Title of Invention

"IMPROVED RAIL JOINT"

Abstract

Improved rail joint for a railway track comprising two rails laid end-to-end and secured to each other, is characterized in that - each rail ( 1,1') comprises machined portions on the outer sides of the head and foot of the rail-end; a load-transfer rail (1A) is positioned against said machined portions of said rails to be joined, said load-transfer rail having machined portions on the inner sides of its head and foot to match the machined portions of the rail-ends; and bolts (3) join the webs of said rail-ends with the web of the load-transfer rail.

Full Text

4(3) The present invention relates to an improved joint for use in a railway track. A railway track essentially consists of lengths of rails laid end to end to form a continuous stretch on which wheels can run smoothly. For practical reasons of production, transportation and laying as also for the purposes of their elongation / contraction under changes of temperature, the actual length of these rails is limited to certain values. The ends of such rail-lengths have therefore to be joined together to form continuous stretches of track. The earliest rail joints as per the known art were formed by placing a pair of fishplates adjacent to the rail-ends and bolting them together to the rail-ends using fishbolts. Such standard fishplated joints were found to be much poorer in strength and rigidity as compared to the rails themselves due to different reasons. These were (i) lesser strength and rigidity of the pair of fishplates vis-a-vis the rails, (ii) frequent loosening of fishbolts under traffic vibration, (iii) development of play due to wear-and-tear on the matching faces of fishplates and rails. These reasons gave rise to different problems at the standard fishplated joints such as (i) battering and hogging (or bending-down) of rail-ends, (ii) bending/breakage of fishbolts, (iii) damage to sleepers used under the rails-ends and (iv) damage to the packed ballast used under the sleepers. Due to the above-mentioned reasons standard fishplated rail-joints are recognised as the weakest links in railway tracks. -2- The weakness at the fishplated rail-joint is further aggravated when the gap between the rail-ends is larger. At special locations such as on girder bridges, railways, have to use joints with larger gaps. At such locations, special joints called "mitred joints' have been tried as per the known art. Such joints make use of larger section fishplates on one side of rails and the ends of the rails themselves are skew-cut. Despite adopting these costly steps, the mitred joints are also weak and suffer from the defects of standard fishplated joints. In fact the defects are more pronounced due to the gaps at the joints being larger. The weakness at fishplated rail - joints is greatly aggravated when the two adjoining rail-lengths are of unequal cross - sectional area. Locations with such unequal cross-sections have to be unavoidably used by railways near railway stations and in railway switches etc. As per the known art, 'combination fishplates' are used in fishplated rail-joints when the rail-lengths to be joined are of symmetrical profile and of unequal cross - section. Such combination fishplated joints also suffer from the defects as existing in standard fishplated rail - joints . Further , satisfactory combination fishplates are difficult to design, manufacture and use, if the inequality in cross - sectional areas of the two rail-ends is very high. In the case of fishplated joints for use at railway switches however, even greater difficulties are encountered if the two rail-ends are not only unequal in cross-sectional -3- area but one of the rail-ends is symmetrical in cross-section whereas the other is asymmetrical. In such cases, as per the known art, 'forged-end rail-joints' are used, wherein the end of the asymmetrical rail is forged over a short length to match the cross-section of the adjoining symmetrical rail The rail - ends are then joined together using Standard fishplated joints. In this solution also, the already known. defects of fishplated joints persist. Further, adopting this solution is a very costly one due to the need for forging the rail-ends on a limited scale, since the number of locations needing such joints is relatively fewer. As per the known art, rail-joints have been welded by any one of several methods to overcome the above-mentioned defects of standard fishplated rail-joints. This solution has solved problems at rail joints to a great extent. However in railway practice, there are several locations where