Side sill of bogie frame for railcar

Abstract

To provide a side beam of a truck frame for a rolling stock capable of reducing weight.SOLUTION: The side beam 20 is formed of a separate structural member comprising an elongated central plate 21 extending between first and second ends thereof in a longitudinal direction, wherein a thickness direction of the central plate is parallel to the transversal direction, and first and second suspension device mounting portions 22 configured for mounting wheel set suspension elements thereto. First and second suspension mounts are cantilevered from the first and second ends of the central plate, respectively, and each suspension mount extends upwardly and longitudinally away from its respective junction with that end of the central plate so as to define a space below the suspension mount for joining a suspension element to the respective axle. At the respective junctions, each suspension mount has a width in the lateral direction that is greater than a thickness of the central plate such that the suspension mount projects laterally outward from the central plate.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a side beam of a bogie frame for a railway vehicle. [Background technology]

[0002] Due to increasing social and political demands for decarbonization, lightweight construction has always been a concern in transportation structures. Although rail vehicles already offer significant environmental advantages compared to other modes of vehicle transportation, reducing structural weight remains a significant challenge. To reduce the weight of rail vehicles, lightweight welded aluminum alloy bogie frames have been proposed. However, there is still room for improvement in the welded joints of such frames in terms of strength, reliability, and maintainability.

[0003] The bogie frame contains structural components for transferring various loads between the railcar body supported by the frame and the wheel sets held by the frame. In addition to such structural components, the bogie frame also typically provides mounting locations for equipment used in running trains, such as motors, suspension items, bearings, brake units, etc. Such equipment occupies space, and there is room for improvement in how such space is provided around the bogie frame.

[0004] The present invention has been devised in light of the above considerations. Summary of the Invention [Means for solving the problem]

[0005] According to a first aspect of the present invention, there is provided side beams for a bogie frame of a railway vehicle, two such side beams defining respective lateral sides of the bogie frame relative to the longitudinal direction of the railway vehicle, and a cross beam extending in the transverse direction of the railway vehicle to join the side beams, the bogie frame being configured to carry front and rear wheel sets in use. The side beams are separate structural members comprising: an elongated central plate extending between its first and second ends in a longitudinal direction between positions occupied by the wheel sets in use, the thickness direction of the central plate being parallel to the lateral direction; first and second suspension mounts configured to mount wheelset suspension elements, the first and second suspension mounts being cantilevered from the first and second ends of the center plate, respectively, each suspension mount extending upwardly and longitudinally away from a respective juncture with that end of the center plate to define a space below the suspension mount for joining the suspension element to a respective wheelset, and at each juncture each suspension mount has a width laterally greater than a thickness of the center plate such that the suspension mount projects laterally outwardly from the center plate; formed of individual structural members comprising: The individual structural members are joined by respective bolted connections.

[0006] The use of bolted connections in side beams offers several advantages over, for example, welded joints. For example, the bolted joints formed by bolted connections avoid exposing the side beams to residual stresses that may be caused by welded joints and also avoid the possibility of heat-affected zones adjacent to welds in aluminum alloys. Also, bolted connections can be easily installed, repaired, or replaced, especially when accessible and located on the outside of the bogie frame. Therefore, the reliability and repairability of the side beams may be improved.

[0007] Additionally, by extending the suspension mounts laterally relative to the center plate at the joints, the side beams of the present invention can provide additional space outside the center plate and longitudinally bounded by the suspension mounts at the ends of the plate. This space can be used to accommodate additional components and modules, such as devices related to the operation of the rail vehicle. For example, the space can accommodate yaw dampers and / or anti-roll systems. These devices are traditionally mounted outside the bogie frame, increasing the width of the bogie in the lateral direction. However, by accommodating the devices within the additional space, a bogie frame using the side beams of the present invention can be reduced in width.

[0008] Each bolted connection can transfer substantially all of the load between the individual structural members of the side beam, thus reducing or completely eliminating the need for other connection methods between the individual structural members, such as welded connections.

[0009] The structural members may be formed from aluminum alloys, which allow for lightweight construction with good mechanical properties.

[0010] Preferably, the center plate of the side beam is formed from a wrought aluminum alloy. For example, the center plate may be forged, extruded, or otherwise formed. The center plate may then undergo further processing, such as machining, to achieve its finished shape. Advantageously, wrought aluminum alloys generally have greater strength and toughness than cast alloys, allowing the center plate's thickness to be reduced while maintaining its mechanical properties.

