GB2087461A

GB2087461A - Railway Base Plates

Info

Publication number: GB2087461A
Application number: GB8036524A
Authority: GB
Original assignee: RICHTBERG KG KARL; Schwihag Gesellschaft fuer Eisenbahnoberbau mbH; Schwihag GmbH
Current assignee: RICHTBERG KG KARL; Schwihag Gesellschaft fuer Eisenbahnoberbau mbH; Schwihag GmbH
Priority date: 1980-11-13
Filing date: 1980-11-13
Publication date: 1982-05-26
Also published as: GB2087461B

Abstract

A baseplate or ribbed plate 4 for interposing between rails and wooden sleepers has an initial shape which curves inwardly and downwardly at 11 from its boundary edges 4' and is designed to be applied flat through elastic deformation to the upper surface 10 of the sleepers or bearing surface of the rail supporting members by means of the sleeper screws 5. <IMAGE>

Description

SPECIFICATION Raiiway Supporting Assembly This invention relates to a railway supporting assembly. More particularly, it relates to device for fastening rails to transverse and/or longitudinal ,sleepers and other rail supporting members of all kinds, particularly to wooden sleepers, for railway tracks, consisting of a baseplate, preferably a ribbed plate, or two cooperating ribbed support plates (hereinafter referred to collectively as "baseplates") which is/are arranged to the bearing surface, which is/are anchored to the transverse and/or longitudinal sleeper or to the rail supporting member by means of sleeper screws or the like and to which or between which the foot of the rail is fixed in resiliently form-locking manner by fixing means such as clip bolts, clamping plates and spring washers or through turnbuckles or strainers.

In rail fastenings of the type in question, the baseplates perform the function of transmitting forces from the rail to the sleeper or rail supporting member and at the same time fixing the position of the two rails relative to one another in such a way that the necessary gauge for the wheels of the vehicles is maintained at each point of the track.

Accordingly, the baseplates are a particularly important part of the rail fastening because they transmit the horizontal forces from the rails to the rail support members. This means that the baseplates can only be prevented from being displaced relative to the upper surface of the sleeper or the bearing surface of the rail supporting member, in particular transversely of the longitudinal axis of the track, by applying the full contact surface of the baseplates under considerable pressure to the upper surface of the sleeper or rail supporting member by means of the sleeper screws or the like so that the free horizontal forces acting on the baseplates may be transmitted without displacement as friction forces to the transverse sleepers or rail supporting member.

These requirements have existed since the introduction of rail fastenings of which the baseplates are fixed to wooden sleepers by means of sleeper screws. Hitherto, however, they have never been satisfactorily fulfilled. Practical experience has shown that, when applied to the transverse sleeper or rail supporting member, most baseplates achieve no friction contact or very little and hence inadequate friction contact between their contact surface and the bearing surface of the rail supporting member. In addition, such friction contact as is achieved becomes weaker, the longer the track is in use.It has been found that, in practice, even where a rail supporting member has only just been installed, forcetransmitting friction contact between the baseplates and the bearing surface of the rail supporting member is only achieved in the immediate vicinity of the sleeper screws or the like, irrespective of whether or not the screws have been braced by spring washers.

However, this initially very effective contact between the baseplates and the upper surface of the sleeper or the bearing surface of the rail supporting member frequently weakens to a considerable extent after only a short time because the upper surface of the sleeper undergoes plastic deformation under the effect of the intense contact forces. In addition to the displacement of the baseplates attributable to the action of horizontal forces with the resulting change in the gauge of the track, there is the further disadvantage that the holed walls of the baseplate are applied to the shanks of the sleepers screws and, under the effect of the loading of the track by rail, traffic, exert bending stresses on the sleeper screws with the result that the permanently firm seating of the screws in the sleepers is impaired.

Since loosening of the baseplates is accompanied by a reduction in the overall stability of the track, double-strength or triple-strength spring washers have also been provided between these plates and the head of the sleeper screws.

However, since spring washers of this type not only have minimal deflection, but also an unfavourable progressive spring characteristic, their effectiveness is often impaired by only relatively slight plastic deformation of the upper sleeper surface. In addition, spring washers of the type in question often break because of their unfavourable spring characteristic.

