AU7861198A - Rail fastener - Google Patents

Description

Regulation 3.2(2)

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Application Number: Lodged: Invention Title: RAIL FASTENER The following statement is a full description of this invention, Including the best method of performing It known to us -1- RAIL FASTENSR The present invention is concerned with rail fasteners, particularly fasteners used where two rail tracks cross.

Heavy haul railroads require, at various points, two rail tracks to cross, and as a result a small gap is created in each rail which the rolling stock must jump. This creates a problem in that the heavy wheel loads cause high impact and vibration, which result in rapid deterioration of the crossing components and produce considerable relative movement of the rail structures.

Typically, such a rail crossing is constructed from wooden ties sitting on top of crushed rock ballast. The ties are affixed to heavy steel base plates. Finally, the rail and rail junctions are held down to the steel plates by elastic rail fasteners.

A significant problem is the premature failure of the rail fasteners which are unable to cope with the large amount of movement produced in the structure.

Many types of rail fasteners have been tried for this application, but have not proved successful.

One solution is to build a bridge so that one track passes completely over the other without a 25 crossing. However, this involves a very large cost and may not be justified in all cases, and hence railroads continue to utilise rail crossings.

Elastic rail fasteners in general use normally have to cope with a vertical oscillation of about Imm, in some extreme cases extending to 1.5mm. However, on a rail crossing a continuous upward movement of 4mm is common, with occasional excursions to about 10mm. A further difficulty with fastening rail crossings relates to the available space for fitting the S 35 fastenings. The rails and frogs (rail junctions) are bolted together with clamping bars which take up

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r -2considerable space and limit the places where rail fastenings can be applied. As a result, there are limited places to attach the fasteners, and often as a consequence there are insufficient fasteners on the S crossing to distribute the load adequately.

One solution to the deflection problem would be to scale up the current fasteners so they could cope with the occasional 10mm deflection. However, this would make them extremely large and would only exacerbate the problem of finding adequate room to apply them to the crossing. A further problem with this approach is that most currently available fasteners require relatively S complex manufacturing tooling. As specialised fasteners for crossings are a relatively small run product, this would cause a major cost problem.

Accordingly, it is desirable to provide a fastener suitable for rail crossings which is able to cope with the necessary deflection, but which is compact enough to be fitted into a restricted space.

According to an embodiment of the present invention there is provided elastic railway rail fastening means for fastening a railway rail to an underlying rail foundation, which fastening means I comprise a main clip having at a free end thereof a toe for applying a downward force to a flange of an adjacent rail when the fastening means are in use and a mounting assembly adapted to be affixed to a base member for retaining the main clip such that it extends in a cantilever arrangement from the mounting assembly towards an adjacent rail flange when the fastening means are in use; characterised by one or more helper clips extending when in use in a cantilever arrangement from said mounting assembly in such a manner as to be generally disposed above and in engagement with the said main clip and to terminate, at a free end thereof, between an adjacent edge of the rail flange and the 1'

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-3mounting assembly, and further characterised in that the said mounting assembly comprises a clamping bar for clamping the said main clip and the or each said helper clip to the said base member.

Preferably the clips have a generally flat, platelike form, most preferably with a lateral taper at the free ends of the main and helper clips.

It is desirable that the main clip and the or each helper clip are dimensioned so as to operatively produce a substantially constant stress in cantilever parts of the main and helper clips.

It is also desirable that the mounting assembly is such that there are no holes in the main and helper clips below the said clamping bar.

Preferably, there is only one helper clip, the free end of which terminates at a distance from the adjacent rail flange edge which is not less than 15% of the span from the rail flange edge to a cantilever edge of the clamping bar and not more than 80% of this span.

Most preferably, the distance from the adjacent rail flange edge is approximately 50% of the span.

Preferably, when there is more than one helper clip, the said helper clips are mounted one upon another. Desirably, the cantilever length of each such helper clip progressively decreases relative to the underlying clip, so that they stagger back from the toe.

In a preferred form, the size of the toe of the Smain clip ("toe depth") is such that the toe can be operatively affixed under a rail junction clamping bar, which holds the rails and junction together.

The arrangement of the present invention provides a multiple clip structure so as to reduce the length of the fastener required to provide the necessary deflection, whilst retaining a simple construction i fsuited to a short run product. As the fastener will P -4occupy a relatively small space, more fasteners can be applied so as to more successfully stabilise the rail and maximise the life span of the crossing components.

A fastener embodying the present invention retains the necessary strength to handle the associated -stresses, whilst retaining an overall compact configuration.

A further advantage of the preferred implementation is that it provides a low profile flat toe which can fit under the clamping bars holding the rails and frogs together to further facilitate adequate fasteners being fitted.

Whilst the primary focus of the inventive fastener is for rail crossings, it will be appreciated that the invention may be advantageously applied wherever similar problems are encountered.

Reference will now be made, by way of example, to the accompanying drawings, in which:- Figure 1 is a side view, partly in section, of fastening means embodying the present invention in place retaining a rail; Figure 2 is a plan view of the fastening means shown in Figure 1; Figure 3 is an end view of the fastening means 25 shown in Figure 1; and SFigure 4 is a plan view showing a possible positioning of such fastening means around a frog.

It will be appreciated that the implementation shown is only one of many possible, and that details may be varied in accordance with the engineering requirements of the particular railroad.

A fastener 20 comprises a substantially flat main clip I, a helper clip 2, and a mounting assembly 7.

