GB2309476A

GB2309476A - Longitudinally overlapping rail joint

Info

Publication number: GB2309476A
Application number: GB9601600A
Authority: GB
Inventors: Timothy Alan Wood; Stephen Bernard Silk
Original assignee: Pandrol Ltd
Current assignee: Pandrol Ltd
Priority date: 1996-01-26
Filing date: 1996-01-26
Publication date: 1997-07-30
Also published as: WO1997027367A1; GB9601600D0; AU1550897A

Abstract

First and second rail sections 101, 102 have overlapping end portions 101f, 102f, and connection means 8', 9'. The end portions are elongate, and extend alongside one another substantially parallel to the longitudinal axis of the rails. At least one bolt 8' extends, transversely to the rail axes, through holes 100 formed in the rail end portions. The end portions may be machined from lengths of standard rail (fig. 4A). Preferably, the gap separating the rail end portions is substantially filled by an elongate insulating member 110 (details, figs. 5A, 5B). Sleeves and bushes (18, 19, figs. 6 and 7) insulate the bolts from the rails. Because fishplates are not used, the joint conforms closely to a standard rail cross-section, and standard rail clips 5' may be used adjacent to the joint. Figs. 1 and 2 show prior art.

Description

RAIL JOINT The present invention relates to a railway rail joint assembly.

In the past joints between successive lengths of railway rail were required to allow for thermal expansion/contraction of the metal rails. Because suitable welding techniques were not available, and because of the large cost involved (joints being required every 10 to 20 metres along the track), simple joints were used. Most commonly, the joints used were squared butt joints, the two adjacent rails being connected together by means of a pair of bars, known as joint bars or "fish plates", shaped so as to fit between the head and foot of the rails and to span the joint between them. The rails and joint bars had holes, typically four in number, along their length through which securing bolts were inserted. Because of the presence of the joint bar, special rail fastening clips and other components may be required in order to secure the rail to the underlying sleeper.

There was some experimentation with joints known as "scarfjoints", which still employed joint bars but in which the ends of the two rails were shaped so as to abut one another at an angle of 450 with respect to the longitudinal axis of the rail. However, the 450 angle proved not to be sufficient to alleviate problems experienced with conventional joints and the 450 scarfjoint met with only limited success.

Nowadays, successive lengths of rail are generally welded together, end to end, but joints are still required when one signalling section is to be electrically insulated from the next, as trains are detected by low voltage current passed through the rails. Joints are now typically required only every two kilometres or so, but they are still expensive and require special maintenance, purpose-made fastenings on adjacent sleepers, and are invariably "factory-made" in a length of a rail typically 10 metres long which is welded into the track. However, in such joints the abrupt discontinuity between successive rails results in damage to the rail ends, known as "rail end batter", shortening the service life of the joint and increasing the amount of maintenance attention required to maintain vertical alignment of the joint.

According to the present invention there is provided a railway rail joint assembly comprising first and second railway rail sections, each rail section having an end portion shaped so as to fit against, or closely adjacent to, the other rail section, and connection means for joining together the first and second railway rail sections when the assembly is in use, wherein the shaping of the end portions is such that those portions are elongate and, when the assembly is in use, extend alongside one another substantially in a direction parallel to the longitudinal axis of the first and second railway rail sections and wherein the said connection means comprise at least one connection element which extends, transversely with respect to said longitudinal axis, through respective holes formed in the said end portions.

Such a railway rail joint assembly can eliminate the problem of rail end batter, since there is a progressive changeover between the rails, thereby not only extending the service life of a joint but also greatly reducing the maintenance attention required to maintain vertical alignment of the joint, which will be especially useful in remote areas. Moreover, the assembly provides a much stronger joint and is cheaper than the prior art. Joint bars are no longer required and therefore standard rail fastening clips, rather than modified components, may be used.

Each rail section is conveniently formed by machining a length of the standard rail with which the joint is to be used. Alternatively, each rail section may be formed by machining a length of steel to the appropriate shape, in a manner similar to that by which standard rails are themselves formed.