welded rail joints cannot be used and fishplated joints have to be necessarily used. Further, the welded joints pose severe problems in three distinct cases : (i) when the rail-ends to be joined are of unequal but symmetrical cross-section (ii) when the rail-ends to be joined are of unequal cross-section with one rail being of symmetrical profile and the other one being of asymmetrical profile and (iii) when the chemical composition of the steel used in the two rails to be joined is dissimilar. As per the known art. limited success has been achieved with case (i) above, However, no satisfactory solution has been found for cases (ii) and {iii) mentioned -4- above. To summarize, each of the solutions as per the known art of making fishplated rail-joints suffer from the defects detailed in the foregoing paragraphs. Even when using welded rail-joints problems persist as highlighted in the previous paragraph. The present invention addresses the problems faced in fishplated rail-joints of the known art and also provides a cost-effective solution to take care of the problems where welded rail-joints are not possible to be used. The present invention provides an improved rail joint for a railway track comprising two rails laid end-to-end and secured to each other, characterized in that -each rail comprises machined portions on the outer sides of the head and foot of the rail-end: a load-transfer rail is positioned against said machined portions of said rails to be joined, said load-transfer rail having machined portions on the inner sides of its head and foot to match the machined portions of the rail-ends; and bolts join the webs of said rail-ends with the web of the load-transfer rail. As per the invention, a portion of the outside head and the outside foot of the rail-ends to be joined together is machined away. A small-length machined rail called 'load-transfer rail1 (with its inside head and inside foot machined away) is then placed against the machined rail-ends in such a manner that the machined portions match together. The web of -5 - the load-transfer rail and the webs of the two rail,-ends of the joint are then bolted together with or without the use of special fishplates. In order to cover the difference between the height of the two rails and also their web-thickness, suitable packing pieces can be used. Further in order to make the whole assembly stronger and more rigid, one or more of ^ the following steps as per the known art may additionally be employed : (i) Reducing the gap between rail-ends to zero value; (ii) Locating a sleeper directly under the centre of the joint: (iii) Using high-tensile bolts to join the rail-ends with the load-transfer rail and {iii) Using high-strength synthetic Epoxy resin between the mating surfaces of the rails to be joined, normally produced by the process of rolling, The rails,which are mnay be of identical section, or of symmetrical section and unequal cross-sectional area. One of the rails can be of symmetrical section while the other rail is of asymmetrical section. Gap between the rail-ends may be of zero-width or of a width in the range of 0-15mm or thereabouts. The bolts are preferably high tensile steel bolts. A fish plate may be located on the side of the rail-end remote from the load-transfer rail, said bolts securing the fish plate, rail-ends and the load-transfer-rail together. A packing piece is preferably provided below the foot of one of the rail-ends to adjust the height of the load-transfer rail to the top level of the heads of the rail-ends. A packing plate may also be provided between the web of the transfer-rail and web of one of the rail-ends. -6- It is also preferable to provide high strength synthetic epoxy resin coatings between the machined surfaces of the load-transfer rail and of the rail-ends. A glass fibre layer,, may also be provided between the mating surfaces of the load transfer rail and of the rail ends. It is also preferable to prefabricate such improved rail joints in short compact lengths of 3-13 metres or thereabouts under controlled conditions in a workshop to ensure the soundness of their quality. The ends of such prefabricated joint can then be welded at site of actual use to the corresponding rail-sections using welding processes of the known art. The invention will now be described with the help of the accompanying drawings wherein - Fig.1.1 shows elevation view of a rail joint of prior art; Fig 1.2. shows sectional view of the rail joint along section line A-A in Fig 1.1; Fig 1.3. shows elevation view of rail joint of Fig.1.1 with a sleeper located right under