WO2010023675A1

WO2010023675A1 - Rail expansion joint

Info

Publication number: WO2010023675A1
Application number: PCT/IN2008/000550
Authority: WO
Inventors: Anuranjan Prasad
Original assignee: Vae Vkn Industries Pvt. Ltd.; Vae Gmbh
Priority date: 2008-09-01
Filing date: 2008-09-01
Publication date: 2010-03-04
Also published as: TN2011000088A1; MA32587B1

Abstract

An improved rail expansion joint for use in railway track located at the end of long welded rails. The said rail expansion joint comprises a pair of identical rails (50, 52) without having any bent, a cast manganese steel chair (60), a mild steel bracket (55), said rails (50, 52) being rested on said cast manganese chair (60) and said mild steel bracket (55) being fastened so that said rails (50, 52) being positioned between said cast manganese chair (60) and mild steel bracket (55).

Description

TITLE

RAIL EXPANSION JOINT

FIELD OF INVENTION

The present invention relates to an improved Rail Expansion Joint (REJ) for use in railway tracks. This invention particularly relates to Rail Expansion Joint otherwise known as Switch Expansion Joint (SEJ) for use in railway tracks at the end of long welded rails fitted to the slippers. In this specification, the term Rail Expansion Joint (REJ) and Switch Expansion Joint (SEJ) are alternatively used for the proper understanding of the invention by the readers.

REJ is used to take the expansion in a long welded rail and is placed at two ends thereof. REJ may be connected to long welded rails only on one side or both sides.

PRIOR ART

In the prior art, the rails were joined by fish plates and this resulted in many disadvantages, some of which are considerable wear and tear, low expansion gap, less life, low economy and discomfort to the passengers due to jerk and jump of the locomotive on railway track. The rails are conventionally joined at both ends by either Flash Butt Welding or Thermit Welding. In the railway tracks, the middle portion of the long welded rail does not move but the ends move, i.e. the breathing length moves. This movement is taken up by SEJ.

The expansion of SEJ or REJ depends on temperature variation during the day time and also through out the year depending upon the season. Even the seasonal variation of temperature may differ significantly from one place to another and the expansion of joint must cater for a specific location. India is conventionally divided into four zones having regard to temperature variation.

Existing SEJ of Indian railways comprises of two rails, namely, a stock rail and a tongue rail; one sliding against the other. Both these rails are running rails and are of 90 KG per mm UTS minimum. The existing SEJ designed was developed when both the rails were of 72 KG/mm UTS minimum.

It is well known that the 90 KG/mm UTS minimum is prone to breakage because of less ductility. Further the design of this type of SEJ is such that the bending of rail is very sharp. Therefore, the chances or probability of breakages of REJ in track is imminent. This could result in serious and unwarranted accidents. Therefore, the Indian railways were looking for an alternative and improved design of SEJ for the safety of the passengers.

It had been the endeavor of the researchers to design an improved and safe Switch Expansion Joint (SEJ) for the use of railways. Generally, two different types of SEJ designs are used in the Indian railways which were developed by concerns other than Indian railways.

In one of these designs, a stock rail is bolted to a third supporting rail. This stock rail moves together with a third supporting rail while the tongue rail slides against the third supporting rail. In this case, there is no bending of any rail. The second type of known design has a long intermediate rail comprising two rails bolted together and which in turn is fastened to the slipper by an elastic rail clip. The two running rails slide at two ends of said long intermediate rail, and in this design also there is no bending of any rail. In the second type, there are two separate expansion joints positioned at the two ends of two long welded rails.

DESCRIPTION OF THE INVENTION

The present invention is based on the use of Austenitic Manganese Steel Chair with explosion hardening on running surface and this is fixed to 3 or 6 sleepers depending upon the switch expansion as required. The expansion permitted for 3 sleeper designs will be 200 mm (maximum) and with 6 sleeper designs, it will be όoo mm.

According to the invention, two running rails will slide on the CMS chair. These two running rails are not bent but are machined at the ends to provide a gap between them. The chair is so designed as to allow the wheel to pass through the said gap.- The passage of the wheel at this point or juncture is very smooth as transition slopes are given for transfer of wheel contact from the rail to the chair. The cast manganese steel chair is so designed that the wheel may be lifted by 3 mm or more over the running rail. Therefore, there will not be any impact when the wheel passes from one rail to another. Further, the two rails are guided by inside steel brackets. This enables the gauge to be maintained accurately. One or two slippers just before entrance to the REJ will have a lower toe load to enable the movement of the rails.