[0011] In contrast, the suspension mount is preferably formed from a cast aluminum alloy. For example, the suspension mount may be sand cast, die cast, continuous cast, pressure die cast, or one-shot cast. The suspension mount may be machined after casting to achieve a finished state. Advantageously, casting an aluminum alloy allows for the formation of complex three-dimensional shapes.

[0012] The individual structural members of the side beams may further include one or more reinforcing elements at each of the joints to support the large width of the respective suspension attachments relative to the thickness of the center plate. In particular, the reinforcing elements may increase the side beams' resistance to bending and / or torsional stresses. The reinforcing elements may be formed of a wrought aluminum alloy. For example, the reinforcing elements may be forged, extruded, or otherwise formed. They may then be machined to their final shape.

[0013] Each of the side beam suspension attachments may have a base that forms a joint with a respective end of the center plate, with the inside of the base joined to the upper surface of the respective end by one or more bolt connections passing through the base and the end, and the one or more reinforcing components of each joint may include a secondary plate extending parallel to the center plate, with the outside of the base joined to the upper surface of the secondary plate by one or more bolt connections passing through the base and the secondary plate. In other words, each suspension attachment may be supported on the inside (by the center plate) and the outside (by the secondary plate). This configuration extends the joint laterally, thereby helping the joint to resist bending and torsional forces. The secondary plate may be laterally spaced from the center plate to further help resist these forces.

[0014] The one or more reinforcing components of each joint may further include a square brace having first and second walls for reinforcing the secondary plate to the central plate, the first wall being joined or connectable in use to the outer surface of the central plate by one or more bolt connections passing through the first wall and the central plate, and the second wall being joined to the side of the secondary plate by one or more bolt connections passing through the second wall and the secondary plate. The square brace thus connects the secondary plate to the central plate and can help the side beams more effectively resist bending and torsional forces. Preferably, the square brace includes one or more reinforcing webs extending between the first wall and the second wall.

[0015] One or more steel reinforcement plates may extend across each joint between each end of the center plate and each suspension mounting point. This may be particularly advantageous when the structural members of the side beams are formed of an aluminum alloy. Steel is denser than aluminum alloy, but it is also stronger and more rigid. Therefore, the use of steel reinforcement across each joint may significantly strengthen and stiffen the joint against bending and torsional forces, with a relatively small increase in overall weight. Additionally, the steel reinforcement plates may help prevent separation of the structural members at the joints under loads from the vehicle body. Inner and outer steel reinforcement plates may extend across the inner and outer sides, respectively, of a given joint.

[0016] At each joint, the lateral width of the suspension mounting portion may be at least two times, preferably at least three times, greater than the lateral thickness of the central plate.

[0017] The center plate may be tapered at its ends so that the vertical height of the center plate is greater at its center than at its ends, which may also help increase the space below the suspension mounts for joining the suspension elements to the respective wheel sets.

[0018] Each bolted connection joining the individual structural members of the side beam may be formed by a bolt passing through at least one through-hole in the structural member and received in a threaded receiving hole in another structural member or, in use, in the cross beam. By providing a threaded receiving hole, the bolted connection may be completed without the use of a nut. A helical insert, e.g., made of steel, may reinforce the threads of the receiving hole. This may be particularly advantageous for holes formed in aluminum alloy structural members.

[0019] The bolted connections joining the individual structural members of the side beam may further comprise sensors for measuring axial strain in the bolts of the bolted connections. The sensors may be embedded in the bolts of the bolted connections. The sensors may be strain gauges, such as piezoelectric strain sensors.

[0020] According to a second aspect of the present invention, there is provided a bogie frame for a railway vehicle, comprising: two side beams according to the first aspect of the invention defining respective lateral sides of the bogie frame in relation to the longitudinal direction of the railway vehicle; a cross beam extending in a lateral direction of the railway vehicle to connect the side beams; Equipped with The cross beams are joined to the center plate of each side beam by respective bolt connections; A bogie frame for a railway vehicle is provided, wherein the use of bolted connections to join the cross beam to each side beam provides advantages compared to, for example, welded joints, as described in the first aspect above.

[0021] The bolted connections joining the cross beams to the center plate can transfer substantially all of the load between the cross beams and the center plate, and as such, can reduce or completely eliminate the need for other connection methods between the cross beams and the center plate.

[0022] The cross beams may be made of an aluminum alloy, again allowing for a lightweight construction with good mechanical properties.

