GB2070110A

GB2070110A - Clamp for Fixing Railway Rails

Info

Publication number: GB2070110A
Application number: GB8102806A
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: 1980-02-02
Filing date: 1981-01-30
Publication date: 1981-09-03
Also published as: FI810245L; IT8147687A1; IT1170677B; BE887322A; HU184374B; YU22981A; RO81494B; DD156091A5; IT8147687A0; FR2475086A1; ZA81593B; ES265233U; JPS56156301A; SE8100493L; ES265233Y; RO81494A; NL8100313A; LU83095A1; AU6667881A; DE3003881A1

Abstract

The clamp (1) has at least one thrust arm (4) to be secured in recesses on the ribs of ribbed plates (19), a bracing member (2) to be placed on the rail base immediately adjacent to the anchoring points, and at least one arcuate spring (3) integrally connecting the thrust arm (4) to the bracing member (2). The bracing member (2) is continuous with the lower end of the arcuate spring (3) and is provided at its free end with a shaped element (5) to be placed on the rail base. The thrust arm (4) extends from the upper end of the arcuate spring and has a downwardly curved end portion (6) which is provided with projections designed to be fitted under tension into the recesses on the ribs of ribbed plates (19). <IMAGE>

Description

SPECIFICATION Clamp for Fixing the Rails of Railroads This invention relates to a clamp used as a tensionally connecting and flexibly yielding means of fixing the rails of railroads with form locking lateral support, the clamp comprising at least one thrust arm designed to be secured at anchoring points on the rail supports, e.g. in recesses on the ribs of ribbed plates, a bracing member designed to be placed on the rail base immediately adjacent to the anchoring points, and at least one arcuate spring arc connecting the thrust arm to the bracing member so that the three parts form a single piece.

In Germany andin other countries where German railroad technology has been used, a method of fixing rails by a form of construction known as the K type construction has been used since about 1 923 and has proved to be satisfactory. This construction consists of a ribbed plate which is connected to the sleeper by means of elastic spring rings and baseplate screws and is connected substantially rigidly but in a form locking manner to the rail base by means of hook bolts, clamping plates and spring rings. In this arrangement, the heads of the hook bolts are seated in a dovetail shaped recess of the ribs.

Fixing rails by the K type construction provided a previously unobtainable resistance to twisting by virtue of the relatively rigid manner in which the rails were braced. The K-type construction has, however, one serious disadvantage in that the devices employed for fixing the construction readily loosen under the increased strain imposed on the railroad by higher travelling speeds, higher axial loads and higher daily tonnage loads resulting inter alia in wear and tear by contact, and they therefore require constant checking and maintenance to keep the hook bolts tightened.

Another disadvantage of the K type construction for fixing rails is that fully automatic installation of the screw connections by means of track laying machinery is not possible with this type of construction.

The so-called tension clamp method of fixing rails to ribbed plates is also known. This provides a permanently tensioned and elastically yielding attachment for the rails with form locking side support. An elastic and tensional connection of this type for fixing rails is shown in German Offenlegungsschrift No. 2,623,944. It comprises ribbed plates and tension clamps which comprise at least one bracing member mounted on the rail base adjacent to the ribs and at least one supporting part with fixing device lying on the ribbed plates. The means for fixing the clamps are, as in the K-type construction, conventional hook bolts which are anchored with their heads in a dovetail shaped recess in the ribs.

This known method of fixing rails by means of tension clamps provides the rails with a resistance to twisting which is at least equal to or even superior to that provided by the K type construction method. In the connection shown in German Offenlegungsschrift No. 2,623,944, this resistance to twisting is mainly achieved by the fact that the bracing element of the tensioning clamp is placed on the rail base in such a manner that it makes linear contact with it along a line which is at some distance from the line of transition between the upper surface of the rail base and its radius of curvature but is in the region of this radius curvature, and overlaps the rail base in the direction towards the rail web but maintaining the distance from it.In this construction, it is essential that the bracing member of the clamp should not lie on the surface of the rail base but at the outermost end of the base, in the region of the radius of transition more specifically, for example at a slight distance from the line of transition between the upper surface of the rail base and the radius of curvature. The method of fixing rails according to German Offenlegungsschrift No. 2,623,944, however, not only increases the resistance of the fixed rail to tilting and twisting, but also substantially reduces the leverage of the vertical force component which determine the maximum bending moment of the tensioning clamp.

