CA1169400A - Arched rail-support plate - Google Patents

Abstract

ABSTRACT
A device for securing rails to transverse and/or longitudinal cross-ties and rail-support points of all kinds, more particularly railroad ties on railroad permanent ways consists of a support- or rib-plate placed upon the surface of the tie or rail-support point, or of two co-operating support-plates anchored by tie-bolts, or the like, to the sleeper or rail-support point. Upon or between these the base of the rail is secured, resiliently and frictionally, either by hook-bolts, clamp-plates and spring-washers, or by tensioning yokes or tensioning clamps. The support- or rib-plates for rails and points are of an initial shape which is arched inwardly and downwardly from the boundary edges and are adapted to be clamped, by the tie-bolts or the like, with elastic deformation, flatly upon the bearing surface of the rail-support point.

Description

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The invention relates to a device for securing rails to transverse and/or longitudinal sleepers and other rail-support points of all kinds, especially wooden ties on railroad permanent ways. Such a device may consist of a support-plate, preferably a rib-plate placed upon the support-surface, or of two co-operating rib-support-plates anchored, by tie-bolts or the like, to transverse and/or longitudinal tie, or to the rail-support point, and upon or between which the base of the rail is secured, resiliently but positively, either by hook-bolts or clamp-plates and spring-washers, or by tensioning yokes or tensioning clamps.
In the case of rail attachments of this kind, the support-plates, rib-plates, or rib-support-plates serve to transfer forces from the rail to the tie and rail-support point and, at the same time, to locate the two rails in relation to each other in such a manner as to maintain the required track gauge for the wheels of the vehicle at any point along the track.
Thus the support-plates, rib-plates, or rib-support-plates are a particularly important component of the raii attachment, since they transfer horizontal forces from the rails to the rail-support points. This means that the said support-plates, rib-plates, or rib-support-plates can be secured against displacement in relation to the surface of the tie, or the bearing surface of the rail-suppor~ point, especially in a direction at right angles to the longitudinal axis of the track, only if the bearing surface of the support-plates, rib-plates, or rib-support-plates is pressed, by the tie-bolts or the like, with considerable force, to the surface of the tie and rail-support point, so that the free hori~ontal forces acting upon the said plates can be trans-ferred as frictional forces and without displacement to the transverse ties or rail-support point.
These requirements have existed ever since the introduction of rail attachments in which support-plates, rib-plates vr rib-support-plates have been secured to wooden ties by means of tie^bolts, but have not as yet been satis-factorily met. It has been found, in practice, that most support-plates, rib-plates, and rib-support-plates, when secured to the tie and rail-support point, achieve, between their bearing surfaces and that of the rail-support point, little or no friction contact, and that any such friction contact as may exist decreases constantly with increasing use of the track. In fact, in practice, even with a newly installed rail-support point, force-transferring friction-contact between the support-plates, rib-plates, or rib-support-plates and the bearing surface of the rail-support point is achieved only in the immediate vicinity of the tie-bolts or the like, regardless of whether or not spring washers are used.
This initially effective attachment between the support-plates, rib-plates, and rib-support-plates, the surface of the ties, and the bearing surface of the rail-support point, soon decreases, however, since the large clamping forces produce plastic deformation of the surface of the tie. In addition to the displacement of the support-plates produced by horizontal forces, and the resulting change in track-width, this has the disadvantage that the holes in the support-plates bear against the shanks of the tie-bolts, so that loads arising from use of the track impose bending loads on these bolts, thus impairing their firm hold in the ties.
Since loosening of the support-plates, rib-plates, or rib-support-plates results in reducing the overall stability of the track, double or triple spring washers have been fitted between the supports and the heads of the tie-bolts. ~owever, since such washers not only have a very short spring travel, but also an unsatisfactorily progressive load-deflection curve, their effective-ness is frequently impaired by relatively slight plastic deformation of the tie-A

