IE51214B1 - Bogie with steerable axles - Google Patents

Abstract

1. Suspension for railway vehicle underframe having two axles, at least one of the axles being mounted, in the vinicity of each of its ends, in an axle box (7), this suspension (6) comprising, for each box (7) of this axle (4), elastic means (9) supported by the axle box and which, on each side of this latter, are applied against the underframe through the intermediary of at least one connecting link pivoted with respect to the underframe (1) and with respect to that end of the elastic means (9) which is associated with the underframe, the two lines (XX', YY') of application of the forces to which these links (13, 14) are subjected and which pass through the pivot points (16, 17, 21) of these latter having opposite inclinations (A, B), one of the links (14) being mounted in tension, and coupling means arranged between the axle box (7) and the pivots (16) connecting the links (13, 14) to the elastic means (9) so that any displacement of the axle box in a longitudinal direction of the underframe (1) produces a corresponding displacement of these pivots (16), characterized in that the upper link (13) is mounted in compression, that the two links (13, 14) have different inclinations (A, B), and that the underframe carries a reference face (31) against which the axle box (7) is applied in a straight line under the action of the threshold of force exerted on it by reason of the difference in inclination of the links (13, 14).

Description

The present invention relates to a suspension for an underframe for a railway vehicle, such as a wagon, having at least two axles.

In the present specification, mechanical 5 means, in part deformable, connecting the axles to the underframe are described as the suspension, the underframe being either that of a wagon having at least two axles or that of a bogie which is pivoted on the frame of a wagon having several bogies.

The present invention also relates to an underframe provided with this suspension.

Xn the particular case of wagons having two axles, each axle, mounted at each end in an axlebox, is held perpendicular to the axis of the underframe by spring systems provided with dampening means, each of which connects an axlebox to the underframe.

In the particular case of wagons having bogies with at least two axles the mounting is similar. According to a particular embodiment according to FR-E-82179, each axlebox supports the underframe by means of at least two helical compression springs mounted on either side of the axle. A spring is compressed between the axlebox and a cap on which part of the weight of the wagon acts. For each axlebox, the underframe rests on one or more springs supported by the axlebox, while the cap is urged obliquely downwards by means of a link connected to the underframe. The axlebox is friction-mounted between a planar reference surface of the underframe and a pushrod moved by the cap which tends to press the axlebox against the reference surface due to the fact thst the pull caused by the link is at an oblique angle. - 3 This mounting provides for simultaneous dampening of spring oscillations and exact positioning of the axle perpendicular to the axis of the underframe.

These suspensions operate in a satisfactory manner on straight track. On the other hand, when the underframe moves along a section of curved track, significant friction between the wheels and the permanent way is caused by the two axles being held simultaneously in a position which is perpendicular to the axis of the underframe. This friction entails premature wear on the wheels, in particular of the shouldered portion or flange of the wheels and of curved sections of the permanent way. Moreover, bogies constructed in this way have difficulty in taking raised curves and certain wagons are known to have even become derailed on sharp curves.

The French Patent FR-A-1072 207 discloses a suspension which is consistent with the preamble of claim 1, and overcomes the above disadvantages. According to this document, both links are tension links, which are symmetrically arranged when the vehicle moves on a straight track, the axlebox being then in a middle position between two limits of longitudinal clearance.

This arrangement has two drawbacks. The straight track position has some stability, for when the axle is deflected towards one side or the other, an increasing return force is generated. However, this stability is not excellent, and some zig-zag effects can be recorded on rectilinear tracks. On the other hand, the increasing return force considerably hinders the axle needing a high deflection in a sharp curve.

The object of the invention is to overcome these drawbacks by providing a suspension in which the axles have a more stable straight line position while following more easily sharp curves. - 4 This object is attained by using the means which are set forth in the characterizing part of claim 1. The difference between the inclinations of the links provides a biasing force urging the axle box against the reference face.

Thus, on a straight track, the axle is in a position which is well-determined by the reference face. For separating the axle therefrom, a little perturbation is no longer sufficient; a force exceeding the force thres hold determined by the difference of inclination between the links is necessary. The axle is thus very stable on a straight track. On curves, such a force exceeding the aforesaid threshold appears. However, as a result of the combination of the tension link with the compression link the initial difference of inclination between the links remains substantially the same while the axlebox travels away from the reference face.