It has also been found that, where the known rail fastenings are used in conjunction with wooden sleepers, very high surface pressure is generated around the sleeper screws, resulting in plastic-elastic deformation of the upper sleeper surface. This in turn gives rise to the disadvantage that the baseplates arch upwards at their centre and are thus lifted off the upper sleeper surface in the vicinity of the rail. When rail traffic passes over the baseplates, they are then suddenly pressed down in the arched region (so-called pumping effect). This pumping naturally results in gradual mechanical destruction of the upper sleeper surface. Attempts have also been made to eliminate this so-called pumping of the baseplates by providing in particular the baseplates intended for switches with a thickness of 20 mm as against 16 mm.However, it was only possible by this expensive measure slightly to reduce the unwanted pumping effect.

The most widely used rail fastening (type K) initially provides for a relatively rigid connection to the baseplate by virtue of the firm fixing of the foot of the rail by clip bolts, clamping plates and spring washers. The so-called lifting wave which automatically develops as traffic passes over the track is thus transmitted undamped to the baseplate in the longitudinal direction of the track.

This in turn gives rise to torsional stressing of the baseplates and transverse sleepers in the direction of travel, with the result that the upper sleeper surface undergoes plastic deformation which is automatically accompanied by loosening of the fastening to the transverse sleepers Although attempts have been made to obviate this disadvantage by using turnbuckles or strainers instead of clip bolts, clamping plates and spring washers and although it has been possible in this way slightly to reduce torsional stressing, it has nevertheless been found that resistance to shearing and twisting-so important to the stability of the tracks undesirably reduced at the same time.

An object of the present invention is to eliminate as far as possible all the disadvantages of known devices of the type in question for fastening rails to sleepers or other rail supporting members. More particularly, an object of the present invention is to provide a device for fastening rails of railway tracks which not only provides for permanent force-locking application of the baseplates or ribbed plates to the bearing surface of the rail supporting member, but also enables the dimensions of the baseplates to be reduced whilst at the same time performing its function free from maintenance and destruction at least over the 40 to 50 year period for which wooden sleepers normally remain in use.

Accordingly, the invention provides a railway supporting assembly, comprising a rail supporting member, a baseplate arranged on the upper surface of the rail supporting member and anchored thereto, and a rail fixed to the baseplate, wherein the baseplate has a natural curvature inwardly and downwardly from at least two opposing boundary edges and is applied flat through elastic deformation to the upper surface of the rail supporting member.

The invention also provides a device for fastening rails to transverse and/or longitudinal sleepers and sleeperless rail supporting members of all kinds, more particularly to wooden sleepers of railway tracks, comprising a baseplate or ribbed plate or two co-operating support plates which is/are arranged on the upper surface of the sleeper or rail supporting member, is/are anchored to the sleeper or rail supporting member such as by sleeper screws or the like and on which or between which the foot of the rail is fixed in resiliently form-locking manner such as by clip bolts, clamping plates and spring washers or through turnbuckles or strainers, wherein the baseplate or ribbed plate and/or the ribbed support plates for tracks and switches has/have an initial shape which curves inwardly and downwardly from its/their boundary edges and is/are designed to be applied flat through elastic deformation to the upper surface of the sleepers or bearing surface of the rail supporting members by fixing means such as sleeper screws or the like.

Although the bearing surface of the rail supporting member still undergoes some basically unavoidable elastic deformation as a result of these measures, the elasticity inherent in the baseplate, which appears as a reset effect, maintains a force-locking frictional connection between the plate and the upper surface of the sleeper or the bearing surface of the rail supporting member even when corrosion sets in between the baseplate and the head of the sleeper screw. Accordingly, there is virtually no need for the sleeper screw to be retightened throughout the entire service life of the transverse sleepers made in particular of wood.

It is possible as required to pre-curve the baseplates linearly, in two demensions or even in three dimensions and then permanently to bias them, the elasticity being directed transversely, longitudinally or even diagonally.

The baseplates used in conjunction with a device according to the invention for fastening rails to rail supporting members. particularly to wooden sleepers of railway tracks, may be made of rolled profile and/or as drop forgings.

It is of particular advantage if the baseplates are first made in the form of a flat rolled or pressed profile and then converted into the curved starting shape by cold die forming. The baseplates may even be formed by casting or assembled by welding.

