GB2076348A - Rail vehicle suspensions - Google Patents

Abstract

A railway bogie has a bogie frame (1) supported on primary coil springs (7) from the wheel axles, the superstructure (9) being supported midway along the bogie on secondary coil springs (11) which are less stiff than primary springs (7). The bogie is stabilised in relation to the superstructure (9) by traction links (23) converging downwardly from points on each side of the superstructure towards a common point at rail level, the lower ends of the traction links being connected to a traction bolster (27) extending across and underneath the bogie frame. The traction bolster (27) has an integral cylindrical shaft or pin (25) extending vertically into a bearing (29) in the bogie frame to permit relative rotation between bogie frame and superstructure and compression of the secondary springs (11). Rolling of the superstructure relative to the wheels is, however, resisted by the relatively stiff primary springs (7). The secondary springs (11) are fixedly mounted at one end to the bogie frame and may be fixed or link mounted (as shown) at the other end to the superstructure (9). <IMAGE>

Description

SPECIFICATION Railway bogie This invention relates to railway bogies and particularly to the suspensions of railway bogies.

It is an object of the present invention to provide a suspension which provides springing against shock movements of the wheels while at the same time limiting the roll of the superstructure relative to the wheels.

A particular difficulty with which the present invention is concerned is excessive rolling of the superstructure when, for example, the coach or wagon is travelling round a bend. At the same time the suspension must preferably not be so rigid as to prevent lateral movement, under, for example, rail shocks, of the bogie relative to the superstructure.

According to the present invention, a railway bogie comprises a bogie frame supported on wheel axles by primary spring means, a superstructure supported on the bogie frame by secondary spring means of lesser stiffness than the primary spring means, and a link arrangement connected between the superstructure and the bogie frame in such manner as to exert no restraint on pure vertical movement of the superstructure but to lock the superstructure rigidly to the bogie frame when the superstructure is subject solely to rolling movement about a longitudinal axis, the arrangement being such that rolling of the superstructure is confined to that permitted by the primary spring means.

The link arrangement preferably comprises a coupling member which is vertically slidable in the bogie frame without restraint but which is rigid in the bogie frame when subject solely to rotational movement about a longitudinal axis through the coupling member, the link arrangement further comprising link members symmetrically disposed about a vertical plane containing a central longitudinal axis, the link members being pivotally coupled to the coupling member on horizontal lateral axis so as to permit pitching of the superstructure relative to the bogie frame.

The coupling member may be a sliding fit in a cylindrical bore in the bogie frame so as to permit rotational movement of the superstructure relative to the bogie frame about a vertical axis.

The coupling member may incorporate a bolster member extending iaterally across the bogie frame, on each side of the bogie two link members being coupled between the superstructure and the bolster member, the two link members lying in a longitudinal vertical plane, being symmetrically disposed about a lateral vertical plane, and being inclined downwardly towards said lateral vertical plane, the extensions of their lines intersecting at or near rail level.

The secondary spring means may comprise a number of coil springs in compression between the superstructure and the bogie frame, the coil springs being fixedly located with respect to the bogie frame but in sliding contact, in a horizontal plane, with the superstructure, the upper ends of the coil springs being connected by auxiliary link means to the bogie frame and to the superstructure in such manner as to connect the upper ends of the coil springs to the superstructure for relative transverse movement of the superstructure and bogie frame, and to the bogie frame for relative rotational movement of the superstructure and the bogie frame about the axis of the coupling member.

The upper ends of the coil springs may be coupled to the superstructure by horizontal link members extending radially from the coil springs towards the axis of the coupling member, and to the bogie frame by horizontal link members extending in a longitudinal direction.

The coil springs may be in two groups, one group on each side of the coupling member, the upper ends of the coil springs of each group having a common housing to which the link members are coupled.

In a modified embodiment the ends of each coil spring are fixedly located on the superstructure and the bogie frame respectively, so that any relative movement between the bogie frame and the superstructure in a horizontal plane is restrained by 'flexicoil' distortion of the coil springs.

A railway bogie in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings, of which: Figure 1 is a diagrammatic perspective view of a bogie with partly broken away superstructure; Figure 2 is a diagrammatic side elevation of a bogie, partly in section, and superstructure; Figure 3 is a plan view of the bogie without superstructure and to one side of a central longitudinal plane; Figure 4 is a side elevation of the bogie and superstructure and to one side of a central lateral plane, and Figure 5 is a cross sectional view along a central lateral plane of a bogie and superstructure showing a modified secondary spring mounting.

Referring to the drawings, the bogie frame 1 is a fabricated frame of H form the transom 2 being of greater depth than the side frames 3. The bogie frame 1 is supported on wheel axles 5 by means of primary springs 7, shown very diagrammatically in Fig. 2. The primary springs in fact comprise pairs of relatively stiff coil springs in well known manner.