This method of fixing rails by means of tensioning clamps according to German Offenlengungsschrift No. 2,623,944 has the same disadvantage as the known K type construction of not allowing fully automatic installation of the screw connections by means of track laying machinery.

One disadvantage common to the method of fixing rails according to German Offenlegungsschrift No. 2,623,944 and another known method using spring bolts or spring clamps on the rails is that the tension acting on the so-called inverted pleat side of the clamps, i.e.

the inner surface of the clamps, substantially reduced their fatigue strength.

Another disadvantage is that the means of fixing rails according to German Offenlegungsschrift No. 2,623,944 requires as large a number of individual parts as the K type construction. The risk of corrosion and of wear at the surfaces of contact between these parts is therefore correspondingly high.

It is an object of the present invention to provide a tensioning clamp for so fixing rails that when force is introduced into the rail base, the clamp holds the rail down with considerable force while providing sufficient resistance to thrust and at the same time ensures firm lateral support and a high resistance to twisting of the rail on its support without any risk of damaging tension acting on the critical area on the inner surface of the clamp. Furthermore, the clamp should be capable of being installed fully automatically.

According to the invention there is provided a clamp adapted to act as a tensionally connecting a flexibly yielding means of fixing the rails of railroads with form locking lateral support, the clamp comprising at least one thrust arm adapted to be secured at anchoring points on rail supports, a bracing member adapted to be placed on the rail base immediately adjacent to the anchoring points, and at least one arcuate spring integrally connecting the thrust arm to the bracing member, wherein the bracing member is continuous with the lower end of the arcuate spring arc and is provided at its free end with a shaped element designed to be placed on the rail base, and wherein the thrust arm extends from the upper end of the arcuate spring arc and has a downwardly curved end portion which is provided with projections adapted to be fitted under tension into the anchoring points of the rail supports.

In the clamp according to the invention, the bracing member which is designed to lie on the rail base can act on the radius of transition of the rail base at a finite angle to the horizontal which is greater than the steepest inclination of the rail base. This produces a large horizontal force component at the line of contact of the bracing member with the rail base. It has been found that this horizontal force component may be at least five times as great in a clamp according to the invention as in known clamping elements. The lateral support of the rail and the resistance of the rail to twisting are thereby substantially increased.

A further advantage is that the bracing member of the clamp can act along a long continuous line of contact, thereby ensuring that if the rail undergoes twisting, the bracing force which in the untwisted state is introduced along a line will, after twisting, act pointwise at the end of the line of contact and hence provide a high leverage to counteract twisting. A relatively large width for the bracing member may considerable reinforce this effect.

It is of considerable value as regards the life of the clamp according to the invention if the stresses of pressure, tension and torsion and the superimposition of these stresses on each other are situated in those zones of the clamp which are particularly suitable for this purpose so that when the clamp is braced, the internal radii (or curvatures) on the inner surface of the clamp will not be subject to any tensile stress but only to compressive stresses.

In a preferred embodiment of the invention, the arcuate spring is continuous with two thrust arms each of whose downwardly curved end portions is situated laterally of the bracing member each on a different side thereof and leaving a gap between itself and the bracing member.

It has also been found important that when rails are fixed by means of clamps, they should be protected against tilting or being overloaded in the event of a load acting obliquely or vertically on the rail head. The lifting movement of the rail base should initially be absorbed with considerable resilience by the clamp which should subsequently limit this movement with a sharply increasing tensioning-force. This can be achieved in an embodiment of the invention by forming inwardly directed lugs on the thrust arms, the lugs being situated above the bracing member and overlapping the bracing member. If a tilting or lifting moment raises the rail base by only a slight amount, e.g. by about 1 millimetre, when the bracing member iying on the rail base encounters the lower edge of the overlying lugs of the thrust arms.The lever arm of the bracing member acting to resist the lifting movement is thereby shortened to such an extent that no plastic deformation occurs in spite of a substantially increased lifting force. The resulting spring characteristic shows a progressive course.