This difference of inclination thus provides a biasing force which, instead of increasing, changes only a little as a function of the axlebox deflection with respect to the position where said box engages the references face. The axle, once having overcome the biasing force, can thus easily get an appropriate orientation, even on sharp curves.

Preferably, the elastic means comprise at least two springs mounted on either side of the axle, at least one spring on each side of the axle being disposed between the box and a cap connected to the underframe by the connecting links.

According to another object of invention the underframe having two axles provided with a suspension of the type described above is characterised in that this suspension is fitted to the two axles of the underframe, the pivot links mounted in tension and in compression occupying, in the both axles, positions substantially symmetrical relative to the transverse median plane of - 5 51214 the underframe.

Thus, both axles of the underframe can be oriented with respect to the underframe as a function of the curvature of the permanent way, which limits angular deviations of the axles in relation to the underframe; also, the behaviour of the underframe is substantially the same, whether the wagon travels in one direction or the other on the permanent way, which is especially advantageous in the case of railway equipment.

Other features and advantages of the invention will become more evident from the following description. - 6 In the attached drawings, which are given as non-limiting examples: Figure 1 is a view in side elevation of a bogie in which the two axles are equipped with the suspension according to the invention; Figure 2 is a half front view of the bogie of Figure 1; Figure 3 is a partial top view of the bogie of Figure 1, Figure 4 is a schematic view, to an enlarged scale, in partial cross-section, of one of the suspensions of the underframe of Figure 1; Figure 5 is a similar view to Figure 4, but is more diagrammatical, showing in broken lines the position taken by the various parts in the case of lateral movement of the axlebox in relation to the underframe.

The bogie illustrated in Figures 1 to 3 includes an underframe which comprises two sideframes 1 connected by a central cross-member 32 and two end cross-members 2 forming with the sideframes 1 a frame supported by four wheels 3 coupled in pairs by means of two axles 4.

Each axle 4 is connected at each end to the underframe through a suspension 6 disposed outside the corresponding wheel 3 in relation to the mid-point of this axle 4.

As shown in particular in Figure 4, each axle 4 is supported at its two ends by an axlebox 7 in which ball-bearings are housed, which allow rotation of the axle 4 in relation to the underframe.

The axlebox 7 has two base-plates 8 extending on either side of the axle 4 at a spacing below the sideframe 1, and on each of which the lower end of a spiral suspension spring 9 bears.

The springs 9 are compressed between these two base-plates 8 and two caps 11, 12 connected to the underframe and on which a part of the weight of the wagon acts, in service.

According to the invention, each of the caps 11, 12 is 5 connected to the sideframe 1 by a pair of connecting links 13 or 14.

The two links 13 or 14 of a single pair are mounted in parallel and pivoted to the corresponding cap 11 or 12, which for this purpose carries on its sides two opposed pivots 16 having an axis substantially parallel to the axle 4.

The links 13 consist of small struts which are mounted in compression between the cap 11 and the underframe 1. From the pivot 16, the links 13 extend on the opposite side from the base plate 8 and are fixed to a pin 17 which pivots in the sideframe 1.

The links 14 are rings mounted in tension between the cap 12 and two ears lb which .re solid with the sideframe 1. These ears 18 are provided at the end of a wing 19 of U-section extending from the sideframe 1 towards the base plate 8; they are an extension of the legs of the U, which are turned towards the spring 9 and they come therefore on either side of the spring. Each link 14 is pivoted to the ear 18 by means of a pivot 21, carried by this ear 18, which extends towards the outside of the wing 19 in a U-shape, with an axis substantially parallel to the axle 4, and nearer the base plate 8 than the pivot 16 of the cap 12. - 8 512 14 In the example shown the distance separating the pivots 16 of the cap 11 from the pin 17 is greater than the distance separating the pivots 16 of the cap 12 from the pivots 21.

