GB2353065A

GB2353065A - Rail mounting clamp

Info

Publication number: GB2353065A
Application number: GB9918774A
Authority: GB
Inventors: Ian Wareing; Barry Wright
Original assignee: Dorman Traffic Products Ltd
Current assignee: Dorman Traffic Products Ltd
Priority date: 1999-08-09
Filing date: 1999-08-09
Publication date: 2001-02-14
Anticipated expiration: 2019-08-09
Also published as: GB2353065B; GB9918774D0

Abstract

There is provided a clamp for mounting an object onto a rail, the rail having a generally vertical middle portion and an upper portion of enlarged cross-section. The clamp comprises a first clamping element, 2, which is constructed and arranged for embracing one side of the upper rail portion. The clamp further comprises the second clamping element, 3, including camping means, 7, movable by rotation about a generally vertical axis 6 from a non-clamping position into a clamping position in which the second clamping element, 3, clampingly embraces the opposite side of the upper rail portion.

Description

2353065 CLAMP

This invention relates to the field of clamps, more specifically to clamps for mounting objects such as marker 5 boards onto rails, particularly railway tracks.

Clamps of various constructional types are known in many technical fields. One particular field is the use of some sort of clamp for mounting marker boards or sighting boards onto railway tracks. Marker boards are used for displaying warning lights or other indicia to inform train drivers of a danger ahead, whilst sighting boards are used to assess the profile of railway tracks by surveyors, for example.

is In this field there are various known clamps for mounting such objects on the rails. one known clamping arrangement comprises a base which fits beneath the heel of a rail and has a tube extending therefrom into which an attachment to the marker board is inserted. This arrangement has the disadvantage that, for use, ballast has to be removed from under the rail before the clamp can be fixed into position. This is a time, effort and cost consuming process.

Another known type of clamp is of the nature of a spring clip, which is commonly used to mount sighting boards onto railway tracks. The clip has a generally rectangular cross section with an open mouth, and is simply forced onto the rail so as to clamp it and the sighting board is mounted on top. The simplicity of this type of clamp, however, means that it lacks stability, especially on rail tracks whose upper edges have been eroded or worn by the passage of trains.

2 A typical railway track has a cross-section with a relatively narrow middle portion and upper and lower portions with an enlarged crosssection in a width dimension. The spring clip-type of clamp referred to above works by embracing the sides of the enlarged upper portion of the rail. The repeated passage of trains however tends over time to erode the upper edge of the rail on its inner side. The resulting modified and asymmetrical cross-section render the spring clip-type of clamp unstable, and it also renders useless (or at least disadvantageous) other forms of clamp which rely for their clamping action on the gripping of sides of the enlarged upper part of the rail.

It is an aim of this invention to provide a clamp that can be attached easily to a railway track without the need for excavation of ballast from beneath the rail and which remains stable even when the top edges of the track becomes worn.

Accordingly, in a first aspect the present invention provides a clamp for mounting an object onto a rail having a generally vertical middle portion and an upper portion of enlarged cross section, the clamp comprising a first clamping element constructed and arranged for embracing one side of the upper rail portion and a second clamping element including clamping means moveable by rotation about a generally vertical axis from a non-clamping position into a clamping position in which the second clamping element clampingly embraces the opposite side of the upper rail portion.

In a preferred embodiment of the clamp of the invention the clamping means of the second clamping element takes the form of a block or disc whose axis of rotation intersects 3 it at a point which is off-centre. Preferably the block or disc is circular and rotatably mounted on the second clamping element in an off- centre manner so that as it is rotated it moves in a cam-like fashion into or out of its 5 clamping position with respect to the upper rail portion. In a particularly preferred form of the clamp of the invention the clamping means actually clamps the rail against the relatively narrow middle-section beneath the enlarged upper rail portion, so that the second clamping element as a whole embraces and clamps the upper rail portion on that side of the rail.

In preferred forms of the clamp according to the invention, just one of the clamping elements includes the clamping means as defined above although it is possible, within the scope of the invention for both the first and second clamping elements to include like clamping means in order to clamp the rail in a corresponding manner on both its sides.

In preferred embodiments of the clamp of the invention the movable clamping means are lockable in their clamping position using suitable locking means at a suitable position on the device. The locking means may for example be formed simply by through-holes formed in each of adjacent movable parts of the clamping means, which holes come in to register when the clamping means are brought into there clamping position and through which may be inserted a locking pin or arm of a padlock, for example.

