GB2280160A - Railway vehicle - Google Patents

Abstract

The wheels of a light railway vehicle can be rotated independently of one another. The vehicle has driven wheels 23 driven through a differential gearbox from a motor which is supported on the vehicle's superstructure. The wheels of the vehicle may have a steel tyre and hub separated by an elastomeric cushion. The bogies of the vehicle can be located longitudinally by ties and can also be pivoted to the superstructure. A flexible coupling for connecting two vehicles together is also disclosed. <IMAGE>

Description

RAILWAY ROLLING STOCK FIELD OF TEE IYVENlION The present invention concerns railway rolling stock especially for light railways as used for urban mass transport.

BACKGROUND OF CHE INVENICION Modern railway rolling stock is based on developments over nearly two hundred years from the original horsedrawn wagons with solid stles and attached wheels. Over this period, the basis for railway rolling stock has remained the solid axle and wheel set.In the 1960's the British Railway Research Centre at Derby undertook a scientific approach to bptimise such solid wheel sets by modifying the proiile of the conicity of wheel tyres, so that after a disturbance from normal running such as a curve or corrugation in a track, the wheel set would return to normal running with the minimum of side-to-side oscillations and would be self-damping to avoid the uncomfortable and potentially dangerous condition of bogiehunting, in which the bogie oscillates about its vertical axis limited only by wheel flanges hitting the rails and even in extreme cases riding over the rail leading to derailment.

Over this period, the new developments in wheel set and bogie design as well as developments in rail vehicle structure has led to heavier rail vehicles. This increase in weight leads to a requirement for the other parts of the rolling stock to be made more robust further increasing the overall weight, a tendency reinforced by regulatory controls arising from accident investigations.

The strength of rail vehicles is largely dictated by the need to meet static vehicle and loading forces rather than the need to survive dynamic impacts unlike automobile engineering where lighter but stronger energy absorbing means enables automobiles to be both lighter and safer than previously.

Tramways or light railways developed from the mid1800's to bring the benefits of railways to generally unmetalled and roughly surfaced urban roads. However whilst light railways developed separately until the 1930's, the basic design remained heavy and based on traditional railway rolling stock. In particular, they relied on the rigid wheel axle set wherein the axle kept the wheels at the correct spacing for the wheel gauge, kept the wheels vertical, transferred the weight of the vehicles through the wheels to the track, and importantly transfers connective forces from the conicity of one wheel to the other wheel. Recent attempts in Great Britain to revive tramways are based on down-sizing heavy mainline rail technologies and as an example the new Manchester tramcars weigh 48 tonnes unladen for a 28 metre carriage length.

The drive has of course changed from horse-drawn to steam, diesel, diesel-electric, diesel hydraulic or electric for mainline trains andto electric for light railways. With diesel-electric, diesel-hydraulic and electric traction, traction wheels are often driven by separate motors but care is taken so the drives are synchronous. In addition some work has been done at the University of Aachen on bogies with wheels not rigidly attached to axles however these were for use on mainline heavy trains.

The present invention aims at reducing the weight of light railway rolling stock.

SUMMARY OF TIlE PRESEWD INVENTION In one aspect of the present invention, light railway rolling stock has independently rotatable wheels.

In another aspect of the present invention, light railway rolling stock has driven wheels driven through a differential gearbox from a common drive which is supported from the rolling stock's superstructure.

In a third aspect of the present invention, light railway rolling stock contains a wheel with a steel or other metallityre and hub with a connection between the hub and the tyre being an elastomeric cushion.

In a fourth aspect of the invention, a bogie for light railway rolling stock is pivottedto superstructure of the rolling stocky a pivot but is located longitudin ally of the rolling stock by ties interconnecting the bogie to the superstructure. It may be possible to dispense with the pivot entirely and thus a fifth aspect of the present invention provides a bogie for light railway rolling stock in which the bogie is located longitudinally of the rolling stock by ties interconnecting the bogie to the superstructure.

The various aspects of the present invention show considerable synergy in that each aspect of the invention can reduce the weight which affects the construction of other aspects and enables those constructions to be even lighter and this goes round enabling the said each aspect construction to be even lighter. Even the track can be lighter.