In all the existing systems, the bearing plates are individual to the sleepers. According to the present invention CMS chair is supported on a number of slippers thereby it transfers the load in a distributed manner. Further, the CMS chair is explosive depth-hardened on the wheel running surface and the tongue rails are head-hardened in the wear prone zone.

The advantages of the present invention are listed herein below.

1) The tongue rails are not bent.

2) The tongue rails are head-hardened.

3) Explosive depth-hardened CMC chair is used which gives a very long life.

4) The wheels get lifted by 3 mm or more to avoid impact with rails.

5) Very smooth transfer of wheel from rail to chair and reverse.

6) Very long life of the tongue rail as the CMS chair is hardened and the CMS chair is positioned at least 3 mm over and above that of tongue rail, thereby the wear and impact on the tongue rails are controlled further.

According to this invention there is provided an improved Rail Expansion Joint (REJ) for use in railway track located at the end of long welded rails, comprising a pair of identical rails without having any bent, a Cast Manganese Steel (CMS) chair, a mild steel (MS) bracket, said rails being rested on said CMS chair and said MS bracket being fastened so that said rails being positioned between said CMS chair head and MS bracket.

In the above mentioned improved REJ rails, said rails are tongue rails having edges are so machined as to provide a gap between said tongue rails on the running edge. Further, said CMS chair is so designed to be located above said tongue rails, preferably at a height of minimum 3 mm to avoid impact with rails.

In the improved Rail Expansion Joint (REJ) of the present invention, CMS chair is explosive depth hardened on the running surface and are fixed by a known method. In the improved Rail Expansion Joint (REJ) of the present invention, said CMS chair is so profiled that transfer of said wheel from said tongue to said CMS chair becomes smooth and said wheel can be subsequently raised.

An improved Rail Expansion Joint (REJ) wherein said tongue is hardened by induction hardening in the wear prone zone.

An improved Rail Expansion Joint (REJ) wherein said CMS chair is made of austenitic manganese steel. The said CMS chair is mounted on 3 or 6 sleepers as per the required design; said REJ brackets are fixed to CMS chair with bolts, which are so positioned that it enables maintenance conveniently.

An improved Rail Expansion Joint (REJ) of the present invention, wherein said CMS chair is assembled to MS brackets with plate screw, rubber pad, bracket, tongue rail, nut, taper washer and bolt sleeper.

The invention will now be explained in more detail with reference to the drawings accompanying the specification, wherein -

Fig. 1 shows a known design of SEJ now not normally used.

Fig. 2 shows another conventional design of SEJ with the stock rail being bent at an angle.

Fig. 3 shows existing SEJ design of Indian Railways.

Fig. 4 shows the new REJ of the present invention for rail section for three sleepers.

Fig. 5 shows the new REJ of the present invention for six sleepers. Fig. 6 shows the sectional view of REJ of the drawing shown in Fig. 4 or

Fig.5.

The conventional SEJ as illustrated in Fig. 1 shows a running rail (10), which is cut at an angle with higher expansion gap than the normal fish plated joint (20). In this case the outer fishplate (25) is raised to prevent any possibility of derailment.

According to Fig. 2 of the drawings, conventional SEJ with a stock rail (30) is bent at an angle as shown and the tongue rail (35) is cut to suit the angle of the stock rail. Both the rails would be supported on bearing plates unlike the earlier design, which had fish plated joint.

Fig. 3 illustrates existing type SEJ design of Indian Railways. Here both the tongue rail (35) and stock rail (30) are bent at a predetermined point- (37 & 39) and machined. Further both the rails are supported on cast iron bearing plates.

