GB2289877A

GB2289877A - Power bogie for tram with continuous low floor

Info

Publication number: GB2289877A
Application number: GB9510385A
Authority: GB
Inventors: Terence Brian Coulbeck
Original assignee: ABB Rail Vehicles Ltd
Current assignee: Alstom Electronics Ltd
Priority date: 1994-05-25
Filing date: 1995-05-23
Publication date: 1995-12-06
Anticipated expiration: 2015-05-23
Also published as: FR2720361B1; ITMI951059A1; ITMI951059A0; IT1274561B; FR2720361A1; GB9410479D0; GB9510385D0; GB2289877B

Abstract

A tram 10 in the farm of articulated modules has drive modules 12, intermediate support modules 16 and suspended passenger carrying compartments 18. Each of the drive modules and intermediate support modules is mounted on a bogie 14, three of the bogies being powered. Each of the powered bogies has a flat bed frame 20 providing a primary suspension arrangement (26, fig. 4) for mounting a respective wheel 36 with an independent drive motor and gearbox arrangement (34, 32, fig. 1) outboard thereof. A secondary suspension for the passenger carrying body of the respective drive or support module is provided by air springs (44, fig. 1). The design is such that each passenger carrying body has a continuous low floor which can align with a continuous low floor of the or each adjacent suspended compartment 18, whereby to provide a continuous low floor throughout the tram. Anti-roll bars may be fitted to the bogies; an electromagnetic track brake may be used. <IMAGE>

Description

Rail Vehicle Bogies This invention relates to a bogie for a rail vehicle, and particularly a bogie for use in a tramway system designed for public transport.

A light rail tramway system finds many advantages in use as public transport, particularly in a city centre location. As well as providing improved transport, such a system can facilitate removal of noise and pollution from the city centre.

It is an object of the present invention to provide a bogie for a light rail vehicle such as a city centre tramway, which facilitates improved designs of trams, particularly in the ability of the tramway to have a continuous low floor throughout.

According to the present invention there is provided a bogie for a rail vehicle, the bogie comprising a frame providing a mounting for independent primary suspension of each of a plurality of wheels, with a drive motor and gearbox arrangement substantially outboard of each of the wheels, means for mounting a passenger carrying body on the frame through a secondary suspension arrangement, whereby the body can have a continuous low floor, and means enabling mounting of a passenger carrying unit on at least one end of the frame, whereby the unit can be retained in a suspended and articulated arrangement, with a continuous low floor of the unit aligned with the low floor of the body.

Preferably the frame is in the form of a flat bed fabrication, and the primary suspension mounting for each wheel may comprise a turret mounted on a respective casting at each side of the frame, the turret providing a mounting face for a suspension spring which faces to the respective end of the bogie and downwardly thereof.

Each turret is preferably formed separately from the respective casting and is accurately located thereon, for example dowel located.

Each spring may be in the form of a flat rubber spring mounted between a respective one of the turrets and a respective radius arm which is pivotally mounted at a free end thereof on the frame. The respective drive motor and gearbox arrangement may be mounted on the respective radius arm.

Preferably each radius arm is pivotally mounted on a pivot pin which has an outer end flange and internal shoulder arrangement to effectively clamp the pivot pin onto the gearbox and thereby transmit lateral loading through the gearbox into the frame.

The secondary suspension for the body on the bogie may be provided by a pair of air springs positioned in lateral alignment at each end of the frame. The air springs may be each of a double convoluted type. A pair of lateral bump stops may be provided between, and in alignment with, each pair of air springs, to be capable of reacting against a respective traction rod when connected directly between the frame and a frame of the unit.

The bogie may be provided with a torsion bar which extends through apertures in the side castings and has connected at each end thereof outwardly of the frame an anti-roll linkage which is connected with the respective body. An arm of one of the anti-roll linkages is preferably sweated onto the torsion bar, and the arm of the other anti-roll linkage may be connected to the torsion bar by a taper lock device.