Further features and advantages of devices according to the invention for fastening rails to rail supporting members, particularly wooden sleepers, of railway tracks are described by way of example in the following with reference to embodiments illustrated in the accompanying drawings, wherein: Figure 1 is a cross-section through a UIC-60 rail with the associated fastening, the clip bolt used as the fastening element being shown before final assembly on the right-hand side and after final assembly on the left-hand side of the Fig.

Figure 2 is a plan view of the rail fastening device shown in Figure 1.

Figure 3 is a side elevation of the rail fastening shown in Figures 1 and 2.

Figure 4 shows a baseplate or ribbed plate used in the rail fastening device illustrated in Figs.

1 to 3 in its pre-curved, non-biassed state (general view).

Figure 5 is a plan view and Figure 6 a side elevation of this baseplate or ribbed plate.

Figure 7 is a view in the longitudinal direction.

Figure 8 a plan view and Figure 9 a side elevation of another embodiment of a device for fastening rails to transverse sleepers which is equipped with ribbed support plates instead of baseplates or ribbed plates.

In the permanent-way field, the actual track is very often laid on the ballast bed by means of transverse sleepers 1. In most cases, impregnated wooden sleepers with oaken sleeper ends are laid as transverse sleepers 1 on the ballast bed. Beech and oak or even firs and tropical timber, such as keruing, may be used as the wood for the sleepers.

The transverse sleepers 1 laid at certain intervals apart from one nother are fastened non-tiltably to the rails 3 by means of a rail fastening 2 to form a relatively rigid track frame or panel. Each of the rail fastenings 2 is made up of a baseplate or ribbed plate 4 (hereinafter referred to as "baseplate"), several, for example four, sleeper screws 5 joining the plate 4 to the transverse sleeper 1, and clamping elements which at one end are designed to be coupled to the baseplate 4 and, at their other end, act on the foot of the rail and which, as shown in Figs 1 to 3, are formed for example by clip bolts 6, clamping plates 6' and spring washers 6". Instead of using clip bolts, clamping plates and spring washers 6, it is of course also possible to use as clamping elements turnbuckles or strainers which are effectively connected to the foot of the rail.

The underside of the foot of the rail rests between the two ribs 7 of the baseplate 4, i.e. not directly on the upper surface thereof. On the contrary, an intermadiate pad 8 is provided there.

The left-hand side of Figure 1 shows the clip bolt 6 used as the clamping element in the assembled state, the clamping plate 6' resting as a pressure member on the foot of the rail whilst the bias is produced via the nut co-operating with the clip bolt and the spring washer 6".

By contrast the right-hand side of Figure 1 shows the clip bolt 6 with the nut, the clamping plate 6' and the spring washer 6" before final assembly.

So far as the effectiveness of the rail fastening 2 is concerned, it is particularly important for the contact surface 9 of the baseplate 4 to be permanently kept in force-locking contact with the upper surface 10 of the sleeper. To achieve this result, the baseplate 4, as shown in Figures 4 and 6, is used with a starting shape which curves inwardly and downwardly from at least two opposite boundary edges, in the present case the two longitudinal boundary edges 4'.

In the embodiment of the basplate or ribbed plate 4 shown in Figs. 4 to 6, the curve 11 extends transversely in such a way that the apex 12 of the curve coincides with the centre line 13 of the baseplate 4.

In other cases,however, the curve 11 may also extend parallel to the longitudinal axis of the baseplate 4 in such a way that the apex 12 of the curve coincides with the transverse middle line 14.

Finally, it is also possible for the curve 12 to extend diagonally of the baseplate 4 in such a way that it preferably forms a spherical surface which in effect has only one apex in the region where the longitudinal centre line and the transverse centre line 14 intersect.

The curve 11 of the contact surface 9 of the baseplate 4 may correspond for example to a circular or elliptical arc or to any other appropriate geometric curve. However, it may also be delimited by straight lines and/or flat arcs arranged adjacent one another at definable adjoining angles.

The baseplates 4 shown in Figs. 4 to 6 may either be made of rolled profiles or may even be in the form of drop forgings, castings or welded assemblies. It can be of particular advantage first to prefabricate these baseplates 4 by flat rolling or pressing and then to provide them with the curve 11 by cold die forming.