[0023] The cross beam may be formed of a cast aluminum alloy. For example, the cross beam may be formed from multiple cast sub-components. The cross beam or its sub-components may be sand cast, die cast, continuous cast, pressure die cast, or one-shot cast. The cross beam or its sub-components may be machined to achieve a finished shape.

[0024] Each bolted connection joining a cross beam to one of the center plates may be formed by a bolt passing through a through-hole in the center plate and received in a threaded receiving hole in the cross beam. By providing a threaded receiving hole, the bolted connection may be completed without the use of a nut. A helical insert, e.g., made of steel, may reinforce the threads of the receiving hole.

[0025] The bolted connections joining the cross beams to the center plate may further comprise sensors for measuring axial strain in the bolts of the bolted connections. The sensors may be embedded in the bolts of the bolted connections. The sensors may be strain gauges, such as piezoelectric strain sensors.

[0026] The bolted connection joining the cross beams and the center plate may further include shims disposed at the interface between the cross beams and the center plate. The shims can thereby fill any gaps between the cross beams and the center plate to control the lateral spacing of the center plate. The shims may be surface treated, e.g., ground and / or coated (e.g., painted), to increase frictional interaction with the cross beams and the center plate, thereby transferring shear loads between the cross beams and the center plate. In this manner, the shims can help reduce bending loads on the bolted connection that could otherwise lead to premature bolt failure.

[0027] According to a third aspect of the present invention, there is provided a bogie for a railway vehicle, comprising the bogie frame according to the second aspect of the present invention and front and rear wheel sets held by the bogie frame.

[0028] According to a fourth aspect of the present invention, there is provided a railway vehicle comprising one or more bogies according to the third aspect of the present invention.

[0029] The present invention includes combinations of the described aspects and preferred features except where such combinations are expressly disallowed or explicitly avoided.

[0030] BRIEF DESCRIPTION OF THE DRAWINGS Embodiments and experiments illustrating the principles of the present invention are described below with reference to the accompanying drawings. [Brief explanation of the drawings]

[0031] [Figure 1] 1 shows a schematic side view of an end of a rail vehicle including a bogie. [Figure 2] The bogie frame is shown in a perspective view. [Figure 3] 3 is a perspective view of the side beam of the bogie frame shown in FIG. 2; [Figure 4] 4 shows a top view of the side beam shown in FIG. 3. [Figure 5] 4 shows an exploded view of the side beam shown in FIG. 3. [Figure 6] 4 shows an enlarged view of the center plate of the side beam shown in FIG. 3. [Figure 7] 4 shows an enlarged view of the auxiliary plate of the side beam shown in FIG. 3. [Figure 8] An enlarged view of the square brace of the side beam shown in Figure 3 is shown. [Figure 9] 3 shows an exploded view of the bogie frame shown in FIG. 2. [Figure 10] An exploded view of part of the modified bogie frame is shown. [Figure 11] The deformed side beam is shown in a perspective view. [Figure 12] 12 is a perspective view of the bogie frame including the side beams of FIG. 11. DETAILED DESCRIPTION OF THE INVENTION

[0032] Further background to the invention, as well as aspects and embodiments of the invention, are described below with reference to the accompanying drawings. Further aspects and embodiments will be apparent to those skilled in the art.

[0033] 1 shows a schematic side view of the end of a railcar 1 including a bogie 5. The bogie 5 is positioned below the railcar 1 on a railroad track 4. The bogie 5 comprises a bogie frame 10 that supports the floor of the railcar 1 and holds two wheel sets 3. A further similar bogie (not shown) is provided at the other end of the vehicle. The bogie 5 provides stability, absorbs vibrations and reduces the effects of centrifugal forces on curved sections of the track 4.

[0034] 2 shows a perspective view of the bogie frame 10. The bogie frame 10 comprises two side beams 20 and a cross beam 11. The two side beams define respective lateral sides of the bogie frame with respect to the longitudinal direction L of the railway vehicle 1, and the cross beam extends in the transverse direction T of the railway vehicle to join the side beams.

[0035] The cross beams 20 are formed from individual structural members made from an aluminum alloy, as described in more detail below. The cross beams may also be made from an aluminum alloy. The cross beams may be a single cast component or may be formed from cast sub-components. For example, in FIG. 2, the cross beam 11 includes four cast sub-components 11a-11d.

[0036] Figures 3 and 4 show an example of a side beam 20 in perspective and top views, respectively. Figure 5 shows an exploded view of the side beam. Figures 6-8 show enlarged views of different individual structural members of the side beam. Figure 9 shows an exploded view of the bogie frame 10.

