GB2044198A - Rapid transit railway truck assembly - Google Patents

Abstract

Known truck assemblies are not really suitable for rapid transit systems as they are too noisy, too heavy and are unable to negotiate sharp curves. The railway truck assembly of the invention overcomes these disadvantages by having a pivot connection between its bolster and the truck frame elements which, in co-operation with direct transmission of the load to the truck frame through the opposite ends of the bolster, allows the use a relatively thinner and centrally nonbulging bolster. This railway truck assembly has a bolster 3 which is substantially bodily displaceable with the car body 2. A pair of side frames 31 and 32 are laterally restrained by means of a link 37, relative to the bolster 3 and support the opposite ends of the bolster. A pair of steering yokes 13 and 14 are longitudinally restrained relative to the car body 2, and pivoted together for radial steering of the respective wheel axes 20 connected thereto. The side frames 31 and 32 are slidably supported by the yokes 13 and 14, and are laterally restrained relative thereto by means of links 38 and 39. The bolster 3 is connected to the side frames 31 and 32 by a centreless pivot connection. <IMAGE>

Description

SPECIFICATION Railway truck assembly This invention relates to a railway truck assembly, and, more particularly, to a pivotal connection in a railway truck designed for a rapid-transit system.

Conventional railway trucks (bogies) have been designed to meet substantially less stringent requirements than those which have to be met by trucks for urban, rapid-transit systems now on the drawing boards and/or under development. Such urban rapid-transit systems are required to be substantially less noisy, to be able to negotiate curves much sharper than those of conventional railways, and to be lighter and thus more compatible with energy conversation.

The ability for a railway truck to negotiate relatively sharp curves with a minimum of wear and noise has been provided by always steering the wheel axles radially to the curve. Such a truck includes a pair of yokes pivoted together about a vertical axis, the yokes being connected respectively to the wheel axles. By pivoting the yokes, the wheel axles are each steered to a radial position relative to a curve.

In its broadest aspect, the present invention provides a railway truck assembly comprising a bolster which is rigidly attachable to a car body to be carried by the railway truck assembly, a pair of side frames laterally restrained, by means of first link means, relative to the bolster and supporting the opposite ends respectively of the bolster, a pair of wheel axles each of which is rotatably supported by a respective steering yoke, the steering yokes being longitudinally restrained relative to the bolster and being pivotally joined together for radial steering of the wheel axles, the side frames being slidably supported by the yokes and laterally restrained relative to the yokes by second link means, wherein the bolster is connected to the side frames and yokes by a centreless pivot connection.

This railway truck assembly is adapted to steer the wheel axles radially to a curve and to reduce wear and noise. The pivot connection between the bolster and the truck frame elements co-operates with direct transmission of the load to the truck frame through the opposite ends of the bolster, to permit the use of a relatively thin and centrally non-bulging bolster.

Thus, more space is made available between the central portion of the bolster and the top of the rails, this space being advantageously used to install equipment such as a linear induction motor.

In another aspect, the invention provides a railway truck assembly comprising a bolster, bolster drag links for connecting the opposite ends of the bolster to a railway car body, a pair of spring suspensions positoned on the opposite ends of the bolster for carrying the car body, a pair of wheel axles, a respective steering yoke rotatably supporting each of the wheel axles, the yokes being pivotably joined together about a vertical axis positioned between the wheel axles, a pair of side frames positioned at the opposite ends respectively of the bolster, pivot means pivotally connecting one end of each side frame to one of said yokes, lateral link means pivotally connecting at least one side frame to the bolster, a steering crossbar having a central portion pivotally connected to one of said yokes, and a pair of yoke drag links for pivotal connection, at one end, to the car body, and at the other end, to the opposite ends respectively of the steering crossbar, whereby the weight of the car body is directly transmitted, in use, through the spring suspensions onto the side frames, and the side frames and yokes are connected to the bolster by an effectively centreless pivot connection.

This railway truck assembly uses link connections which involve small angular displacements and so may simply have swivelling rod ends to allow the necessary freedom of pivoting and twisting motions between the movable components.

