Dampened Railway Car Truck

Abstract

A railway train having articulated vehicle bodies. A steering beam spans across each two adjacent vehicle bodies. Each beam is vertically pivoted or ball-jointed at points along the longitudinal center line of the adjacent vehicle bodies at some distance from the end of each vehicle body. The steering beam acts as a structure to which a suspension unit (bogie truck) is attached. The suspension unit is attached to the beam in a manner which permits the suspension unit to rotate in yaw about a vertical axis. The yaw rotation may be accomplished either freely or against the restraint of springs, viscous dampers or friction devices.

Parent Case Text

This application is a continuation-in-part of our U. S. application Ser. No. 849,322, filed Aug. 12, 1969, and now abandoned.

Description

This invention relates to railway trains and is directed to the problem of steering railway vehicles making up a train round curved track.

The object of the invention is to provide a mechanism for articulated trains that (a) provides geometric steering of suspension units (bogie trucks) between vehicles into an attitude substantially tangential to the track when on curves of constant curvature and (b) permits gross yaw misalignments of the suspension units relative to the vehicle centerlines so that curves of varying curvature, particularly reverse curves (S- curves), can be negotiated without risk of derailment.

According to this invention a railway train comprises at least two vehicle bodies articulated at their adjacent ends to restrain relative lateral displacement therebetween but to permit relative angular displacement therebetween, a rigid beam (hereinafter termed a "steering beam" connected at its ends to the two vehicle bodies at a distance longitudinally of the vehicle bodies from their articulated connection with each other and in a manner permitting said relative angular displacement of said vehicle bodies, and a suspension unit including at least one wheelset mounted on said beam, the suspension unit being attached to the steering beam in a manner which permits it to rotate in yaw about a vertical axis.

Preferably said vertical axis passes through the body articulation point on straight track.

The yaw rotation may be accomplished either freely or against the restraint of springs, viscous-dampers or friction devices.

The invention will now be further explained with the aid of the accompanying drawings, in which:

FIG. 1 shows a schematic plan view of an intermediate vehicle and its two adjacent vehicles in a train having a configuration according to the invention and negotiating a curved track of constant curvature; the radius of curvature of the track related to the length of the vehicles has been shown much smaller than would be experienced in practice so that the relative displacements of the vehicle bodies etc. when the train is negotiating curved track can be readily appreciated from the drawings.

FIG. 2 shows a schematic plan view of two of the adjacent vehicles shown in FIG. 1 negotiating a reverse curve.

FIG. 3 is a side elevation of one form of connecting and suspension arrangement at the adjacent ends of adjacent vehicle bodies of the train.

FIG. 4 is a plan view of the arrangement shown in FIG. 3,

FIG. 5 is a side elevation of a second form of connecting and suspension arrangement at the adjacent ends of adjacent vehicle bodies of the train, and

FIG. 6 is a plan view of the arrangement shown in FIG. 5.

In FIGS. 1 and 2 the vehicle bodies 1, 2 and 3 are represented by their longitudinal center lines and the track 4 is represented by its center line. The vehicle body 1 is articulated to the bodies 2 and 3 at joints J. Extending across each of the joints J between the bodies 1 and 2 and bodies 1 and 3 are steering beams S. Each steering beam S is connected at points S.sub.1 and S.sub.2 to the two associated vehicle bodies by pin joints or other means of lateral constraint on the longitudinal center lines of the bodies 1, 2 and 3 and which permit the bodies 1, 2 and 3 freely to take up their relative angular position on curved track.

Each of the steering beams S carries a suspension unit in the form of a bogie with two wheelsets W.sub.1 and W.sub.2, the wheelsets being of a kind having their axles mounted for rotation in axle boxes and their wheels connected for rotation with the axles. Each suspension unit, as described hereinafter with reference to FIGS. 3 to 6, is mounted for yaw rotation about a vertical axis which in straight track passes through the articulation points J.

Throughout the length of the train up to the leading and last vehicle bodies the arrangement will be similar to that shown in FIGS. 1 and 2.