[0037] The individual structural members of the side beams 20 include an elongated central plate 21 extending in the longitudinal direction L with the plate's thickness direction in the transverse direction T, suspension attachment points 22 at either end of the central plate, and additional reinforcing elements 23, 24 at the junctions between the central plate and the suspension attachment points. Most of the structural members of each side beam are joined to each other with smaller bolt connections 30, while each side beam is joined at its central plate to the respective ends of the cross beams 11 with larger bolt connections 14. However, as explained below, some of these larger bolt connections 14 have the additional function of also joining the structural members of the side beams to each other.

[0038] Each suspension mount 22 includes a base 22a that forms a junction with the respective end 21a of the center plate, and a curved body portion 22b to which a wheelset suspension element (not shown) is attached. The suspension mounts 22 are formed from a cast aluminum alloy; the casting process is suitable for forming the relatively complex shapes of the mounts, and the aluminum alloy allows for a combination of light weight and good mechanical properties.

[0039] The suspension mounting portion 22 is cantilevered from the central plate 21. In particular, a curved body portion 22b rises upwardly and longitudinally away from the end 21a of the central plate 21 to provide space below the suspension mounting portion in which wheelset suspension elements are positioned.

[0040] The bases 22a of the suspension mounts 22 have a greater lateral width relative to the thickness of the center plate 21. This allows the suspension mounts to protrude laterally outward at their junctions with the center plate, with only the inner strip of each base 22a in direct physical contact with the upper surface of the center plate. Outward of this strip, each suspension mount is supported by additional stiffening components in the form of auxiliary plates 23 and angle braces 24. At each junction, the lateral width of the suspension mounts may be at least two times, and preferably at least three times, greater than the lateral thickness of the center plate. As best shown in FIG. 4, the relative overall dimensions of the suspension mounts and the center plate cause the side beams 20 to be waisted at the center of the center plate, leaving a protected space 25 outside the plate center for mounting equipment to the bogie frame 10. This space is particularly useful for mounting devices (e.g., yaw dampers and / or anti-roll systems) that are required or preferred to be mounted outside the bogie frame. Additionally, the relatively small thickness of the center plate 21 helps reduce the structural weight of the side beams 20 .

[0041] Each bolted connection 14, 30 typically comprises a respective fastening bolt 14a, 30a that is inserted into a through hole in one component and threaded into a threaded hole in the other component (thereby avoiding the need for a separate tightening nut to complete the bolted connection). Multiple bolted connections typically connect each pair of joined components to provide redundancy and reduce loads on individual connections. Threaded holes in aluminum alloy components may be reinforced with helical steel inserts, e.g., Helicoil™.

[0042] The center plate 21 of the side beam 20 is formed of a wrought and machined aluminum alloy for increased strength and toughness. Referring to the enlarged view in FIG. 6, the plate has through holes 21e and threaded receiving holes 21b for its bolt connections 30, as well as a larger-diameter through hole 21d for accepting a larger-diameter fastening bolt 14a. The center plate may have one or more voids 21f to reduce the plate's weight. Additional through holes 21c may be incorporated into the center plate for attaching additional items to the side beam 20, as described below with respect to FIGS. 11 and 12. The center plate tapers at its ends 21a so that the vertical height of the center plate is greater at its center than at its ends. This increases the space below the suspension mounting portions 22 for joining the suspension elements to the respective wheel sets.

[0043] The secondary plates 23 and angle braces 24 are also formed from a wrought and machined aluminum alloy for increased strength and toughness. Each secondary plate 23 is positioned parallel to but laterally spaced from a respective end 21 a of the center plate 21 and is joined to the base of the suspension mount 22 by bolt connections 30 so that the outer strips of the base are in direct physical contact with the top surface of the secondary plate. Each angle brace 24 has a first wall 24 a joined to the center plate by bolt connections 14 and a 90° second wall 24 b joined to the side of the secondary plate by bolt connections 30.

[0044] 7, each auxiliary plate 23 has a through hole 23b and threaded receiving holes 23a, 23c for its bolt connection 30. Like the central plate 21, the auxiliary plates may also have one or more weight-saving voids 23e. Additional holes 23d may be incorporated into the auxiliary plates for attaching additional items to the side beams 20, as described below with respect to FIGS. 11 and 12.

