AU2014262128A1

AU2014262128A1 - Drawbar for rail wagons

Info

Publication number: AU2014262128A1
Application number: AU2014262128A
Authority: AU
Inventors: Matthew Noel THURSTON
Original assignee: Bradken Resources Pty Ltd
Current assignee: Bradken Resources Pty Ltd
Priority date: 2013-05-01
Filing date: 2014-05-01
Publication date: 2015-10-29
Also published as: AU2018202233B2; AU2020200317A1; WO2014176635A1; CN105163996A; AU2018202233A1

Abstract

A drawbar for interconnecting first and second rail wagons. The drawbar comprises first and second metal terminations disposed at opposite end regions of the drawbar. The terminations are forged and shaped for interconnecting with a respective drawgear mounting on the first and second rail wagons. The drawbar further comprises an elongate shank interconnecting the terminations and extending in a longitudinal direction between the terminations.

Description

WO 2014/176635 PCT/AU2014/000482 1 DRAWBAR FOR RAIL WAGONS TECHNICAL FIELD This disclosure relates to rail wagons and, more particularly, to drawbars that form 5 part of drawgear arrangements for interconnecting rail wagons. BACKGROUND ART Rail wagons have long been used to transport material and may be coupled to one another by way of drawgear arrangements that incorporate drawbars. The drawbars arc mounted at opposite ends to drawgear components that are disposed on the respective 0 wagons. Traditionally, cast 'fixed' drawbars in the form of hollow sections have been used to couple rail wagons. However, demand for larger wagons that are capable of transporting heavier loads has created a need for high capacity drawbars. 'Rotary' drawbars are also known in the art. In particular, use of rotary drawbars can L 5 eliminate the need for couplers (i.e. used to allow rotation of the wagons when using a fixed drawbar). Rotary drawbars experience the same tensile loading as fixed drawbars, and in addition to this can experience torsional loading. Cast rotary drawbars can be susceptible to rapid fatigue failure due to this further loading. The above references to the background art do not constitute an admission that the art 20 forms part of the common general knowledge of a person of ordinary skill in the art. The above references are also not intended to limit the application of the drawbar as disclosed herein. SUMMARY Disclosed is a drawbar for interconnecting first and second rail wagons. The drawbar 25 comprises first and second metal terminations disposed at opposite end regions of the drawbar. The terminations are forged and shaped for interconnecting with a respective drawgear mounting on the first and second rail wagons. The drawbar further comprises an elongate shank interconnecting the terminations and extending in a longitudinal direction between the terminations.

