GB2391034A

GB2391034A - Railway points assembly

Info

Publication number: GB2391034A
Application number: GB0216908A
Authority: GB
Inventors: William David Prosser
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-07-19
Filing date: 2002-07-19
Publication date: 2004-01-28
Anticipated expiration: 2022-07-19
Also published as: GB2391034B; GB0216908D0

Abstract

The points assembly (14) comprises a pair of parallel entry rails (12, 13) extending to a points location; a pair of parallel main exit rails (16, 17) extending away from the points location generally in alignment with the pair of entry rails (12, 13) or at an angle thereto; and a pair of parallel branch exit rails (19, 20) extending away from the points location at an angle to the pair of main exit rails (16, 17). First and second switching plates (24, 25) are mounted for rotation about respective vertical axes at the points location, each switching plate (24, 25) defining first and second rail sections profiled so that with the plate in a main setting the first rail section is aligned with the entry (12, 13) and main exit rails (16, 17) and with the plate (24, 25) turned to a branch setting, the second rail section is aligned with the entry (12, 13) and branch exit rails (19, 20). The plates (24, 25) carry respective rails or are grooved, and are synchronised via toothed gears and pinions during operation by an electric motor.

Description

RAILWAY POINTS ASSEMBLY

This invention relates to a points assembly for a railway track, and in particular, but not exclusively, a standard gauge railway track for passenger and goods trains.

5 The design of points has not changed significantly for a very long time.

Conventionally, at a points assembly there is a pair of rails usually referred to as the stock rails (or mail rails) and which extend straight through the points. A train may be switched to a branch line by means of a pair of sliding blades (usually referred to as switch rails) which in effect are rail sections pivoted at to their one ends and arranged for sliding movement at their other ends towards and away from the stock rails. When the other ends of the switch rails are moved away from the stock rails, a train will pass straight through the points, on the main rails. When the points are switched so that the other ends of the switch rails bear against the stock rails, a train will be diverted on to the branch 15 line. Though conventional points are in general very reliable, as has been demonstrated over the very long period that such points have been used, they are not entirely free of problems. For example, the switch rails must taper down towards their other ends, so as to be able to give a smooth transfer from the 20 stock rails to the switch rails, leading to the branch line. The consequent thinning of the switch rails reduces their strength and so there is a tendency for those rails to crack or even break. A further problem is that there must be a cross-over between one of the stock rails and one of the switch rails, to permit a train to divert on to the branch line. This leads to considerable vibration as a 25 multi-truck or multi-carriage train passes over the points and this can result in

- 2 loosening of the tie-bars and rods which hold the stock rails and, in particular, the switch rails in the required positions.

With a conventional points assembly, when a train is diverted from the straight-through track, all of the inward (centripetal) force on the train is derived 5 from the flanges of the train wheels on the outside of the curve, bearing on the sides of the rail on the outside of the curve. No centripetal force on the train is derived from the wheels on the inside rail of the track at the curve. This can result in large forces on the rails on the outside of the curve, leading to premature failure. A support rail can be provided for the inside rail on a curved 10 track, on the side thereof nearer to the outside rail and which support rail is contacted by the flanges of the wheels running on the inside rail. However, such a support rail cannot be provided at points, to extend along the inside rail in the immediate vicinity of the switch rail. As such, at the points all of the force required to divert a train on to the branch line must be derived from the flanges 5 of the wheels bearing against the outside switch rail.

It is a principal aim of the present invention to provide a novel design of points which addresses the disadvantages discussed above and so can lead to more reliable operation.

According to one aspect of this invention, there is provided a points 20 assembly for a railway track, comprising: - a pair of parallel entry rails extending to a points location; - a pair of parallel main exit rails extending away from the points location generally in alignment with the pair of entry rails or at an angle thereto; - a pair of parallel branch exit rails extending away from the points 25 location at an angle to the pair of main exit rails;

- first and second switching plates mounted for rotation about respective vertical axes at the points location, each switching pate defining first and second rail sections profiled so that with the plate in a main setting the first rail section is aligned with the entry and main exit rails and with the plate fumed 5 to a branch setting, the second rail section is aligned with the entry and branch exit rails; and - drive means to effect rotational fuming movement of the two plates between their main and branch settings, so switching the points assembly.

It will be appreciated that with the points assembly of this invention, no 10 stock rail nor switch rail is provided, unlike conventional designs of points.

