Title of Invention	"CROSS-ANCHOR RAILWAY BOGIE"
Abstract	CROSS-ANCHOR RAILWAY BOGIE The invention concerns a cross-anchor railway bogie (10). The bogie (10) has generally U-shaped sub-frames (28) which are connected to axleboxes (18) of the bogie. The sub-frames are themselves interconnected by cross-anchors (30) lying substantially on the bogie diagonals (36). The cross-anchors (30) are connected to the U-shaped .sub-frames (28) at connections (58) lying substantially in the plane (60) of the bogie axles (24), whereby the cross-anchors themselves lie substantially in that plane.

Title of Invention

"CROSS-ANCHOR RAILWAY BOGIE"

Abstract

CROSS-ANCHOR RAILWAY BOGIE The invention concerns a cross-anchor railway bogie (10). The bogie (10) has generally U-shaped sub-frames (28) which are connected to axleboxes (18) of the bogie. The sub-frames are themselves interconnected by cross-anchors (30) lying substantially on the bogie diagonals (36). The cross-anchors (30) are connected to the U-shaped .sub-frames (28) at connections (58) lying substantially in the plane (60) of the bogie axles (24), whereby the cross-anchors themselves lie substantially in that plane.

Full Text	FORM 2 THE PATENTS ACT 1970 [39 OF 1970] COMPLETE SPECIFICATION [See Section 10] "CROSS-ANCHOR RAILWAY BOGIE" HERBERT SCHEFFEL, a German Citizen, of 83A Van Wouw Street, 0181 Groenkloof, South Africa, The following specification particularly describes the nature of the invention and the manner in which it is to be performed:- WO 00/30914 PCT/IB99/01890 "CROSS-ANCHOR RAILWAY BOGIE" BACKGROUND TO THE INVENTION THIS invention relates to a cross-anchor railway bogie. Railway bogie wheelsets having conical or profiled wheel treads have the ability to align themselves radially on curved track as a result of the difference in the rolling radii of the inner and outer wheels of the wheelset. However for dynamic stability it is necessary that the wheelsets be suspended to the bogie frame in a manner allowing flexibility in the horizontal plane, with the flexibility of the suspension being carefully selected in order to ensure adequate curving performance and stability. While high flexibility in the longitudinal direction improves curving performance, it reduces inter-axle shear stiffness which in turn reduces hunting stability at high speeds. This is particularly so in the case of three-piece bogies in which the connections between the side frames and the bolster employ friction wedges which provide only limited shear stiffness between the wheelsets of the bogie. To provide for higher levels of inter-axle shear stiffness it is common practice, at least in the case of narrow gauge bogies, i.e. bogies running on 1067mm narrow gauge track, to employ so-called cross-anchors connected obliquely between diagonally opposed axleboxes. Because of space constraints. U-shaped sub-frames are connected to me axleboxes of the wheelsets and the cross-anchors are pin-jointed to the corners of the sub-frames. WO 00/30914 PCT/IB99/01890 It is necessary to pin the cross-anchors to the corners of the U-shaped sub-frames because, with this arrangement, it is possible to insert the cross-anchors, during bogie assembly, through the standard windows in the bogie side frames. While the cross-anchor design described above operates adequately in narrow gauge bogies, it has several inherent weaknesses when applied to standard gauge (1435mm) or broad gauge (1676mm) bogies, with the result that this design has met with limited acceptance in those applications. The following disadvantages of the known cross-anchor design, particularly in standard and broad gauge applications, may be noted: 1. Whereas the cross-anchors are pinned to the corners of the U-shaped sub-frame in narrow gauge applications, this is not desirable in standard and broad gauge applications. One reason for this is that the increased length of the cross-anchors increases the tendency for them to buckle under applied compressive loads. This problem is exacerbated by the fact that the increase in angle between the cross-anchors and the longitudinal direction, as a result of the increase in bogie width, increases the forces acting in the cross-anchors. 2. In the conventional design the sub-frames are forked at the cross-anchor connection points to receive the ends of the cross-anchors. The ends of the cross-anchors are pinned there with cylindrical pins acting in flexible, typically elastomeric rubber bushes. Because the corners of the sub-frames are close to the brake shoes where there is limited space it is necessary for the cross-anchors to lie in planes spaced from the plane of the axles themselves. WO 00/30914 PCT/IB99/018 The couples acting on the cylindrical pins as a result of this off-set lead to edge wear of the bushes. While this wear can be tolerated in narrow gauge applications, the larger forces in the cross-anchors in standard and broad gauge applications, and the increased braking forces used in such applications, lead to unacceptable wear rares. 3. Where conventional "wing-type" axleboxes are used, each U-shaped sub-frame and axlebox assembly rests directly on the journal roller bearings of the wheelset and thus increases the unsprung mass and yaw moment of inertia of the wheelset. This has a destabilising effect. In standard and broad gauge applications this effect is more damaging as the wheelset is already heavier and the U-shaped sub-frames are bigger and have to be made sturdier for the same degree of rigidity. The present invention seeks to address these problems and to provide a cross-anchor bogie which will be suitable for use in standard and broad gauge applications. SUMMARY OF THE INVENTION According to this invention there is provided a cross-anchor railway bogie which Comprises generally U-shaped sub-frames which are connected to axieboxes of the bogie and which are interconnected by cross-anchors, wherein the cross-anchors act substantially on the bogie diagonals and are connected to the V-shaped sub-frames at connections lying substantially in the plane of the bogie axles, whereby the cross-anchors themselves lie substantially in that plane. WO 00/30914 PO7IB99/01890 Typically the cross-anchors are connected to the U-shaped sub-frames at spherical bearings, and the spherical bearings are provided at the lower ends of downwardly cantilevered pins carried by the sub-frames. The term "diagonal" as used in this specification refers to an imaginary line extending diagonally, in plan, from the centre of an axlebox of one wheelset on one side of the bogie to the centre of an axlebox of the other wheelset on the other side of the bogie. Further according to the invention, each U-shaped sub-frame