the joint gap; Fig.2.1. shows in elevation a mitred rail joint of prior art; Fig 2.2 shows in plan the rail joint of Fig.2.1 highlighting the gaps between the rails and also shows the skew-cut ends of rails; Fig.2.3 shows sectional view of the rail joint of Fig.2.2 along section line B-B in Fig.2.2; Fig 3.1 shows elevation view of a combination fishplated - 7 - rail joint of prior art; Pig.3.2 shows plan view of the rail joint of Fig.3.1; Fig 3.3 shows sectional view of the rail joint of Fig:3.1; Fig.4.1 shows elevation view of a forged-end rail joint of prior art; Figs.4.2 & 4,3 show the rail joint of Fig.4.1 in section along section lines C-C and D-D in Fig.4,1; Fig.5.1 shows in elevation a welded rail joint of prior art; Figs.5.2 and 5.3 show the cross-sectional view of rails of the rail joint along section lines C'-C and D'-D'in Fig 5.1; Fig.6.1 shows plan view of an embodiment of the rail joint of the present invention; Fig 6.2 and 6.3 show sectional view of the rail joint of Fig 6.1 along section, lines E-E and F-F in Fig 6.1; Figs. 6.4 and 6.5 show cross-sectional view of the rails of the joint of Fig 6.1 along section lines G-G and Fig 7.1 shows in plan a second embodiment of the rail joint of the present invention; Figs. 7-2 and 7.3 show the sectional view of the embodiment of Fig 7.1 along sectional lines I-I and J-J in Fig.7.1; and Figs.7.4 and 7.5 show cross-sectional views of the rails of the embodiment of Fig.7.1 along section lines K-K and L-L. -8- Figs. 1.1, 1.2, 1.3 show a standard fishplated rail-joint as per the known art. In Fig.1.1, rails 1 and 1' are joined at their ends using fishplates 2 & 2, with the help of fishbolts 3. A gap 4 exists between the ends of rails . ,,, - ¦¦»« 1 & I1. The rail-ends are made to rest on sleepers 5. As per the known art, the gap 4 is sometimes reduced to zero and " t sometimes, the sleeper 5 is located directly under the centre of the rail-joint as shown in Fig. 1.3, in order to minimize the defects in performance of the joint. Figs. 2.1, 2.2, 2.3 show a 'mitred joint' with a larger gap used at special locations such as girder bridges. In Fig. 2.1 the rails are marked 1 and 1', the inside fishplate is marked 2 and the outside special fishplate is marked 2' and the bolts are marked 3. The gap between rail-ends 4 and the skew-cut rail-ends can be seen in Fig.2.2 Fig 2.3 shows the sectional view of the joint along line B-B in Fig 2.2. Figs. 3.1,3.2,3.3 show a 'combination fishplated joint1 which is used when joining rail-ends with unequal cross-sectional area and when both the rail sections are of symmetrical profile. 'Rails 1 & 1' , fishplates 2 & 21 , fishbolts 3 and gap 4 have the same connotation as in the earlier Figures. Figs. 4.1,4.2,4.3 show a 'forged-end joint'. The rail 1 is of symmetrical profile, while 1' is the asymmetrical rail. The end of rail 1' is forged over a short length to match the cross-section of rail 1 in order to use standard fishplates 2 & 2'. Fishbolts 3 and gap 4 have the same -9- connotation as in earlier Figures. Figs.5.1,5.2,5.3 show a welded rail joint which is normally used when the two rails to be joined are of identical cross-section or when the two rails are symmetrical but have a small difference in cross-sectional area. In Fig. 5.1, the rails are marked 1 and 1'. Welded joints are not normally used when the difference in cross-sectional area is high or when one of the rails is symmetrical in cross-section and the other is asymmetrical. -- Figs-6.1,6.2,6.3,6.4,6.5 show an embodiment of the joint according to the present invention for use when both the rails to be joined are symmetrical in profile. In Fig.6.1, rail 1 is taller in height than rail I1. A rail 1A (which is a rolled piece ofrail identical, in cross-section to the rolled rail 1) is used as a load-transfer rail. Heads and feet of rails 1, I1 and 1A are machined/contoured to mate closely with each other after assembly. Fig.6.4 shows the cross-section of rolled rail 1 and Fig. 6.5 shows the cross-section of rolled rail I1. Packing piece 6 is used below end of rail 1' to cater to the difference in the height of rails 1A and 1 & 1'. Special fishplate 2 can be used as optional measures as shown in Fig 7.2. Bolts 3 are high-tensile steel bolts and are used to connect the webs of the rail 1A to the webs of rails 1,1'. Bearing plate 8 is used under the rail as per normal railway practice. A coat of synthetic epoxy resin or an intermediate glass-fiber layer or both can be used between the mating surfaces of the rails -10- as an optional measure to increase the strength and rigidity of the joint. Figures 