[0045] Referring to the enlarged view of FIG. 8 , the first and second walls 24a and 24b of each square brace 24 are strengthened and rigidified by one or more reinforcing webs 24c extending between the two walls. The brace includes through-holes 24f for its bolted connection 30 to the auxiliary plate 23 and through-holes 24d for its bolted connection 14 to the center plate 21. The fastening bolts 14a of these bolted connections 14 pass through the through-holes 24d and the aligned through-holes 21d in the center plate, and then thread into threaded holes 11e in the cross beam 11. They thus serve the dual function of joining the square brace to the center plate and joining the entire side beam to the cross beam. Additional holes 24e may be incorporated into the square brace for attaching additional items to the side beams 20, as described below with reference to FIGS. 11 and 12 .

[0046] The spacing of the secondary plate 23 from the central plate 21 and its reinforcement by the square braces 24 increases the resistance of the side beams to bending and torsional forces.

[0047] The use of bolted connections 14, 30 can simplify assembly of the bogie frame 10, especially when the heads of the fastening bolts 14a, 30a are accessible on the outside of the frame where they can be tightened with conventional tools such as a torque wrench. The structural members of the side beams can also be easily replaced if they are damaged. This applies particularly to the base plates 23, which are most susceptible to damage from ballast strikes. Additionally, the bolted connections can be easily accessible for safety inspection.

[0048] The bolted connection 14 may further include shims at the interface between the cross beam 11 and the side beams 20. For example, as shown in FIG. 9, shims 14b are disposed on the inner surface of the center plate 21. The shims are used to fill the gap between the cross beams and the side beams, thereby adjusting the lateral spacing between the center plates 21. Advantageously, each shim may be a washer into which the respective fastening bolt 14a is inserted. This ensures that the shim remains in place unless the bolt is removed. Advantageously, the shims may be surface treated to increase frictional interaction with the cross beam and center plate, thereby facilitating the transfer of shear loads between the cross beams and the center plate and thereby reducing bending loads on the bolts 14a.

[0049] 10 shows a partial exploded view of a modified version of the bogie frame 10. In this modified version, the bolted connection 14 further includes a sensor 14c for measuring the axial strain of the fastening bolt 14a. In this manner, the condition of the bolted connection can be monitored. For example, the fastening bolt 14a may have a hollow portion to accommodate a strain gauge (such as a piezoelectric strain sensor) with connecting wires extending therefrom for powering the gauge and reading signals from the gauge.

[0050] Fig. 11 shows a perspective view of a modified side beam, and Fig. 12 shows a perspective view of a bogie frame including the side beam of Fig. 11. In this modification, the side beams 20 further include steel reinforcing plates 25 to further strengthen the side beams against bending and torsional forces and to help prevent separation of the side beam structural members due to loads from the car body. In particular, the steel reinforcing plates 25 may be attached to the inside and outside of the side beams so as to extend across the joint between the end 21 a of the center plate 21 and the suspension mounting portion 22.

[0051] Further, bolted connections 25a may be used to join the reinforcing plates 25 to the side beams 20. In particular, the bolted connections may comprise fastening bolts inserted through through-holes in the reinforcing plates. On one side of each joint, these bolts are threaded into threaded holes 22c (see FIG. 5) formed in the suspension mounting part 22. On the other side of the joint, if the plate is on the outside of the side beam, the bolts are threaded into threaded holes 23d (see FIG. 7) formed in the auxiliary plate 23, or if the plate is on the inside of the side beam, into threaded holes 24e (see FIG. 8) formed in the square brace 24 (in this case, the bolts also pass through through-holes 21c formed in the central plate 21—see FIG. 6).

[0052] The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, are expressed in terms of their particular form or means for performing a disclosed function, or in terms of a method or process for obtaining a disclosed result, and may be utilized, where appropriate, separately or in any combination of such features to realize various forms of the invention.

[0053] While the present invention has been described in conjunction with the exemplary embodiments set forth above, many equivalent modifications and variations will be apparent to those skilled in the art given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various modifications to the described embodiments can be made without departing from the spirit and scope of the invention.

[0054] For the avoidance of doubt, any theoretical explanations provided herein are provided for the purpose of enhancing the understanding of the reader, and the inventors do not wish to be bound by any of these theoretical explanations.

[0055] Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

[0056] Throughout this specification, including the claims which follow, unless the context otherwise requires, the words "comprise" and "include," and variations thereof such as "comprises," "comprising," and "including," will be understood to imply the inclusion of a stated integer or step or group of integers or steps, but not the exclusion of other integers or steps or groups of integers or steps.