comprises two L-shaped members, a first arm of each L-shaped member being connected to an axlebox and the other, second arm of the L-shape member extending transversely adjacent the bolster of the bogie frame, and means for connecting the second arms of the L-shaped members rigidly to one another. In one embodiment, the second arm of one L-shaped member ends in a bifurcation defined by upper and lower elements and the second arm of the other L-shaped member includes an extension which is received in the bifurcation, between the upper and lower elements, and is connected to the upper and lower elements at spaced apart positions by means of the downwardly cantilevered pins to which the ends of the cross-anchors are connected. In another embodiment, the second arms extend beyond the cross-anchor connection points and the ends of a link are connected non-rotatably to the ends of arms to connect me L-shaped members rigidly to one another. The cross-anchor railway bogie of the invention is typically designed as a standard gauge bogie or a broad gauge bogie. The bogie may be a three-piece bogie with a central bolster mounted to side frames to which wheelsets are suspended at wing-type axleboxes, the ends of the U-shaped sub-frames WO 00/30914 PCT/IB99/0189I being connected to the wing-type axleboxes. Alternatively, the bogie may be a three-piece bogie with a central bolster mounted to side frames suspended on journal roller bearings via bearing adaptors and shear pads which are inclined to the vertical, the ends of the U-shaped sub-frames being connected to the bearings adaptors. In a preferred embodiment, the bogie comprises yaw constraint means providing a constraint to relative yawing movements of the wheelsets of the bogie, the yaw constraint means operating in a degressive manner. The yaw constraint means may comprise, for each end of each wheelset, a coil spring which is preloaded in twist and which has respective inner and outer ends, an element acting between a U-shaped sub-frame and the inner end of each spring and an element acting between an axlebox or bearing adaptor and the outer end of each spring, the spring being arranged to apply a relatively large yaw-constraining force to the wheelset for relatively small yaw deflection and thereafter a relatively small yaw-constraining force to the wheelset for subsequent yaw deflection. BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings. In the drawings: Figure 1 shows a top perspective view of a self-steering, three- piece cross-anchor bogie according to this invention; WO 00/30914 PCTYIB99/OI890 Figure 2 shows a view similar to that of Figure 1, but with the bolster and one side frame of the bogie omitted; Figure 3 shows a partly sectioned, partial side view illustrating the axlebox connection of the L-shaped member of the U-shaped sub-frame; Figure 4 shows a partly sectioned longitudinal view of the axlebox connection; Figure 5 shows a partly ghosted plan view of the bogie; Figure 6 shows a detail of one embodiment of cross-anchor connection; Figure 7 shows a partial plan view of another embodiment of cross-anchor connection; Figure 8 shows a cross-sectional detail of the embodiment of Figure 7; Figure 9 illustrates a cross-anchor railway bogie according to the invention fitted with a degressive yaw constraint; Figure 10 shows a side view of the arrangement illustrated in Figure 9; Figure 11 shows a detail of the Figure 9 arrangement in an internal view; WO 00/30914 PCT/IB99/0I! Figure 12 shows a detail of the Figure 9 arrangement in an external view; and Figure 13 shows a partial side view of another embodiment of cross-anchor railway bogie including a modified axle box suspension. DESCRIPTION OF PREFERRED EMBODIMENTS Referring to Figure 1, a three piece, self-steering cross-anchor bogie 10 according to this invention has a transverse bolster 12 and side frames 14 to which wheelsets 16 are suspended at axlebox housings 18. Referring also to Figure 3, each axlebox housing 18 includes a saddle 20 which receives the journal roller bearing 22 for the axle 24 of a wheelset 16. The side frames of the bogie are suspended on the wheelsets on flexible elements 26 which provide flexibility in the vertical, lateral and longitudinal directions. The bogie 10 also includes a pair of U-shaped sub-frames 28 connected at their ends to the axlebox housings 18, and cross-anchors 30 which cross over one another at the geometrical centre of the bogie (see Figure 2) and which are connected pivotally to the U-shaped sub-frames 28. As thus far described, the bogie 10 is generally conventional. However, whereas in a conventional three-piece cross-anchor bogie, the cross-anchors are typically connected co the comers of the U-shaped sub-frames, the illustrated cross-anchors 30 are connected to the sub-frames 28 at connections 32 located inwardly of the corners 34. The arrangement is such that the cross-anchors lie, in plan view, on the diagonals of the bogie. The WO 00/30914 PCT/IB99/01890 diagonals, which are indicated with the numeral 36 in Figure 5, extend between the centres of diagonally opposed axlebox housings 18. As in conventional designs, the cross-anchors 30 provide the bogie 10 with inter-axle shear stiffness during curving. Each U-shaped sub-frame 28 includes two L-shaped members 38. One arm 40 of each L-shaped member is an integral, longitudinal extension of the associated axlebox housing 18, as will be apparent from Figures 1, 2, 3 and 5. The other arm 42 of each L-shaped member extends transversely from the comer 34, adjacent and generally parallel to the bolster 12. Referring particularly to Figures 4 and 5, it will be seen that the L-shaped members 38 extend around the associated wheel 44 and then over the associated brake assembly 46. In the embodiment of Figures 1 to 6, the arm 42 of one L-shaped member 38 of each sub-frame 28 has upper and lower elements 48 and 50 defining a bifurcation at the end of that arm. The arm 42 of the other L-shaped member of the same sub-frame 28 has an integral, narrower extension 52, in the form of a tongue, which locates in the bifurcation between the upper and lower elements 48 and 50. Vertical pins 54 and 56 connect the L-shaped members 38 of each sub-frame rigidly to one another and also provide pivotal connections for the ends of the cross-anchors 30. Referring to Figure 4 the pin 54 is press-fitted through aligned openings in the upper and lower elements 48 and 50 and in the end of the tongue 52. The pin 56 is similarly press-fitted through aligned openings in the ends of the elements 48 and 50 and in the arm 42. With this arrangement, it will be understood that the arms 42 of the two L-shaped members are accurately aligned