WO 2014/176635 PCT/AU2014/000482 2 Also disclosed is a method of manufacturing a drawbar having first and second metal terminations disposed at opposite end regions of the drawbar and an elongate shank interconnecting the terminations and extending in a longitudinal direction between the terminations. The method comprises forging at least one blank to form the terminations of 5 the drawbar. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments will now be described by way of example only, with reference to the accompanying drawings in which L 0 Fig. 1 is a perspective view of a typical rail wagon coupling arrangement. Fig. 2 and 2b are perspective views of a drawbar according to an embodiment of the disclosure. Fig. 3a and 3b are a perspective and section view respectively of a drawbar including a stiffening member. L 5 Fig. 4 is a perspective view of a further embodiment of a drawbar. Fig. 5a and 5b are perspective and section views of a further embodiment of a drawbar. Fig. 6a, b and c are perspective and section views of a further embodiment of a drawbar. 20 Fig. 7a and b are perspective and section views of a further embodiment of a drawbar. Fig 8a and b are a perspective and section view respectively of a typical rotary drawgear arrangement. Fig 9 is a flow chart of an embodiment of a method for manufacturing a drawbar. 2 5 DETAILED DESCRIPTION In the following detailed description, reference is made to accompanying drawings which form a part of the detailed description. The illustrative embodiments described in the WO 2014/176635 PCT/AU2014/000482 3 detailed description, depicted in the drawings and defined in the claims, are not intended to be limiting. Other embodiments may be utilized and other changes may be made without departing from the spirit or scope of the subject matter presented. It will be readily understood that the aspects of the present disclosure, as generally described herein and 5 illustrated in the drawings can be arranged, substituted, combined, separated and designed in a wide variety of different configurations, all of which are contemplated in this disclosure. Disclosed is a drawbar for interconnecting first and second rail wagons. The drawbar comprises first and second metal terminations disposed at opposite end regions of the drawbar. The terminations are forged and shaped for interconnecting with a respective L 0 drawgear mounting on the first and second rail wagons. The drawbar further comprises an elongate shank interconnecting the terminations and extending in a longitudinal direction between the terminations. In practice, the size of the terminations may be restricted by the drawgear present in the wagons being connected. Forging the terminations may provide improved strength and L 5 fatigue properties (e.g. through grain alignment, absence of defects, etc.) to the terminations without the need to increase their size. In some forms the terminations have grains aligned generally in the longitudinal direction of the shank. The alignment of the grains may be a result of how the forging process is performed. Thus, the process used to forge the terminations may be configured to 20 produce terminations having the desired alignment. In some forms at least one of the terminations incorporates a bore to receive a connecting pin of a respective drawgear mounting. In some forms the bore is milled into the termination(s). In some forms the shank is forged and integrally formed with the terminations. 25 Again, the forging of the shank may be performed in such a way that aligns the grains in a desired configuration. In some forms the shank includes opposing flanges extending in the longitudinal direction. The shank may be interconnected by a web. In some forms the web extends along respective edges of the flanges to form a 30 generally 'C' shape in cross-section.

WO 2014/176635 PCT/AU2014/000482 4 In some forms the web extends along intermediate opposite edges of the flanges to form a generally 'I' shape in cross-section. In some forms a first part of the web extends along a first portion of the shank along respective lower edges of the flanges. A second part of the web extends along a second 5 portion of the shank along respective upper edges of the flanges. A third part of the web interconnects the first and second web parts and extends between the upper and lower edges of the flanges. In some forms the drawbar further comprises a stiffening member connected the opposing flanges. The stiffening member is spaced from the web to form a hollow closed L 0 section. Traditional cast drawbars are often formed so as to comprise hollow cross-sections. This can reduce the weight of such drawbars without heavily impacting their strength and ability to transfer torsional loading. In other words, hollow-sections can provide the high strength-to-weight ratio that may be required in use. However, due to the nature of the forging process, it can be difficult to form forged drawbars (i.e. in a single piece) having L 5 hollow sections. The addition of a stiffening member gives the drawbar a hollow section, which may allow it to gain the strength benefits of having such a section. In some forms the stiffening member may be welded to the opposing flanges. In some forms the stiffening member is shaped such that when connected to the flanges the neutral axis of the cross-section of the drawbar through the shank and connected 20 stiffening member may generally be aligned with the resultant compression or tension loads induced under buff and draw in use. Aligning the neutral axis (i.e. second moment of inertia) with the axis of the in-use resultant load (e.g. from buff and draw of connected wagons) may reduce or avoid bending of the shank. In some forms the stiffening member may be shaped such that when connected to the 25 flanges the neutral axis of the cross-section of the draw is generally aligned with the resultant compression or tension loads in use. In some forms the drawbar further comprises ribbing disposed between the opposing flanges. In some forms the flanges extend between upper and lower edges in the same 30 direction as the bore in at least one of the termination(s).