Alternatively, the locking means may be more elaborate, a preferred form of which, which also acts as an antivibration locking means, comprises a spring-loaded locking pin which normally engages in one of a plurality of locking slots formed in the wall of the rotatable clamping means in 4 order to lock it in its clamping position as required, yet which locking pin may be withdrawn from the slot against the force of the spring to allow rotation of the clamping means when it is desired to release it from its clamping. 5 position.

Conveniently the main components of the clamp may be formed from a suitable moulded engineering plastic, for example polycarbonate, such as that commercially available as IIXENOY CL10011. This allows the clamp to be durable, but in the event of a train accidentally passing over the clamp, the device shatters and thus prevents derailment of the train and damage to the train wheels.

Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, in which: Figure I is a schematic cross-sectional view of a 20 first preferred embodiment of the clamp according to the invention; and Figure 2 is a part-sectional view of a second preferred embodiment of the clamp according to the 25 invention.

Referring to Figure 1, railway track 1 has a narrow middle portion la and an upper portion lb of enlarged crosssection 1b. (The lower enlarged rail portion is omitted in the drawing.) A first clamping element is in the form of a substantially rigid arm 2 with a hooked lower end 2a which rests under the lower edge of one side of the enlarged upper rail portion 1b. The arm 2 extends around the right hand side (as shown in the drawing) of the upper rail portion lb and is connected to a housing 3, one side 3a of which abuts the opposite side of the rail 1 from that embraced by the arm 2. The housing 3 contains a cylindrical tube 4 rotatably mounted therein about axis 6 by means of upper and lower retaining discs Sa and 5b. At its lower end, the tube 4 is attached off-centre to a circular clamping block 7.

In its non-clamping position, the side 7a of the clamping block 7 that is furthest away from the point of intersection with its axis of rotation 6 is spaced from the rail 1. To achieve its clamping position, the clamping block 7 is rotated about the axis 6 such that its side 7a comes into contact with and so as to abut both the lower edge of the upper rail portion lb and the narrow middle rail portion la, as shown in the drawing.

Thus, owing to the clamping action effectively being onto the middle rail portion, the clamp can be successfully used on rails that have had one or even both upper edges eroded or worn. In particular if the rotatable clamping block 7 is positioned on the side of the rail suffering from erosion or wear, the clamp is still able to remain stable, unlike the prior art clamps in this field.

The housing 3 of the clamp is attached to a mount 8 upon which is carried and secured a marker board 9 (of which only the lower part is shown in the drawing). Typically, for railway track applications such a marker board 9 carries a number of warning lights 10 and/or other hazard or warning indicia.

In order to lock the clamp in its clamping position, in this embodiment two holes, one 11a in the clamping block 7 6 and one 116 in the housing 3, are provided, which come into register upon the clamping block 7 reaching its clamping position to form a through- hole extending through both parts. Any suitable locking means, such as a locking pin or the locking arm of a padlock can then be inserted through the holes to prevent the clamping block being rotatably retracted from its clamping condition on the rail.

Turning now to Figure 2, here there is shown an alternative construction of clamp which employs a different, more elaborate and reliable locking means to lock the clamp in its clamping position. In this Figure the railway track is omitted for clarity, as is the marker board mounted on the mount 8 of the clamp.

As shown in the Figure, this second embodiment of clamp again comprises a substantially rigid clamping arm 2 for clampingly embracing one side of the enlarged upper portion of the rail (not shown). Similarly, the central housing 3 of the clamp includes one side 3a thereof which abuts the other side of the upper portion of the rail and mounted therewithin is rotatable cylindrical tube 4 whose lower end extends downwardly, radially outwardly and integrally into circular clamping block 7. -The cylindrical tube section 4 is retained in the housing 3 above and below by means of through-bolt Sc, upper retaining disc 5a and locking nut 5d. As illustrated in this embodiment, but also applicable to the first embodiment of Figure 1, mounted around a lower shoulder 4a of the cylindrical tube 4, in a small gap between it and the lower periphery of the housing 3 is an O-ring 15, e.g. of nitrile rubber, in order to provide a degree of sealing and/or frictional bearing between these relatively rotatable parts.

7 Also applicable to both this second embodiment of Figure 2 and the f irst embodiment of Figure 1 is the provision of a plurality of gripping ribs 17 disposed around the outer periphery of the clamping block 7, which not only provide a means for gripping the clamping block 7 when it is manually rotated into or out of its clamping position, but also act to improve the grip exerted by the side 7a of the clamping block 7 which bears against the middle portion of the rail when the clamp is in its clamping position. The ribs 17 are ideally integrally moulded with the rest of the clamping block 7.