with and rigidly connected to one another to form the rigid sub-frame 28. WO 00/30914 PCT/1B99/0189I The pins 54 and 56 cantilever downwardly to positions beneath the sub-frames 28 and the ends of the cross-anchors 30 are connected to the lower ends of the pins at spherical joints 58 as shown in Figure 6. The spherical joints 58 lie in the plane 60 of the axles of the bogie as shown in Figures 3 and 6. Hence the cross-anchors themselves lie in the plane 60. This configuration gives rise to a number of advantages, particularly in the context of a bogie 10 designed for use on standard or broad gauge track: 1. Because the cross-anchors lie on the diagonals 36 of the bogie, they are considerably shorter than would be the case were they to be connected to the corners 34 of the U-shaped sub-frames 28. The shorter cross-anchors have greater buckling resistance under applied compressive loading during curving. This feature is particularly important in the case of standard or broad gauge track because cross-anchors connected to the corners of the sub-frames of bogies in such cases would be even longer, and hence more prone to buckling, than in the case of narrow gauge track. 2. The fact that the joints 58, and hence the cross-anchors 30, lie in the plane 60 of the axles, together with the fact that the joints 58 are spherical joints, ensures that the cross-anchors are always loaded axially and are not subjected to bending moments when the pins 54 and 56 are subjected to shear and braking forces. 3. As explained previously conventional cross-anchor designs have the cross-anchors lying in a plane off-set from the plane of the axles, giving rise to force couples being applied by me connecting pins to the flexible bushes in which they are mounted when the bogie is WO 00/30914 PCT/IB99/01890 subjected to shear and longitudinal braking forces. The result is wear of the bushes and this will be particularly pronounced in the case of standard and broad gauge track. In the present case the three-dimensional curvature of the L-shaped members 38 provides a degree of the required flexibility at the cross-anchor connection. Because spherical joints 58 are used, the pins 54 and 56 can themselves have a degree of flexibility to accommodate the shear and braking forces. It will be understood that many variations are possible within the scope of the invention. For instance, instead of the connection of the L-shaped members to one another using the above-described arrangement with a bifurcation on one member receiving a tongue-like extension on the other member, an arrangement such as that seen in Figures 7 and 8 could be used. In this case the arms 42 of the L-shaped members are identical and are formed with forked extremities 70. These extremities are connected rigidly to one another by tandem links 72. The pins 54, 56 pass through aligned openings in the extremities 70 and links 72. The extremities and links are made non-rotatable with respect to the pins 54, 56 and hence with respect to one another. In the case of the tandem links 72 this is achieved by means of spring steel roll pins 74 located in aligned holes in the links and the pins 54, 56. Similar roll pins 76 are used in the case of the forked extremities 70. It will of course be understood that in this arrangement the ends of the arms 42 need not be forked and could be solid. Further modifications are illustrated in Figures 9 to 13 of the drawings. The cross-anchor bogie of the invention may, for instance, incorporate a degressive yaw constraint which is adapted to provide a degressive constraint on yawing motions undergone by the wheelsets 16. An example of a degressive yaw constraint which can be included for this purpose is illustrated in Figures 9 to 12 which show one end of one wheelset only. In WO 00/30914 PCT/IB99/0I890 these Figures, components corresponding to components described above are indicated by the same reference numerals. The degressive yaw constraint 80 illustrated in Figures 9 to 12 makes use of a coil spring 82 which has projecting ends 84 and 86 and which is installed in a prestressed state in a housing 88. The extends extend laterally with respect to the longitudinal direction of the bogie. The prestress which is applied is in twist as opposed to axially and is achieved by inserting the spring 82 in the housing with its inner end 84 locating against an inner preload stop 90 (see the enlarged portion of Figure 9 and Figures 11 and 12). A twisting force which has the effect of reducing the diameter of the coils is then applied to the outer end 86 until a predetermined prestress or preload has been attained. The outer end 86 is then locked in position by means of a preload stop 92 which is fixed to the housing 88 by, for instance, bolts or welding (not shown). The housing is fixed by means of a fixing structure 91, possibly welded or bolted in position, to the side frame 14 of the bogie within the side frame window 93. The design of the spring 82 is such that when the desired preload force has been attained, the ends 84 and 86 lie in a vertical plane 94 which bisects the spring. Also, referring to Figure 10 the position of the housing, and hence of the spring 82, is such that the ends 84 and 86 lie in a horizontal plane 96 passing centrally through the journal bearings 22, i.e. the horizontal plane of the axles 24. Rollers 98, 100 are fitted to the ends 84, 86 respectively. An inner push-arm 102 is fixed to and extends from the adjacent L-shaped member 38 and acts on the inner roller 98 via an assembly 104 of wear and packing plates. An outer push-arm 106 is fixed to and extends from the associated WO 00/30914 PCT/IB99/01890 axlebox housing 18, and acts on the outer roller 100 via a corresponding assembly of wear and backing plates plates 108. The push-arms 102 and 106 are fixed to the L-shaped member 38 and the axlebox housing 18 by any suitable means (not shown) such as welding or bolting. It will be understood that corresponding degressive yaw constraints are provided adjacent both ends of each wheelset. In use if the wheelset with which the degressive yaw constraint is associated starts to yaw in a sense which causes the inner push-arm 102 to press against the roller 98 and hence the inner end 84 of the spring, the force on the roller will increase until the preload twist force on the spring is reached. As a result of the inherent flexibility of the push-arm 102, of the roller 98 and of the end 84, there will be a predetermined, small amount of deflection (typically 1mm to 2mm) of the end 84 when the design preload force is reached. If the yawing motion of the wheelset exceeds this deflection, the inner push-arm 102 presses the inner end 84 off the