Load-bearing one piece bogie center pivot

Abstract

 A one-piece, load-bearing bogie center pivot (10) consisting of an element made of suitable elastomeric material (15) (such as a rubber sandwich). This element is fitted between two parallel end plates (11,12). The upper end plate (11) is firmly attached to the underside of the underframe of the railway vehicle and the lower end plate (12) is firmly attached to the top of the crossbar (bolster) of the bogie frame. Due to the flexibility of the elastomeric material (15) the elastic element has a low resistance to torsion about its vertical axis thus allowing the bogie to rotate virtually freely relatively to the vehicle body. By virtue of the horizontal flexibility of the elastomeric material (15) the bogie center pivot (10) also allows the vehicle body to move laterally in an elastically controlled manner relatively to the bogie frame. This controlled lateral motion gives the vehicle a significantly better riding quality than the rigid lateral connection between the bogie frame and the vehicle body resulting from the existing two-piece bogie center bearing. In order to ensure the effective transmission of longitudinal traction and braking forces the upper and lower end plates (11,12) of the bogie center pivot (10) are provided with suitable vertical walls which deactivate the flexibility of the elastic element in the fore and aft direction.
For direct interchangeability the one-piece bogie center pivot (10) has the same height as the standard two-piece bogie center bearing and its upper and lower end plates (11,12) are fixed to the underside of the vehicle underframe and the top of the crossbar (bolster) of the bogie frame, respectively, in the same manner as the standard two-piece bogie center bearing.

Description

Background to the Invention.

[0001] This Invention relates to bogie centers of railway bogies. Conventionally the bogie centre is a bearing made of two parts namely the upper bogie center spigot and the lower bogie center bowl. The upper bogie center spigot is firmly attached to the underside of the underframe of the vehicle body, and the lower bogle center bowl is firmly attached to the crossbar or bolster of the bogie frame. The bowl and the corresponding spigot can be flat or spherical. Figure 1 shows the spherical bogie center bearing fitted to the Y25 bogie which is the standard bogie of the European railways. As will be seen from the drawing the upper bogle center pivot fits neatly into the lower bogie center bowl. And the bogie center bearing transmits the vertical load from the vehicle body to the bogie and via its vertical walls also transmit all forces in the horizontal plane which will arise in operation through an angle of 360 degrees. These horizontal forces are mainly the longitudinal traction and braking forces but also lateral forces such as centrifugal forces arising on curved track. Thus the standard two-piece bogie center bearing allows the bogie only one degree of freedom for motions relative to the vehicle body In the horizontal plans namely the rotation about the vertical axis through the geometrical center of the bogie center bearing. This rotational freedom allows the bogie frame to align itself radially to the vehicle body on curved track.
Now the Invention proposes to replace the two piece bogie center bearing by a one-piece bogie center pivot of the same height as the existing two-piece bogie center bearing. The proposed one piece bogle center pivot is load bearing and contains an elastic element made of suitable elastomeric material which has a high stiffness In the vertical direction-which ensures that the deflection under the load of the vehicle is very small-but has a very low stiffness In torsion about the vertical axis of the bogie center pivot. For this reason it offers only negligible elastic resistance to the rotation of the bogie frame relatively to the vehicle body. Typically, the elastic element of the one-piece bogie centre pivot is a single rubber sandwich or a symmetrically arranged multiple of rubber sandwiches.

Summary of the invention

[0002] According to the invention there is provided a load-bearing one piece bogie center pivot consisting of an upper and lower end plate interspaced by an elastic element made of elastomeric material.
The upper end plate is firmly connected to the underside of the underframe of the vehicle body and the lower end plate is firmly connected o the top of the crossbar of the bogie frame
the elastic element consisting of elastomeric material having a low stiffness in torsion about the vertical axis through the center of the bogie center pivot and inherent flexibility and damping in the direction transverse to the direction of travel thus allowing elastically controlled and damped lateral movements between the bogie frame and the vehicle body which improves the riding quality of the railway vehicle.

[0003] The upper and lower end plates having fore and aft upper walls which engage with each other thus providing a stiff connection between the underframe of the vehicle body and the bogle frame in the fore and aft direction as is required for the effective transmission of traction and braking forces.

[0004] Other preferred features of the invention are set forth in the appended claims.

Brief description of the drawings

[0005] The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which:

Figure 1 shows a sketch of the conventional bogie center bearing fitted to Y25 bogies used by European railways in accordance with UIC-leaflet 510-1 appendix B.

Figure 2 shows a transverse section through the bogie center pivot where to top and bottom layers of the elastomeric material are bonded to the upper and lower end plate, respectively.