Referring to FIG. 1, the ratio between the lengths b.sub.1 and b.sub.2 is chosen so that the steering beam lies substantially tangential to the track at point T. Clearly, if the vehicle bodies are of equal lengths so that the vehicle body points of tangency Q.sub.1 and Q.sub.2 are at the mid-lengths of the vehicles, the steering-beam is symmetrical about point T, i.e. b.sub.1 = b.sub.2. The case where b.sub.1 does not equal b.sub.2 is considered below. When the vehicles articulate as shown in FIG. 1, i.e., when the steering beam is tangential, it is evident that the suspension unit carried by the steering-beam S is steered into a tangential position without resultant yaw rotation between the suspension unit and the steering beam. The steering beam thus acts as a coarse steering mechanism for the axles. Since the two axles are each displaced by distances afrom the point of tangency T, they are not steered by the steering beam into perfect radial alignment. However, provided the error is small, creep forces (friction forces due to microslip between wheel tread and rail) are, within the limits of adhesion, able to yaw the axles more nearly into the desired radial alignment against the restraint of primary yaw suspension springs.

Since the triangle S.sub.1 JS.sub.2 in FIG. 1 varies in size as a function of track curvature, relative longitudinal freedom must be incorporated into one of the joints, S.sub.1, J, or S.sub.2. Conveniently, joint J is chosen to have longitudinal freedom, so that the steering beam can act as a coupling member between adjacent vehicles, and so transmit traction, braking, and longitudinal buffing forces down the train.

FIG. 2 shows a schematic plan-view of two vehicles negotiating a reverse curve, the suspension unit being shown as straddling the point of inflection of the track. In this case, the center lines of two adjacent vehicle bodies may be substantially in line, so that the steering beam cannot be aligned tangential to the track. It follows, however, that the suspension unit must rotate in yaw relative to the steering beam by angle .psi. in order to negotiate the curve. Therefore, the suspension unit must be pivoted, actually or effectively, at a single point on the steering beam. Also, the restraint in yaw must not be excessive, otherwise a dangerous tendency to derail may ensue.

Although a two-axled bogie suspension unit is shown in FIGS. 1 and 2, the suspension unit could equally be single-axled, three-axled, etc.

As mentioned above the lengths b.sub.1 and b.sub.2 have to be different if the steering beam S is to take up a tangential attitude on constant curvature track when the beam is attached to vehicles of dissimilar lengths. Q.sub.1 and Q.sub.2 are the points along the vehicle bodies which are chosen to be tangential to constant curvature track. Assuming that the track center line radius Ro is very large compared with the vehicle dimensions, we may write, for the steering beam to be tangential at point T,

JS.sub. 1 T = j.sub. 1 /Ro

JS.sub. 2 T = j.sub. 2 /Ro

where j.sub.1 and j.sub.2 are the distances shown on FIG. 1. Therefore, the throwover distance TJ may be written as

b.sub. 1 j.sub.1 /Ro = b.sub. 2 j.sub.2 /Ro

Hence, if length b.sub.1 is specified, from consideration of other factors, length b.sub.2 must be arranged to be

b.sub.2 = j.sub.1 /j.sub.2 b.sub.1

Referring now to FIGS. 3 and 4, these show the suspension and interconnecting arrangement at the adjacent ends of two adjacent bodies. For convenience the arrangement will be considered as that at the adjacent ends of vehicle bodies 1 and 2 of FIGS. 1 and 2.

In FIGS. 3 and 4 the articulation joint J is represented by ball joint 26, the steering beam S by member 24 and the joints S.sub.1 and S.sub.2 by ball joints 25.

The suspension unit comprises a bogie frame (i.e. a truck frame) 11 supported on the axles boxes 12 of wheelsets W.sub.1 and W.sub.2 via primary vertical and yaw suspensions represented diagrammatically at 12'. A secondary frame 33 is connected to the bogie frame 11 by swing links 34 providing a lateral suspension. The steering beam 24 is supported on the secondary frame 33 and hence on the bogie frame by vertical springs 35. The weight of the bodies 1 and 2 is supported in turn by the steering beam 24.

Connected between the bogie frame 11 and the steering beam 24 is a yaw suspension of the relaxation type. In this yaw suspension the bogie frame 11 is connected rigidly in yaw by rods 13 to the cross beam 16 pivoted at 40 to the steering beam. This beam 16 is restrained in yaw to the steering beam by viscous dampers and springs, 22 and 23, in series. Thus the whole bogie pivots against the yaw suspension about the vertical axis provided by pivot 40.