A railway car incorporating railway truck assemblies constructed in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure lisa side elevation of the railway car which is provided with a pair of railway truck assemblies constructed in accordance with the invention; Figure 2 is a side elevation of one of the railway truck assemblies of Figure 1; Figure 3 is a plan view of the railway truck assembly of Figure 2; Figures 4 and 5 are cross-sections taken respectively on lines 4-4 and 5-5 of Figure 3; Figure 6 is an enlarged detail view of a suspension link-and-pin assembly; Figure 7 is a schematic plan view showing the pivotal relationship between the pivoting elements the pair of truck assemblies and the railway car body carried by the truck assemblies; and Figure 8 is an enlarged view of the left-hand truck assembly of Figure 7.

Referring to the drawings, Figure 1 shows a pair of railway trucks 1 which are used to carry a car body 2 of any desired construction. Each railway truck 1 forms part of a railway truck assembly also comprising a bolster 3 and associated elements to support the car body. As each railway truck assembly is identical, only one of them (that is to say that ringed by the dash-dot lines 2 in Figure 1) will be described.

The bolster 3 includes a central portion 4 of tubular, square cross-section, as best shown in Figures 3 and 4. Each end of the bolster 3 includes a baseplate portion 5 which is positioned lower than the central bolster portion 4. Stiffening ribs 6 are secured against the base of each baseplate portion 5, and extend longitudinally of the bolster 3. Each baseplate portion 5 is provided with a pair of side plates 7 upwardly extending edgewise along the opposite sides thereof. A generally C-shape top plate 8 is fixed to the upper edges of each of the adjacent side plates 7 to co-operate with the latter and with the corresponding baseplate portion 5 to form a protected recess for an air spring unit 9, which may be of any appropriate and known construction.The two air spring units 9 of each bolster 3 are fixed to the railway car body 2 by bolts 10, and carry the load of the corresponding end of the car body. The two side plates 7 on the inboard side of the bolster 3 are connected to the car body 2 by means of a pair of bolster drag links (or rods) 11. More specifically, each bolster drag link 11 has one end pivoted to the corresponding side plate 7 of the bolster 3, and the other end pivotally connected to a bracket 12 fixed to, and downwardly projecting from, the base of the railway car body 2. The opposite ends of each bolster drag link 11 are vertically pivotable to accommodate the springing movement between the car body 2 and the bolster 3, and they are also provided with resiliently twisting rod ends to accommodate the very small transverse displacement of the car body relative to the bolster.

The railway truck assembly further includes an outboard yoke 13 and an inboard yoke 14. The outboard yoke 13 includes a main frame 15, while the inboard yoke 14 includes a main frame 16. Each main frame 15 and 16 includes a pair of laterallyspaced projections 17, to which is secured a journal housing 18. Each main frame 15 and 16 is formed with an underlying transverse beam portion 19. The journal housings 18 of each yoke 13 and 14 rotatably retain a respective wheel axle 20 having a flanges wheel 21 on each of the two opposite outer ends thereof. Thus, the flanged wheels 21 are adapted to roll on rails 22 and to carry the yokes 13 and 14 and the remainder of the railway truck assembly.

The outboard yoke 13 is provided with a longitu dinal bar 23 rigidly secured centrally to the main frame 15 and projecting inboard therefrom. Similarly, the main frame 16 is provided with a longitudinal bar 24 which is rigidly secured centrally thereto and projects outboard thereform. The two bars 23 and 24 have their free ends pivoted to one another at equal distances from the wheel axles 20, that is to say centrally under the bolster 3.

A bracket 25 (see Figure 6) is fixed to the outboard side of the bolster 3 and at the centre thereof. A pair of yoke suspension links 26 are pivoted, at their upper ends, to the bracket 25, and, at their lower ends, to the head of a vertical pivot pin 27. The pin 27 pivotally suspends the free end of the bar 23 of the outboard yoke 13. Owing to the pivotal connection between the free ends of the bars 23 and 24, the pivot pin 27 effectively supports both bars relative to the bolster 3.