preload stop 90 and the twist in the spring will increase as the outer push-arm 106 will lose contact with the outer roller 100, leaving the outer end 86 pressing hard against the preload stop 92. However the increased twist in the spring will cause the force acting between the inner roller 98 and the inner push-arm 102 to increase only slightly. This is because the stiffness of the spring is relatively small and the preload twist deflection of the spring (typically of the order of 100mm) is much greater than the maximum possible additional deflection (typically of the order of 10mm only). The force transmission which is achieved is accordingly of a degressive nature. It will be understood that if yawing takes place in the opposite sense the outer push-arm 106 will press against the outer roller 100 and the inner push-arm will lose contact, with sufficient yawing movement, with the inner roller 98. The specification of applicant's co-pending Indian Patent Application No. IN/PCT/2000,00702/MUM describes various types of force transmitting device which can serve as degressive yaw constraints to constrain wheelset yawing in a degressive manner, thereby to provide a bogie with enhanced hunting stability at high speeds. It will also be understood that the degressive yaw constraint 80 described above can serve similarly as a force transmitting device with a degressive characteristic, and that appropriate ones of the devices described in the aforementioned co¬pending patent application may also be used in place of the constraint 80. It is however believed that in this application the constraint 80 will be advantageous in that its construction is relatively simple, in that it can be installed in a convenient manner in the side frame window 93 and in that it will require little maintenance. In a modification of the degressive yaw constraint 80, the rigid push-arms 102 and 106 could be replaced by straps or ropes which would act in tension on the ends 84, 86 of the spring 82. Figure 13 illustrates another modification within the scope of the invention. The embodiment illustrated in Figure 1 employs so-called "wing-type" axleboxes 18 in which there is a saddle 20, at each end of each wheelset, which straddles and receives the journal roller bearing 22. This type of axlebox is described in more detail with reference to Figures 5 and 6 of applicant's aforementioned co-pending Indian Patent Application No. IN/PCT/2000,00702/MUM Instead of the "wing-type" axleboxes the embodiment of Figure 13 includes, at each end of each wheelset, an axlebox including a bearing adaptor 110 with pairs 112 of inclined rubber shear pads 114, in a manner WO 00/30914 PCT/IB99/0I890 similar to that described with reference to figure 25 of the aforementioned co-pending patent application. In this case, the ends of the arms 40 of the L-shaped members 38 of the sub-frames 28 will be welded at inboard positions to the bearing adaptors 110. Compared to the earlier described "wing-type" axleboxes, it is believed that the use of axleboxes of the type illustrated in Figure 13 may be preferable, at least in some cases, in that this type of construction can reduce the overall mass of the sub-frame/axlebox assembly which rests directly on the journal roller bearings. I CLAIM: 1. A cross-anchor railway bogie which comprises generally U-shaped sub-frames which are connected to axleboxes of the bogie, which are interconnected by cross-anchors and each of which comprises a plurality of sub-frame elements, wherein the cross-anchors act substantially on the bogie diagonals and are connected to the U-shaped sub-frames at connections lying substantially in the plane of the bogie axles, whereby the cross-anchors themselves lie substantially in that plane, characterised in that the sub-frame elements of each U-shaped sub-frames are connected rigidly to one another by means of pins to which the cross-anchors are connected. 2. A cross-anchor railway bogie as claimed in claim 1, wherein the cross-anchors are connected to the pins at spherical bearings at lower ends of the pins. 3. A cross-anchor railway bogie as claimed in claim 1 or 2 wherein each U-shaped sub-frame comprises two L-shaped members, a first arm of each L-shaped member being connected to an axlebox and the other, second arm of the L-shaped member extending transversely adjacent the bolster of the bogie frame, and means for connecting the second arms of the L-shaped members rigidly to one another. 4. A cross-anchor railway bogie as claimed in claim 3, wherein the second arm of one L-shaped member ends in a bifurcation defined by upper and lower elements and the second arm of the other L-shaped member includes an extension which is received in the bifurcation, between the upper and lower elements, and is connected to the upper and lower elements at spaced apart positions by means of the pins. 5. A cross-anchor railway bogie as claimed in claim 3, wherein the second arms of the L-shaped members extend beyond the cross-anchor connection points and, in each U-shaped sub-frame, the ends of a link are connected non-rotatably to the ends of the second arms thereby to connect the L-shaped members rigidly to one another. 6. A cross-anchor railway bogie as claimed in any one of claims 1 to 5 wherein the bogie is a three-piece bogie with a central bolster mounted to side frames to which wheelsets are suspended at wing-type axleboxes, the ends of the U-shaped sub-frames being connected to the wing-type axleboxes. 7. A cross-anchor railway bogie as claimed in any one of claims 1 to 5, wherein the bogie is a three-piece bogie with a central bolster mounted to side frames suspended on the journal roller bearings via bearing adapters and shear pads which are inclined to the vertical, the ends of the U-shaped sub-frames being connected to the bearing adaptors. 8. A cross-anchor railway bogie as claimed in any one of 1 to 7 claims comprising yaw constraint means providing a constraint to relative yawing movements of the wheelsets of the bogie, the yaw constraint means operating in a degressive manner and including, for each end ol each wheelset, a coil spring which is preloaded in twist and which has respective inner and outer ends, an element acting between a U-shaped sub-frame and the inner end of each spring and an element acting between an axlebox or bearing adaptor and the outer end of each spring, the spring being arranged to apply a relatively large yaw constraining force to the wheelset for relatively small yaw deflection and thereafter a relatively small yaw-constraining force to the wheelset for subsequent yaw deflection. Dated this 24th day of July, 2000. F. S. GROSER of GROSER & GROSER AGENT FOR THE APPLICANT