To aid easy and fully automatic installation of the clamps, the thrust arms may carry projections situated approximately at the same height as the lugs but directed outwardly. The thrust arms of the clamps can be pushed downwards so elastically by means of a pressure lever that the projections with which they are designed to be locked in their supports can be moved to the anchoring points of the rail supports where they automatically lock into position after release by the key. It is desirable to limit the elastic deformability of the thrust arms to the amount which is absolutely necessary for installation and dismantling of the clamps. To achieve this the length of the lugs formed on the inner sides of the downwardly curved end portions of the thrust arms is preferably slightly less than the lateral distance between the thrust arms.

It may also be advantageous for the shaped element of the bracing member to comprise an upwardly bent portion and supporting and guide flaps extending sideways in opposite directions.

This assists correct cooperation of the clamps with the anchoring parts of the rail supports, e.g.

with the ribs of ribbed plates, since the bracing member of the clamp will then first come to lie on the support surface of the anchoring parts on the rail supports when the clamp is being installed and then, when the clamp is subsequently shifted into position, the bracing member can slide off the anchoring parts and springs under a bias tension on to the rail base where it assumes a position of neutralisation free from tension.

In the accompanying drawings: Figure 1 is a side view of a clamp according to the invention in the relaxed state; Figure 2 is a top plan view of the clamp of Figure 1; Figure 3 is a front view of the clamp of Figures 1 and 2 taken in the direction of the arrow Ill; Figure 4 is a side view, partially in section, of a clamp of Figures 1 to 3 in its preassembled position on a ribbed plate; Figure 5 is a side view, partially in section, of a clamp according to the invention in its finally installed state in operative connection with a ribbed plate and the rail resting on said plate; and Figure 6 is a view corresponding to Figure 5 of a ribbed plate and a rail resting on said plate but with the clamp in a so called position of neutralisation.

The examplary embodiment of a clamp 1 illustrated in Figures 1 to 3 is made of a springy elastic flat material, preferably a flat steel strip.

The outline of the clamp is first cut or punched out of a piece of flat material and then bent into a loop as shown in Figure 1.

The clamp 1 comprises a bracing member 2 integrally continuous with an arcuate spring 3 which in turn is integrally continuous at its other end with a thrust arm 4.

It is essential that the bracing member 2 should be continuous with the lower end of the arcuate spring 3 and be provided at its free end with a shaped element 5 designed to be placed on the rail base while the thrust arm 4 extends from the upper end of the arcuate spring 3 and is provided on its downwardly curved end portion 6 with projections 7 designed to be moved with a biassing force into the anchoring parts of the rail supports.

Figure 1 shows that in its relaxed state the arcuate spring 3 is substantially semicircular and continues at its lower end into a straight section of the bracing member 2. The upper end of the arcuate spring 3 is also continuous with a straight section 9 which forms part of the thrust arm 4.

This straight section 9 of the thrust arm is continuous with a curved section 10 substantially in the form of a quarter of a circle, which continues downwards with a slight inward curvature into the end portion 6 of the thrust arm 4.

Figures 2 and 3 show that the thrust arm 4 has a cut out portion 11 extending from the free end 'of the end portion 6 through the curved section 10 and straight section 9 into the upper part of the arcuate spring 3, thereby subdividing the arm 4 into two equal arms 4' and 4" formed symmetrically on the two sides of a vertical midplane 12-12.

Figures 1 to 3 show that the downwardly curved end portions 6, i.e. 6' and 6" of the two parts 4' and 4" of the thrust arm 4 extend laterally to the two sides of the bracing member 2 at a distance 13' and 13", respectively therefrom.