A steering crossbar 28 transversely extends through the yoke bar 23, and is centrally pivoted therein by the pivot pin 27 (see Figure 6). A pair of yoke drag links (or rods) 29 are pivotally connected, at one end, to a corresponding end of the steering crossbar 28, and at the other end, to a bracket 30 rigidly depending from the car body 2 (See Figure 3).

Each end of each of the links 29 is pivotally connected by a resiliently twistable rod end to allow restricted twisting as well as rotation. It must be noted that the inboard end of each drag link 29 is pivoted about a horizontal axis to permit the resilient suspension between the car body 2 and the yokes 23 and 24. The other (or outboard) end of each drag link 28 is pivoted about a vertical axis relative to the steering crossbar 28.

A pair of parallel, longitudinally-extending side frames 31 and 32 are positioned on the opposite sides of the railway truck 1. Each side frame 31 and 32 has its inboard end pivoted, at 33, on the corresponding journal housing 18 and rests on a resilient pad 34. Each side frame 31 and 32 has its outboard end resting on a slide pad 35. Each end of the bolster 3 rests on a slide pad 36 at the centre of the corresponding side frame 31 or 32. Thus, the load of the railway car 2 is transmitted directly through the air spring units 9, and the opposite ends of the bolster 3, onto the slide pads 36 at the centre of the side frames 31 and 32. The slide pads 35 and 36 allow relative longitudinally displacement between the journal bearings 18 (or between the yokes 13 and 14), and between the bolster 3 and the side frames 31 and 32.Such displacement occurs in a curve upon angular displacement of the car body 2 (and hence the bolster 3) relative to the side frames 31 and 32 and the railway truck 1 as a whole. As will be explained later, the angular displacement of the truck 1 relative to the car body 2 steers the yokes 13 and 14to align the wheel axles 20 radially to the curve. Such steering displacement of the yokes 13 and 14 results in relative sliding between the yoke 13 and the side frames 31 and 32 on the slide pads 35.

A lateral stabilisation link (or rod) 37 extends laterally of the truck 1 and is pivotally connected to the central portion 4 of the bolster 3, and to the side frame 31 (see Figure 5). This anchor rod 37 accurately restrains the side frame 31 in a lateral direction. A pair of yoke centring links 38 extend laterally from, and are pivotally connected to one end to, the outboard end of the yoke 13. The other ends of the links 38 are pivotally connected to the corresponding side frames 31 and 32. A third yoke centring link 39 extends laterally from, and is pivotally connected at one end to, the inboard end of the yoke 14. The other end of the link 39 is pivotally connected to the side frame 31. These links 38 and 39 are provided to centre the side frames 31 and 32.

A steering actuation device is provided to actuate the steering crossbar 28, the steering actuation device comprising an arm 40 which is fixed to the central portion 4 of the bolster 3, and which arm extends longitudinally of the railway car body 2. This arm 40 and the adjacent drag link 29 are each provided with a series of longitudinally-spaced adjustment holes 41. An adjustable link 42 is pivotally connected, at each end, in any one of the holes 41 of both the arm 40 and the link 29. A stabilising link 43 (see Figure 5) is connected parallel to, and beneath the crossbar 28 to stabilise the pivot pin through the end of the crossbar and to resist the action thereon by the link 42.

The detailed operation of the railway truck assemblywill now be explained in detail with particular reference to Figures 7 and 8. When the railway car is on a curve, the body 2 thereof is at an angle "a" relative to the longitudinal axis of each railway truck 1. Since the bolsters 3 are restrained relative to the car body 2, they also make the same angle relative to the trucks 1.

The link 42 of each truck assembly acts to keep the steering cross-bar 28 laterally centred with respect to the car body 2. This will shift the yokes sufficiently with respect to the truck centre line to pivot the yokes 13 and 14 in opposite directions, so that both the wheel axles 20 will take a radial alignment relative to the curve.

Although the curves of a rapid transit system may be sharper than those of conventional railway, the maximum steering angle of each wheel axle 20 is limited to about 21/2 degrees. Figures 7 and 8 exaggerate the relative angular pivoting between the pivotable components. In fact, the bars 23 and 24 shift only slightly laterally and thus the vertical pivot between the two shifts only slightly sideways out of alignment with the pivot centre of the trucks 1 relative to the car body 2.