Full Text

FORM 2
THE PATENTS ACT 1970
[39 OF 1970]
COMPLETE SPECIFICATION [See Section 10]
"CROSS-ANCHOR RAILWAY BOGIE"
HERBERT SCHEFFEL, a German Citizen, of 83A Van Wouw Street, 0181 Groenkloof, South Africa,
The following specification particularly describes the nature of the invention and the manner in which it is to be performed:-

WO 00/30914 PCT/IB99/01890
"CROSS-ANCHOR RAILWAY BOGIE"
BACKGROUND TO THE INVENTION
THIS invention relates to a cross-anchor railway bogie.
Railway bogie wheelsets having conical or profiled wheel treads have the ability to align themselves radially on curved track as a result of the difference in the rolling radii of the inner and outer wheels of the wheelset. However for dynamic stability it is necessary that the wheelsets be suspended to the bogie frame in a manner allowing flexibility in the horizontal plane, with the flexibility of the suspension being carefully selected in order to ensure adequate curving performance and stability. While high flexibility in the longitudinal direction improves curving performance, it reduces inter-axle shear stiffness which in turn reduces hunting stability at high speeds. This is particularly so in the case of three-piece bogies in which the connections between the side frames and the bolster employ friction wedges which provide only limited shear stiffness between the wheelsets of the bogie.
To provide for higher levels of inter-axle shear stiffness it is common practice, at least in the case of narrow gauge bogies, i.e. bogies running on 1067mm narrow gauge track, to employ so-called cross-anchors connected obliquely between diagonally opposed axleboxes. Because of space constraints. U-shaped sub-frames are connected to me axleboxes of the wheelsets and the cross-anchors are pin-jointed to the corners of the sub-frames.

WO 00/30914 PCT/IB99/01890

It is necessary to pin the cross-anchors to the corners of the U-shaped sub-frames because, with this arrangement, it is possible to insert the cross-anchors, during bogie assembly, through the standard windows in the bogie side frames.
While the cross-anchor design described above operates adequately in narrow gauge bogies, it has several inherent weaknesses when applied to standard gauge (1435mm) or broad gauge (1676mm) bogies, with the result that this design has met with limited acceptance in those applications. The following disadvantages of the known cross-anchor design, particularly in standard and broad gauge applications, may be noted:
1. Whereas the cross-anchors are pinned to the corners of the U-shaped sub-frame in narrow gauge applications, this is not desirable in standard and broad gauge applications. One reason for this is that the increased length of the cross-anchors increases the tendency for them to buckle under applied compressive loads. This problem is exacerbated by the fact that the increase in angle between the cross-anchors and the longitudinal direction, as a result of the increase in bogie width, increases the forces acting in the cross-anchors.
2. In the conventional design the sub-frames are forked at the cross-anchor connection points to receive the ends of the cross-anchors. The ends of the cross-anchors are pinned there with cylindrical pins acting in flexible, typically elastomeric rubber bushes. Because the corners of the sub-frames are close to the brake shoes where there is limited space it is necessary for the cross-anchors to lie in planes spaced from the plane of the axles themselves.

WO 00/30914 PCT/IB99/018
The couples acting on the cylindrical pins as a result of this off-set lead to edge wear of the bushes. While this wear can be tolerated in narrow gauge applications, the larger forces in the cross-anchors in standard and broad gauge applications, and the increased braking forces used in such applications, lead to unacceptable wear rares.
3. Where conventional "wing-type" axleboxes are used, each U-shaped sub-frame and axlebox assembly rests directly on the journal roller bearings of the wheelset and thus increases the unsprung mass and yaw moment of inertia of the wheelset. This has a destabilising effect. In standard and broad gauge applications this effect is more damaging as the wheelset is already heavier and the U-shaped sub-frames are bigger and have to be made sturdier for the same degree of rigidity.
The present invention seeks to address these problems and to provide a cross-anchor bogie which will be suitable for use in standard and broad gauge applications.
SUMMARY OF THE INVENTION
According to this invention there is provided a cross-anchor railway bogie which Comprises generally U-shaped sub-frames which are connected to axieboxes of the bogie and which are interconnected by cross-anchors, wherein the cross-anchors act substantially on the bogie diagonals and are connected to the V-shaped sub-frames at connections lying substantially in the plane of the bogie axles, whereby the cross-anchors themselves lie substantially in that plane.

WO 00/30914 PO7IB99/01890
Typically the cross-anchors are connected to the U-shaped sub-frames at spherical bearings, and the spherical bearings are provided at the lower ends of downwardly cantilevered pins carried by the sub-frames.
The term "diagonal" as used in this specification refers to an imaginary line extending diagonally, in plan, from the centre of an axlebox of one wheelset on one side of the bogie to the centre of an axlebox of the other wheelset on the other side of the bogie.
Further according to the invention, each U-shaped sub-frame comprises two L-shaped members, a first arm of each L-shaped member being connected to an axlebox and the other, second arm of the L-shape member extending transversely adjacent the bolster of the bogie frame, and means for connecting the second arms of the L-shaped members rigidly to one another. In one embodiment, the second arm of one L-shaped member ends in a bifurcation defined by upper and lower elements and the second arm of the other L-shaped member includes an extension which is received in the bifurcation, between the upper and lower elements, and is connected to the upper and lower elements at spaced apart positions by means of the downwardly cantilevered pins to which the ends of the cross-anchors are connected.
In another embodiment, the second arms extend beyond the cross-anchor connection points and the ends of a link are connected non-rotatably to the ends of arms to connect me L-shaped members rigidly to one another.
The cross-anchor railway bogie of the invention is typically designed as a standard gauge bogie or a broad gauge bogie. The bogie may be a three-piece bogie with a central bolster mounted to side frames to which wheelsets are suspended at wing-type axleboxes, the ends of the U-shaped sub-frames