BRIEF DESORIPTION OF THE DRAWINGS Figure 1 is a side elevation of a single car carriage for light railway rolling stock, Figure 2 is a side elevation of a multiple car carriage for light railway rolling stock, Figure 3 is an end view of the carriage shown in Figure 1 or Figure 2, Figure 4 is a schematic side elevation of a floor pan for use in the embodiment of Figure 1, Figures 5 and 6 are respectively a side elevation and a plan view of a driven bogie, Figure 7 illustrates an undriven bogie as shown schematically in Figure 4, Figure 8 is a detail of an end of a traction rod as shown in Figure 5, Figure 9 illustrates an articulation joint which can be used in Figure 2, Figures 10 and 11 illustrate methods of articulation fur use in Figure 2, Figure 12 shows a method of supperting tbe articulation, Figures 13 and 14 illustrate springing for use at the articulation of Figure 12, Figure 15 shows another method of supporting the articulation, Figure 16 shows an altern-ative method of springing for use with the method of Figure 15, and Figure 17 is a part section through a wheel.

DESCRIPTION OF E2hEPIARY EMBODIME2S Figures 1 and 2 are side views of single and multiple car carriages. Each car consists of a superstructure 21 of monocoque construction built onto a floor pan 22 supported by bogies 23 at the front and 24 at the rear of the whole carriage. In the multiple car carriage of Figure 2, the cars are joined by an articulation 25 supported by wheels 26. These Figures are simplified by omitting details to avoid over-complicated drawings. Figure 3 is a front view of a driver's cab end of a carriage as shown in Figure 1 or Figure 2. This view shows that the wheels are inset and shrouded by sill 27 (Figures 1 and 2).

Figure 4 illustrates the floor plan 22 which is stepped to provide high floor regions 28 over the bogies and a generally low floor region 29 for the greater part of the carriage. In a multiple car carriage another high floor region can be provided at the articulation or simple wheel arches can be used so that a continuous low floor region can extend for the greater part of the length of the carriage.

Figure 5 is a side elevation and Figure 6 a plan view of a driven bogie and Figure 7 is a plan view of an undriven bogie0 In all these Figures there are a pair of longitudinal beams 31 supporting axles 32 on which are mounted wheels 33. Each beam is spaced from the floor pan by an air spring damper 34 such as used in heavy good vehicles. Each bogie is attached to the floor pan 22 by ties 35 which extend substantially horizontally each from a column 36 rigidly upstanding from an end of an axle 32 to an anchor 37 attached to the floor pan or to the floor pan itself. The attachment of the ties is such as to allow the bogie to pivot; the dampers 34 have a degree of sideways play as shown in broken lines to allow this pivotal movement.The driven bogie of Figures 5 and 6 differs from the undriven bogie of Figure 7 by the feature of a Cardan shaft 38 and differential gear boxes 39 (which can be those in a shortened Rockwell Heavy Goods Vehicle Differential Axie) which transmit a drive from a prime mover 40 (Figure 4) mounted below and from the floor pan 22.

A great advantage of this construction compared to separately driven wheels is that the unsprung weight of the bogie is substantially minised apart from the fact that the total weight of the carriage is reduced since a single prime mover and a Cardan drive weigh less than four separate drives.

She axles on the undriven bogie can be stub axles and not extend the full width between the wheels and resemble the axles to be described in Figures 12, 15 and 17 provided the beams are spaced by stays 41.

The ties 75 extend substantially horizontally as mentioned so that vertical movement of a bogie relative to the floor pan has little effect on the horizontal distance between the axles and the pin. However these ties are made compliant by an elastomeric fastening between the top of each colon and ends of the ties. The end of each tie is bifurcated at 42 and joined to a pin 43 passing through an elastomeric bush 44 in a bracket 45 secured to the column, as shown in Figure & Thus these ties can cope with compression or expansion of the dampers 34 by the resilient play in the bushes.