Claims (12)

1. A railway truck assembly comprising a bolster which is rigidly attachable to a car body to be carried by the railway truck assembly, a pair of side frames laterally restrained, by means of first link means, relative to the bolster and supporting the opposite ends respectively of the bolster, a pair of wheel axles each of which is rotatably supported by a respective steering yoke, the steering yokes being longitudinally restrained relative to the bolster and being pivotally joined together for radial steering of the wheel axles, the side frames being slidably supported by the yokes and laterally restrained relative to the yokes by second link means, wherein the bolster is connected to the side frames and yokes by a centreless pivot connection.

2. A railway truck assembly comprising a bolster, bolster drag links for connecting the opposite ends of the bolster to a railway car body, a pair of spring suspensions positioned on the opposite ends of the bolster for carrying the car body, a pair of wheel axles, a respective steering yoke rotatably supporting each of the wheel axles, the yokes being pivotably joined together about a vertical axis positioned between the wheel axles, a pair of side frames positioned at the opposite ends respectively of the bolster, pivot means pivotally connecting one end of each side frame to one of said yokes, lateral link means pivotally connecting at least one side frame to the bolster, a steering crossbar having a central portion pivotally connected to one of said yokes, and a pair of yoke drag links for pivotal connection, at one end to the car body, and, at the other end, to the opposite ends respectively of the steering crossbar, whereby the weight of the car body is directly transmitted, in use, through the spring suspensions onto the side frames, and the side frames and yokes are connected to the bolster by an effectively centreless pivot connection.

3. A railway truck assembly as claimed in Claim 2, further comprising a steering actuation device for connecting the railway car body to at least one of said yokes whereby the yokes and the wheel axles are steerable in response to pivoting of the railway car body relative to the wheel axles.

4. A railway truck assembly as claimed in Claim 3, wherein the steering actuation device includes steering link means rigidly connected to the bolster, the steering actuation device being pivotally con nected to the steering crossbar whereby the steering crossbar is laterally displaceable in response to pivoting of the car body relative to the wheel axles.

5. A railway truck assembly as claimed in Clain 4, wherein the lateral link means includes a lateral anchor link pivotally connected, at one end, to the bolster, and, at the other end, to one of the side frames.

6. A railway truck assembly as claimed in any one of Claim 2 to 5, wherein each of the bolster drag links is pivotally connectible, at one end, to the railway car body on one side of the bolster, and is pivotally connected, at the other end, to a respective end of the bolster.

7. A railway truck assembly as claimed in Claim 6 when appendant to Claim 4, wherein the yokes are positioned on the opposite sides of the bolster, the steering crossbar is pivoted to the yoke on the opposite side of the bolster relative to said one side thereof, and said other end of each yoke drag link is pivotally connected to the respective end of the steering crossbar on said opposite side of the bolster.

8. A railway truck assembly as claimed in any one of Claims 2 to 7, further comprising slide pads interposed between the top of the side frames and the opposite ends respectively of the bolster, slide pads being interposed between the other yoke and the side frames, the slide pads allowing the side frames to slide relative to the bolster and said other yoke to slide relative to the side frames.

9. A railway truck assembly as claimed in any one of Claims 2 to 8, wherein the lateral link means includes yoke centring links laterally extending relative to the side frames and each having one end pivotally connected to one side frame and the other end pivotally connected to a corresponding yoke.

10. A railway truck assembly as claimed in any one of Claims 2 to 9, further comprising a pivot pin pivotally joining the steering crossbar to said other yoke, and a suspending link pivotally suspended to the bolster, pivotally connected to the pivot pin, and pivotally suspending the yokes and steering crossbar from the bolster.

11. A railway truck assembly substantially as hereinbefore described with reference to, and as illustrated by, the accompanying drawings.

12. A railway car comprising a car body supported by two railway truck assemblies each as claimed in any one of Claims 1 to 11.