GB2295130A

GB2295130A - Drawbar coupling for railway wagons - uses elastic sleeve to reduce wear

Info

Publication number: GB2295130A
Application number: GB9523556A
Authority: GB
Inventors: Voitto Riihiaho; Timo Heikkinen; Olavi Maeenpaeae; Pasi Kaikkonen
Original assignee: Rautaruukki Oyj
Current assignee: Rautaruukki Oyj
Priority date: 1994-11-18
Filing date: 1995-11-17
Publication date: 1996-05-22
Also published as: FI97041C; FI945431A0; SE508565C2; FI97041B; DE19543183A1; GB9523556D0; SE9503842L; SE9503842D0

Description

1 jitle: Improvements in or relating to railway wagons

Field of the invention

2295130 The invention relates to railway wagons and particularly concerns coupling of adjacent wagons to form a wagon unit.

Backeround to the invention A typical railway wagon comprises a chassis with a respective wheel truck at each end. Adjacent wagons are linked by a variety of different couplings.

A coupling device of a "central buffer type" is very frequently used. This consists of a buffer bar attached by means of a joint located on the longitudinal axis of a wagon and carrying at its outer end a coupling unit for coupling to another similar buffer bar on an adjacent wagon. Such central buffer type coupling devices are generally provided with flexible means, and in some cases they include means for providing compressed air and liquid communications between the wagons, possibly with further optional communications in the coupling unit. Figure 1 of US Patent No 4 580 686 illustrates a prior art slackless central buffer type in which longitudinal and transverse forces are exerted against the joint point as successive railway wagons pass into a curve. Figure 2 of US 4 580 686 illustrates the forces exerted by this central buffer type coupling as successive railway wagons run on a straight rail section, for instance in a braking situation. The relatively great lateral forces illustrated are due to the fact that the joint point in the buffer bar of this prior art central buffer is placed relatively close to the wagon end, so that the buffer bar is short. A study, not presented in this specification, leads to the conclusion that the lateral forces exerted on the wagon depend on the distance between the truck centres in the wagon, the distance between the truck centres of two adjacent wagons, and the distance between the turning joint of the coupling bar and the centre of the truck at the same wagon end.

0 1 DE Patent Specification No 42 26 731 depicts a similar coupling based on a short drawbar. In this case, however, the drawbar is stationary at the successive wagon ends and no coupling units are provided between the wagons. Instead, the wagon ends with their associated drawbars are replaceable, so that this drawbar coupling may be replaced with a conventional coupling, e.g. based on buffers and a hook attachment. The drawbar coupling described DE 4226731 has all the drawbacks described above, and in fact, the reference relates to the exchangeable end part of the wagon.

The invention described in US 4 580 686 attempts to reduce lateral forces caused by curves and braking by replacing a previously known coupler of central buffer type with a solid slackless drawbar, whose turning joints have been brought as close as possible to the truck centres, as illustrated in Figure 3 of the reference. Thus the distance between the turning joint of the drawbar and the truck centre is reduced, and with the train running in curves, the lever arm of the force turning the wagon to the side is reduced, as described in the reference. It is particularly advantageous to replace this short central buffer with a solid longitudinal drawbar in cases where the wagons do not have to be decoupled very often. This is due to the fact that flexible central buffers including couplers are very complex and expensive components, and are also subject to wear, and hence often malfunction. However, the long drawbar described, with its turning joint close to the truck centre, is hard to implement with a truck of European type which includes a generally rectangular bar or side member surrounding the truckwheels, as the side member prevents the turning joint from being placed close to the truck centre. Nonetheless, US 4 580 686 primarily concerns the design of the drawbar joint, recommending the use of a ball pivot without play. Such a ball pivot has the very serious drawback that the motion of the ball in the pivot relative to the joint housing wall causes considerable wear and corrosion while the train is running, thus entailing high repair cost. The absence of flexible means causes impact load on the joint, thus increasing wear. Since a long drawbar including joints is difficult to overhaul and replace without decoupling the wagons in the train unit, the design described here is rarely used.

End overhangs in railway wagons, that is the distance between the midpoint or centre of a truck and the adjacent wagon end, are small, nearly always less than about 10% of the 0 3 distance between truck centres, due partly to permitted loading gauges and partly to allowed lateral forces. In fact, an increase in the wagon end overhang will increase transverse forces in several ways, and also readily results in exceeding the permitted lateral loading guage.

Summary of the invention

According to the present invention there is provided a wagon unit comprising two railway wagons linked by a coupling, each wagon comprising a chassis with a respective wheel truck adjacent each end, the coupling comprising a drawbar attached by means of respective joints to end regions of the chassis of the wagons, the distance, L2, between the centre of a truck and the adjacent wagon end being at least about 15% of the distance, LI, between the truck centres of a wagon, and each joint between the drawbar and the wagon chassis comprising a sleeve of an elastic material located between and fixedly secured to both a joint pin in the wagon chassis and a joint housing in the drawbar, in order to provide a non-wear joint construction.