Rather, the entry rails to the points, the main exit rails and the branch rails are all fixed and all connect to a pair of switching plates, effectively radially with respect thereto. The switching plates carry suitable rail sections for transferring wheels from the entry rails either on to the main exit rails or on to the branch 15 exit rails, depending upon the angular setting of the switching plates. Thus, to effect switching of the points, the switching plates are merely synchronously rotated to either of their two possible settings.

Most preferably, the upper surface of each switching plate is substantially co-planar with the upper surface of the rails at the points location.

20 Then, the rail sections may be defined by grooves formed in the thickness of the switching plate. For example, each switching plate could comprise a relatively thick circular plate, into which appropriate grooves are machined. In the alternative, sectors could be secured to the switching plate such that the grooves are defined therebetween. With either construction, a wheel on the

-4- inside of the curve leading to the branch track may be supported both as it passes over the switching plate and also on the branching track.

An alternative is for there to be conventional rail sections secured to the upper surface of each switching plate, and again a separate support rail could 5 also be secured to each switching plate, such that a wheel on the inside of the curve is again supported.

Depending upon the diameter of the switching plates and the angle at which the branch track makes to the main track, the first and second rail sections on each switching plate may either cross-over or may be in a near o parallel disposition, with one rail essentially linear for the straight-through setting and the other rail curved, for the branch setting.

It is important that the two rails of each track are always at the same setting and to this end it is preferred that the switching plates are geared together, for simultaneous rotation. This may be achieved by providing toothed as gears on, or toothing the periphery of, both switching plates and further providing a pinion between the two sets of teeth, meshing therewith. In this way, both switching plates will rotate simultaneously and in the same sense, by virtue of the presence of the pinion.

The drive means may comprise an electric motor coupled to the pinion 20 through a suitable gearbox. Altematively, a separate drive could be provided to one or the other switching plate, to effect rotation thereof.

In order to prevent incorrect operation, a locking mechanism should be provided for the switching plates, and which holds the switching plates against rotation until released, immediately before operation of the drive means for the as plates. Further, a feedback arrangement may be provided to monitor the

instantaneous position of the switching plates and to compare that to a selected setting, for example selected at a signal box. All signals in the vicinity of the points could be set at danger until the actual position of the switching plates coincides with the selected setting and the locking mechanism has engaged. In 5 this way, safety in operation may be assured.

A points assembly according to this invention may be made as a standardised unit which may be installed where needed to interface with fixed track having no moving parts. Such a unit may be removed for maintenance or repair, and when so removed, may be replaced by another, fully serviceable 10 unit. Thus, all moving parts and wearing components may be serviced in a workshop, so easing quality control and enhancing safety, both for trains running on the tracks and also for service personnel.

By way of example only, one specific embodiment of points assembly of this invention and certain modifications thereof will now be described in detail, 15 reference being made to the accompanying drawings in which: Figure 1 is a diagrammatic plan view of points of this invention, in the straight through setting; Figure 2 is a view corresponding to Figure 1 but with the points in the branch setting; 20 Figure 3 is a side view of one switching plate, as used in the points; Figure 4 is a plan view on an alternative form of switching plate; Figures 5 and 6 are respectively side and isometric views of the switching plate of Figure 4; Figure 7 is a view similar to that of Figure 3, but of a modified form of 25 switching plate as also shown in Figures 8 and 9; and

-6 Figures 8 and 9 correspond to Figures 4 and 5 but show the modified form of switching plate of Figure 7.

Of necessity, the drawings accompanying this specification are very

diagrammatic and are intended to illustrate only the principles of the points 6 assembly. On account of the scaling needed to produce the drawings and also to show the detail, the drawings do not accurately represent the actual angles at which the rails typically would lie in a real-life installation. For example, in a full-size points installation, the branch line may lie at only 2 or so, initially, to the main line whereas in the drawings, it is diagrammatically represented at Jo around 30 .

Referring to the drawings, the normal direction of advancement of a train along the railway track 10 is in the direction of arrow A. As such, the length of track shown at 11 can be regarded as providing the entry rails 12,13 to the points assembly 14; the length of track 15 as the main exit rails 16 and 17 and 15 the length 18 as the branch exit rails 19 and 20. Each of these lengths of track comprise conventional rails pinned to sleepers 21 for example with conventional chairs and spring hooks illustrated at 22.

Each of the rails 12, 16 and 19 terminate at the periphery of a first switching plate 24 and each of the rails 13, 17 and 20 at the periphery of a 20 second switching plate 25. Though not shown in the drawings, the free ends of the rails typically would be supported immediately adjacent the respective switching plate, in order to permit a smooth transfer from and to those rails.