Referring now to FIGS. 5 and 6, this shows an alternative arrangement to that shown in FIGS. 3 and 4. As far as possible the same reference numerals have been used for parts having corresponding parts in the FIGS. 3 and 4 arrangement.

A rigid longitudinal steering beam 24 interconnects the two adjacent bodies 1 and 2, the vehicle bodies being connected to the beam by universal joints 25 and interconnected at their adjacent ends by a universal joint 26. A pair of the transverse beams 16 are pivotally mounted at their centers to the steering beam 24 at each end thereof. A pair of load bearing swing arms 13' are pivotally mounted to the ends of each of the beams 16 and connect to a respective end frame 11' each end frame carrying a wheelset. A pair of combined dampers and springs 22/23 are connected between the beams 16 and the beam 24 as shown in FIG. 6.

An intermediate frame 27 is arranged between the two end frames 11' and is supported on the end frames 11', being connected thereto at each end by a pair of vertical links 28 provided with a ball joint 29 at each end. A transverse tie rod 30 or some other device is connected between each end frame 11' and a longitudinal extension 31 of the intermediate frame 27 and restrains lateral movement but allows relative longitudinal and yawing movements between the end frames 11' and the intermediate frame 27. Ball joints 32 are provided at each end of the tie rod 30. Other forms of vertical support which do not restrict relative horizontal movement between the frame 27 and the frames 11' can be used.

A secondary frame 33 is suspended from the side members of intermediate frame 27 by way of transverse swing links 34 or other lateral suspension which allow only transverse relative movement between the secondary frame 33 and the intermediate frame 27. A vertical spring 35 is arranged between the secondary frame 33 and the steering beam 24. This spring 35 provides the main vertical springing for the vehicle.

The secondary frame 33 is restrained relative to the steering beam 24 for example by means of tie rods or guides (not shown) to allow only vertical and yawing motions of the secondary frame, and hence the intermediate frame 27, relative to the steering beam 24. Longitudinal and transverse movements of the secondary frame 33 relative to the steering beam 24 are prevented by these tie rods. Similarly since the swing links 34 only allow relative transverse movement between the secondary frame 33 and the intermediate frame 27, the latter is also prevented by the tie rods connected between the secondary frame and the steering beam, from moving longitudinally relative to the steering beam 24.

When the vehicle bodies 18 move sideways relative to the wheelsets in a pure lateral motion when the vehicle is travelling on a straight section of track, the steering beam 24 also moves laterally and carries the secondary frame 33 with it by way of the tie rods. The intermediate frame 27 is tied to the two end frames 11' by the lateral tie rods 30 and is thus prevented from following this lateral movement of the secondary frame 33 which thus moves laterally relative to the intermediate frame 27 on its swing links 34. As the beam 24 moves laterally, the two transverse beams 16 are carried with it and the two pairs of swing arms 13' swing sideways to a position at an angle to the direction of travel of the vehicle. This sideways movement of the swing arms 13' causes each of the frames 11' to move to a short distance longitudinally towards the beams 16, away from the intermediate frame 27, causing the vertical links 28 to pivot longitudinally of the track, outwardly from the frame 27. The lateral tie rod 30 also pivots relative to the arm 31 on its joints 32.

One or more dampers (not shown) are connected for example between the steering beam 24 and the intermediate frame 27 to damp out these lateral movements of the vehicle relative to the wheelsets.

When the railway vehicle goes round a curve in the track, the vehicle bodies 1 and 2 and the steering beam 24 move to take up the position shown in FIG. 1.

If we assume that the vehicle as shown in plan in FIG. 6 is rounding a curve whose center of curvature is towards the bottom of the sheet, the vehicle bodies 1 and 2 and the steering beam 24 will move, relative to the wheelsets, towards the top of the sheet. The left hand end frame 11' will yaw anti-clockwise and the right hand end frame 11' clockwise. If the curve is of constant radius both end frames 11' will yaw, relative to the steering beam 24 by approximately equal amounts and the intermediate frame 27 will remain substantially unyawed with respect to the beam 24. The ball joints 29 at the ends of the vertical links 28 allow the links 28 to move longitudinally so allowing the end frames 11' to yaw relative to the intermediate frame 27. Each of the end frames 11' is provided with projecting arms 36 on either side of the arm 31 on the intermediate frame 27. Resilient members 37 may be positioned between these arms 36 and each of the arms 31 to control the yawing movements of the frames 11' relative to the intermediate frame 27. For yawing movements greater than a predetermined maximum, one of these resilient members 37 will become fully compressed and further yawing movement of the wheelset relative to the intermediate frame 27 will be prevented. In this way excessive yawing motions of the end frames 11' are prevented.