surface. Moreover, because of their unsatisfactory spring characteristics, washers of this kind frequently fracture.
It has also been found that when known rail attachments are used with wooden ties, the pressure around the tie-bolts becomes very high and causes plastic-elastic deformation of the tie surface. This again has the disadvantage of causing the support-plates to arch centrally upwards and thus to lift off the surface of the cross-tie.
Thus when the train travels over the support plates, the arched areas are slammed down, producing a so-called pumping action, leading to gradual mechanical destruction of the tie-surface. Attempts have been made to eliminate this pumping action of the support-plates by making them 20 mm instead of 16 mm thick, especially in the vicinity of points. However, this expensive measure brings about only a slight reduction in the pumping action.
The most widely known K-type rail attachment, as a result of firm clamping of the base of the rail by means of hook-bolts, clamp-plates and spring-washers, initially produces a very rigid connection with the support-plates.
The so-called lift-wave of the rail, which inevitably occurs when the train passes is therefore transferred, in the longitudinal direction of the track, without any damping, to the support-plates and/or rib-plates. This again pro-duces torsion-loading of these plates and transverse ties, in the direction of travel. This, in turn, causes plastic deformation of the tie-surface, followed by loosening of the attachment.
Although attempts have been made to eliminate this disadvantage by using tensioning yokes or tensioning clamps instead of hook-bolts, clamp-plates and spring-washers, and although this produces a slight reduction in torsion-loading, the result is an undesirable reduction in resistance to pull-through and torsion.
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It is the purpose of the invention to eliminate, very largely, all of the disadvantages of devices of this type for securing rails to sleepers or other rail-support points and to provide a device for attaching railroad rails which not only ensures permanent, frictional securing of the support-plates and rib-plates to the bearing surface of the rail-support point, but also makes it possible to reduce the dimensions of the support-plates, rib-plates or rib-support-plates, and will perform this function, without maintenance or destruc-tion, for the normal life of a wooden sleeper, i.e. between 40 and 50 years.
The invention provides a dev ce for securing a rail having a flanged base to a rail-support surface, said device comprising:
a support plate adapted to be placed upon the rail-support surface and anchored thereto by first fastener means, said support plate in unstressed con-dition having an arched configuration such that it extends inwardly and down-wardly from opposite edges thereof, said support plate being adapted to be clamped by said first fastener means with elastic deformation to flatten said arched configuration so that the support plate lies flatly upon said rail-support surface; and second fastener means carried by said support plate and adapted to engage the flange of the rail and press i~ downwardly so that the rail is resiliently secured and frictionally located with respect to said rail-support surface.
The support-plate may be arched transversely of the rail and have an intermediate section which lies beneath the base of the rail and two end sections which lie on opposite sides of the rail. Alternatives the support plate may comprise two individual plate sections adapted to abut opposite sides of the rail and each arched longitudinally of the rail.
Although even when these measures are used, there is still slight, r3 basically unavoidable, elastic deformation of the bearing surface of the rail-support_point, the inherent elasticity of the support-plates produces a restor-ing action which maintains a frictional connection between them and the surface of the tie or the bearing surface of the rail-support point, even when wear due to corrosion occurs between the plates and the heads of the tie-bolts. This practically eliminates the need for re-tightening of tie-bolts throughout the installed life of the tie, especially in the case of wooden ties.
In advantageous configurations the support-plates may be linearly, flatly, or spatially pre-arched, as required, and may then be permanently pre-stressed, the direction of the imparted elasticity running transversely, longitudinally or diagonally of the rail.
The support-plates used to secure rails at rail-support points, more particularly wooden ties in railroad permanen~ ways, may be made from rolled-steel sections or drop-forgings. The plates may be produced initially as rolled or pressed sections, and then converted to the arched shape by cold-forming-in dies. The plates may also be cas-tings or welded components.
The invention is explained hereinafter in greater detail, in con-junction with the embodiments illustrated, by way of example only, in the drawings attached hereto, wherein:
Figure 1 is a cross section of a UIC 60 rail with the relevant secur-ing device, the hook-bolt serving as the securing element being shown partially assembled in the right half and finally assembled in the left half of the Figure;
Figure 2 shows the device according to Figure 1 in plan view;
Figure 3 is a side elevation of the rail-securing device according to Figures 1 and 2;
Figure 4 shows the support-plate used in the device according to Figures 1 to 3, in front elevation, in the pre-arched and unclamped condition;

while Figure 5 is a plan view, and Figure 6 is a side elevation of this support- or rib-plate;
Figure 7 is a front elevation; Figure 8 is a plan view, and Figure 9 is a side elevation of another design of the device for securing rails to ties, equipped with rib-support-plates instead of support-plates.
In railroad permanent ways, the actual track is very frequently laid upon the ballast bed by means of transverse ties 1. The ties are usually of impregnated wood with calibrated ends. Woods used are beech and oak, also pine and tropical woods such as keruing.
The ties are laid at specific distances from each other and are con-nected to rails 3 by means of attachment 2, in such a manner that no tilting occurs. Each attachment 2 consists of a support-plate 4 having a plurality, for example four bolts 5 securing it to the tie, and clamping elements er.gaging with the plate 4 and with the base of the rail, the clamping elements being, for example, in the form of hook-bolts 6, clamp-plates 6', and spring-washers 6". It is, of course, also possible to use instead of the hook-bolts clamp-plates, and spring-washers, such elements as tensioning yokes or tensioning clamps in operative connection with the base of the rail.
The under-surface of the rail-base is located between ribs 7 of the support-plate 4, but does not rest upon the upper surface thereof. Instead, a spacer or pad 8 is arranged therebetween.
In the left hand half of Figure 1, the hook-bolt 6 is shown in fully assembled condition in which the clamp-pla~e 6' bears, as a compression-member upon the base flange of the rail, the pre-load being produced by the nut and spring-washer 6 " co-operating with the hook-bolt.
In contrast to this, the right hand half of Figure 1 shows the hook-A~ -6-~b.3~