It is important that the baseplates or ribbed plates 4 with the curve 11 should be able to be elastically braced by means of the four sleeper screws 5 each extending with fairly wide clearance through a hole, particularly an oval hole 15, and hence applied with their entire contact surface 9 to the upper surface 10 of the sleeper in force-locking manner. By correspondingly tightening the sleeper screws 5 or the like, it is thus possible to generate a certain surface pressure between the contact surface 9 of the baseplate or ribbed plate 4 and the upper surface 10 of the sleeper. This is then used to transmit the horizontal forces applied by the rail 3 to the baseplate 4.The greater the elastic distance 11 to be travelled in the vertical direction (Fig. 4), the higher the surface pressure which can be generated, depending on the type of material used, the dimensions of the plates and the form of the curve. Tests have shown that the optimal form for the curve 11 is that of a simple curve. A certain polygonal form with different connecting angles or a geometric cruve with square or cubic components or components of higher order may of course also be used for achieving an optimal surface pressure. Finally, however, the curve 11 may also be formed by coupling more or less long straight lines with flat arcs and straight intermediate lines. Different curves for the upper and lower surfaces and.for the interior and exterior are also possible.

By using baseplates 4 designed in this way as an integral functional component of rail fastening devices, the elastic application of the baseplate 4 to the upper surface 10 of the sleeper and the anchoring effect in the region of the ribs 7 can be expected to be maintained for the entire service life of wooden sleepers, i.e. for about 40 to 50 years, despite the wheel load acting statically and dynamically from outside, with the maximal surace and edge pressures exceeding the permitted long-term surface pressures of the woods and other materials used for sleepers.

By virtue of the described configuration and bracing of the baseplates 4, there is no longer any need for the spring washers hitherto used between the sleeper screws 5 and the baseplates.

The elastically braced baseplate 4 performs the function of maintaining a force-locking connection between itself and the upper surface of the sleeper to far greater effect than spring washers of the type in question. Spring washers have a very small progressive deflection which is unfavourable for this particular application. As a result, the maintenance of tension diminishes to a considerable extent, even in the event of minor elastic and plastic deformation of the upper sleeper surface 10. By contrast, pre-curved baseplates have a considerably greater, and hence more favourable, flatter force-spring travel (approximately a linear trend) for the application in question.

A structurally modified embodiment of a device for fastening rails to transverse sleepers is shown in Figs. 7 to 9.

In this case, two so-called ribbed support plates 1 7 are used instead of a single baseplate 4 for forming rail fastenings 1 6 to transverse sleepers 1. The two ribbed support plates 1 7 are arranged with a lateral spacing adjacent one another on the upper surface 10 of the sleeper in such a way that the foot of the rail 3 can be placed on an intermediate pad 1 8 in the space left in between.

The two ribbed support plates 1 7 are identical with one another, being arranged at 1 800 relative to one another on either side of the foot of the rail.

Clamping elements consisting of clip bolts 6, clamping plates 6' and spring washers 6" cooperate with the ribs 19 of each ribbed support plate 1 7 in the same way as with the already described embodiment of a single baseplate or ribbed plate 4. However, turnbuckles or strainers may be used as clamping elements in this case, too. As can readily be seen from the left-hand side of Figure 9, these ribbed support plates 17 before final assembly also have a starting shape which curves inwardly and downwardly from opposite boundary edges, in this case the transverse boundary edges 17', the apex 21 of the curve coinciding with the transverse centre line 22 of each ribbed support plate 17.

The sleeper screws 5 cooperate with the ribbed support plates 1 7 through engagement slots 23 which open into their transverse boundary edges 17' and are inclined towards the longitudinal axis of the rails and which are used for correcting the position of the track in such a way that any longitudinal displacement of the ribbed support plates 17 relative to the sleeper screws 5 automatically produces a movement in the transverse direction as well. In this way, the ribbed support plates 1 7 may also be transversely applied to the foot of the rail and, by tightening the sleeper screws 5, may be permanently applied to the upper sleeper surface 10 in force-locking manner with a bias resulting from the curve 20, as can be seen from the right-hand side of Figure 9.

Finally, it is pointed out that, in many cases, it is of advantage to provide the contact surface 9 of the baseplate of ribbed plate 4 or of the ribbed support plates 1 7 with surface roughenings, for example in the form of serrations, knurling, undulations, projections, or even to roughen it by sandblasting. These measures not only increase the coefficient of friction, but they also ensure effective mechanical engagement with the upper surface 10 of the sleeper.

In addition. the baseplates or ribbed plates 4 or the ribbed support plates 1 7 may also be cemented to the upper surface 10 of the sleeper.