Each switching plate may be approximately 1 m diameter, with its axis of rotation disposed vertically and in line with the entry and main exit rails 12,16 25 with which the plate is associated. The switching plate carries a linear rail

-7 section 26 and a curved rail section 27, disposed more or less side-byside on the upper surface of the switching plate and suitably positioned so that, as shown in Figure 1, the linear rail section 26 may join together entry rail 12 (or 13) with the main exit rail 16 (or 17). Then, when the switching plate is rotated from the main position to the branch position shown in Figure 2, the curved rail section 27 may join together entry rail 12 (or 13) with the branch exit rail 19 (or 20). Both of the switching plates 24 and 25 are toothed extemally, though not shown in the drawings. A pinion 28 engages with the teeth of both of the 10 switching plates, and an electric motor (also not shown) is drivingly coupled to the pinion. In this way, rotation of the pinion by the motor will rotate both switching plates simultaneously, in the same sense and through the same angle. Each switching plate 24,25 is mounted on a metal base plate 29 secured 5 to a concrete block 30 set in the ground at the points assembly. Figure 3 shows only switching plate 24; for this plate the base plate 29 carries a main bearing (not shown) for a shaft 31 connected to the axis of the switching plate 24, and a circular metal track 32 extending beneath the periphery of the switching plate, and mounted on the base plate. A ball race diagrammatically go shown at 33 carries the periphery of the switching plate on the circular track 32 such that the plate is adequately supported for a train passing thereover, despite the axle weight of that train. A similar arrangement is provided for switching plate 25.

The base plate 29 is releasably secured to the concrete block 30, such 2s that on releasing the base plate the entire assembly may be lifted away from

- 8 the track as a single integrated unit. Once removed, for maintenance, service or repair, it may immediately be replaced by a fully functioning unit, so minimising the time the track is out of service in the event that repair or servicing is required.

5 Though not shown in the drawings, support rails may be provided alongside the inner face of the curved rail section 27 on the second switching plate 25 - that is to say, to support the flanges of the wheels on the inside of the curve and so to take some of the load off the flanges of the outside wheels, which bear against curved section 26. Of course, no such support rails are 10 needed when the points are set as shown in Figure 1.

Figures 4 to 6 show an alternative design of switching plate. Here, the plate 35 is considerably thicker than that shown in Figure 3 and the upper surface 36 of the plate is in the same plane as the upper surface of the entry and exit rails. Rail sections are formed in that plate by cutting grooves 37 15 therein which grooves are suitably profiled to accommodate the flanges of the wheels to be used on the track. Thus, as shown in Figure 4, one edge 38 of a groove 37 is in alignment with an edge 39 of a rail 40 such that the flange of a wheel may be smoothly transferred into the groove or out of the groove from or to a rail.

20 The arrangement of Figure 4 utilises a solid plate into which the grooves are cut. As an altemative, four part-circular sectors may appropriately be profiled and then secured to the switching plate, so giving the same effect as that described above. In either case, the grooves formed in the switching plate cross-over as shown, rather than being arranged in a side-by-side manner as as shown in Figures 1 and 2. As a result, the switching plate of Figures 4 and 5

- 9 - must be turned through a greater angle in order to change the setting of the points, and typically through approximately 90 .

It will be appreciated that with the modified switching plates of Figures 4 to 6, guidance of both wheels is achieved by virtue of the grooves in the plates.

5 As a result, the only possible route through the points when switched to the branch setting is to follow round to the branch track, so minimising the likelihood of a derailment.

Figures 7 to 9 show a modified form of the switching plate of Figures 4 to 6. Here, the switching plate 45 carries four check rails (or fences) 46 alongside 10 those edges 38 of the grooves 37 along which run the flanges of the wheels of a carriage truck running on the track. These check rails 46 serve to give further support to a wheel running through the switching plate 45 and further resist derailment notwithstanding the transfer to and from the switching plate.

As shown in Figure 7, the upper surface of the switching plate 45 is 15 essentially co-planar with the upper surface of the rails 12 and 16 and the check rails 46 stand up above that surface. The switching plate 45 has a greater thickness than that shown in Figure 3 but in other respects corresponds to the arrangement of Figure 3. Like parts are given like reference characters and will not therefore be described in further detail, here.

zo Though not shown in the drawings, a locking mechanism for the switching plates preferably is provided, to secure each switching plate in either of its main or branch settings. Such a locking mechanism may include a spring loaded pawl which engages in either of two notches provided in the switching plate, such that the plate is locked against rotation when so engaged. The pawl z5 may be electrically operated to be moved against the spring-loading and so to

- 10 release the lock only when the switching plate is to be fumed, from one of its settings to the other. For a case where teeth are formed directly in the outer periphery of the switching plate, the pawl could alternatively engage with those teeth but this has the disadvantage that there are many angular settings of the 5 switching plate where the pawl could be engaged.