bolt 6, with the nut, clamp-plate and spring-washer in the partially assembled condition.
It is particularly important, if the rail attachment 2 is to be effective, for the bearing surface 9 of support-plate 4 to be held in overall, permanent, frictional contact with the surface ]0 of the tie. To this end, and as shown in Figures 4 and 6, a support-plate is used which is initially arched inwardly and downwardly from at least two opposing boundary edges, in this case the longitudinal edges 4'.
In Figures 4 to 6, the curvature 11 extends transversely of the support-plate 4, in such a manner that the apex 12 of the curve coincides with longitudinal centreline 13 of the plate.
In other cases, however, the curvature may also be parallel to the length of the plate 4, in which case the apex 12 of the curve coincides with the transverse centreline 14.
Finally, it is also conceivable for the curvature to be diagonal to the plate 4, in such a manner as to form a preferably part-spherical surface having an apex at the intersection of longitudinal centreline 13 and transverse centreline 14.
The curve 11 for bearing surface 9 of the plate 4 may be the arc of a circle or of an ellipse, or of some other suitable geometrical curve. However, it may also be defined by strai~ht line and/or segmental arcs arranged at specific connecting angles.
Support-plates 4 according to ~igures 4 to 6 may be made from rolled sections, drop-forgings, castings or welded components. It may be particularly desirable for these plates to be rolled or pressed flat initially and for the curvature 11 to be imparted subsequently by cold-forming in dies.
It is important for the curved support-plates 4 to be clamped resilient-A

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ly by means of bolts 5, or the like, passing through holes, more particular oval holes 15, with a certain amount of play, in such a manner that the entire bearing surface 9 is clamped frictionally to the tie surface lO. Appropriate tightening of bolts 5 produces a specific pressure per unit-area between the bearing surface 9 and tie surface 10. This is then used to transfer the horizontal forces applied by the rail 3 to the plate 4. In this connection, the greater the amount of resilient travel 11' in the vertical direction (Figure 4), the greater the pressure per unit area achievable, depending upon the quality of the ~aterial, the dimensions of the plate, and the shape of the curve. Tests have shown that the optimal configuration for the arch 11 is a curve. Obviously, in order to achieve an optimal pressure per unit area, it is also possible to use a specific polygonal profile with different connecting angles, or a curved geometrical shape with square or cubic members or members of a higher order. Finally, however, it is also possible to form the arch 11 by uniting more or less long straight lines with segmental arcs and intermediate straight lines. Also conceivable are varying curvatures in the top and bottom surfaces and in the inner and outer areas.
It is expected that the use of support-plates 4 of this design, as a functional part of devices for securing rails, will effect and maintain resilient attachment of the plates to the surface of the tie, and the anchorage in the vicinity of ribs 7, in continuous service, over the total operative life of the wooden ties, i.e. for between 40 and 50 years, in spite of the externally acting static and dynamic wheel-loading, and that the maximal surface and edge-pressures will not exceed the permissible surface pressures of the types of wood and other materials used for the ties.
The foregoing configuration and clamping of the support-plates 4 can eliminate the spring-washers hitherto used between them and the bolts 5. The A-g~