In accordance with the invention, it has now surprisingly been found that the end areas of the railway wagon can be appreciably reduced by using a long drawbar (which may be of known construction) as a coupling between the wagons, by shifting the coupling joint between the drawbar and the wagon from the area of the truck towards the wagon end, and by forming this joint between the drawbar and the wagon by means of a sleeve of a flexible material which is stationary relative to the wagon and the drawbar. First, such a design can provide a large wagon end overhang calculated from the truck centre, and sufficiently small angles between the drawbar and the wagon centre line, and consequently lateral forces can be kept within safe limits. A second advantage of the invention is that the joint design has been carried out with stationary elements, so that, under the effect of the long drawbar, relatively small angular variations alone between the wagon longitudinal line and the drawbar length are received and transmitted merely by means of a deformation of the elastic sleeve, so that wear of the joint components is avoided.

The invention can, in preferred embodiments at least, allow an appreciable increase in the 0 4 overall length of a railway wagon compared to the length allowed by conventional techniques, while nevertheless, meeting construction regulations regarding railway rolling stock, which limit the wagon loading gauges because of the limited dimensions of the railway network, and the turning joints of couplings between the wagons because of safety.

The invention can also provide an arrangement that can allow a train to be run on ramps onto a ship and back without interference of the coupling between the wagons. This implies that the drawbar between the wagons must be able to pivot also vertically over an angle of at least +2'. Further, the joint design of the coupling between the wagons has the advantage of not being exposed to wear or corrosion, and having as straightforward a design as possible.

An embodiment of the invention will be described below, by way of illustration, with reference to the accompanying drawings, in which:

Figure 1A is a side view of two adjacent railway wagons forming a wagon unit in accordance with the invention, seen from direction I in Figure 1B; Figure 1B is a top plan view of the railway wagons of Figure 1A, seen from direction II in Figure 1A; Figure 1C is a view similar to Figure 1B, showing the wagons of Figures 1A and 1B on a curve; Figure 2A is a side view of one end of one of the wagons of Figure 1, to an enlarged scale; Figure 2B is a top plan view of the coupling between the railway wagons of Figure 1, to an enlarged scale; Figure 3 is a horizontal section along plane Ill-III in Figure 1A showing one embodiment 0 of a joint in accordance with the invention; and Figure 4 is a vertical section along plane IV-IV in Figure 213 showing a second embodiment of a joint in accordance with the invention.

Detailed description of the drawings

The drawings show two similar adjacent or successive railway wagons 1, the adjacent ends 7 of which have been designed in accordance with the invention. Wagon ends 7 are linked by a coupling 3 comprising a drawbar 5. The two coupled wagons 1 together constitute a wagon unit, which is generally retained as a single, semi-permanent unit. The drawbar 5 does not include coupling units and is generally not intended to be detached from the wagons, although the wagons can be decoupled if desired by detaching the drawbar from the wagons. The opposed wagon ends 8, facing away from each other, have been designed to include ordinary double buffers and attaching hook arrangements, by means of which the wagon unit can be coupled either to further similar wagon units or to ordinary railway wagons (not shown).

Each railway wagon 1 comprises a chassis 10 with a respective wheel truck 2 adjacent each wagon end 7 and 8. Each wheel truck 2 includes two pairs of wheels on respective axles enclosed by a generally rectangular bar or side member 13 (Figure 2A,B), the trucks being connected to the wagon chassis 10 from the truck centres 12 in known manner.

As noted above, coupling 3 comprises a drawbar 5. The drawbar is attached to the chassis 10 of the adjacent wagons 1 by means of joints 4, each joint 4 being located in the relevant wagon between the wagon end 11 and the truck side member 13, usually as close as possible to the side member and thus to the truck centre 12. This implies that the distance S between the vertical axial line 6 of the joint 4 and the side member 13 is as small as possible. At its minimum, this distance S may be zero, which is readily understood from Figures 2A and 2B. In this case, the axial line 6 of the joint is aligned with the side of the side member 13 parallel to the axial lines of the truck wheels. However, whenever needed, the distance S can be increased within the limits allowed by c 6 running safety calculations, in order to obtain sufficient space for the vertical angular deviation KI, of the drawbar 5, to be discussed below.

