GB2199062A

GB2199062A - A base plate for supporting a railway rail

Info

Publication number: GB2199062A
Application number: GB08729861A
Authority: GB
Inventors: Paul Vernon
Original assignee: Pandrol Ltd
Current assignee: Pandrol Ltd
Priority date: 1986-12-22
Filing date: 1987-12-22
Publication date: 1988-06-29
Anticipated expiration: 2007-12-22
Also published as: GB8630564D0; GB2199062B; GB8729861D0

Abstract

A base plate 1 is a moulded body of electrically insulating material including a plate-like part 2 and two projections 3 extending upwardly from the plate-like part 2, between which the foot of a rail is to be located. A passageway 6 extends through each projection 3 to receive a straight leg of a rail clip and beside each passageway there is a platform 7 for receiving the heel of the clip. A metallic anti-scuffing member has a portion in the passageway 6, to prevent the clip touching the roof of the passageway, and a portion 9 on the platform 7, to prevent the clip touching the latter. The same function could be performed by two separate metallic members. A ledge 5 extends outwardly from the upper edge of the part 2, at least part of its upper surface sloping downwardly to assist run-off of rainwater. <IMAGE>

Description

A base plate for supporting a railway rail According to a first aspect of the invention, there is provided a base plate for supporting a railway rail, the base plate being a moulded body of electrically insulating material including a plate-like part, two projections extending upwardly from the top of the plate-like part on opposite sides of a portion thereof which is to lie under the rail, each projection being formed with a passageway to receive part of a rail-fastening clip, and a ledge extending outwardly from the upper edge of the plate-like part, at least part of the upper surface of the ledge sloping downwardly to assist run-off of rainwater.

Preferably, the ledge is endless, that is to say it extends around the entire periphery of the platelike part.

There is preferably a well in the upper surface of the plate-like part to receive a resilient pad on which the rail is to stand.

The upward projections may in each case include a platform upon which part of a rail-fastening clip may bear downwardly, the platform being beside a taller portion of the projection through which the passageway passes, the two passageways being substantially horizontal and parallel to each other and to a rail when it is positioned on the plate-like part.

Two anti-scuffing elements made of metal may each have a portion lying on one of the platforms and portions extending over opposite sides of the projection concerned, to prevent movement of the,anti- scuffing element parallel to the length of the rail.

Another part of the anti-scuffing element may lie within the passageway, in order to separate the clip from the roof of the passageway.

According to a second aspect of the invention, there is provided a base plate which is suitable for supporting a railway rail, the base plate being a moulded body of electrically insulating material including a plate-like part, two projections extending upwardly from the top of the plate-like part on opposite sides of a portion thereof which is to lie under the rail, each projection being formed with a passageway to receive part of a rail-fastening clip, the two passageways being substantially horizontal and parallel to each other and to a rail when it is positioned on the plate-like part, each of the upward projections including a platform upon which part of a rail-fastening clip may bear downwardly, the platform being beside a taller portion of the projection through which the passageway passes, there being a metallic portion within each passageway, in order to separate the clip from the roof of the passageway, and a metallic portion on each platform, in order to separate the clip from the platform, whereby scuffing of the base plate by the clips is reduced.

An installation on a railway track may include a base plate according to the first or the second aspect of the invention, a flange-footed rail standing on said portion thereof between the two projections and located by them and two rail-fastening clips each having one portion driven into the passageway in the projection and another portion baring downwardly on a part of the base plate which, as seen from the rail, is beyond the passageway.

An example in accordance with the invention is described below with reference to the accompanying drawings, in which: Figure 1 diagrammatically shows a perspective view of a base plate, for supporting a railway rail, with two anti-scuffing elements on it, Figure 2 shows a sectional view of the same base plate, taken as indicated by the arrows II in Figure 1, with parts of one of the anti-scuffing elements also being shown, Figure 3 shows a perspective view of one of the anti-scuffing elements, Figure 4 shows an end view of a concrete railway sleeper, a base plate lying on it and a rail standing on the base plate, Figure 5 shows an enlarged view of part of what is shown in Figure 4, Figure 6 shows a side view of a railway sleeper with a base plate lying on it, a rail standing on the base -plate and clips holding the rail down, and Figure 7 shows a perspective view of part of a modified base plate.

The base plate shown in Figure 1 is intended to solve, or at least mitigate, the problem that when metallic base plates lie on steel or concrete railway sleepers or on other electrically conductive structures and the rails standing on the base plates carry return traction currents, there are always leakage currents, which cause corrosion not only of the base plates and the devices which secure the rails to them but also of neighbouring metallic parts. Instead of being made of metal, the base plate 1 shown in Figure 1 is a moulded body of suitably robust electrically insulating material, for example plastics material, possibly incorporating fibres.A suitable material is an engineering plastics material such as a polyacetal (i.e. a homopolymer or a copolymer) or a polyamide or a thermoplastic polyester, or a material having properties similar to any of these, possibly incorporating glass fibres. The moulded body includes a plate-like part 2, two projections 3 extending upwardly from the top of the part 2, on opposite sides of a portion 4 of the part 2, and a ledge 5 extending outwardly from the upper edge of the part 2. Each upward projection 3 has a straight passageway 6 through it, the passageway being of circular cross-section, to receive the straight leg of a so-called "round-toe PR clip" as shown in British Patent Specification No. 869 385, or a so-called "flat-toe PR clip" as shown in British Patent Specification No. 1213762 or a so-called "e-clip" as shown in British Patent Specification No.