Characteristic of this second embodiment of clamp according to the invention is the more elaborate form of locking means, which are provided on the side of the housing 3 opposite the side 3a which abuts against the upper portion of the rail. This opposite side of the housing 3 comprises a moulded locking cage or frame 20 in which is mounted a spring-loaded locking pin 24. The locking pin 24 is loaded by compression spring 26 against push-button 28 which under the force of the spring 26 normally abuts against an inner wall 21 of the cage or frame 20. The locking pin 24 traverses within apertures 22a and 22b formed in the inner and outer walls of the cage or frame 20 and is mounted securely to the push-button 28 by means of through-pin 30.

Thus, the locking pin 24 constitutes a first element of the locking means, but a second element of the locking means is constituted by one of a plurality of longitudinal locking slots 33 formed in the wall of the central cylindrical tube 4 of the clamping means. There may for example be about ten such locking slots 33 disposed equiangularly around the cylindrical tube 4, allowing for the locking pin 24 to be inserted in any one of the desired slots 33 to lock the 8 clamping block 7 in any respective desired rotational position. Normally, of course, this locking means will be used to lock the clamping block 7 either in its clamping position in which it directly and firmly abuts against the middle portion of the rail once the clamp has been installed thereon, or alternatively the clamping block 7 may be locked in its unclamped position once the clamp has been removed from the rail. To actuate the locking means, the push button 28 is pulled back by the fingers of a user's hand against the force of the spring 26, thereby withdrawing the locking pin 24 from its respective locking slot 33. This leaves the cylindrical tube 4 and integral clamping block 7 free for rotation into whatever position is desired. Once the desired position has been reached, the push button 28 is released, thereby bringing the locking pin 24 back into its locking position within a different appropriate one of the locking slot 33.

The above described locking means as illustrated in Figure 2 is particularly useful in providing the locking capability, but in particular in a manner which prevents unwanted release or loosening of the clamping means such as due to vibrations from the rail, the ground or the marker board.

The present invention has been described above by way of illustrative examples according to preferred embodiments. However, it is to be understood that various modifications from that which has been specifically described and illustrated may be made within the purview of persons skilled in the art, but still within the scope of the present invention as defined by the claims annexed to this specification.

Claims

9 CLAIMS

1. A clamp for mounting an object onto a rail having a generally vertical middle portion and an upper portion of S enlarged cross section, the clamp comprising a first clamping element constructed and arranged for embracing one side of the upper rail portion and a second clamping element including clamping means moveable by rotation about a generally vertical axis from a non-clamping position into a clamping position in which the second clamping element clampingly embraces the opposite side of the upper rail portion.

2. A clamp according to claim 1, wherein the clamping means of the second clamping element is in the form of a block or disc whose axis of rotation intersects it at a point which is off-centre.

3. A clamp according to claim 2, wherein the block or disc is circular and rotatably mounted on the second clamping element in an off-centre manner so that as it is rotated it moves in a cam-like fashion into or out of its clamping position with respect to the upper rail portion.

4. A clamp according to any one of claims 1 to 3 wherein the clamping means of the second clamping element clamps the rail against the relatively narrow middle-section beneath the enlarged upper rail portion, so that the second clamping element as a whole embraces and clamps the upper rail portion on that side of the rail.

5. A clamp according to any preceding claim, wherein one only of the first and second clamping elements includes the said clamping means.

6. A clamp according to any one of claims 1 to 4, wherein both the first and second clamping elements each include respective said clamping means in order to clamp the rail in a corresponding manner on both its sides.

7. A clamp according to any preceding claim, wherein the clamping means are lockable in their clamping position using locking means at a suitable position on the device.

8. A clamp according to claim 7, wherein the locking means is an antivibration locking means comprising a spring-loaded locking pin which normally engages in one of a plurality of locking slots formed in the wall of the rotatable clamping means in order to lock it in its clamping position as required, yet which locking pin may be withdrawn from the slot against the force of the spring to allow rotation of the clamping means when it is desired to release it from its clamping position.

9. A clamp according to any preceding claim, whose main components are formed from moulded engineering plastics material S 10. A clamp according to claim 1, substantially as described herein with reference to the accompanying drawings.