The base plate 29 carries an electric motor and drive gear box for the pinion 28, as well as any other required control gear, locking mechanisms and so on.

An active control system could be employed, integrated with the 10 signalling system for a railway incorporating the points assembly. Thus, all signals in the vicinity of the points could be set to danger unless the switching plates have been locked with their respective rail sections in alignment with both the entry rails and either the main exit rails or the branch exit rails.

Further, release of the lock mechanisms could be inhibited whenever proximity 15 detectors sense the presence of a train on the track in the vicinity of the points assembly.

Claims

- 1 1 CLAIMS

1. A points assembly for a railway track, comprising: - a pair of parallel entry rails extending to a points location; - a pair of parallel main exit rails extending away from the points 5 location generally in alignment with the pair of entry rails or at an angle thereto; - a pair of parallel branch exit rails extending away from the points location at an angle to the pair of main exit rails; - first and second switching plates mounted for rotation about respective vertical axes at the points location, each switching pate defining first 10 and second rail sections profiled so that with the plate in a main setting the first rail section is aligned with the entry and main exit rails and with the plate turned to a branch setting, the second rail section is aligned with the entry and branch exit rails; and - drive means to effect rotational turning movement of the two plates 1s between their main and branch settings, so switching the points assembly.

2. A points assembly as claimed in claim 1, wherein the upper surface of each switching plate is substantially co-planar with the upper surface of the rails at the points location, the first and second rail sections being defined by grooves formed in the switching plate.

20

3. A points assembly as claimed in claim 1, wherein the upper surface of each switching plate is below the level of the rails at the points location, the first and second rail sections being mounted on and upstanding from the upper surface of the switching plate.

- 12

4. A points assembly as claimed in any of the preceding claims, wherein the first and second rail sections on each switching plate crossover on the plate.

5. A points assembly as claimed in any of the preceding claims, wherein 5 the two switching plates are mounted with their axes on a line extending at perpendicularly to the rails of the entry rails.

6. A points assembly as claimed in claim 5, wherein the two switching plates are directly geared together for simultaneous rotation, through the same angles. 10

7. A points assembly as claimed in claim 6, wherein a toothed gear is associated with each switching plate, and a pinion is drivingly meshed with both of the two toothed gears, so synchronizing the movement thereof.

8. A points assembly as claimed in claim 7, wherein the periphery of each switching plate is toothed to form the toothed gear.

1s

9. A points assembly as claimed in claim 7, wherein each toothed gear is separately formed and is secured to the underside of the respective switching plate.

10. A points assembly as claimed in any of claims 7 to 9, wherein an electric motor is drivingly coupled to the pinion, to effect rotation thereof.

20

11. A points assembly as claimed in any of the preceding claims, wherein a releasable locking mechanism is provided for each switching plate, which locking mechanism serves to secure against rotation the respective switching plate other than when the switching plate is to be fumed between its two settings.

- 13

12. A points assembly as claimed in claim 11, wherein the locking mechanism includes a pawl engageable in a selected one of two notches provided in the periphery of the associated switching plate.

13. A points assembly as claimed in claim 11 or claim 12, wherein the s locking mechanism is spring-urged to the locked setting, electrical control means being provided to release the mechanism.

14. A points assembly as claimed in any of claims 11 to 13, wherein a vehicle sensor is provided to sense the presence of a vehicle on the tracks in the vicinity of or on the switching plates, which sensor provides an output 10 inhibiting release of the locking mechanism when such a vehicle is detected.

15. A points assembly as claimed in any of the preceding claims, wherein feedback means is provided to monitor the angular position of the two switching plates and compare the actual position thereof with a chosen setting, selected at a remote switching station.

15

16. A points assembly as claimed in any of the preceding claims, wherein each switching plate is mounted for turning movement on a peripheral bearing provided between the underside of the plate and a track formed therebelow.

17. A points assembly as claimed in claim 1 and substantially as hereinbefore described, with reference to and as illustrated in the 20 accompanying drawings.

18. A railway track system whenever including a points assembly as claimed in any of the preceding claims.