1510224, the two passageways being horizontal and parallel to each other and also parallel to the length of a rail when it stands on the base plate. The rail actually stands on a resilient and electrically insulating pad, which is not shown in Figure 1, this pad being placed in a rectangular well 2A at two opposite extremities of which are retaining walls 2B, which do not extend over the whole width of the well since openings 2C are formed at their ends to allow rainwater to run off. The top of the pad is higher than the tops of the walls 2B. The other two opposite extremities of the well 2A are defined by the inside flanks of the upward projections 3 and by upstanding retaining walls 2D. The floor of the well is flat but inclined to the horizontal, as are the tops of the walls 2B, when the base plate stands on a horizontal surface since it is desired that the rail should lean slightly. There may be several hollows underneath the portion 4 and indeed over the entire length and width of the base plate, in order to save material. For the same purpose the upper surface 11 of each projection 3 is formed with grooves 12.

The projections 3 include portions 7 each of which forms a platform to receive the so-called "heel" of the clip, which bears downwardly on the platform whilst the straight leg of the clip bears upwardly on the roof of the passageway and the so-called "toe" bears downwardly on the upper surface of the flange at the bottom of the rail.

Figures 1 to 3 show an anti-scuffing element 8 which is a piece of sheet steel that has been suitably pressed to provide a portion 9 lying on the platform 7, wings 10 on two opposite sides of the projection 3, to prevent it moving in a direction parallel to the passageways 6, and a portion 13 of arcuate crosssection which extends from one of the wings 10 almost to the other. Two elements 8 are placed in the mould which forms the base plate, before the electrically insulating material is admitted to the mould, so that the parts 9 and 10 adopt the illustrated positions on the moulded base plate and the portions 13 line the roofs of the passageways 6 so that they later hold the clips out of contact with the insulating material there.

The base plate is substantially rectangular, as seen in plan view, but an ear 15 projects from the left-hand end away from the right-hand end, the ear being near the left-hand side, and a similar ear 15 projects from the right-hand end away from the lefthand end, this ear being near the right-hand side; in other words the two ears are diagonally opposite one another. Holes 16 through the base plate are formed partly in these ears to receive fixing elements to secure the base plate to an underlying structure such as a concrete or steel railway sleeper.

The whole of the upper surface 5A of the ledge 5, which is endless, in other words it extends around the entire periphery of the plate-like part 2, is inclined to the horizontal so that rainwater can more readily run off the ledge. The ledge ensures that the path for leakage currents, from the rail to the structure underlying the base plate, is a long one and increases the proportion of the time during which at least part of the path is dry.

Figure 2 also shows recesses 17 in the lower side of the base plate. These could be square, rectangular or circular, as seen from below, or the recesses could instead be long grooves extending along the base plate.

Grooves extending across the base plate could be provided instead or in addition.

Figure 4 shows a concrete railway sleeper 20 having steel reinforcing bars 21 running along it and further steel bars 44, which are fastened to the bars 21 and extend across the sleeper and out of both sides of it. The bars 44 are termed "hedgehogs". The sleepers are laid on a concrete base and adjusted in position and then a wet concrete mix is placed on the base between the sleepers and surrounds the bars 44. A base plate 1 according to Figure 1 lies on the top of the sleeper and is fixed to the sleeper by a fixing element in the form of a bolt 22 having a screwthreaded upper end carrying a collar 23 and a nut 24.

The bolt passes through one of the holes 16 through the base plate and surrounding it, partly within the hole 16, is a collar 25 - see Figure 5 - made of compressible electrically insulating material which forms a water-tight seal. The part of the bolt 22 which extends into the concrete is separated from the concrete by electrically insulating material 26, which may be a cast epoxy resin or a filled polyester adhesive. The shank and the head of the bolt 22 may be coated with insulating material such as a fluidized epoxy coating.

Figure 6 shows that the concrete sleeper 20 has a raised portion 30 upon which lies the base plate 1.

The floor of the well 2A in the base plate is inclined to the horizontal so that the rail 31 standing on it leans to the left. A resilient pad 32 of electrically insulating material lies under the bottom of the flange on the rail and in this case an electrical insulator 33, as described in British Patent Specification 1213762, lies on each edge of the rail flange and a flat lower surface on the toe of an e-clip 34 presses downwardly on the upper surface of each side of the rail flange via an insulator 33.