The bogie is preferably provided with an electromagnetic track brake suspended from the bogie frame and connected through a bell crank arrangement to a respective gearbox whereby to enable consequential movement of the track brake on movement of a respective wheel, and thus maintain a constant gap between the track brake and the track. The track brake may be suspended from the frame by a-yoke through respective end brackets.

An embodiment of the present invention will now be described by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a top plan view of a tramway powered bogie according to the invention; Fig. 2 is a side elevation of the bogie of Fig. 1; Fig. 3 is a section on A-A of Fig. 1; Fig. 4 is a section on B-B of Fig. 1; Fig. 5 is a section on C-C of Fig. 1; and Fig. 6 is a diagrammatic representation in elevation of an articulated tram using the bogie of Figs. 1 to 5.

Referring to the drawings, a tramway designed for public transport use, for example in a city centre loCation, comprises rolling stock in the form of seven articulated modules. At each end, the tram 10 has drive module 12 in the form of a driver's cab mounted on a bogie 14 according to the invention. The tram further includes two intermediate support modules 16, each again mounted on a bogie 14 according to the invention, and each having a passenger carrying facility. Three of the bogies 14 are powered as shown in the drawings. The tram is completed by three passenger carrying compartments 18, two of which are suspended between a respective drive module 12 and a respective support module 16, while the other is suspended between the two intermediate support modules. Such a design of tram has been previously proposed and has the advantage of reducing tail swing in the corners of the track rails.

In addition, the bogies 14 need not move so far out of alignment with the bodies of the modules.

It will be appreciated that the modular design has the benefit that the length of the tram can be varied as necessary. For example, the tram could be reduced to five modules or increased to nine modules. The five module design would comprise two drive modules 12, an intermediate support module 16, and two suspended passenger carrying compartments 18. The nine module design would consist of two drive modules 12, alternate intermediate support modules 16, and the appropriate number of suspended passenger carrying compartments 18.

The bogie 14 is designed to enable the tram 10 to have a continuous low floor throughout the length thereof, i.e. a floor at a height above the ground less than the axle height of wheels of the bogie, for example 350 mm above rail level. Such a low floor greatly facilitates access to the passenger carrying areas of the tram and reduces the height of platforms for use in association with the tram. As there is no equipment under the compartments 18, each of the latter has a totally unobstructed floor which provides total flexibility in seating design.

To accommodate the continuous low floor, each of the powered bogies 14 has a frame 20 in the form of a flat bed steel fabrication provided at each outer side thereof with a pair of castings 22 mounted into the fabrication. Mounted on each of the castings 22 is a turret 22a which is angled to provide a mounting face 24 facing respectively forwardly or rearwardly of the bogie 14 and downwardly angled, whereby to provide a mounting for a respective primary suspension arrangement 26.

Each of the latter comprises a flat rubber spring 28 mounted between the mounting face 24 of the respective turret 22a and a mounting face of a radius arm 30, which is pivotally mounted at a lower end thereof in a non-resilient manner on the bogie frame 20. The radius arm 30 mounts a gearbox 32 which transfers drive from a pinion on the end of a drive motor 34 through a reduction gear to a drive shaft constituting an axle of a respective independent wheel 36. Each of the wheels 36 with its individual drive motor 34 is therefore outboard of the low floor area of the module mounted on the bogie. Each gearbox 32 is outboard of the respective wheel 36.

The load path of the bogie 14 is through the primary suspension units 26 and the respective wheels 36 to the rail of the track. Because the passenger carrying compartments 18 are suspended from the drive modules 12 and the intermediate support modules 16 at respective ends thereof, the frame 20 has to be in the form of a sufficiently strong casting around the areas of the primary suspension units 26 to be able to accommodate the consequential forces. Reinforcement of the respective areas of the casting may be required.

Also, because the machining requirements cannot be carried out with the turrets 22a welded into the castings 22, the turrets 22a are separately fabricated and dowel located on the castings 22 for accuracy.