In accordance with the invention, the railway wagon ends 7 linked by drawbar 5 have an end overhang of a length L2, i.e. the distance between the truck centre 12 and the wagon end 11, that is at least about 15% of the distance L1 between the truck centres of the wagon. However, in accordance with the invention, it is possible to increase the end overhang L2 up to 20% and more of the distance L1 between the truck centres. The joints can still remain close to the trucks and the truck centres, with the length of the drawbar 5 being increased analogously so that transverse forces generated by braking and running in curves will be kept within acceptable limits. The length LS of the drawbar 5 is then 20- 40% and typically 25-30% of the distance L1 between the truck centres of the wagon, at the same time that the distance L4 between the centres of adjacent trucks in successive wagons is nearly 40-50% and typically of the order of 450X, of the distance L1 between the truck centres of the wagon. Thus, it has been possible to increase the length of the wagon, L3, by 10-25% depending on whether the end overhang has been increased at both wagon ends or at only one end alone.

As such railway wagons 1 are being run, for instance on a ship ramp, the drawbar 5 will be vertically tilted over an angle K1 (Figure 2A), which is of the order of +2' at the most. The advantage of a long drawbar lies in the fact that, as the wagons are running around curves or on meandering railway sections, or as the train is braking, an angle K2 (Figure 1Q between the wagon centre line and the drawbar length will arise, the angle varying at a maximum within the range + 10'. These relatively small angular variations K1 and K2 allow the joint 4 to have the design in accordance with the invention, consisting preferably of a vertical (Figure 4) or optionally horizontal (Figure 3) joint pin 20 that is fixed relative to the wagon chassis 10, with a surrounding joint housing 22 constituting part of the solid element of the drawbar, and inbetween these, a generally cylindrical sleeve 21 of an elastic material, fixedly secured relative to both pin 20 and housing 22.

In the preferred vertical joint design in accordance with the invention, as illustrated in c 7 Figure 4, the joint housing 22 is a cylindrical body surrounding a cylindrical joint pin 20. The elastic sleeve 21 has been placed between the joint pin 20 and the housing 22, and the sleeve 21 is likewise generally cylindrical. The outer surface of sleeve 21 is vulcanised, flued or otherwise fixedly secured to the inner surface 18 of the surrounding joint housing 22, so that the surfaces will adhere to each other. The inner surface of the sleeve 21, also of an elastic material, has been analogously vulcanised, glued or otherwise fixedly secured to the outer surface 17 of the inner joint pin so that the surfaces will adhere to each other. In this embodiment the axial line 6 of the joint pin 20 is vertical, i.e. perpendicular to the maximum plane of the angular variation K92 of the drawbar 5. Thus the plane of the smaller angular variation K1 runs through the axial line 6.

As the drawbar 5 in this design pivots horizontally in the direction the angle K92, a peripheral deformation occurs in the cylindrical elastic sleeve 21, allowing this deviation without the sleeve joint being detached from the inner surface 18 of the joint housing and the outer surface 17 of the joint pin. As the drawbar 5 is moving vertically forming the angle K1, this simpler embodiment, in which the outer surface 17 of the joint pin 20 is cylindrical surface 14b, as illustrated in Figure 4, will involve a compression strain at the upper edge of the sleeve 21 facing the drawbar 5 and a tensile strain at the lower edge, with a respective tensile strain at the upper edge and compression strain at the lower edge of the sleeve 21 on the opposite side of the drawbar. The strain described here in the plane parallel to the axial line allows the necessary small vertical angular variation without the joint of the elastic sleeve being detached from the inner surface 18 of the joint housing and the outer surface 17 of the joint pin. In this case, the accepted vertical deviation K1 of the drawbar 5 is smaller than in the case of Figure 3, but is sufficient at least for any normal railway operation, since the required angular deviation is only of the order of + 2'. Consequently, during the motion of the drawbar 5, there will be no friction between the surfaces, but any movement of the drawbar will be allowed by the elastic deformation of the sleeve 21. Moreover, this design is preferably without play so that there will be no need for devising special means to compensate for the dimensional variation caused by wear, there being no wearing components in the absence of play.

When needed, the joint 4 can be designed with its axial line 6 horizontal, which facilitates c 8 attachment and detachment of the joint to and from the wagon. For this purpose the horizontal play of the drawbar 5, i.e. the angle K22, has to be enlarged by designing the outer surface 17 of the joint pint 20 as a part spherical surface 14a, as illustrated in Figure 3. Thus the deformation also in the horizontal direction K2, implying in this case a deformation in a plane parallel to the axial line 6, is of the same type as the deformation in the vertical direction K1, i.e. in the peripheral direction of the axial line. Hence in both directions K1 and K2 the same type of strain causing a shearing stress is involved, since the two deviations K1 and K2 take place in the peripheral directions of the part spherical surface 14a of the joint. As in the simpler Figure 4 embodiment, the outer surface of the elastic sleeve 21 has been vulcanised, glued or otherwise secured to the inner surface 18 of the surrounding joint housing so that the surfaces will adhere to each other, and similarly, the inner surface of the sleeve 21 of an elastic material has been vulcanised, glued or otherwise secured to the outer surface 17 of the inner joint pin so that the surfaces will adhere to each other. The peripheral deformations of the sleeve described here allow the deviations K1 and K2 without the joint of the sleeve being detached from the inner surface 18 of the joint housing and from the outer surface 17 of the joint pin. It is also possible to place the axial line 6 of the joint including this ball surface 14a vertically as shown in the figures.