If desired, the plate-like part 2 may be formed with an upwardly-projecting circular boss through which the hole 16 passes, in order to reduce the possibility of rainwater entering the hole. Instead, or in addition, the ears 15 could be omitted, so that the base plate is rectangular but with rounded corners.

There would be more grooves 12 than are shown There could be more than two anti-scuffing elements.

The modified base plate of which part is shown in Figure 7 is as shown in Figures 1 and 2 except as indicated below and it is used in an assembly as shown in Figures 4 to 6. In this example there are two separate metallic anti-scuffing members 40 and 41. The member 40 is a metallic tube which has a slight taper, externally and internally (although it could be only externally), and is a push fit in the passageway 6 in the upward projection 3. Its uppermost portion separates the straight leg of the clip from the roof of the passageway. The member 41 is a metallic plate consisting of a first part 41A, which has a substantially flat upper surface which is substantially horizontal when the bottom of the plate is horizontal, and a second part 41B which is inclined to the horizontal when the bottom of the plate is horizontal.

The part 41A lies in a rectangular recess 42 in the top of the portion 7 of the base plate and is a push fit in the recess. The part 41B lies on an inclined surface 43 on the portion 7 and is not held other than by virtue of the fact that it is integral with the part 41A which is held in the recess 42. When the straight leg of the clip is driven into the member 40, the heel of the clip rides up the upper surface of the part 41B, which forms a ramp, on to the upper surface of the part 41A.

Figure 7 shows only one upward projection 3, on one side of the portion 4 of the plate; the other upward projection in this example is similar and has two similar anti-scuffing members 40 and 41 push-fitted into it.

Claims

1. A base plate which is suitable for supporting a railway rail, the base plate being a moulded body of electrically insulating material including a plate-like part, two projections extending upwardly from the top of the plate-like part on opposite sides of a portion thereof which is to lie under the rail, each projection being formed with a passageway to receive part of a rail-fastening clip, and a ledge extending outwardly from the upper edge of the plate-like part, at least part of the upper surface of the ledge sloping downwardly to assist run-off of rainwater.

2. A base plate according to claim 1 in which the ledge is endless.

3. A base plate according to claim 1 or 2 in which there is a well in the upper surface of the plate-like part to receive a resilient pad on which the rail is to stand.

4. A base plate according to any preceding claim in which each of the upward projections includes a platform upon which part of a rail-fastening clip may bear downwardly, the platform being beside a taller portion of the projection through which the passageway passes, the two passageways being substantially horizontal and parallel to each other and to a rail when it is positioned on the plate-like part.

5. A base plate according to claim 4 in which two anti-scuffing elements made of metal each have a portion lying on one of the platforms and portions extending over opposite sides of the projection concerned, to prevent movement of the anti-scuffing element parallel to the length of the rail.

6. A base plate according to claim 5 in which another part of each anti-scuffing element lies within the passageway, in order to separate the clip from the roof of the passageway.

7. A base plate according to claim 4 having two first anti-scuffing members, each a push fit into a recess in one of the platforms and serving to separate the clip from the platform, and, separate from the first anti-scuffing members, two second anti-scuffing members, each a push fit into one of the passageways and serving to separate the clip from the roof of the passageway.

8. A base plate according to claim 7 in which each first anti-scuffing member has a first part which has a substantially flat upper surface which is substantially horizontal when the bottom of the plate is horizontal and has a second part which has a substantially flat upper surface which is inclined to the horizontal when the bottom of the plate is horizontal, whereby when one part of a clip is driven into the passageway another part of the clip rides up the upper surface of the second part, which forms a ramp, on to the upper surface of the first part

9. A base plate according to claim 7 or 8 in which each second anti-scuffing member is tubular and, at least externally, tapered.

10. A base plate substantially as hereinbefore described with reference to Figures 1 to 6 of the accompanying drawings or Figures 1 to 6 modified in accordance with Figure 7.

11. A base plate which is suitable for supporting a railway rail, the base plate being a moulded body of electrically insulating material including a plate-like part, two projections extending upwardly from the top of the plate-like part on opposite sides of a portion thereof which is to lie under the rail, each projection being formed with a passageway to receive part of a rail-fastening clip, the two passageways being substantially horizontal and parallel to each other and to a rail when it is positioned on the plate-like part, each of the upward projections including a platform upon which part of a rail-fastening clip may bear downwardly, the platform being beside a taller portion of the projection through which the passageway passes, there being a metallic portion within each passageway, in order to separate the clip from the roof of the passageway, and a metallic portion.on each platform, in order to separate the clip from the platform, whereby scuffing of the base plate by the clips is reduced.

12. An installation on a railway track including a base plate according to any preceding claim, a flange-footed rail standing on said portion thereof between the two projections and located by them and two rail-fastening clips each having one portion driven into the passageway in the projection and another portion baring downwardly on a part of the base plate which, as seen from the rail, is beyond the passageway.