In a conventional bogie, which has each pair of wheels on a single axle, the back to back dimension of the wheels of each pair can be relatively accurately achieved, but wheel alignment is more difficult to achieve in a bogie design where the wheels are independent of one another. To achieve a required tolerance on wheel alignment, accurate machining is required at various connections, and of importance is the load path through a pivot pin 38 of each radius arm 30. In the present design, outer end flanges 40 cooperate with internal shoulders 42 on the ends of the respective pivot pin 38 to effectively clamp the pin onto the gearbox 32, to transmit the lateral loading through the gearbox 32 into the frame 20.

Secondary suspension for the respective module on the frame 20 is provided by a pair of air springs 44 positioned in lateral alignment at respective ends of the bogie frame 20. The air springs 44 are each of a double convoluted type and enable the provision of suitable frequency levels for comfort in the passenger environment.

The air springs are supplemented by vertical dampers 46, each of the latter being positioned outwardly close to a respective air spring 44. The vertical dampers 46 may be hydraulic or pneumatic. Additionally, a further pair of lateral dampers 48 are provided at diagonally opposite areas of the bogie frame 20, each extending between the frame 20 and a head stop located underneath the adjacent suspended compartment 18.

The air springs are further supplemented for emergency purposes with bump stops, vertical bump stops 50 being positioned inwardly of the air springs 44, and a pair of lateral bump stops 52 being provided between, and in alignment with, each pair of air springs 44.

Each pair of lateral bump stops 52, which accommodate lateral forces, can react against a respective traction rod 54 which, as shown in the drawings in relation to the bogie 14 of an intermediate support module 16, is connected directly between the bogie frame 20 and the frame of each adjacent suspended compartment 18.

To provide a surge reservoir for each pair of air springs 44, in order to soften the suspension, open spaces in the frame 20 are sealed and a barrier is provided across the centre of the frame 20, so that the sealed spaces in each half of the frame 20 define respective reservoirs. The reservoir design enables the provision of a reservoir for each pair of air springs 44 in the region of twenty four litres.

The bogie 14 is provided with an anti-roll bar system where a torsion bar 56 extends through apertures in the fabricated side sections. The single bar 56 is connected at each end outwardly of the frame 20 to a conventional anti-roll linkage 58 which connects with the respective module. Because the torsion bar 56 is passed through apertures in the frame 20, the bar 56 cannot be pre-assembled at each end with respective arms 60 of the anti-roll linkage 58. One arm 60 is sweated on to the torsion bar 56, and the other arm 60 is connected by a taper lock device.

Each wheel 36 comprises a resilient element, for example a rubber ring, fitted between a rim and a central part of the wheel. Each wheel 36 is bolted onto a flange on the respective drive axle, and connected to the back of each wheel is an earth return mechanism 62 for safety and current return. The mechanism 62 is conventionally fastened onto an axle box, but, because the gearbox 32 in the present design is the effective axle box and is outboard of the wheel, a stabiliser bar 64 is provided to prevent rotation of the mechanism 62 with the wheel 36.

A conventional friction brake 66 with disc and pads is provided in association with each wheel 36. A conventional electromagnetic track brake 68 is also provided which is suspended from the bogie frame 20 by a yoke 70 through respective brackets 72. In order to maintain the correct height of the track brake above the rail in non-operating conditions, a shaft 74 extends upwardly through a hold-off spring and is connected at its upper end with a bell crank 76 which is pivotally mounted on a bracket on the frame 20, and is connected through a link to the gearbox 32, whereby movement of a respective wheel 36 downwardly into a track dip will move the track brake 68 upwardly and vice versa. A 10 mm gap can be maintained between the brake 68 and the track through all suspension movements.