If the radius of the curve is non-uniform, in particular if the curve is a reverse curve (S-curve), gross yaw misalignments must be allowed between a longitudinal line joining the wheelset centers and the steering beam 24. Relative to the beam 24, one frame 11' is displaced laterally in one direction and the other frame 11' is displaced in the opposite direction. As a result the intermediate frame 27 and the secondary frame 33 yaw substantially about the central point of the beam 24 that is in effect about vertical axis 40. The motions are also accompanied by yawing of the two end frames 11' so that the two transverse beams 16 are activated by the swing arms 13' to yaw together in the same sense. Thus the suspension unit will take up the position of FIG. 3.

Since yaw movements of these beams 16 may be rapid and lead to substantial angular displacements of the beams, a device is incorporated into the yaw suspension to ensure that excessive forces are not generated which could result in derailment. The yaw suspension comprising springs 23 and dampers 22 is fitted with blow-off valves in the dampers so that pressures are limited to a pre-determined maximum. Similarly, if a spring and friction slide arrangement is used, the `break-out` friction force is set to an acceptable level.

Thus in the arrangement of FIGS. 5 and 6 the rotations in yaw of the suspension unit are about an effective vertical axis 40, not an actual pivot. This is accomplished by combined in-phase yaw movements of the two beams 16 and anti-phase lateral movements of frames 11' relative to the steering-beam. The basis of this suspension unit is the parallel linkage arrangements of beams 16, arms 13', and frames 11'. An important feature of this suspension unit is the facility of frames 11' to yaw relative to each other under the control of springs 37 and links 30, so that the wheelsets can adopt nearly a radial alignment on curves under the action of creep forces.

Claims

We claim:

1. A railway train comprising:

a. at least two vehicle bodies articulated at their adjacent ends to restrain relative lateral displacement therebetween but to permit relative angular displacement therebetween.

b. a rigid beam connected at its ends to the two vehicle bodies at a distance longitudinally of the vehicle bodies from their articulated connection with each other and in a manner permitting said relative angular displacement of said vehicle bodies, and

c. a suspension unit including at least two wheelsets, the suspension unit being attached to said beam in the region of the mid-length of said beam in a manner which permits it to yaw relatively to said beam about a vertical axis between the wheelsets.

2. A railway train according to claim 1, wherein said vertical axis passes through the articulation point of the vehicle bodies, when the vehicle bodies are on straight track.

3. A railway train according to claim 1, wherein said suspension unit comprises a frame in which are mounted at least two wheelsets, said frame being pivotally connected to said rigid beam through a yaw suspension for rotation against the restraint of said yaw suspension about said vertical axis.

4. A railway train as claimed in claim 3, wherein said wheelsets are mounted in said frame through a further yaw suspension permitting a restrained yawing movement of said wheelsets relatively to said frame.

5. A railway train as claimed in claim 1, wherein said suspension unit comprises an intermediate frame connected to said steering beam through a lateral suspension arrangement, a first end frame carrying a first wheelset and connected at one end to one end of the intermediate frame and at its other end to said beam through a yaw suspension so that it can yaw relatively to said beam and the intermediate frame and a second end frame connected at one end to the other end of said intermediate frame and at its other end to said beam through a yaw suspension so that it can yaw relatively to said beam and the intermediate frame, said intermediate frame being connected to said end frames so that it is restrained from lateral movement relative to said end frames.

6. A railway train comprising:

a. at least two vehicle bodies articulated at their adjacent ends to restrain relative lateral displacement therebetween but to permit relative angular displacement therebetween,

b. a rigid beam connected at its ends to the two vehicle bodies at a distance longitudinally of the vehicle bodies from their articulated connection with each other and in a manner permitting said relative angular displacement of said vehicle bodies,

c. at least two wheelsets located in the region of the mid-length of said beam, and

d. a yaw suspension through which said wheelsets are mounted to said beam and which restrains said wheelsets against angular movements in a horizontal plane.