WO 2014/176635 PCT/AU2014/000482 5 In some forms the drawbar is formed from first and second parts which are interconnected. Each part includes a shank portion and termination portions. The shank portions of the first and second parts are generally C shaped which form a closed hollow section when interconnected. 5 In some forms at least one of the termination portions of each of the first and second parts includes a portion of a bore. The bore portions form a bore through the termination when the parts are interconnected. In some forms the first and second parts of the drawbar are welded together. In some forms the terminations include respective transition regions which allows for L 0 load transfer between the shank and the terminations. In some forms the drawbar is rotatable relative to one of the first and second wagons. In some forms localised hardening is applied to at least one surface of the drawbar. In some forms the at least one surface is the outer surface of at least one of the terminations and the localised hardening comprises one of induction or flame hardening. L 5 In some forms the surface of the bore is shot peened. Also disclosed is a method of manufacturing a drawbar having first and second metal terminations disposed at opposite end regions of the drawbar and an elongate shank interconnecting the terminations and extending in a longitudinal direction between the terminations. The method comprises forging at least one blank to form the terminations of 20 the drawbar. In some forms the forging of the terminations is performed so as to align the grains of terminations in the longitudinal direction of the shank. In some forms the method further comprises the step of forging the shank of the draw bar. 25 In some forms the terminations and the shank are forged as a unitary component. In some forms the step of forging the shank comprises forging the two flanges interconnected by a web to form a generally C shape in cross-section.