The drive motors 34 are cooled by a water and glycol mixture. A cooling arrangement 78 includes a radiator and reservoir unit together with a circulation pump, the arrangement being attached to the bogie frame 20. From the cooling arrangement, pipes transfer the coolant in four directions to the respective drive motors 34. There are three circuits for piping fluid from a control unit 80 to the hydraulic brakes, i.e. an application circuit, a return circuit and a parking brake release. The latter is the only part of the hydraulic system which leads into the body of the supported module, i.e. to the brake module in the roof thereof. A further piping system is provided for the air springs 44 which are each provided with a conventional levelling valve 82 attached to the adjacent body and the frame 20, a compensating valve and a load weigh valve.

It will be appreciated that the bogie 14 of each of the drive module 12 connects through a respective traction rod 54 with an adjacent suspended compartment 18 to one side thereof, and it will also be appreciated that, apart from the absence of drive motors, the design of an unpowered bogie is substantially the same as that of a powered bogie.

Various modifications may be made without departing from the invention, which is not restricted to the specific component designs and layout as described and shown in the drawings.

Claims

Claims:

1. A bogie for a rail vehicle, wherein the bogie comprises a frame providing a mounting for independent primary suspension of each of a plurality of wheels, with a drive motor and gearbox arrangement substantially outboard of each of the wheels, means for mounting a passenger carrying body on the frame through a secondary suspension arrangement, whereby the body can have a continuous low floor, and means enabling mounting of a passenger carrying unit on at least one end of the frame, whereby the unit can be retained in a suspended and articulated arrangement, with a continuous low floor of the unit aligned with the low floor of the body.

2. A bogie according to Claim 1, wherein the frame is in the form of a flat bed fabrication.

3. A bogie according to Claim 1 or 2, wherein the primary suspension mounting for each wheel comprises a turret mounted on a respective casting at each side of the frame, the turret providing a mounting face for a suspension spring which faces to the respective end of the bogie and downwardly thereof.

4. A bogie according to Claim 3, wherein each turret is formed separately from the respective casting and is accurately located thereon.

5. A bogie according to Claim 4, wherein each turret is dowel located on the respective casting.

6. A bogie according to any of Claims 3 to 5, wherein each spring is in the form of a flat rubber spring mounted between a respective one of the turrets and a respective radius arm which is pivotally mounted at a free end thereof on the frame.

7. A bogie according to Claim 6, wherein the respective drive motor and gearbox arrangement is mounted on the respective radius arm.

8. A bogie according to Claim 7, wherein each radius arm is pivotally mounted on a pivot pin which has an outer end flange and internal shoulder arrangement to effectively clamp the pivot pin onto the gearbox and thereby transmit lateral loading through the gearbox into the frame.

9. A bogie according to any of the preceding Claims, wherein the secondary suspension for the body on the bogie is provided by a pair of air springs positioned in lateral alignment at each end of the frame.

10. A bogie according to Claim 9, wherein the air springs are each of a double convoluted type.

11. A bogie according to Claim 9 or 10, wherein a pair of lateral bump stops is provided between, and in alignment with, each pair of air springs, to be capable of reacting against a respective traction rod when connected directly between the frame and a frame of the unit..

12. A bogie according to any of the preceding Claims, when dependent on Claim 3, wherein the bogie is provided with a torsion bar which extends through apertures in the side castings and has connected at each end thereof outwardly of the frame an anti-roll linkage which is connected with the respective body.

13. A bogie according to Claim 12, wherein an arm of one of the anti-roll linkages is sweated onto the torsion bar.

14. A bogie according to Claim 13, wherein the arm of the other anti-roll linkage is connected to the torsion bar by a taper lock device.

15. A bogie according to any of the preceding Claims, wherein the bogie is provided with an electromagnetic track brake suspended from the bogie frame and connected through a bell crank arrangement to a respective gearbox whereby to enable consequential movement of the track brake on movement of a respective wheel, and thus maintain a constant gap between the track brake and the track.

16. A bogie according to Claim 15, wherein the track brake is suspended from the frame by a yoke through respective end brackets.