Figure 9 is a section through a coupling for use at an articulation. The coupling comprises a ball 4t6 mounted at the end of an arm 47 having a flanged end 4'8 sandwiched between layers of resilient material 49 secured to part of the floor pan or a member attached to the floor pan. This ball joint would be attached to one car and a socket (not shown) would be attached to the other car.

Conveniently, the articulation contains a link 50 having two socket ends 51 engaged with a ball 46 nounted on each car as shown in Figure 7D or 11.

In Figure 11 the link contains a flexible joint 52 between two link parts. One link part 53 would have a flanged end 54 received in a resilient material 55 contained in a cup 56 formed on the other part 57.

Tigures 12 to 14 illustrate wheels supporting an articulation. Each wheel 26 is pivotal about a vertical axis 58 on a cranked arm59 -The two cranked arms are connected by a track rod 60 keeping the wheels parallel. A mechanical or other linkage 61 between two cars steers the wheels the wheels and associated linkages are supported below the floor pan 22 by a suspension framework 63 supporting the wheels from a bracket 64 welded to the floor pan.

This framework comprises a pair of A-frames 65 disposed one above another and hinged to the bracket at one end 66 and at the other end hinged to a rack rod 67 to form a parallelogram suspension framework. Across a diagonal of this parallelogram there is a spring/ damper unit 69.

Figure 1 5 illustrates another articulation support system. In this system, the wheels are mounted-on a sub-frame 70 joining two cars. This sub-frame is rigid and is steered by a linkage 71 to keep the wheels aligned with 8 rail trRck even on curves. In this system springing of the wheels canbe by a simple arm 72 (Figure 16) pivoted to the sub-frame with a spring-damper unit 73 between the arm 72 and the sub-frame. It would be best to arrange this arm as a trailing arm. A similar system could be adapted for use with the system of figure 12.

Figure 17 shows a half section through a wheel.

The wheel has a steel wheel tyre 75 bonded onto a resilient cushion 76 gripped between two flanges 77 and 78 held together by bolts 79. One of these flanges can be integral with a metal wheel centre,or both flanges can be secured to the wheel centre 80, by bolts 79.

For undriven wheels, that is wheels supporting an articulation or wheels on an undriven bogie or indeed undriven wheels on a driven bogie, this wheel centre 80 would be mounted on low friction bearings 81 on a preferably hollow shaft 82.

It will be appreciated that by combining the various aspects and features of the present invention substantial reduction is the total weight of a carriage along with an appreciable reduction in the unsprung weight of the wheels can be achieved. This has a further advantage in that the loading on the track is reduced so the track can be constructed more cheaply and this extends to any bridges and other engineering works.

Claims (11)

1. Light railway rolling stock having independently rotatable wheels.

2. Light railway rolling stock according to claim 1 having an axle with independently rotatable wheels at its ends.

3. Light railway rolling stock having driven wheels driven through a differential gearbox from a common drive which is supported from the rolling stock's superstructure.

4. Light railway rolling stock containing a wheel with a steel or other metallic tyre and hub with a connection between the hub and the tyre being an elastomeric cushion.

5. Rolling stock according to claim 4 wherein the cushion is bonded to the tyre adhesively and clamped to the hub.

6. A bogie for light railway rolling stock is pivotted to superstructure of the rolling stock by a pivot but is located longitudinally of the rolling stock by ties interconnecting the bogie to the superstructure.

7 A bogie for light railway rolling stock which is located longitudinally of the rolling stock by ties interconnecting the bogie with the superstructure.

8. A bogie located longitudinally of superstructure as claimed in claim 6 or claim 7 wherein at least one end of at least some ties is mounted resiliently to the superstructure or bogie by a resilient mounting.

9. Light railway rolling stock in the form of a multiple car carriage having each car supported by at least one bogie and having and articulation between adjoining cars wherein the articulation is supported by an axle having a pair of independently rotatable wheels wherein the axle is steerable by a linkage to facilitate the articulation going around a curve.

10 Light railway rolling stock according to claim 9 wherein the articulation wheels are sprung by a suspension which also :=weeps the wheels in the correct orientation.

11. Light railway rolling stock substantially as herein described with reference to one or more of the accompanying drawings.