Figure 3 shows a longitudinal cross-section through the bogie center pivot Indicating the vertical walls which limit the fore and aft motion of the bogie center pivot.

Figure 4 shows a horizontal cross-section through the bogie center pivot.

Figure 5 shows a transverse cross-section of a bogie center pivot having an elastic element which is made up of a multitude of symmetrically arranged separate rubber sandwiches. Furthermore a method of fitting the separate rubber sandwiches to the upper and lower end plates is shown.

Figure 6 shows a plan view of the bogie center pivot of 5g.5.

Figure 7 shows a plan view of a bogie center pivot having a ring shaped elastic element to allow for the fitting of a conventional center pin. Furthermore an aöternative embodiment for the vertical walls which limit the fore and aft movements is shown,

Figure 8 shows a transverse cross-section of the bogie center pivot of figure 7.

Description of the Embodiments.

[0006] The proposed bogie center pivot has a upper and a lower end plate plate which are parallel to each other and spaced apart by the elastic element made of elastomeric material such as a rubber sandwich. The upper end plate is firmly secured to the underside of the underframe of the vehicle body in the same manner as is the upper bogie center of the existing two-piece bogie center. This ensures full interchangeability between the existing bogie center and the proposed single piece bogie center pivot. In other words no changes are required to the vehicle underframe to replace the existing two-piece bogie center by the proposed single piece bogie center pivot.

[0007] Now as has been mentioned above the bogie center pivot has a low torsional stiffness. This means that it is also soft for any deflections in the horizontal plane.

Claims

1. A load-bearing bogie center pivot 10 for railway vehicles having upper end means 11 for attachment to the underframe of the vehicle and lower end means 12 for attachment to the crossbar or bolster of the railway bogie characterized by means 15 interspacing the upper 11 and lower 12 end means having flexibility in the horizontal plane resulting in improved riding qualities of the vehicle, and a low elastic resistance to motions in torsion about a vertical axis through the bogie center pivot enabling the bogie frame to rotate virtually freely relatively to the vehicle body, and means for limiting relative motions in the fore and aft direction between the bogie frame and the vehicle body.

2. A bogie center pivot in accordance with claim 1 where the upper end means is an upper end plate 11 and the lower end means is a lower end plate 12 interspaced by an elastic element of elastomeric material 15.

3. A bogie center pivot in accordance with claim 2 where the elastic element is a single rubber sandwich 15 consisting of multiple layers of rubber 16 separated by intermediate steel plates 17 bonded to their adjacent layers of rubber.

4. A bogie center pivot in accordance with claim 2 where the elastic element is a multitude of rubber sandwiches 18.1, 18.2.

5. A bogie center pivot in accordance with claim 3 where the upper 16.1 and lower 16.2 layer of rubber is bonded to the upper 11 and lower 12 end plate, respectively.

6. A bogie center pivot in accordance with claim 3 or 4 where the elastic element is a single rubber sandwich 15 or a multitude of rubber sandwiches 18.1, 18.2 with steel end plates, the upper steel end plate being attached to the upper end plate 11 and the lower steel end plate to the lower end plate 12 by means of setscrews 19, bolts, rivets or other suitable mechanical means.

7. A bogie center pivot in accordance with claim 3 where the upper 11 and lower 12 end plate and the rubber sandwich 1 has a central hole 20 for the insertion of a center pin 24 having spherical washers 23 below the pin head and above the retainer bracket 24 for free lateral motion.

8. A bogie center pivot in accordance with claim 1 where the means of limiting relative motions in the fore and aft direction are vertical walls 13, 14 at the front and back end of the upper 11 and lower 12 end plate which vertical walls are an integrate part of their respective end plate and engage each other without clearance, and the sides of the walls facing each other are of convex shape for unimpaired rotational motion of the bogie frame relative to the vehicle body.

9. A bogie center pivot in accordance with claim 1 where the means of limiting relative motions in the fore and aft direction are a circular vertical wall or sections of a vertical circular wall 25 forming an integral part with the lower end plate 12 and having the center point of its circle coinciding with the geometrical center of the bogie center pivot in plan view, and straight vertical walls 26 at right angles to the fore and aft direction forming an integral part with the upper end plate 11, and where the two spaces formed by the straight vertical walls 26 and the circular vertical walls 25 are each taken up by a slide shoe 21 having corresponding circular and straight vertical faces.

10. A bogie center pivot in accordance with claim 9 where liners made of high molecular weight polymer material having a low coefficient of friction are fitted between the straight vertical faces of the slide shoes 21 and the straight vertical faces of the upper end plate 11, and the circular vertical faces of the slide shoes 21 and the circular vertical faces of the lower end plate 12, respectively.

Drawing