WO 00/30914 PCT/IB99/0189I
being connected to the wing-type axleboxes. Alternatively, the bogie may be a three-piece bogie with a central bolster mounted to side frames suspended on journal roller bearings via bearing adaptors and shear pads which are inclined to the vertical, the ends of the U-shaped sub-frames being connected to the bearings adaptors.
In a preferred embodiment, the bogie comprises yaw constraint means providing a constraint to relative yawing movements of the wheelsets of the bogie, the yaw constraint means operating in a degressive manner. The yaw constraint means may comprise, for each end of each wheelset, a coil spring which is preloaded in twist and which has respective inner and outer ends, an element acting between a U-shaped sub-frame and the inner end of each spring and an element acting between an axlebox or bearing adaptor and the outer end of each spring, the spring being arranged to apply a relatively large yaw-constraining force to the wheelset for relatively small yaw deflection and thereafter a relatively small yaw-constraining force to the wheelset for subsequent yaw deflection.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings.
In the drawings:
Figure 1 shows a top perspective view of a self-steering, three-
piece cross-anchor bogie according to this invention;

WO 00/30914

PCTYIB99/OI890

Figure 2

shows a view similar to that of Figure 1, but with the bolster and one side frame of the bogie omitted;

Figure 3

shows a partly sectioned, partial side view illustrating the axlebox connection of the L-shaped member of the U-shaped sub-frame;

Figure 4

shows a partly sectioned longitudinal view of the axlebox connection;

Figure 5

shows a partly ghosted plan view of the bogie;

Figure 6

shows a detail of one embodiment of cross-anchor connection;

Figure 7

shows a partial plan view of another embodiment of cross-anchor connection;

Figure 8

shows a cross-sectional detail of the embodiment of Figure 7;

Figure 9

illustrates a cross-anchor railway bogie according to the invention fitted with a degressive yaw constraint;

Figure 10

shows a side view of the arrangement illustrated in Figure 9;

Figure 11

shows a detail of the Figure 9 arrangement in an internal view;

WO 00/30914 PCT/IB99/0I!
Figure 12 shows a detail of the Figure 9 arrangement in an
external view; and
Figure 13 shows a partial side view of another embodiment of
cross-anchor railway bogie including a modified axle box suspension.
DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to Figure 1, a three piece, self-steering cross-anchor bogie 10 according to this invention has a transverse bolster 12 and side frames 14 to which wheelsets 16 are suspended at axlebox housings 18.
Referring also to Figure 3, each axlebox housing 18 includes a saddle 20 which receives the journal roller bearing 22 for the axle 24 of a wheelset 16. The side frames of the bogie are suspended on the wheelsets on flexible elements 26 which provide flexibility in the vertical, lateral and longitudinal directions. The bogie 10 also includes a pair of U-shaped sub-frames 28 connected at their ends to the axlebox housings 18, and cross-anchors 30 which cross over one another at the geometrical centre of the bogie (see Figure 2) and which are connected pivotally to the U-shaped sub-frames 28.
As thus far described, the bogie 10 is generally conventional. However, whereas in a conventional three-piece cross-anchor bogie, the cross-anchors are typically connected co the comers of the U-shaped sub-frames, the illustrated cross-anchors 30 are connected to the sub-frames 28 at connections 32 located inwardly of the corners 34. The arrangement is such that the cross-anchors lie, in plan view, on the diagonals of the bogie. The

WO 00/30914 PCT/IB99/01890

diagonals, which are indicated with the numeral 36 in Figure 5, extend between the centres of diagonally opposed axlebox housings 18. As in conventional designs, the cross-anchors 30 provide the bogie 10 with inter-axle shear stiffness during curving.
Each U-shaped sub-frame 28 includes two L-shaped members 38. One arm 40 of each L-shaped member is an integral, longitudinal extension of the associated axlebox housing 18, as will be apparent from Figures 1, 2, 3 and 5. The other arm 42 of each L-shaped member extends transversely from the comer 34, adjacent and generally parallel to the bolster 12. Referring particularly to Figures 4 and 5, it will be seen that the L-shaped members 38 extend around the associated wheel 44 and then over the associated brake assembly 46.
In the embodiment of Figures 1 to 6, the arm 42 of one L-shaped member 38 of each sub-frame 28 has upper and lower elements 48 and 50 defining a bifurcation at the end of that arm. The arm 42 of the other L-shaped member of the same sub-frame 28 has an integral, narrower extension 52, in the form of a tongue, which locates in the bifurcation between the upper and lower elements 48 and 50.
Vertical pins 54 and 56 connect the L-shaped members 38 of each sub-frame rigidly to one another and also provide pivotal connections for the ends of the cross-anchors 30. Referring to Figure 4 the pin 54 is press-fitted through aligned openings in the upper and lower elements 48 and 50 and in the end of the tongue 52. The pin 56 is similarly press-fitted through aligned openings in the ends of the elements 48 and 50 and in the arm 42. With this arrangement, it will be understood that the arms 42 of the two L-shaped members are accurately aligned with and rigidly connected to one another to form the rigid sub-frame 28.

