pad, the apertures in one row being aopposite those in the other row and the apertures being equally spaced in each row.

4. A base pad for location between the underside of a railway rail and a foundation substantially as hereinbefore described with reference to the accompanying drawings.

5. A set of pads for location between the underside of a railway rail and a foundation on which the rail stands comprising a base pad which is normally used on its own and located between the rail and foundation and has at least two spaced apart apertures therein, and one or more similar packing pads for location between the base pad and the foundation or rail, the packing pad having at least one aperture therein and one stud projecting from one face thereof, the location of and spacing between the stud and aperture being identical to the location and spacing of the apertures in the base pad.

6. A set of pads according to claim 5 wherein the or each packing pad is provided with two apertures and a stud in one row with the stud located mid-way between the two apertures and, in a second row, spaced from the first row by an amount similar to the spacing of the stud from the apertures in that row, with two studs and an aperture, with the latter located mid-way between the studs, and spaced therefrom by the same amount as the spacing of the stud and apertures in the first row, an aperture in one row being opposite a stud in the other row.

7. A set of pads for location between the underside of a railway rail and a foundation on which the rail stands substantially as hereinbefore described with reference to the accompanying drawings.

8. A packing pad for use with with a base pad as claimed in any one of claims 1-4, the packing pad having at least one stud projecting from its surface and engageable in a respective complementary aperture in the surface of the base pad and having at least one aperture therein to receive the stud of an identical packing pad.

9. A packing pad according to claim 8 and having one aperture and one stud in one row and one stud and one aperture in the other row with the spacing between stud and aperture in each row being the same and the stud in one row being opposite the aperture in the other row and vice-versa.

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

11. A method of packing the space between the underside of a railway rail and a foundation for the rail substantially as hereinbefore described with reference to the accompanying drawings.