The bracing member 2 is reduced in width or stepped on both sides behind its shaped element 5 so that it is substantially T-shaped and in its reduced or stepped region it receives the lateral projections 7' and 7" of the off-set end portions 6' and 6" of the thrust arms 4' and 4".

Figures 2 and 3 further show that the two parts 4' and 4" of the thrust arm 4 diminish in width from the arcuate spring 3 to their downwardly curved end portion 6 or 6', 6" and have inwardly directed lugs 14' and 14" formed on them which are situated above the bracing member 2 and overlap it. The distance 1 5 between the sides of the two lugs 14' and 14" facing each other is preferably such that these sides at best abut against each other when the two arms 4' and 4" have been flexibly pushed towards each other to such an extent that the distances 13' and 13" normally present between the inner surfaces of the two end parts 6' and 6" on the one hand and the outer surfaces of the narrow regions of the bracing member 2 on the other have beenvirtually eliminated.

Outwardly directed projections 16' and 16" are provided on the thrust arms 4' and 4", substantially at the same height as the lugs 14' and 14", to enable the two arms 4' and 4" to be pushed towards each other by deformation using a suitable tool such as tongs or the like. When the clamp is in its finally assembled state (Figure 5), these projections 16' and 1 6" serve as upper horizontal supports resting against a supporting rib 35.

As shown in particular in Figure 1, the shaped element 5 of the bracing member 2, which element is designed to be placed on the rail base, has a substantially Z-shaped bend such that the surface 17 which acts on the upper surface of the rail base is inclined to the main plane of the straight portion 8 of the bracing member 2. The relative inclination of the surface 1 7 to the straight portion 8 of the bracing member 2 determines the angle at which the whole length of the shaped element 5 lies on the upper surface of the rail base.

The shaped element 5 of the bracing member 2 has supporting and guide flaps projecting laterally in opposite directions, which may cooperate with the upper surfaces of the ribs or ribbed plates in a manner described below. These guide flaps also serves as cantilever arms for the application of a test instrument for testing the tightness of the rail base.

Figure 4 shows a section through half of a ribbed plate 19 having ribs 20 formed on its upper surface Each of these ribs 20 consists of two pieces which are mirror image formations of each other and together form an undercut recess into which the projections 7', 7" situated at the ends 6', 6" of the thrust arms 4', 4" can be fitted.

An intermediate layer 21 is provided on the ribbed plate 19 in the usual manner, between the ribs 20 facing each other.

The ribbed plate 19 is attached to a sleeper or similar rail support in the usual manner, for example by means of plate screws 22.

Figure 4 also shows, in side view and partially in section, a clamp 1 preassembled on the ribbed plate 1 9. The supporting and guide flaps 18', 18" of the clamp 1 are seated on a supporting surface 23 at the top of the tib 20, i.e. of the elements forming this rib; in such a manner that the clamp does not extend beyond the inner surface 24 of the ribs 20. The thrust arm 4 (or two thrust arms 4', 4") is placed into position by fitting the projection. 7 (or 7', 7") at the end portion 6 (or 6', 6") under a step 25 forming a catch in the undercut recess situated on both sides on the two surfaces facing each other of the rib elements forming the rib 20.The projections 7 or 7', 7" on the downwardly directed end portion 6 or 6', 6" of the thrust arms 4 or 4', 4" bear with a certain horizontal and vertical biassing force against the step 25 because the clamp not only rests on the supporting surface 23 of the rib 20 by means of its supporting and guide flaps 1 8', 1 8" but may also rest on the upper surface of the ribbed plate 19 in the region 26 close to the lower end of its arcuate spring.

When the clamp 1 is in the preassembled position shown in Figure 4, the rail 27 with rail base 28 can be placed from above on to the intermediate layers 21 of the ribbed plate 19 between the ribs 20 situated opposite each other, as indicated in Figure 5.