When the railway rail joint assembly is to be used at the joint between one signalling section and the next, insulation between the two sections must be provided. Accordingly, the gap separating the end portions of the first and second railway rail sections is substantially filled by an elongate insulating member.

This enables better insulation to be maintained and assists in decreasing noise levels at the joint.

Reference will now be made, by way of example, to the accompanying drawings, in which: Figures 1A to 1C show respective cross-sectional, plan and side elevational views of a conventional railway rail joint assembly, Figure 1A being a part cross-section taken along the line I-I in Figure 1B; Figure 2 shows a plan view of another previouslyproposed railway rail joint assembly; Figures 3A to 3C show respective plan, crosssectional and side views of a railway rail joint assembly embodying the present invention, Figure 3B being a part cross-section taken along line III-III in Figure 3A; Figures 4A to 4D show respective plan, end elevational, side elevational and cross-sectional views of one railway rail section for use in an assembly embodying the present invention, the cross-sectional view of Figure 4D being taken along the line IV-IV in Figure 4A;; Figures 5A and 53 show respective plan and side elevational views of an insulating member for use in an assembly embodying the present invention; and Figures 6A and 6B and Figures 7A and 7B show further components for use in an assembly embodying the present invention.

Figures 1A to 1C illustrate the type of conventional joint assembly mentioned above which employs joint bars, Figures 1A to 1C showing only one of the two adjoining rails in the assembly. In Figures 1A to 1C, a rail 1, having a head la, foot 1b and interconnected web ic, rests on a concrete sleeper 2.

Although not shown, the end of the rail abuts against the end of a successive rail such that the angle of the joint between them is perpendicular to the length of the rails. Between the foot 1b of the rail 1 and the surface of the sleeper 2 there is a resilient rail pad 3 of moulded plastics material. The rail 1 is positioned between a pair of anchoring devices 4 each having a head portion 4a, located above the surface of the sleeper 2 and having a passageway 4b running therethrough parallel to the longitudinal axis of the rail 1, and a leg portion 4c, embedded in the concrete sleeper 2.The rail 1 is held in place by resilient rail fastening clips 5, each having a leg Sa, which abuts against the roof of the passageway 4b in one of the anchoring devices 4, a heel portion 5b which rests on a ledge 4d provided on the head portion 4a of the anchoring device 4 at the side of the passageway 4b remote from the rail 1, and a toe portion Sc which bears down on the foot ib of the rail 1, the toe portion Sc being flattened along its side which faces the rail. The toe portion Sc of each clip 5 and the rail 1 are electrically isolated from one another by respective interposed nylon insulators 6.

The illustrated rail 1 is joined to another (not shown) by means of a pair of joint bars 7 located on either side of the rail webs lc at the rail joint and shaped so as to fit between the head la and the foot 1b of the rail 1 and connected to one another by means of four bolts 8 (only one of which is shown), secured by respective nuts 9, which pass through holes ld provided in the rail web lc and passageways 7a formed in the joint bars 7. Epoxy resin insulators 10 are provided so as to electrically isolate the joint bars 7 from the rail webs lc and insulating bushes 11 are provided so as to electrically isolate the bolts 8 from the rail 1.

The scarfjoint assembly of Figure 2 is shown in less detail than that of Figure 1, but differs essentially only in that the ends of the rails 1 are shaped such that at the joint the angle between successive rails is 450 to the length of the rails 1.

An embodiment of the present invention is shown in Figures 3A to 3C. In use, a rail joint assembly embodying the present invention is welded into place between two standard rails (not shown). The joint comprises first and second rail sections 101, 102, spanning the gap between two adjacent sleepers 2', each rail section 101, 102 resting on respective resilient rail pads 3'.