WO 2014/176635 PCT/AU2014/000482 6 In some forms the step of connecting a stiffening member across the flanges to form a closed cross-section along at least a portion of the shank. In some forms the stiffening member is welded to the flanges. As set forth above with respect to the forged terminations, a forged drawbar may offer 5 greater component integrity, steel cleanliness and consistency (e.g. it may not experience issues related to shrinkage or inclusion of foreign materials) when compared to a cast drawbar. Further, a forged drawbar may possess improved material strength (i.e. when compared to a cast drawbar) due to the ability to use highly refined input material (e.g. source billets produced in advanced steel making processes, including vacuum degassing) in the L 0 forging process. Forging of a drawbar may allow the grain alignment of the drawbar material to be controlled. In use, a drawbar may experience high tensile loading in this direction. Alignment of the grains in the direction of the principal stresses (i.e. the longitudinal direction of the shank) may provide the drawbar with improved strength and fatigue L 5 properties. Such grain alignment may additionally or alternatively be in the direction of the principal stresses in the vicinity of the bore (i.e. when a bore is present) in one of the terminations. In use, the bore may be an area of high stress concentration, and therefore aligning the grains in the direction of these stresses may improve the strength and fatigue properties of the drawbar. 20 Such improved strength and fatigue properties may be especially relevant to rotary drawbars. Rotary drawbars may experience torsional loads (i.e. due to the 'tippling' of wagons during the unloading process) in addition to the tensile loading experienced by fixed drawbars. 25 Referring initially to Fig. 1, disclosed is a drawgear arrangement comprising a drawbar 110 for interconnecting first and second rail wagons 112. The drawgear further comprises two drawgear mountings 116, each for interconnecting the drawbar 110 with a respective wagon 112. The drawbar 110 is a fixed cast steel drawbar of the type generally used for interconnecting wagons. In the context of the present specification, the term 30 "drawbar" is used to describe a rigid component that is pinned to a wagon at each end; as opposed to, for example, a coupler, which is generally in the form of an assembly of several WO 2014/176635 PCT/AU2014/000482 7 interlocking components for the coupling of two wagons. The differences between a drawbar and a coupler would be understood by a person skilled in the art. Two drawgear mountings are shown in Figs. 8a and 8b. In these figures, a cast rotary drawbar 810 is shown interconnected with typical rotary drawgear mountings 816 (i.e. of the 5 type generally used to receive rotary drawbars) at each of its respective terminations 814. This arrangement comprises a 'fixed' drawgear mounting 816b at one end and a 'rotary' drawgear mounting 816a at the other end. Each drawgear mounting 816 comprises a draft pack 864 to aid in dissipating buff and draw loads. At the rotary end, the termination 814a may be shaped to fit inside a rotary collar to L 0 which it is connected a connecting pin 866a. This arrangement may allow the drawbar 810 and collar 868 to turn inside the rotary yoke 862a which is fixed in the wagon body. The drawbar 110 and collar 868 may thus be permitted to rotate freely relative to the wagon in which they are fixed. At the fixed end, the drawbar 810 is connected to the yoke 862b directly by a L5 connecting pin 866b. The yoke 862b is fixed to the wagon and does not allow for any rotational movement (i.e. only buff or draw movements of the drawbar 810 at the 'fixed end are possible). In buff, one of the two drawbar terminations 814 engages a respective draft pack 864 directly, or a respective draft pack follower 870 (although a follower 870 is not always 20 present). At the fixed end under draft loading, the drawbar 810 transmits the load through the pin 866b to the yoke 862b which engages the draft pack 864b in normal application, or in the case of the rotary end, the load is passed from the drawbar 810 to the pin 866a to the rotary collar 868 to the yoke 862a to the draft pack 864a. Referring now to Fig. 2a and 2b, disclosed is an embodiment of a drawbar 210, which 25 comprises first and second metal terminations 214 disposed at opposite end regions of the drawbar 210. The terminations 214 are forged and shaped for interconnecting with a respective drawgear mounting on the first and second rail wagons. The drawbar further comprises an elongate shank 218 interconnecting the terminations 214 and extending in a longitudinal a direction between the terminations 214. The drawbar 210 is specifically 30 shaped so that at least a major portion of the drawbar 210 (being the terminations 214 and shank 218) are formed in a single piece through a forging process. In this respect the shape WO 2014/176635 PCT/AU2014/000482 8 formed in the forging process wholly or substantially resembles the final product. Thus, minimal to no machining is required in order to produce the drawbar 210. Moreover, that the drawbar 210 is forged from a single piece means that minimal to no welding is required along the load path (e.g. such that the welds could be pulled apart in use when under tension). 