WO 00/30914 PCT/1B99/0189I

The pins 54 and 56 cantilever downwardly to positions beneath the sub-frames 28 and the ends of the cross-anchors 30 are connected to the lower ends of the pins at spherical joints 58 as shown in Figure 6. The spherical joints 58 lie in the plane 60 of the axles of the bogie as shown in Figures 3 and 6. Hence the cross-anchors themselves lie in the plane 60.
This configuration gives rise to a number of advantages, particularly in the context of a bogie 10 designed for use on standard or broad gauge track:
1. Because the cross-anchors lie on the diagonals 36 of the bogie, they are considerably shorter than would be the case were they to be connected to the corners 34 of the U-shaped sub-frames 28. The shorter cross-anchors have greater buckling resistance under applied compressive loading during curving. This feature is particularly important in the case of standard or broad gauge track because cross-anchors connected to the corners of the sub-frames of bogies in such cases would be even longer, and hence more prone to buckling, than in the case of narrow gauge track.
2. The fact that the joints 58, and hence the cross-anchors 30, lie in the plane 60 of the axles, together with the fact that the joints 58 are spherical joints, ensures that the cross-anchors are always loaded axially and are not subjected to bending moments when the pins 54 and 56 are subjected to shear and braking forces.
3. As explained previously conventional cross-anchor designs have the cross-anchors lying in a plane off-set from the plane of the axles, giving rise to force couples being applied by me connecting pins to the flexible bushes in which they are mounted when the bogie is

WO 00/30914 PCT/IB99/01890
subjected to shear and longitudinal braking forces. The result is wear of the bushes and this will be particularly pronounced in the case of standard and broad gauge track. In the present case the three-dimensional curvature of the L-shaped members 38 provides a degree of the required flexibility at the cross-anchor connection. Because spherical joints 58 are used, the pins 54 and 56 can themselves have a degree of flexibility to accommodate the shear and braking forces.
It will be understood that many variations are possible within the scope of the invention. For instance, instead of the connection of the L-shaped members to one another using the above-described arrangement with a bifurcation on one member receiving a tongue-like extension on the other member, an arrangement such as that seen in Figures 7 and 8 could be used. In this case the arms 42 of the L-shaped members are identical and are formed with forked extremities 70. These extremities are connected rigidly to one another by tandem links 72. The pins 54, 56 pass through aligned openings in the extremities 70 and links 72. The extremities and links are made non-rotatable with respect to the pins 54, 56 and hence with respect to one another. In the case of the tandem links 72 this is achieved by means of spring steel roll pins 74 located in aligned holes in the links and the pins 54, 56. Similar roll pins 76 are used in the case of the forked extremities 70. It will of course be understood that in this arrangement the ends of the arms 42 need not be forked and could be solid.
Further modifications are illustrated in Figures 9 to 13 of the drawings. The cross-anchor bogie of the invention may, for instance, incorporate a degressive yaw constraint which is adapted to provide a degressive constraint on yawing motions undergone by the wheelsets 16. An example of a degressive yaw constraint which can be included for this purpose is illustrated in Figures 9 to 12 which show one end of one wheelset only. In

WO 00/30914 PCT/IB99/0I890

these Figures, components corresponding to components described above are indicated by the same reference numerals.
The degressive yaw constraint 80 illustrated in Figures 9 to 12 makes use of a coil spring 82 which has projecting ends 84 and 86 and which is installed in a prestressed state in a housing 88. The extends extend laterally with respect to the longitudinal direction of the bogie. The prestress which is applied is in twist as opposed to axially and is achieved by inserting the spring 82 in the housing with its inner end 84 locating against an inner preload stop 90 (see the enlarged portion of Figure 9 and Figures 11 and 12). A twisting force which has the effect of reducing the diameter of the coils is then applied to the outer end 86 until a predetermined prestress or preload has been attained. The outer end 86 is then locked in position by means of a preload stop 92 which is fixed to the housing 88 by, for instance, bolts or welding (not shown). The housing is fixed by means of a fixing structure 91, possibly welded or bolted in position, to the side frame 14 of the bogie within the side frame window 93.
The design of the spring 82 is such that when the desired preload force has been attained, the ends 84 and 86 lie in a vertical plane 94 which bisects the spring. Also, referring to Figure 10 the position of the housing, and hence of the spring 82, is such that the ends 84 and 86 lie in a horizontal plane 96 passing centrally through the journal bearings 22, i.e. the horizontal plane of the axles 24.
Rollers 98, 100 are fitted to the ends 84, 86 respectively. An inner push-arm 102 is fixed to and extends from the adjacent L-shaped member 38 and acts on the inner roller 98 via an assembly 104 of wear and packing plates. An outer push-arm 106 is fixed to and extends from the associated

WO 00/30914 PCT/IB99/01890
axlebox housing 18, and acts on the outer roller 100 via a corresponding assembly of wear and backing plates plates 108. The push-arms 102 and 106 are fixed to the L-shaped member 38 and the axlebox housing 18 by any suitable means (not shown) such as welding or bolting.
It will be understood that corresponding degressive yaw constraints are provided adjacent both ends of each wheelset. In use if the wheelset with which the degressive yaw constraint is associated starts to yaw in a sense which causes the inner push-arm 102 to press against the roller 98 and hence the inner end 84 of the spring, the force on the roller will increase until the preload twist force on the spring is reached. As a result of the inherent flexibility of the push-arm 102, of the roller 98 and of the end 84, there will be a predetermined, small amount of deflection (typically 1mm to 2mm) of the end 84 when the design preload force is reached. If the yawing motion of the wheelset exceeds this deflection, the inner push-arm 102 presses the inner end 84 off the preload stop 90 and the twist in the spring will increase as the outer push-arm 106 will lose contact with the outer roller 100, leaving the outer end 86 pressing hard against the preload stop 92. However the increased twist in the spring will cause the force acting between the inner roller 98 and the inner push-arm 102 to increase only slightly. This is because the stiffness of the spring is relatively small and the preload twist deflection of the spring (typically of the order of 100mm) is much greater than the maximum possible additional deflection (typically of the order of 10mm only). The force transmission which is achieved is accordingly of a degressive nature.
It will be understood that if yawing takes place in the opposite sense the outer push-arm 106 will press against the outer roller 100 and the inner push-arm will lose contact, with sufficient yawing movement, with the inner roller 98.