This is of particular advantage in cases where softwood sleepers, for example of pine, are used.

In this case, however, baseplates or ribbed plates 4 or ribbed support plates 17 having a slightly larger contact surface 9 should be used. It is particularly useful to cement the elastically biassed baseplates or ribbed support plates in the case of supporting points for ballast-free permanent way or for concrete sleepers. Sleeper screws 5 of which the collar is provided at its contact surface with rounded peripheral edges to prevent penetration into the plate surface should be used in conjunction with the baseplates or ribbed plates 4 or ribbed support plates 1 7 described in the foregoing.

Claims

1. A railway supporting assembly, comprising a rail supporting member, a baseplate arranged on the upper surface of the rail supporting member and anchored thereto, and a rail fixed to the baseplate, wherein the baseplate has a natural curvature inwardly and downwardly from at least two opposing boundary edges and is applied flat through elastic deformation to the upper surface of the rail supporting member.

2. A device for fastening rails to transverse and/or longitudinal sleepers and sleeperless rail supporting members of all kinds, more particularly to wooden sleepers of railway tracks, comprising a baseplate or ribbed plate or two co-operating support plates which is/are arranged on the upper surface of the sleeper or rail supporting member, is/are anchored to the sleeper or rail supporting member such as by sleeper screws or the like and on which or between which the foot of the rail is fixed in resiliently form-locking manner such as by clip bolts, clamping plates and spring washers or through turnbuckles or strainers, wherein the baseplate or ribbed plate and/or the ribbed support plates for tracks and switches has/have an initial shape which curves inwardly and downwardly from its/their boundary edges and is/are designed to be applied flat through elastic deformation to the upper surface of the sleepers or bearing surface of the rail supporting members by fixing means such as sleeper screws or the like.

3. A device as claimed in Claim 2, wherein the apex of the curve coincides with the centre line of the baseplate or ribbed plate or ribbed support plate.

4. A device as claimed in Claim 2 or 3, wherein the curve runs parallel to the longitudinal axis of the baseplate or ribbed plate or of the ribbed support plates.

5. A device as claimed in Claim 2 or 3, wherein the curve extends parallel to the transverse axis of the baseplate or ribbed plate.

6. A device as claimed in Claim 2 or 3, wherein the curve extends diagonally of the baseplate or ribbed plate and preferably delimits a spherical surface.

7. A device as claimed in any of Claims 2 to 6, wherein the curve in the baseplate or ribbed plate or in the ribbed support plates follows a circular or elliptical arc or any other appropriate geometric curve.

8. A device as claimed in any of Claims 2 to 6, wherein the curve is delimited by straight lines or flat arcs arranged adjacent one another at definable adjoining angles.

9. A device as claimed in any of Claims 2 to 8, wherein the baseplate or ribbed plate or.the ribbed support plates are made from a rolled profile or section.

10. A device as claimed in any of Claims 2 to 8, wherein the baseplate or ribbed plate or the ribbed support plates are in the form of dropforgings.

11. A device as claimed in any of Claims 2 to 10, wherein the baseplate or ribbed plate or the ribbed support plates consist(s) of a profile which has been flat rolled or pressed and then curved by cold die forming.

12. A device as claimed in any of Claims 2 to 10, wherein the baseplate or ribbed plate or the ribbed support plates consist(s) of a casting, particularly of cast steel or spheroidal cast iron.

13. A device as claimed in any of Claims 2 to 10, wherein the baseplate or ribbed plate or the ribbed support plates are assembled by welding with ribs or parts of ribs fixed to flat plates.

14. A device as claimed in any of Claims 2 to 13, wherein the bearing surface of the baseplate or ribbed plate or of the ribbed support plates is provided with surface roughenings, for example serrations, knurling, undulations, projections, or is roughened by abrasion (sand-blasting).

1 5. A device as claimed in any of Claims 2 to 14, wherein the bearing surface of the baseplate or ribbed plate or of the ribbed support plates is adapted to be cemented to the upper surface of the sleeper or rail supporting member.

1 6. A device as claimed in any of Claims 2 to 15, constructed as abnormal baseplates, for example ribbed plates, ribbed sliding plates, tongue root, crossing and guide rail plates, for switches and crossings of all kinds.

1 7. A railway supporting assembly substantially as hereinbefore described with reference to and as shown in the accompanying drawings.