By application of a substantially horizontal thrust in the direction of the arrow 29 and a substantially vertical pressure in the direction of the arrow 30, the clamp 1 may then be displaced relatively to the ribbed plate 19 and the rail 27 to bemoved into its final assembled position indicated in Figure 5. In this final position of the clamp, the supporting and guide flaps 18', 18" of the shaped element 5 of the bracing member 2 have slipped off the supporting surfaces 23 of the ribs 20 so that the shaped element 5 presses with the whole length of its surface 17 against the upper surface of the rail base 28, more specifically against its radiussed edge 31, as may be seen from Figure 5.In this position, the surface 17 of the element 5 and the surface of the rail base enclose an angle of contact 32 which is inclined to the horizontal and the magnitude of which determines the vertical force and the horizontal force for fixing the rail.

The pressure applied substantially vertically in the direction of the arrow 30 pushes the projections 7 or 7', 7" on the end portions 6 or 6', 6" of the thrust arms 4 or 4', 4n underneath a step 33 which is not only substantially lower than the step 25 between the elements which form the rib 20 but is also closer to the rail base.

As clearly shown in Figure 5, when the clamp 1 is in its finally mounted position, the lower edge of the lugs 14', 14" formed on the inside of the end portions 6 or 6', 6" of the thrust arms 4 or 4', 4" is only slightly above the bend in the shaped element 5 on the bracing member. This means that the slightest tilting or lifting movement of the rail base 28 of the rail 27 is sufficient to cause the shaped element 5 of the bracing member 2 to bear against the lugs 14' and 1 4e The length of the lever arm which counteracts this lifting movement is thereby reduced to such an extent that no plastic deformation occurs in the bracing member 2 in spite of a substantially greater lifting force. The resulting spring characteristic takes a progressive course.

Figure 5 also shows that when the clamp is in its finally mounted position, the two projections 16', 16" bear horizontally against the supporting rib 35, thereby providing the necessary condition for optimum clamping to be achieved.

Practical tests have shown that when the clamps 1 are in their finally mounted position indicated in Figure 5 they are quite capable of producing a vertical force of 1120 kp and a horizontal force of 522 kp because of the inclination to the horizontal of the angle of contact 32 between the radius 31 of the rail base and the surface 17 of the shaped element 5. An even greater horizontal force may be obtained simply by bending the shaped element 5 in relation to the straight portion 8 of the bracing member 2 so that an even greater angle of contact 32 is obtained between the surface 17 and the radius 31 of the rail base. This relationship is particularly important for the horizontally yielding mounting, i.e. the lateral support of the rail 27 and determines the magnitude of the resistance to twisting.

The clamp 1 may also be shifted from the final mounting position of Figure 5 into a so-called neutralisation position indicated in Figure 6, in which the shaped element 5 of the bracing member 2 is basically left in its position on the base 28 of the rail 27 but the clamp 1 is - completely freed from tension by shifting the projections 7 or 71, 7" at the end portions 6 or 6', 6" of the thrust arms 4 or 4', 4'1 from the step 33 into a third step 34 situated above it. The clamps 1 may be brought into this position of neutralisation by exerting pressure against the projections 16', 16" by a movement from above downwards using a forked tool.The thrust arms 4 or 4', 4" are thereby pushed towards each other with elastic deforniation so that their distances 13' and 13" from the outer edges in the narrow region of the thrust member 2 are reduced. The projections 7', 7" of the end portions 6 or 6', 6" of the thrust arms 4 or 4', 4" are thereby disengaged from the step 33 so that the clamp 1 is relaxed and the projections 7 or 7', 7" move under the step 34. The position of neutralisation of the clamps 1 may be used, for example, for carrying out final welding of the rails while they are exactly aligned but still longitudinally displaceable on the ribbed plates 19 of the rail supports.

It should also be mentioned that when the clamps 1 are moved from their preassembled position of Figure 4 into the final position of Figure 5 or into the neutralisation position of Figure 6, the part of the clamp which forms the transition from the lower end of the arcuate spring 3 to the adjacent straight portion 8 of the bracing member 2 is lifted from the upper surface of the ribbed plate 18 so that the straight portion 8 which slopes downwards from the rail base is raised into at least an approximately horizontal position.