5 Welds in the load path can provide areas of structural weakness, which can reduce the overall strength properties of the drawbar 210, especially when located along the load bearing path (e.g. during buffing and drawing of the wagons). Whilst not shown in these figures, the drawbar 210 is formed from steel and is forged so that is has a grain alignment in the longitudinal direction along the shank 218. In use, the L 0 shank 218 may experience principal stresses in the longitudinal direction due to opposing forces at each end of the shank 218 (i.e. due to buffing and drawing of the wagons). However, the drawbar 210 is not limited to having a grain alignment in the longitudinal direction along the shank 218, and it would be understood by a person skilled in the art that other grain alignments may be suitable, dependent on the direction of the principal stresses L 5 during use. Forming the drawbar 210 such that it has a grain alignment in the direction of the principal stresses may provide the drawbar with improved strength and fatigue properties. In the illustrated form, each of the terminations 214 incorporates a bore 220 to receive a connecting pin of a respective drawgear mounting 216. However, the drawbar 210 is not limited to this and, for example, only one termination 214 may incorporate a bore 220, or 20 neither termination 214 may incorporate a bore 220. Similarly, each termination 214 may incorporate more than one bore (not shown in this embodiment). The bores 220, in the illustrated form, are milled into respective terminations 214. In other embodiments, the bores may be formed by another process, and may, for example, be integrally formed during the forging process. Moreover, the bores 220 are not limited to having a circular cross-section, 25 and may, for example, have cross sections that are square, rectangular, triangular, ovoid etc. Whilst the shank 218 could be formed separate to the terminations 214, it is preferable that the shank 218 is also forged (i.e. in addition to the terminations 214) and integrally formed with the terminations 214. Such a configuration may eliminate the need for welding, or otherwise bonding or fixing, the terminations 214 and the shank 218 which, in some cases, 30 could introduce areas of weakness into the drawbar 210. The shank 218 includes opposing flanges 222 extending in the longitudinal direction along the shank 218. The flanges 222 are interconnected by a web 224. In the illustrated WO 2014/176635 PCT/AU2014/000482 9 form of the embodiment in Fig. 2a and 2b the web 224 extends along respective edges of the flanges 222 to form a generally C shape in cross-section. In other forms, the web 224 may extend along intermediate opposite edges of the flanges 222 to form a generally I shape in cross-section (an example of which is shown in Fig. 7a and 7b and which will be described 5 later in more detail). The web 224 may provide further structural support to the drawbar 210. The web 224 in the illustrated form further comprises apertures 225 extending through the web 224. In this form, the apertures are 225 circular in shape, however in other forms, the apertures may be rectangular, triangular, elongate etc. The apertures 225 may, for example, provide for drainage of rain or other materials that may collect in the space formed L 0 in the shank 218 by the flanges 222 and the web 224. The flanges 222 extend between tipper and lower edges in the same direction as the bore 220. In other forms the flanges 222 may extend between upper and lower edges at an angle offset to the direction of at least one of the bores 220. For example, the flanges 222 could extend between upper and lower edges at an angle that is perpendicular to the direction L 5 of at least one of the bores 220 (an example of which is shown in Fig. 6a to 6c and which will be described in more detail below). Each termination 214 includes a transition region 226, which allows for load transfer between the shank 218 and the termination 214. The transition regions 226 in the illustrated form have a smooth profile, such that the load path between the terminations 214 and the 20 shank 218 is smooth. This may reduce stress concentrations in use, and improve the fatigue properties of the drawbar 210. One or more of the terminations 214 may be differentially hardened (e.g. flame or induction hardening), which may reduce wear, galling and/or friction. This may extend the wear and/or fatigue life of the drawbar 210. Similarly, one or more of the terminations 214 may be carburised, which may provide self-lubrication properties to the 25 termination 214. This may improve wear of the termination 214 and therefore the fatigue life of the drawbar 210. Other processes that may be applied to the terminations 214 and/or the bores 220 may include finishing or shot peening. The drawbar 210 is configured such that at least one of the first and second wagons (not shown in Fig. 2) is rotatable about a respective termination 214, relative to the drawbar 30 210. In this sense, the drawbar 210 may be considered a 'rotary drawbar'. A rotary drawbar may negate the need for rotatable couplers, which are required to permit rotation of the wagons when using a 'fixed drawbar'. This may, for example, lead to a reduction in WO 2014/176635 PCT/AU2014/000482 10 maintenance and part costs, and may also reduce the overall mass of e.g. a standard '2-pack' (i.e. two wagons and a drawgear), which may have two couplers (rotary and fixed) that can be replaced with a single rotary drawbar if an individual wagon in the pack is required to rotate relative to the other wagon in the pack. 5 Referring now to Fig. 3a and 3b, a further embodiment of the drawbar 310 is shown The drawbar 310 is similar to the previous embodiment (shown in Fig. 2a and b), and also comprises first and second metal terminations 314, and an elongate shank 318 interconnecting the terminations 314. Each termination 314 comprises a bore 320 for receipt of a connecting pin of a respective drawgear mounting and a transition region 326, which L 0 allows for load transfer between the shank 318 and the termination 314. The shank 318 includes opposing flanges 322 that are interconnected by a web 324 to form a generally C shape in cross-section. The drawbar 310 is also configured such that at least one of the first and second wagons (not shown) is rotatable about a respective termination 314, relative to the drawbar 310. Thus, like the drawbar 210 illustrated in Fig. 2a and b, this drawbar 310 may L 5 be considered a 'rotary drawbar'. The drawbar 310 further comprises a stiffening member 328 connected to the opposing flanges 322 such that the stiffening member 328 and the shank 318 form a shank assembly 331. The stiffening member 328 is spaced from the web 324 to form a closed hollow section 330 (as set forth above, a hollow section can provide the drawbar 310 with a 20 high strength-to-weight ratio. In the illustrated form, the stiffening member 328 is welded 329 to the flanges 322 and the terminations such that it almost fully encloses the space formed between the flanges and the terminations. In other forms the stiffening member 328 may only extend partway along the flanges 322 and may be fastened (e.g. chemically, mechanically, etc.) to the flanges 322. The stiffening member 328 may be formed of the 25 same material as the flanges 322 or may be formed of a different material to the flanges 322. The addition of the stiffening member 328 can improve the stiffness of the shank, including under torsional loading. Without the stiffening member 328 the neutral structural axis (i.e. second moment of inertia) of the drawbar 310 would be offset from the axis of the resultant load in use when under tension or compression (buff or draw loads). Under such an 30 arrangement the drawbar 3 10 would be susceptible to bending, which is not desirable because the pins connecting the drawbar 310 to wagons on either end would not be loaded evenly. The presence of the stiffening member 328 moves the neutral structural axis towards the axis WO 2014/176635 PCT/AU2014/000482 11 of the resultant load such that they are aligned with the axis of the resultant load, which avoids or at least reduces bending of the drawbar 310 when under tension and compression. The stiffening member 328 is shaped to ensure this general alignment when welded to the drawbar. It would be understood by a person skilled in the art that the alignment of the axes 5 does not have to be exact in order to reduce bending of the drawbar, but that the closer the alignment the less likely there will be bending of the drawbar. The incorporation of the stiffening member 328 as a separate element, which is subsequently fixed to shank 318, enables the shank 318 to be initially formed as a forged component, yet still allows the drawbar 310 to have the structural properties of a closed L 0 section when the stiffening member 328 is affixed. Referring now to Fig. 4, an embodiment of a drawbar 410 is shown. The drawbar 410 has a similar form to the embodiment of the drawbar illustrated in Fig. 2a and b, except that it further comprises ribbing 432 disposed between the opposing flanges 422. The ribbing 432 has a wave-like form (i.e. when the drawbar is viewed from above) between the flanges 422. L5 However, in other forms the ribbing may, for example, be perpendicular to the flanges 422. In the illustrated form, the ribbing 432 is integrally formed (e.g. forged) with the flanges 422 and web 424. In another form, the ribbing 432 may be in the form of a separate part that is connected to (e.g. welded, fastened etc.) the flanges 422 and/or web 424. Referring now to Fig. 5, disclosed is a further embodiment of the drawbar 510 (again, 20 having a similar form to the embodiments shown in Fig. 2a, 2b and 4) wherein a first part 534 of the web 524 extends along a first portion 536 of the shank 518 along respective lower edges 538 of the flanges 522. A second part 540 of the web 524 extends a long a second portion 542 of the shank 518 along respective upper edges 544 of the flanges 522. A third part 546 of the web interconnects the first 534 and second 540 web parts and extends between 25 the upper 544 and lower 538 edges of the flanges 522. This 'dual sided' forging may allow control and smoothing of the load path such that, in use, the load path flows to the external walls of the drawbar 510. The path of the web 524 from the lower edges 538 to the upper edges 544 of the flanges 544 may provide further torsional stiffness through the central portion of the drawbar 510. Whilst not shown in the illustrated form, this embodiment of the 30 drawbar 5 10 may further comprise one or more stiffening members (not shown) to provide further structural support to the drawbar 510.