7.1,7.2,7.3,7.4, and 7.5 show an alternative embodiment of the joint of the present invention for use when one of the rails to be joined is symmetrical in profile while the other is asymmetrical. In Fig. 7.1, rail 1 is symmetrical* j while rail I1 is asymmetrical. Load - transfer rail 1A and- rails 1, I1 are suitably machined / contoured on the foot and head and assembled together. Packing piece 6 is used to "cater to the difference in the height of rails 1A and 1 &~ 1 and packing piece 7 is used to cater to the difference in webs of rails. Special fishplate 2, bolts 3 and bearing plate 8 have the same purpose and connotation as described under Figs. 6.1 - 6.5. Use of special fishplate 2 and packing piece 7 is optional. An optional coat of synthetic epoxy resin or an intermediate glass-fiber layer or both can be used as described with reference to Figs. 6.1 - 6.5. -li- 1. Improved rail joint for a railway track comprising two rails laid end-to-end and secured to each other, characterized in that - each rail ( 1,1') comprises machined portions on the outer sides of the head and foot of the rail-end; a load-transfer rail (1A) is positioned against said ' machined portions of said rails to be joined, said load- transfer rail having machined portions on the inner sides of its head and foot to match the machined portions of the rail-ends; and bolts (3) join the webs of said rail-ends with the web of the load-transfer rail. 2. Improved rail joint as claimed in claim 1, wherein said rails (1,1' and 1A1) are of identical section in as rolled condition. 3. Improved rail joint as claimed in claim 1, wherein said rails (1,1') are of symmetrical section and of unequal cross-sectional area and one of the rails (1) and the load transfer rail (1A) are of identical cross section in as-rolled condition. 4. Improved rail joint as claimed in claim 1, wherein one of said rails (1) is of symmetrical section while the other rail is of asymmetrical section and the said rail (1) and the load-transfer rail (1A) are of identical cross section in as-rolled condition. 5. Improved rail joint as claimed in any of claims -12- 1-4, wherein said bolts are high tensile steel bolts. 6. Improved rail joint as claimed in any of claims 1-5, wherein the gap between the rail-ends is of zero width. 7. Improved rail joint as claimed in any of claims 1-5 wherein the gap between the rail-ends is of zero to 15 mm width. 8. Improved rail joint as claimed in any of claims 1 to 7 wherein a fish plate (2) is located on the side of the rail-end remote from the load-transfer rail, said bolts (3) securing the fish plate, rail-ends and the load-transfer-rail together. 9. Improved rail joint as claimed in claim 1 or any of the claims 3 to 8, wherein a packing piece (6) is provided below the foot of one of the rail-ends (1') to adjust the height of the load-transfer rail to top level of the head of the rail-end. 10. An improved rail joint as claimed in claim 1 or any of the claims 3-9, wherein a packing plate (7) is provided between the web of the load-transfer rail and the web of one of the rail ends. 11. Improved rail joint as claimed in any of claims 1-10, wherein high - strength synthetic epoxy resin coatings are provided between the machined surfaces of the load-transfer rail and of the rail ends. 12. Improved rail joint as claimed in any of claims 1-11, wherein a glass-fiber layer is provided between -13- the mating surfaces of the load transfer rail and of the rail ends. 13. Improved rail joint as claimed in any of claims 1-12, wherein the joint is fabricated in small compact lengths of 3-13 metres. 14. Improved rail joint for a railway track substantially as herein described, particularly with reference to the accompanying drawings. -14- Dated this 29th day of August, 1997. Improved rail joint for a railway track comprising two rails laid end-to-end and secured to each other, is characterized in that - each rail ( 1,1') comprises machined portions on the outer sides of the head and foot of the rail-end; a load-transfer rail (1A) is positioned against said machined portions of said rails to be joined, said load-transfer rail having machined portions on the inner sides of its head and foot to match the machined portions of the rail-ends; and bolts (3) join the webs of said rail-ends with the web of the load-transfer rail.

Documents:

01593-cal-1997-abstract.pdf

01593-cal-1997-claims.pdf

01593-cal-1997-correspondence.pdf

01593-cal-1997-description(complete).pdf

01593-cal-1997-drawings.pdf

01593-cal-1997-form-1.pdf

01593-cal-1997-form-2.pdf

01593-cal-1997-form-3.pdf

01593-cal-1997-g.p.a.pdf