It is to be noted that the illustrated form of clamps may be used not only in combination with ribbed plates or the like in which the anchoring parts on the ribs are equipped with steps 25, 33 and 34 as shown in Figures 4 to 6 but may also be anchored in a somewhat modified form in a K ribbed plate with dovetail.

The important condition is only that the anchoring parts for the clamps 1 should be so formed that the thrust arms 4 or 41, 4" can act on them from above while the bracing member 2, situated below, can be passed through between the anchoring parts to lie on the rail base 28.

This formation is essential because it ensures that no tenstile stresses but only compressive stresses can occur on the internal surfaces of the arcuate spring arc 3.

The special advantage of the clamps according to the invention described herein is that they can be installed using simple tools, little expenditure of energy and short operating cycles and with high reproducibility, and little servicing is required to maintain the geometry of contact with the rail and anchoring part. Since only a small number of individual parts is required for fixing rails when the clamps 1 are used, the wear due to contact and corrosion can be reduced so that there is virtually no risk of loosening of the fitting. The rail is thereby maintained in a stable position in the lateral direction so that correct maintenance of the gauge is constantly ensured. Permanent lateral contact of the rail base 28 with the rigid boundary surfaces 24 of the ribs 20 or similar anchoring parts can be avoided if the clamps 1 are also elastic in the horizontal direction but with a steeper spring characteristic than in a vertical direction.

Another important advantage of the clamps described herein is that they are suitable for fully automatic installation.

Claims

1. A clamp adapted to act as a tensionally connecting and flexibly yielding means of fixing the rails of railroads with form locking lateral support, the clamp comprising at least one thrust arm adapted to be secured at anchoring points on rail supports, a bracing member adapted to be placed on the rail base immediately adjacent to the anchoring points, and at least one arcuate spring integrally connecting the thrust arm to the bracing member, wherein the bracing member is continuous with the lower end of the arcuate spring arc and is provided at its free end with a shaped element designed to be placed on the rail base, and wherein the thrust arm extends from the upper end of the arcuate spring arc and has a downwardly curved end portion which is provided with projections adapted to be fitted under tension into the anchoring points of the rail supports.

2. A clamp according to claim 1 , which is in the form of a loop in which the downwardly curved end portion of the thrust arm is situated laterally of the bracing member, leaving a gap between itself and the bracing member.

3. A clamp according to claim 1, wherein the arcuate spring is continuous with two thrust arms each of whose downwardly curved end portions is situated laterally of the bracing member, each on a different side thereof and leaving a gap between itself and said bracing member.

4. A clamp according to claim 3, wherein the bracing member is reduced in width or stepped inwards on both sides behind its shaped element which is designed to be placed on the rail base, and the downwardly curved end portions of the thrust arms are situated in these regions of constriction.

5. A clamp according to claim 3 or 4, wherein the bracing member, arcuate spring and thrust arms are made in one piece from a curved, shaped piece of steel strip, the bracing member being substantially T-shaped in outline and each of the two thrust arms diminishing in width from the arcuate spring to its downwardly curved end portion.

6. A clamp according to any one of claims 3 to 5, wherein inwardly directed lugs are formed on the thrust arms which lugs are situated above the bracing member and overlap said member.

7. A clamp according to claim 6, wherein the thrust arms carry projections situated approximately at the same height as the lugs but directed outwards.

8. A clamp according to claim 7, wherein the length of the lugs formed on the inner sides of the downwardly curved end portions of the thrust arms is slightly less than the lateral distance between the thrust arms and the bracing member, and the thrust arms are elastically deformable sideways towards the bracing member and towards each other to reduce the distance therebetween.

9. A clamp according to any preceding claim, wherein the said shaped element of the bracing member comprises an upwardly bent portion and supporting and guide flaps extending sideways in opposite directions.

10. A clamp for fixing the rails of railroads, substantially as herein described with reference to the accompanying drawings.