WO 2014/176635 PCT/AU2014/000482 12 Referring now to Fig. 6, disclosed is an embodiment of the drawbar 610 (having a similar form to that shown in previous embodiments) formed from first 646 and second 648 parts which are interconnected. In the illustrated form, the first 646 and second 648 parts are connected by way of a weld, however it would be understood by a person skilled in the art 5 that forms of connection may be utilised including, for example, temporary fasteners, permanent fasteners, locking arrangement etc. Each part 646, 648 includes a shank portion 650 and termination portions 652, wherein the shank portion 650 of the first 646 and second 648 parts are generally C shaped. In this way, when the first 646 and second 648 parts are interconnected, the shank portions 650 of the respective parts 646, 648 form a closed hollow L 0 section 654. In other forms, at least one of the parts 646, 648 may further comprise one or more stiffening members 628 and/or ribbing 632 as disclosed above with respect to other forms of the drawbar 610. The termination portions 652 of each of the first 646 and second 648 parts include a portion of a bore 656. In other forms, only one of the termination portions 652 may include a L 5 portion of a bore 656. When the parts 646, 648 are interconnected, the bore portions 654 align, such that at least one bore 620 is formed through the respective termination 614. In use, and when a pin is received through the bore 620, the pin may help (i.e. in addition to welding, fasteners etc.) to prevent movement of the first 646 and second 648 parts, relative to one another. The illustrated form further comprises fins 658 located in the vicinity of the 20 bore portions 656 which, in use (i.e. when the parts 646, 648 are interconnected via e.g. welding), may provide further resistance against rotational loads. Now referring to Fig. 7, a further embodiment of the drawbar 710 (having a similar form to that shown in previous embodiments) is shown comprising an 'H-section' type shank 718. The shank 718 is forged such that protrusions 760 are formed along the upper 744 and 25 lower 738 edges of the flanges 722. In this way, the edges 738, 744 are formed such that they are thicker than the intermediate portions of the flanges 722 and therefore more material is located at the corners of the shank 718. This may provide the drawbar 710 with more torsional strength in use, while helping to minimise the overall weight of the drawbar 710 (i.e. due to less material being used at the intermediate portions of the flanges 722). 30 Referring now to Fig. 9, a flow chart is shown that depicts a method of manufacturing a drawbar according to an embodiment of the invention. The method as shown comprises preheating a billet 823, which may be performed by way of an induction oven. The billet is WO 2014/176635 PCT/AU2014/000482 13 preheated to a temperature that is suitable for forging and is then forged 864 by applying pressure so as to be shaped into a blank that approximately resembles the intended product (i.e. having approximately similar dimensions and form). In this embodiment the entire drawbar is manufactured by way of forging and thus the intended product is the drawbar. In 5 other embodiments, it may be that only the terminations are manufactured by forging, whilst the shank of the drawbar is manufactured by way of a casting process. In such an embodiment the terminations would then be fixed to the shank by e.g. welding. Following the forging process 864, the blank is reheated 866 and then enters a further forging process 868. In this further forging process 868, the blank (having the rough form of LO the drawbar) is shaped in e.g. an open die, so as to take on a form that is substantially the same as drawbar. In this embodiment the drawbar that is manufactured comprises a generally C-shaped cross section formed by flanges and an interconnecting web. Both forging processes 964, 968 are performed in such a way that the grains of at least the terminations are aligned in the direction of the principal stresses of the drawbar in L5 use. In the drawbar manufactured from the illustrated method the grains are aligned in the direction of the longitudinal axis of the shank of the drawbar. In another form, the drawbar (or component thereof) may be formed in a single forging step. Following the second forging process 968 the drawbar is heat treated 970 to improve the strength properties of the material of the drawbar. A stiffening member is then welded 20 972 to the flanges of the drawbar to form a shank assembly having a closed cross-section along at least a portion of the shank of the drawbar. In this respect, the drawbar formed by the illustrated method is similar to that shown in Fig. 3a and b. In other embodiments, a stiffening member may not be welded to the flanges of the drawbar. After the stiffening member has been welded 972, the drawbar (including the stiffening member) is tempered to 25 improve its structural properties. In the claims which follow and in the preceding summary of the invention except where the context requires otherwise due to express language or necessary implication, the word "comprising" is used in the sense of "including", that is, the features as above may be associated with further features in various embodiments of the invention. 30 Variations and modifications may be made to the parts previously described without departing from the spirit or ambit of the invention.