The specification of applicant's co-pending Indian Patent Application No. IN/PCT/2000,00702/MUM describes various types of force transmitting device which can serve as degressive yaw constraints to constrain wheelset yawing in a degressive manner, thereby to provide a bogie with enhanced hunting stability at high speeds. It will also be understood that the degressive yaw constraint 80 described above can serve similarly as a force transmitting device with a degressive characteristic, and that appropriate ones of the devices described in the aforementioned co¬pending patent application may also be used in place of the constraint 80. It is however believed that in this application the constraint 80 will be advantageous in that its construction is relatively simple, in that it can be installed in a convenient manner in the side frame window 93 and in that it will require little maintenance.
In a modification of the degressive yaw constraint 80, the rigid push-arms 102 and 106 could be replaced by straps or ropes which would act in tension on the ends 84, 86 of the spring 82.
Figure 13 illustrates another modification within the scope of the invention. The embodiment illustrated in Figure 1 employs so-called "wing-type" axleboxes 18 in which there is a saddle 20, at each end of each wheelset, which straddles and receives the journal roller bearing 22. This type of axlebox is described in more detail with reference to Figures 5 and 6 of applicant's aforementioned co-pending Indian Patent Application No. IN/PCT/2000,00702/MUM
Instead of the "wing-type" axleboxes the embodiment of Figure 13 includes, at each end of each wheelset, an axlebox including a bearing adaptor 110 with pairs 112 of inclined rubber shear pads 114, in a manner

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similar to that described with reference to figure 25 of the aforementioned co-pending patent application. In this case, the ends of the arms 40 of the L-shaped members 38 of the sub-frames 28 will be welded at inboard positions to the bearing adaptors 110.
Compared to the earlier described "wing-type" axleboxes, it is believed that the use of axleboxes of the type illustrated in Figure 13 may be preferable, at least in some cases, in that this type of construction can reduce the overall mass of the sub-frame/axlebox assembly which rests directly on the journal roller bearings.

I CLAIM:
1. A cross-anchor railway bogie which comprises generally U-shaped sub-frames which are connected to axleboxes of the bogie, which are interconnected by cross-anchors and each of which comprises a plurality of sub-frame elements, wherein the cross-anchors act substantially on the bogie diagonals and are connected to the U-shaped sub-frames at connections lying substantially in the plane of the bogie axles, whereby the cross-anchors themselves lie substantially in that plane, characterised in that the sub-frame elements of each U-shaped sub-frames are connected rigidly to one another by means of pins to which the cross-anchors are connected.
2. A cross-anchor railway bogie as claimed in claim 1, wherein the cross-anchors are connected to the pins at spherical bearings at lower ends of the pins.
3. A cross-anchor railway bogie as claimed in claim 1 or 2 wherein each U-shaped sub-frame comprises two L-shaped members, a first arm of each L-shaped member being connected to an axlebox and the other, second arm of the L-shaped member extending transversely adjacent the bolster of the bogie frame, and means for connecting the second arms of the L-shaped members rigidly to one another.
4. A cross-anchor railway bogie as claimed in claim 3, wherein the second arm of one L-shaped member ends in a bifurcation defined by upper and lower elements and the second arm of the other L-shaped member includes an extension which is received in the bifurcation, between the

upper and lower elements, and is connected to the upper and lower elements at spaced apart positions by means of the pins.
5. A cross-anchor railway bogie as claimed in claim 3, wherein the second arms of the L-shaped members extend beyond the cross-anchor connection points and, in each U-shaped sub-frame, the ends of a link are connected non-rotatably to the ends of the second arms thereby to connect the L-shaped members rigidly to one another.
6. A cross-anchor railway bogie as claimed in any one of claims 1 to 5 wherein the bogie is a three-piece bogie with a central bolster mounted to side frames to which wheelsets are suspended at wing-type axleboxes, the ends of the U-shaped sub-frames being connected to the wing-type axleboxes.
7. A cross-anchor railway bogie as claimed in any one of claims 1 to 5, wherein the bogie is a three-piece bogie with a central bolster mounted to side frames suspended on the journal roller bearings via bearing adapters and shear pads which are inclined to the vertical, the ends of the U-shaped sub-frames being connected to the bearing adaptors.
8. A cross-anchor railway bogie as claimed in any one of 1 to 7 claims comprising yaw constraint means providing a constraint to relative yawing movements of the wheelsets of the bogie, the yaw constraint means operating in a degressive manner and including, for each end ol each wheelset, a coil spring which is preloaded in twist and which has respective inner and outer ends, an element acting between a U-shaped sub-frame and the inner end of each spring and an element acting between an axlebox or bearing adaptor and the outer end of each spring, the spring being arranged to apply a relatively large yaw

constraining force to the wheelset for relatively small yaw deflection and thereafter a relatively small yaw-constraining force to the wheelset for subsequent yaw deflection.
Dated this 24th day of July, 2000.

F. S. GROSER of GROSER & GROSER
AGENT FOR THE APPLICANT

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Patent Number

204571

Indian Patent Application Number

IN/PCT/2000/00216/MUM

PG Journal Number

24/2007

Publication Date

15-Jun-2007

Grant Date

27-Feb-2007

Date of Filing

24-Jul-2000

Name of Patentee

HERBERT SCHEFFEL

Applicant Address

83A VAN WOUW STREET, 0181 GROENKLOOF, SOUTH AFRICA.

Inventors:

#	Inventor's Name	Inventor's Address
1	HERBERT SCHEFFEL	83A VAN WOUW STREET, 0181 GROENKLOOF, SOUTH AFRICA.

PCT International Classification Number

B 61 F 5/38

PCT International Application Number

PCT/IB99/01890

PCT International Filing date

1999-11-25

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	98 / 10828	1998-11-26	South Africa