From the said one end 101e, 102e, each rail section 101, 102 narrows such that, as shown in the drawing, the narrowed parts 101f, 102f of each rail section 101, 102, can be laid so as to extend alongside one another in such a manner that together respective head parts 101a, 102a of each rail section present largely the appearance of a continuous rail head.In particular, proceeding from the said one end 101e, 102e of each rail section 101, 102, at which the rail section is the same width as the standard rail, the rail section 101, 102 comprises a first part 1011 and 1021 at which the rail section is cut away on one side of the head 101a, 102a to a location approximately one third of the way across the head 101a, 102a; a second part 1012, 1022 at which the width of the head is tapered along one side of its length to approximately half of its original width for a short distance; a third part 1013, 1023 at which the width of the head is maintained constant; and finally a fourth part 1014, 1024 at which the width of the head 101a, 102a tapers along its said one side again to approximately a third of its original width.Webs 101c, 102c of the rail sections 101, 102 connecting the heads 10la, 102a and feet 101b, 102b thereof, are shaped so as to mirror the profile of the respective heads 101a, 102a.

The rail sections 101, 102 are separated from one another by an insulating member 110 (shown in more detail in Figures 5A and 5B) made of a flexible material, which is held between the two rail sections, 101, 102, so as to extend between the second parts 1012, 1022 and fourth parts 1014, 1024 of the rail sections 101, 102. The first part 1011, 1021 of one rail section 101, 102 abuts the fourth part 1014, 1024 of the other, and at this point the rail sections 101, 102 lie between a pair of anchoring devices 4', similar to those of Figures 1A to 1C, in which rail fastening clips 5', similar to those of Figures 1A to 1C, are mounted so as to bear on the feet 101b, 102b of each rail section 101, 102.It should be noted that the rail fastening clips 5' may be standard components used elsewhere along the track and, unlike the prior art assembly of Figures 1A to 1C, need not be specially modified components used only at the rail joint. In particular, it is not necessary to flatten the side of the toe of each clip 5' adjacent to the rail web 101c, 102c.

The rail sections 101, 102 are held together by four bolts 8' (only one being shown), which pass through respective holes 100, 110a formed in the webs 101c, 102c and insulating member 110 and are secured by respective nuts 9'. At either end of each hole 100, so as to electrically isolate the bolt 8' from the two rail sections 101, 102, there are provided respective bushes 18 (shown in more detail in Figures 6A and 6B) made of insulating material. The shank of each bolt 8' is furthermore surrounded by a compression stop 19 (shown in more detail in Figures 7A and 7B). Such a stop 19 may not always be necessary, however, and may be omitted.

The rail sections 101, 102 are identical to one another. Figures 4A to 4D show the rail section 102 and in chain dotted line the outline of a length of standard rail which has been bent so as to assume a shape suitable for machining to achieve the desired rail section 102.

In particular, the Figures illustrate a section of BS113A rail, of overall length before bending of approximately one metre. Proceeding 80mm in from one end 102e of the rail length, the length of rail is bent such that the web of the rail becomes inclined to a first direction parallel to that of the web 102c in the part 102e by an angle a of approximately 70 for a distance 114mm measured parallel to the first direction. The rail section is then bent back so that the web again runs parallel to the first direction for a distance of 448mm, and is finally bent once again by the same angle a for the remainder of its length. The rail section is then ready for machining.

Claims

1. A railway rail joint assembly comprising first and second railway rail sections, each rail section having an end portion shaped so as to fit against, or closely adjacent to, the other rail section, and connection means for joining together the first and second railway rail sections when the assembly is in use, wherein the shaping of the end portions is such that those portions are elongate and, when the assembly is in use, extend alongside one another substantially in a direction parallel to the longitudinal axis of the first and second railway rail sections and wherein the said connection means comprise at least one connection element which extends, transversely with respect to said longitudinal axis, through respective holes formed in the said end portions.

2. An assembly as claimed in claim 1, wherein each rail section is formed from a length of the standard rail with which the joint assembly is to be used.

3. An assembly as claimed in claim 1 or 2, wherein there is a gap separating the end portions of the first and second railway rail sections which is substantially filled by an elongate insulating member.