Figs.4 and 5 illustrate the new rail expansion joint, otherwise called REJ of the present invention for rail sections. The said rail joint essentially comprises the following items:

(a) Left hand tongue rail (50);

(b) Right hand tongue rail (52);

(c) Brackets (55);

(d) CMS chair (60);

(e) Pre-cast concrete sleeper (65) of known standard design (may be RDSO design);

(f) Rubber pads (70);

(g) Plate screws (85);

(h) Bolts and nuts (go, 92); and (i) Washers (95, 100)

The left hand tongue rail and the right hand tongue rail are welded to long welded rails on both sides. Two adjacent sleepers on both sides of the CMS chair are to be with low toe load fastening. The tongue rail is head-hardened from the end to about two meters for six sleepers REJ and 1200 mm for three sleepers REJ. Both these tongue rails slide on the CMS chair. The CMS chair is mounted on three or six sleepers as per the pre-determined design and requirement. The CMS chair is explosive head-hardened on the top running surface and is raised over the tongue rail at the gap to enable smooth running and long life. The transfer of wheel from rail to CMS chair is smooth because of the gradient on the CMS chair running surface and it ensures that there is no impact and the wheel is at all times supported adequately by rail or CMS chair or both. The CMS chair is fixed to the PSC sleeper with plate, screws and spring washers, and a rubber pad is placed under the CMS chair.

The MS brackets are fixed to the CMS chair with bolts. These MS brackets ensure that the sliding tongue rail can take place and the gauge is maintained at all times. The bolts are so positioned that it would enable maintenance at any time quickly.

Fig. 6 shows the arrangement at section A-A and section B-B, as per Fig. 5. Fig. 6 shows the assembly of CMS chair, plate screw, rubber pad, bracket, tongue rail, nut, taper washer, bolt and sleeper.

According to the present invention it is possible to achieve the following -

1. An improved REJ for use in railway track at the end of long welded rails fitted to the sleepers. The new REJ can be used for any rail section. The two rails are not bent and are of identical construction. These rails are resting on CMS chair and the MS bracket is fastened so that the rails are in between the CMS chair head and MS brackets.

2. There is a gap in between two tongue rails on the running edge.

3. CMS chair is raised 3mm or more over the tongue rail for longer life.

4. CMS chair is explosive depth-hardened on the running surface.

5. CMS chair is so profiled that the transfer of the wheel from the tongue rail to the CMS chair is smooth and the wheel is subsequently raised. 6. The tongues are head-hardened by induction hardening in the wear prone zone.

7. CMS chair is being supported by three or six sleepers as per design so as to give a distributed load on many sleepers generated from the wheels.

The Rail Expansion Joint (REJ) as described and illustrated herein above may have workshop improvement or modification which are well within the knowledge of a person skilled in the art are also intended to be covered within the scope of the present invention.

Claims

What is claimed is:

1. An improved Rail Expansion Joint (REJ) for use in railway track located at the end of long welded rails, comprising a pair of identical rails without having any bent, a Cast Manganese Steel (CMS) chair, a mild steel (MS) bracket, said rails being rested on said CMS chair and said MS bracket being fastened so that said rails being positioned between said CMS chair head and MS bracket.

2. An improved Rail Expansion Joint (REJ) as claimed in claim l wherein said rails are tongue rails having edges so machined to provide a gap between said tongue rails.

3. An improved Rail Expansion Joint (REJ) as claimed in claim 1 and claim 2 wherein said CMS chair is so designed to be located above said tongue rails, preferably at a height of minimum 3 mm to avoid impact with rails.

4. An improved Rail Expansion Joint (REJ) as claimed in claim 3 wherein said CMS chair is explosive depth-hardened on running surface and are fixed by a known method.

5. An improved Rail Expansion Joint (REJ) as claimed in any of the preceding claims wherein said CMS chair is so profiled that transfer of said wheel from said tongue to said CMS chair becomes smooth so that said wheel can be subsequently raised.

6. An improved Rail Expansion Joint (REJ) as claimed in claim 1 wherein said tongue are hardened by induction hardening in the wear prone zone. η. An improved Rail Expansion Joint (REJ) wherein said CMS chair is made of austenitic manganese steel.

8. An improved Rail Expansion Joint (REJ) as claimed in claim l wherein said CMS chair is mounted on 3 or 6 sleepers as per the required design.

9. An improved Rail Expansion Joint (REJ) as claimed in claim 1 wherein said bracket are fixed to CMS chair with bolts, which are so positioned that it enables maintenance conveniently.

10. An improved Rail Expansion Joint (REJ) as claimed in claim 1 wherein said CMS chair is assembled to MS brackets with plate screw, rubber pad, bracket, tongue rail, nut, taper washer, bolt sleeper.