As shown in Figure 4, the line XX' which joins the pin 17 and 5 the pivot 16 of one or the other of the links 13 and the line YY1 which joins the pivots 16 and 21 of the link 14 which faces it are inclined in opposite directions to each other in relation to the axis ZZ1 of the springs 9 which is substantially vertical when the bogie is in a working position on a horizontal permanent way and these lines converge downwardly, below the axlebox 7. Also the angle of inclination B of the line YY' is greater than the angle of inclination A of the line XX' in relation to the axes ZZ' in the example illustrated. However, an exchange of the positions of the ring 14 and the small strut 13 in relation to the median axis of the axlebox may be envisaged. In this case the angle A of the small strut must be greater than the angle B of the ring.

The inclination of the lines XX' and YY', which are substantially the lines of action of the forces on the caps 11 and 12, determines a pull of the caps towards one another and towards the axlebox 7.

Under the effect of this pull, the caps 11 and 12 bear on one side or the other of the axlebox 7 by means of two opposing pushrods 23. The pushrods 23 comprise a tail 24, the end of which bears against the caps 11, 12, and the tail is slidably mounted in a bore 26 provided in the bjse of the U of the wing 19 for one of the pushrods 23 - 9 and, for the other pushrod 23, in a wing 22 solid with the sideframe! and facing the base of the U of the wing 19 on the other side of the axlebox 7.

The pushrods 23 also comprise a head 27, the front surface of which, which is flat, bears against the flat side surfaces of the axlebox 7. Friction rings 28, 29 in steel or manganese for example, are welded onto the front surfaces of the heads 27 of the pushrods 23 as well as onto the flat side surfaces of the axlebox 7.

The pushrods 23 cannot penetrate into the bores 26 beyond a fully retracted position in which the rear surface of their heads 27 abuts against a boss 31 in which each of the bores 26 emerges on the side of the axlebox 7.

The bogie illustrated in Figure 1 includes at the two ends of each of the axles 4 a suspension of the type which has just been described. The mounting of these suspensions is symmetrical in relation to the transverse median plane of the bogie, so that for each suspension, the links 13 which work in compression are associated with the spring 9 disposed opposite the other axle 4 in relation to the axlebox 7 in question and these links having a lesser inclination than the links 14 which work in tension.

The operation of the suspension described above is as follows: The forces which act on the caps 11, 12 designated as Rl and R2 in Figure 4 have a component Pl or P2 directed along 11' and a component Fl or F2 directed along the axis of the pushrods. The components Pl and P2 which tend to compress the springs 9 are substantially equal, while, due to the difference in the - 10 inclination of the lines XX' and YY', the component Fl applied to the cap 11 is less than the component F2 applied to the cap 12.

When the bogie travels in a straight line, this difference between Fl and F2 pushes the axlebox 7 towards the cap 11, so that the pushrod 23 associated with this cap 11 is in its retracted position with its head 27 abutting against the boss 31. This arrangement allows a stable equilibrium to be taken up by the two axles in the course of movement of the wagon in a straight line.

In this position, the axes of the pushrods 23 are disposed in the same plane as the axes of the pivots 16 of the caps 11, 12.

Also, the distance D (Figure 5) existing between the rear surface of the head 27 of the pushrod 23 associated with the cap 12 and the corresponding boss 31 determine the maximum lateral travel of the axlebox 7 in relation to the chassis. In the case of a bogie, the distance D can be 12mm for example.

Due to the symmetry of the bogie suspensions in relation to the median plane of the bogie, on each side of the bogie the wheels 3 are spaced as far as possible from each other.

Also, when the wheels 3 encounter unevenness in the permanent way, the axlebox takes yp, in relation to the chassis, oscillations which are dampened by the friction of the rings 28 of the pushrods 23 on the rings 29 of the axlebox 7.

When the bogie reaches a curve, the flange of the wheel 3 which is on the outside of the curve and which belongs to the axle 4 arriving in the lead, bears against the rail and tends to lie flat against it. - 11 This effect exerts on the axle 4 a moment which tends to push the axlebox 7 on the outside of the curve to a greater degree against the pushrod 23 which is already in a retracted position, and tends to pull back the other axlebox 7 in the direction of the cap 12.

If the force being exerted by this moment on the axlebox 7 on the inside of the curve is greater than the difference between the forces FI and F2, this displacement of the axlebox 7 takes place and the axlebox takes up, for example, the position illustrated in broken lines in Figure 5.

In this position, the displacement of the axlebox 7 has brought about a corresponding displacement of the caps 11, 12 so that there is no fear of any lateral deformation of the springs 9.