Claims

1. A drawbar for interconnecting first and second rail wagons comprising: first and second metal terminations disposed at opposite end regions of the drawbar, the terminations being forged and shaped for interconnecting with a respective 5 drawgear mounting on the first and second rail wagons, and an elongate shank interconnecting the terminations and extending in a longitudinal direction between the terminations.

2. A drawbar according to claim 1, wherein the terminations have grains aligned generally in the longitudinal direction of the shank. L 0

3. A drawbar according to claim 1 or 2, wherein at least one of the terminations incorporates a bore to receive a connecting pin of a respective one of the drawgear mountings.

4. A drawbar according to claim 3, wherein the bore is milled into the at least one termination.

5. A drawbar according to any preceding claim, wherein the shank is forged and integrally L5 formed with the terminations.

6. A drawbar according to claim 5, wherein the shank includes opposing flanges extending in the longitudinal direction and being interconnected by a web.

7. A drawbar according to claim 6, wherein the web extends along respective edges of the flanges to form a generally C shape in cross-section. 20

8. A drawbar according to claim 5, wherein the web extends along intermediate opposite edges of the flanges to form a generally I shape in cross-section.

9. A drawbar according to claim 6, wherein a first part of the web extends along a first portion of the shank along respective lower edges of the flanges and a second part of the web extends along a second portion of the shank along respective upper edges of the flanges, and 25 a third part of the web interconnects the first and second web parts and extends between the upper and lower edges of the flanges. WO 2014/176635 PCT/AU2014/000482 15

10. A drawbar according to any one of claims 6 to 9 further comprising a stiffening member connected to the opposing flanges, the stiffener being spaced from the web to form a hollow closed section.

11. A drawbar according to claim 10, wherein the stiffening member is welded to the 5 opposing flanges.

12. A drawbar according to claim 10 or 11 wherein the stiffening member is shaped such that when connected to the flanges the neutral axis of the cross-section of the drawbar through the shank and connected stiffening member is generally aligned with the resultant load induced tinder buff and draw in use. L 0

13. A drawbar according to any one of claims 6 to 12, further comprising ribbing disposed between the opposing flanges.

14. A drawbar according to any one of claims 6 to 13, when dependent on claim 3, wherein the flanges are extend between tipper and lower edges in the same direction as the bore in the at least one termination. L 5

15. A drawbar according to claim 5, formed from first and second parts which are interconnected, each part including a shank portion and termination portions, wherein the shank portion of the first and second parts are generally C shape which form a closed hollow section when interconnected.

16. A drawbar according to claim 15, wherein at least one of the termination portions of each 20 of the first and second parts includes a portion of a bore which forms a bore through the termination when the parts are interconnected.

17. A drawbar according to claim 15 or 16, wherein the first and second parts are welded together.

18. A drawbar according to any preceding claim, wherein the terminations include respective 25 transition regions which allows for load transfer between the shank and the terminations.

19. A drawbar according to any preceding claim which is rotatable relative to one of the first and second wagons. WO 2014/176635 PCT/AU2014/000482 16

20. A drawbar according to any preceding claim wherein localised hardening is applied to at least one surface of the drawbar.

21. A drawbar according to claim 18 wherein the at least one surface is the outer surface of at least one of the terminations and the localised hardening comprises one of induction or flame 5 hardening. 20. A drawbar according to claim 3 and any one of claims 4 to 19 when dependent on claim 3, wherein the surface of the bore is shot peened. 21. A method of manufacturing a drawbar having first and second metal terminations disposed at opposite end regions of the drawbar and an elongate shank interconnecting the LO terminations and extending in a longitudinal direction between the terminations, the method comprising forging at least one blank to form the terminations of the drawbar.

22. A method according to claim 21, wherein the forging of the terminations is performed so as to align the grains of terminations in the longitudinal direction of the shank.

23. A method according to claim 21 or 22, further comprising the step of forging the shank of L5 the draw bar.

24. A method according to claim 23, wherein the terminations and the shank are forged as a unitary component.

25. A method according to claim 24, wherein the step of forging the shank comprises forging the two flanges interconnected by a web to form a generally C shape in cross-section. 20

26. A method according to claim 25, further comprising the step of connecting a stiffening member across the flanges to form a closed cross-section along at least a portion of the shank.

27. A method according to claim 26, wherein the stiffening member is welded to the flanges.