Mounted on the bogie frame is a rigid superstructure 9, shown in the drawings as merely a rectangular block. In general it will be fabricated form and provides a base or part of the base for the coach or wagon to be carried. Two such bogies as shown in the drawings would of course be used to carry the coach and the superstructure extends over the two bogies.

The superstructure is supported on the bogie frame by means of secondary springs 11 of which there are four arranged symmetrically in two pairs one pair at each end of the bogie frame transom 2. The springs 11 are housed in the bogie frame structure and protrude slightly at their upper ends (unlike the simplified diagrammatic arrangement shown in Fig. 2). Their lower end is fixedly located but there is substantial lateral clearance for the remainder of the spring in the housing.

The upper ends of each pair of springs 11 are housed in a common cap or housing 1 3 which has a flat, low-friction upper surface.

Corresponding location plates 1 5 on the under side of the superstructure engage these low-friction surfaces.

The manner of locating the spring housing 1 3 is a feature of this embodiment of the invention. Each housing 1 3 has a longitudinal link 1 7 pivoted to it and to a fixing bracket 1 9 on the bogie frame, the pivot axes being in a lateral direction. These links 1 7 therefore ensure that the spring housing 13, and therefore the upper ends of the springs, cannot move in a longitudinal direction relative to the bogie frame. In addition to the longitudinal links 17, the spring housings 1 3 are located by radial links 21 which extend from each end of the spring housing 1 3 radially toward a vertical axis through the centre of the bogie.

The radial links are pivoted on vertical axes at one end to a spring housing 1 3 and at the other end to pivot brackets (not shown) on the underside of the superstructure.

Movement of the superstructure relative to the bogie frame is therefore possible to a small extent in a lateral direction by sectoral movement of the longitudinal links 1 7. Rotation of the bogie frame relative to the superstructure about the above mentioned vertical axis is also possible by sectoral movement of the radial links 21, the movement in both cases being are right angles to the links and thus without restraint by the links.

In addition to the above described coupling between the superstructure and the bogie frame there is a stabilising coupling provided by four traction links 23. These links lie two on each side of the bogie, in longitudinal vertical planes, equally inclined towards a central lateral plane. At their upper ends they are pivotally connected to the superstructure on horizontal lateral axes, while at their lower ends they are similarly coupled to a bolster and pin assembly providing a coupling member for the traction links. This assembly comprises a vertical pin 25 of substantial crosssection (as shown in Fig. 3) and a bolster member 27 which extends across the bogie frame under the transom 2, the pin being fixed rigidly in the centre of the bolster member 27 so as to provide an integral assembly.

The pin 25 is of approximately cylindrical form, having two cylindrical portions separated by a slightly tapered portion. The cylindrical portions engage corresponding bearing surfaces of a cylindrical bore 29 in the transom 2 the axis of which bore is the central vertical axis previously mentioned. The pin is free to rotate and to slide vertically in the bore 29 having a tolerance such that the axes of the pin and the bore cannot be misaligned.

The inclinded traction links 23 are disposed so that the downward extensions of their axes intersect at or near the rail level. It may thus be seen that the superstructure may pitch fore and aft about a point at rail level subject to the restraining force exerted by the secondary springs. Since the superstructure effectively extends the length of the coach, this tendency is limited by the restraining effect of the attachment to the next bogie.

The action of the traction links 23 satisfies the requirement for low weight transfer. An advantage of the arrangement of the links 23 in cooperation with the bolster and pin assembly is in limiting rolling of the superstructure relative to the bogie frame. For pure rolling motion about a longitudinal axis, the superstructure and the bolster/pin assembly 27/25 are effectively rigidly coupled together and the superstructure cannot roll without tilting the axis of the pin 25 sideways at the same time. This tilting or twisting of the pin 25 is of course resisted by its close engagement in the bore 29 which causes the bogie frame to roll in the same way. The primary springs 7 are, however, significantly stiffer than the secondary springs and consequently they resist this rolling of the bogie frame and the superstructure.Compression of the secondary springs 11 is of course unaffected by pure rolling, because of the effectively rigid coupling provided by the links 23.

The operation of the linkage to the second^ ary springs 11 will be clear from the above explanation of its construction. Lateral movement of the superstructure is permitted by deflection of the links 1 7 but restrained by the resulting distortion of the secondary springs 11. These springs have lower and upper ends which are maintained in horizontal planes by their housings. Lateral movement of the upper ends relative to the lower ends therefore causes a very shallow S-shaped distortion of the spring, known as 'flexicoil' distortion, which resists the lateral movement that caused it. Lateral movement of the superstructure is therefore resiliently restrained, thus absorbing shocks imposed by the rails.