The links 13 and 14 have pivoted about the pin 17 and the pivots 21 so that the cap 11 is also moved slightly upwards towards the sideframe 1 while the cap 12 is on the other hand moved nearer the base plate 8.

In the course of this displacement of the axlebox 7, the inclinations of the lines XX'. and YY' both increase, so that the difference between components FI and F2 does not vary in any substantial waY and can even be held substantially constant.

This property constitutes one of the considerable advantages of the suspension according to the invention as it permits axles to take tight curves, with it being necessary for the force applied to the boxes 7 by the wheels 3 to be unduly increased. - 12 As soon as the second axle 4 reaches the curve of the permanent way, the flange of its wheel 3 on the outside of the curve bears against the rail and tends also to displace the axlebox 7 on the inside of the curve towards the cap 12.

Thus, the two wheels 3 on the inside of the curve tend to approach one another while the other two wheels 3 remain at a distance from each other which is substantially unchanged.

The suspension according to the invention thus permits the simultaneous dampening of oscillations and steering of the axle 4 to be provided with a greatly reduced number of parts.

The invention also offers an excellent compromise between an exact positioning of the axles 4 on straight track and a sterring of the axles 4 in a curve produced by relatively moderate forces Of course, the invention is not limited to the examples described and numerous modifications can be applied to these examples without departing from the scope of the invention.

Thus links working in tension could be connected to the spring opposite the other axle of the underframe in relation to the axlebox in question, and be less inclined than the links working in compression.

Also, it may be necessary to equip only one axle with the suspension according to the invention.

Claims (6)

1. Suspension for railway vehicle underframe having two axles, at least one of the axles being mounted, in the vicinity of each of its ends, in an axlebox , this suspension comprising, for each box of this axle , elastic means supported by the axlebox and wnich, on each side of this latter, are applied against the underframe through the intermediary of at least one connecting link pivoted with respect to the underframe and with respect to that end of the elastic means which is associated with the underframe, the two lines of application of the forces to which these links are subjected and which pass through the pivot points of these latter having opposite inclinations one of the links being mounted in tension, and coupling means arranged between the axlebox and the pivots connecting the links to the elastic means so that any displacement of the axlebox in a longitudinal direction of the underframe produces a corresponding displacement of these pivots, wherein the upper link is mounted in compression, the two links . have different inclinations and the underframe carries a reference face against which the axlebox is applied in a straight line under the action of the threshold of force exerted on it by reason of the - 14 difference in inclination of the links.

2. Suspension in accordance with claim 1, wherein the two lines . of action of the forces to which the links are subjected 5 converge downwardly, and the coupling means comprise two opposing friction push-rods interposed between the axlebox and the pivot connecting the links to the elastic means.

3. Suspension in accordance with either claim 1 10 or claim 2, wherein the elastic means comprise at least two springs mounted on each side of the axle , at least one spring on each side of the axle being located between the box and a cap connected to the underframe by the connecting 15 links

4. Suspension in accordance with any one of claims 1 to 3, wherein the coupling means associated with the pivot link in compression are intended to exert on the axlebox a lateral force 20 which is lower than the force exerted by the coupling means associated with the pivot link in tension. 5. Suspension in accordance with any one of claims 1 to 4, in which the coupling means are push-rods 25 wherein, in a position of equilibrium in a straight line, the push-rod which is intended - 15 to exert the weakest lateral force on the axlebox is fully retracted and bears against the reference face. 6. Suspension in accordance with claim 5, 5 wherein the fully retracted push-rod in a position of equilibrium in a straight line is located opposite the other axle relative to the axlebox . 7. Underframe having two axles provided with a suspension in accordance with any one of claims 1 to 6, 10 wherein this suspension is fitted to the two axles of the underframe, the pivot links mounted in tension and in compression occupying, in both axles , positions substantially symmetrical relative to the transverse median plane of the underframe. 15 8. A suspension for an underframe of a railway vehicle substantially as herein described with reference to the accompanying drawings. Dated this 27th day of February 1981. BY: TOMKINS & CO., cants'Agents, (Signed): j

5. Dartmouth Road, DUBLIN

6. USINES ET ACIERIES DE SAMBRE ET MEUSE