If desired, the grip between the surfaces of the elastic sleeve and the outer surface 17 of the joint pin 20 and/or the inner surface 18 of the joint housing 22 can be enhanced by making these surfaces, in a manner not shown in the figures, grooved, cross-grooved or otherwise roughened, and for instance by attaching the sleeve 21 to this surface structure by vulcanising. This operation ensures that the sleeve 21 will not be detached from either surface, but that the joint will serve reliably owning to the deformations of the elastic material, without relative motion and consequent friction between the components.

The elastic sleeve may be of any material having suitable elastic properties, including rubber or plastics materials.

The drawbar 5 and wagons 1 normally remain secured together, but if necessary the wagons can be uncoupled from each other by removing the joint pin 20 to release the D 9 drawbar.

In addition, in accordance with the invention, the potential vertical angular variation of the drawbar 5 is increased by placing the joint 4 as low as possible. Thus the maximum height H1 of the joint 4 will be of the same order as the height H2 of the upper edge 16 of the wagon wheels 15. If the joint 4 is placed significantly higher than this, the large wagon end overhang L2 will not allow the drawbar 5 to turn sufficiently upwards in the direction illustrated in Figure 2A, but the drawbar may touch the loading plane 9 (Figure 4). It is obvious that the joint 4 can be placed at a lower height H1, for example close to the axial lines of the wagon wheels 15. In this direction, the only limitation will be posed by permitted loading gauges for the wagon 1.

Because of permitted loading gauges, the wagon end overhang L2 has additionally, when necessary, been formed with its width W2 tapered towards the end 11, as illustrated in Figures 1B, 1C, and 2B. Theoretically this tapering would reduce the loading surface from its maximum. However, for most cargos length is crucial, so that a minor reduction in width does not entail substantial drawbacks. Moreover, the wagon ends 11 may curve convexly, as appears from Figures 1B and 1C. In this case, the ends of successive wagons can be placed very close to each other, so that one can run over the joint with a wheel vehicle without having to use ramps to cross the coupling point.

11,3

Claims

C369/R Claims

1. A wagon unit comprising two railway wagons linked by a coupling, each wagon comprising a chassis with a respective wheel truck adjacent each end, the coupling comprising a drawbar attached by means of respective joints to end regions of the chassis of the wagons, the distance, L2, between the centre of a truck and the adjacent wagon end being at least about 15% of the distance, Ll, between the truck centres of a wagon, and each joint between the drawbar and the wagon chassis comprising a sleeve of an elastic material located between and fixedly secured to both a joint pin in the wagon chassis and a joint housing in the drawbar, in order to provide a non-wear joint construction.

2. A wagon unit according to claim 1, wherein the joint housing comprises a cylindrical body surrounding the joint pin, the joint pin is fixed in rotation relative to the wagon chassis, and the sleeve of an elastic material is generally cylindrical, with its outer surface connected to the inner surface of the surrounding joint housing, and with its inner surface connected to the outer surface of the joint pin.

3. A wagon unit according to claim 2, wherein the axial line of the joint pin is vertical and the outer surface of the joint pin has a cylindrical shape.

4. A wagon unit according to claim 2, wherein the axial line of the joint pin is either horizontal or optionally vertical, and that the outer surface of the joint pin is partspherical.

5. A wagon unit according to claim 22, 3 or 4, wherein the inner surface of the joint housing and/or the outer surface of the joint pin are provided with a surface pattern to ensure a grip between the elastic sleeve and these surfaces.

6. A unit according to any one of the preceding claims, wherein distance L2 is about 20% of the distance Ll.

3 11

7. A wagon unit according to any one of the preceding claims, wherein the vertical height of the joint above ground is as small as possible, the joint being nearly at the height of the upper edge of the wagon wheels or lower, to allow a sufficient vertical angular deviation for the drawbar.

8. A wagon unit according to any one of the preceding claims, wherein the wagons have tapered end regions in the area of the end overhang.

9. A wagon unit according to any one of the preceding claims, wherein each joint is located between a wheel truck side member and the adjacent wagons end, being as close as possible to the side member.

10. A wagon unit substantially as herein described with reference to, and as shown in, Figures 1, 2 and 4 of the accompanying drawings.

11. A wagon unit according to claim 10, modified substantially as shown in Figure 3 of the accompanying drawings.