Rotational movements between the superstructure and the bogie frame, such as may be caused by intercoach forces, are accommo dated by the non-positive i.e. sliding coupling between the superstructure and the housings 1 3 of the secondary springs. The spring housings 1 3 are maintained in position on the bogie frame by the links 1 7 acting approximately in a circumferential direction around the central vertical axis. As the superstructure rotates, the bolster 27 and pin 25 rotate freely with it, imposing no forces on the bogie frame.

The pivots at the inner ends of the radial links 21 are carried around the central axis by their attachment to the superstructure, but their radial disposition is such that initially they impose negligible tensile of compressive forces on the spring housings 1 3. Rotation of the superstructure is therefore substantially unrestrained.

In addition to the various coupling arrangements described above, there are hydraulic dampers connecting various parts of the structure. Thus, there is a lateral damper 31 between the bogie frame and the superstructure and a vertical damper 33 between the end of the bogie frame transom and the superstructure.

In a modification, shown in Fig. 5, of the embodiment described above, the upper ends of the secondary springs 11 are positively fixed to the underside of the superstructure by bolting or welding the housing 1 3 to the superstructure. Any movement, lateral or rotary, of the bogie relative to the superstructure is then restrained by the 'flexicoil' action of the secondary springs.

This modification differs from the arrangement shown in Figs. 1 to 4 in that the pivot 19, longitudinal link 17, radial links 21 and the location plates 15, for each pair of secondary springs, are all omitted.

Claims (11)

1. A railway bogie comprising a bogie frame supported on wheel axles by primary spring means, a superstructure supported on the bogie frame by secondary spring means of lesser stiffness that the primary spring means, and a link arrangement connected between the superstructure and the bogie frame in such manner as to exert no restraint on pure vertical movement of the superstructure but to lock the superstructure rigidly to the bogie frame vvhen the superstructure is subject solely to rolling movement about a longitudinal axis, the arrangement being such that rolling of the superstructure is confined to that permitted by the primary spring means.

2. A railway bogie according to Claim 1, wherein said link arrangement comprises a coupling member which is vertically slidable in the bogie frame without restraint but which is rigid in the bogie frame when subject solely to rotational movement about a longitudinal axis through the said coupling member, the link arrangement further comprising link member symmetrically disposed about a vertical plane containing a central longitudinal axis, said link members being pivotally coupled to said coupling member on horizontal lateral axes so as to permit pitching of the superstructure relative to the bogie frame.

3. A railway bogie according to Claim 2, wherein said coupling member is a sliding fit in a cylindrical bore in the bogie frame so as to permit rotational movement of the superstructure relative to the bogie frame about a vertical axis.

4. A railway bogie according to Claim 2 or Claim 3, wherein the coupling member incorporates a bolster member extending laterally across the bogie frame, and wherein on each side of the bogie two said link members are coupled between the superstructure and the bolster member, the said two link members lying in a longitudinal vertical plane, being symmetrically disposed about a lateral vertical plane, and being inclined downwardly towards said lateral vertical plane, the extensions of their lines intersecting at or near rail level.

5. A railway bogie according to Claim 3 or to Claim 4 as appendent to Claim 3, wherein said secondary spring means comprises a number of coil springs in compression between the superstructure and the bogie frame, the coil springs being fixedly located with respect to the bogie frame but in sliding contact, in a horizontal plane, with the superstructure, the upper ends of said coil springs being connected by auxiliary link means to the bogie frame and to the superstructure in such manner as to connect the said upper ends of the coil springs to the superstructure for relative transverse movement of the superstructure and bogie frame, and to the bogie frame for relative rotational movement of the superstructure and the bogie frame about the axis of said coupling member.

6. A railway bogie according to Claim 5, wherein the upper ends of said coil springs are coupled to the superstructure by horizontal link members extending radially from the coil springs towards the axis of said coupling member.

7. A railway bogie according to Claim 5 or Claim 6, wherein the upper ends of said coil springs are coupled to the bogie frame by horizontal link members extending in a longitudinal direction.

8. A railway bogie according to Claim 7 wherein the horizontal link members extending in a longitudinal direction are two in number, one being positioned on each side of the longitudinal vertical plane, the links further being on either the same side or opposite sides of the lateral vertical plane.

9. A railway bogie according to any of Claims 5, 6, 7 and 8, wherein said coil springs are in two groups, one group on each side of said coupling member, the upper ends of the coil springs of each group having a common housing to which said link members coupled.

10. A railway bogie according to Claim 3 or to Claim 4 as appendent to Claim 3, wherein said secondary spring means comprises a number of coil springs in compression between the superstructure and the bogie frame, the ends of each coil spring being fixedly located on the superstructure and the bogie frame respectively, so that any relative movement between the bogie frame and the superstructure in a horizontal plane is restrained by 'flexicoil' distortion of the coil springs.

11. A railway bogie substantially as hereinbefore described with reference to Figs. 1 to 4 of the accompanying drawings or to Figs. 1 to 4 as modified by Fig. 5.