Helper clip 2 is applied on top of main clip 1 so that helper clip 2 does not extend to a toe 4 of the main clip i, which bears on a rail flange 3. The helper I clip 2 terminates at a free end lying approximately midway between the mounting assembly 7 and the rail flange edge. In order to maximise the possible toe load and available deflection for a given mass of steel, and also allow the length of the main clip 1 to be reduced, the size and shape of the main clip 1 and helper clip 2 are chosen such that the stress in the cantilever parts (extending from the mounting assembly 7 towards the rail flange 3) is substantially constant.

In particular, although the idealised configuration would be for the tapered edges of the main clip 1 to meet at a point which sits directly over j the rail flange edge and for the tapered edges of the helper clip to meet at a point which sits midway between the mounting assembly 7 and the rail flange edge, since this would give the same uniform stress in both clips (when the same thickness of material is used), for practical reasons this configuration is preferably modified- Thus, the toe of the main clip 1 has been designed so as to overlap the rail flange edge slightly, to ensure that the clip 1 does not come off the rail if there is any sidewards rail movement, and to have a small, flat end, so that the bearing area is large enough to give a bearing pressure which will not cause undue wear on the main clip 1. The same shape has been used on the free end of the helper clip 2 for convenience in manufacture, since the same blanking tool can be used for both the main and helper clips 1, 2.

Main clip 1 and helper clip 2 are held to the mounting assembly 7 by a clamping bar 11 which is tensioned by bolts 9 and respective nuts 10. If necessary the bolts can be easily replaced by removing the clamping bar 11 and sliding them sideways out of slots 8. It will be appreciated that the clamping bar 7 7 -6could be held down by other means such as a cam locking device.

There are no holes in the main and helper clips 1, 2 beneath the clamping bar 11; thus the helper clip 2 is able to contribute to the overall deflection of the fastening without having to be used to compensate for weaknesses which would otherwise be caused by holes in a high stress area of the clips. Since there are no significant stress concentrations in the clips, it is possible to use a high working stress, thus providing an efficient design with high deflection.

Since the flat toe 4 has a low profile, it can fit underneath the rail junction clamping bars so that many more fastenings can be applied if required than in the prior art.

Mounting assembly 7 may be either a welded fabrication or a steel casting. Operatively, mounting assembly 7 would generally be held to the base plate by field welds 6. Stops 12 and plate 13 locate the end of the clip 1 and helper 2. Base plate 5 is attached to the wooden ties (not shown) by screwspikes and spring washers It will be appreciated that the general principle of the present invention may be implemented in various ways. For example, the main clip 1 and helper clip 2 may have different thicknesses if desired. A flat profile is preferred for main clip 1 and helper clip 2 largely for reasons of manufacturing economy, but different profiles could be used if desired. Multiple helper clips 2 could be provided, each overlapping progressively less of the clip beneath.

In figure 4, an assembly incorporating fasteners |i embodying the present invention is illustrated. A plurality of fasteners 20 are attached around the frog, so as to hold it firmly in position on base plate The gaps in the rails occur at point 16 on frog 3.

3 -7- Ties 14 are shown in outline but are operatively beneath the base plate 5, and affixed to the plate by screwspikes and spring washers 15- It can be seen that the compact structure of the fasteners 20 allows an adequate number to be positioned so as to hold the rail 'crossing firmly in place.

In the attached claims use of the word "rail" should be taken to encompass railway rail junctions ("frogs") as well as ordinary railway rails.

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Claims (9)

1. Elastic railway rail fastening means for fastening a railway rail to an underlying rail foundation, which fastening means, include a main clip having at a free end thereof a toe for applying a downward force to a flange of an adjacent rail when the fastening means are in use and a mounting assembly adapted to be affixed to a base member for retaining the main clip such that it extends in a cantilever arrangement from the mounting assembly towards an adjacent rail flange when the fastening means are in use; characterised by one or more helper clips extending when in use in a cantilever arrangement from said mounting assembly in such a manner as to be generally disposed above and in engagement with the said main clip and to terminate, at a free end thereof, "between an adjacent edge of the rail flange and the mounting assembly, and further characterised in that the said mounting assembly includes a clamping bar for clamping the said main clip and the or each said helper clip to the said base member.

2. Fastening means as claimed in claim 1, wherein the main clip and the or each helper clip have a generally flat plate-like form.

3. Fastening means as claimed in claim 2, wherein the main claim and at least one helper clip are formed with a lateral taper at their free ends. j

4. Fastening means as claimed in claim 3, wherein the main clip and the or each helper clip are dimensioned so as to operatively produce a substantially constant stress in cantilever parts of the main and helper clips.

Fastening means, as claimed in any preceding claim, wherein the mounting assembly is such that there are no holes in the main and helper clips below the said clamping bar. 9

6. Fastening means as claimed in any preceding claim, wherein there is only one helper clip, the free end of which terminates at a distance from the adjacent rail flange edge which is not less than 15% of the span from the rail flange edge to a cantilever edge of the clamping bar and not more than 80% of this span.

7. Fastening means as claimed in claim 6, wherein the free end of the helper clip terminates at a distance from the adjacent rail flange edge which is approximately 50% of the span from the rail flange edge to the cantilever edge of the clamping bar.

8. 8. Fastening means as claimed in any one of claims 1 to 5, wherein, when there is more than one helper clip the said helper clips are mounted one upon another.

9. Fastening means as claimed in claim 8, wherein when there is more than one helper clip, the cantilever length of each helper clip progressively decreases relative to the clip below. Fastening means as claimed in any preceding claim, wherein the size of the said toe of the main clip is such that the toe can be operatively affixed under a rail junction clamping bar. DATED this 27th day of July, 1998. PANDROL LIMITED WATERMARK PATENT TRADEMARK ATTORNEYS LEVEL 4, AMORY GARDENS 2 CAVILL AVENUE ASHFIELD N.S.W. 2131 AUSTRALIA PNF-GL DOC022 AU002748.WPC