[0057] It should be noted that, as used in the specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from "about" one particular value and / or to "about" another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when values ​​are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms another embodiment. The term "about" is arbitrary in relation to numerical values ​​and means, for example, + / - 10%. [Explanation of symbols]

[0058] 1. Railway vehicles 3 wheelset 5 carts 10 Bogie frame 11 Crossbeam 11e Threaded receiving hole 14 volt connection 14a bolt 14b Sim 14c Sensor 20 Side beam 21 Center plate 21a End 21d through hole 22 Suspension mounting part 22a base 23 Auxiliary plate 24 Square brace 24a First wall 24b Second wall 30 volt connection 30a bolt L Longitudinal direction T horizontal direction

Claims

1. side beams of a bogie frame of a railway vehicle, two such side beams defining respective lateral sides of the bogie frame relative to a longitudinal direction of the railway vehicle, and cross beams extending in a transverse direction of the railway vehicle to join the side beams, the bogie frame being configured to carry front and rear wheel sets in use; The side beams are individual structural members, an elongated central plate extending between first and second ends in the longitudinal direction between positions occupied by the wheel sets in use, the thickness direction of the central plate being parallel to the lateral direction; first and second suspension mounts configured to mount wheelset suspension elements, the first and second suspension mounts being cantilevered from the first and second ends of the center plate, respectively, each suspension mount extending upwardly and longitudinally away from a respective juncture with the end of the center plate to define a space below the suspension mount for joining the suspension element to the respective wheelset, and at each juncture each suspension mount has a width in the lateral direction that is greater than a thickness of the center plate such that the suspension mount projects laterally outward from the center plate; formed of individual structural members comprising: the individual structural members being joined together by respective bolt connections; Side beam.

2. The side beam of claim 1 , wherein each said bolted connection transfers substantially all of the load between said individual structural members.

3. 3. The side beam of claim 2, wherein the center plate is formed of a wrought aluminum alloy and the suspension mounts are formed of a cast aluminum alloy.

4. 4. The side beam of claim 3, wherein the individual structural members further comprise one or more reinforcing components at each of the joints to support the increased width of the respective suspension mounting portions relative to the thickness of the center plate.

5. 5. The side beam of claim 4, wherein each suspension mounting portion has a base that forms the joint with the respective end of the center plate, an inner side of the base joined to an upper surface of the respective end by one or more bolt connections that pass through the base and the end, and the one or more reinforcing components at each joint include a secondary plate extending parallel to the center plate, and an outer side of the base joined to an upper surface of the secondary plate by one or more bolt connections that pass through the base and the secondary plate.

6. 6. The side beam of claim 5, wherein the one or more reinforcing components at each joint further include a square brace having first and second wall portions for reinforcing the secondary plate to the central plate, the first wall portion being joined or joinable in use to an outer surface of the central plate by one or more bolt connections passing through the first wall portion and the central plate, and the second wall portion being joined to a side surface of the secondary plate by one or more bolt connections passing through the second wall portion and the secondary plate.

7. 7. The side beam of claim 6, wherein at each joint, the lateral width of the suspension mounting portion is at least two times greater than the lateral thickness of the center plate.

8. 8. The side beam of claim 7, wherein said central plate is tapered at its ends such that said vertical height of said central plate is greater at its center than at its ends.

9. 9. A side beam according to claim 8, wherein each bolted connection is formed by a bolt passing through a through hole in at least one of the structural members and received in a threaded receiving hole in another of the structural members or, in use, in the cross beam.

10. A bogie frame for a railway vehicle, comprising: - two side beams according to any preceding claim defining respective lateral sides of the bogie frame in relation to the longitudinal direction of the railway vehicle; a cross beam extending in a lateral direction of the railway vehicle for joining the side beams; Equipped with the cross beam is joined to the center plate of each side beam by a respective bolt connection; Truck frame.

11. The bogie frame of claim 10, wherein the bolted connections joining the cross beams to the center plate transfer substantially all of the load between the cross beams and the center plate.

12. 12. The bogie frame of claim 11, wherein each bolted connection joining the cross beam to one of the center plates is formed by a bolt passing through a through hole in the center plate and received in a threaded receiving hole in the cross beam.

13. The bogie frame of claim 12 , wherein the bolted connections joining the cross beams to the center plate further comprise sensors for measuring axial strain in the bolts of the bolted connections.

14. The bogie frame of claim 13 , wherein the bolted connections joining the cross beams and the center plate further comprise shims disposed at the interfaces between the cross beams and the center plate.

15. A railway vehicle comprising one or more bogies, the or each bogie comprising a bogie frame according to any one of claims 10 to 14 and front and rear wheel sets held by the bogie frame.

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