plates perform the function of maintaining frictional connection with the surface of the ties substantially better than do spring-washers. The latter have a very small, unfavourable, progressive, characteristic spring travel which is unsuitable for this purpose, as a result of which their holding power decreases sharply with very small amounts of elastic and plastic deformation of the tie surface. In contrast to this, pre-arched support-plates have a sub-stantially longer, flatter and therefore more favourable characteristic travel, approximating a lin~ar pattern and better suited to the purpose.
A modified design of device for securing rails to transverse ties is shown in Figures 7 to 9.
In this case the continuous, one-piece support-plate 4 of Figures 1 to 6 is replaced by two so-called rib-support-plates 17 to form rail attachments 16 to the tie 1, these plates being spaced apart on the tie surface 10 in such a manner that the flange of the rail 3 may be placed therebetween upon a spacer pad 18.
The design of the two rib-support-plates is identical. They are arranged on each side of the rail base at 180 to each other. Clamping means in the form of hook-bolts 6, clamp-plates 6', and spring-washers 6 " co-operate with ribs 19 in the same way as described in conjunction with the continuous plates 4 hereinbefore. Here again tensioning yokes or tensioning clamps may also be used as clamping means.
As may be seen in the left half of Figure 9, plates 17, in their initial unstressed form, arch inwardly and downwardly from opposite ends, in this case the transverse edges 17~, the apex 21 of the arch coinciding with the trans-verse centreline 22 of each rib-support-plate 17.
Bolts 5 co-operate with the plates 17 through slots 23 which open towards the edges 17' and run at an angle to the longitudinal axis of the track.
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These may be used to correct the position of the rail in that when the plates 17 are moved longitudinally in relation to the bolts 5, a compcnent of motion in the transverse direction also takes place. This makes it possible to clamp the plates 17 transversely against the base of the rail. ~Ioreover, when t'ne bolts are tightened, the pre-load produced by the arch 20 results in the plate being secured permanently, by friction, to the tie surface 10, as shown in the right half of Figure 9.
It should also be pointed out that it is often desirable to roughen bearing surfaces 9 of the plates 4 and 17. This roughening may be in the form of grooves,knurling, protuberances, nipples, and the like, or may be produced by sand-blasting. This not only increases the coefficient of friction, but also effects mechanical engagement with the surface 10 of the sleeper.
Plates 4 and 17 may also be bonded to the surface 10 of the tie as an additional measure. This is particularly desirable when the ties are made of a soft wood such as pine. In this case, however, the bearing surfaces 9 of the plates should be slightly larger. Gluing the resiliently pre-loaded plates is particularly useful for support points for unballasted tracks and for ties made of cement. In conjunction with plates 4 and 17, described hereinbefore, it is desirable to use bolts 5 of which the shoulder at the bearing surface has a rounded peripheral edge to prevent penetration into the surface of the plate.

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Claims (17)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A device for securing a rail having a flanged base to a rail-support surface, said device comprising:
a support plate adapted to be placed upon the rail-support surface and anchored thereto by first fastener means, said support plate in unstressed condition having an arched configuration such that it extends inwardly and down-wardly from opposite edges thereof, said support plate being adapted to be clamped by said first fastener means with elastic deformation to flatten said arched configuration so that the support plate lies flatly upon said rail-support surface; and second fastener means carried by said support plate and adapted to engage the flange of the rail and press it downwardly so that the rail is resiliently secured and frictionally located with respect to said rail-support surface.

2. A device according to claim 1, wherein said support plate is arched transversely of the length of the rail and has an intermediate section adapted to lie beneath the base of the rail and two end sections adapted to lie on opposite sides of the rail, said first fastener means being engageable with each said end section, and said second fastener means being carried on each said end section and engaging said rail flange on opposite sides of the rail.

3. A device according to claim 1, wherein said support plate comprises two similar individual plate sections adapted to be positioned on said rail-support surface in abutment with opposite sides of the rail flange, each said plate section being arched longitudinally of the rail, said first fastener means engaging opposite ends of each plate section, and said second fastener means being carried on each plate section and engaging opposite sides of the rail flange.

4. A device according to claim 1, wherein the apex of the arch coincides with the centreline of the support-plate.

5. A device according to claim 4 wherein the arch runs parallel with the longitudinal direction of the support-plate.

6. A device according to claim 4 wherein the arch runs parallel with the transverse direction of the support-plate.

7. A device according to claim 2 wherein the arch runs in the diagonal direction of the support-plate and defines a part-spherical surface.

8. A device according to claim 1, 2 or 3 wherein the arch of the support-plate is in the form of a suitable geometrical curve.

9. A device according to claim 1, 2 or 3 wherein the arch is defined by rows of straight lines defined by determinable connecting angles and/or segmental arcs.

10. A device according to claim 1, 2 or 3 wherein the support-plates are made from rolled sections.

11. A device according to claim 1, 2 or 3 wherein the support-plates are in the form of drop-forged parts.

12. A device according to claim 1, 2 or 3 wherein the support-plates con-sist of rolled or pressed sections subsequently arched by cold-forming in dies.

13. A device according to claim 1, 2 or 3 wherein the support-plates are castings, more particularly steel or spheroidal-graphite castings.

14. A device according to claim 1, 2 or 3 wherein the support-plates are of welded design, with ribs or rib-parts on flat plate-elements.

15. A device according to claim 1, 2 or 3 wherein the support-plate has a bearing surface roughened by means of grooves, knurling, protuberances, nipples, or abrasion.

16. A device according to claim 1, 2 or 3 wherein the support-plate has a bearing surface that is bonded to the rail-support surface.

17. A device according to claim 1, 2 or 3 wherein the support-plate is designed as an irregular support-plate, in the form of a rib-plate, sliding and supporting rib-plate, tongue-root plate, frog-plate or wheel-guide plate, for points and crossings of all kinds.