WO 2014/135852 PCT/GB2014/050625 1 Description Title of Invention: RAIL JUNCTION ASSEMBLY Technical Field [0001] This invention relates to rail junction assemblies. This invention relates to methods of directing first and second rail vehicle wheels. This invention also relates to wheel urging members for use with rail junction assemblies. This invention relates to rail switching arrangements. More particularly, but not exclusively, this invention relates to rail junction assemblies having two fixed main rails and two fixed switch rails. Background Art [0002] Rail junctions, such as found on railway lines, typically comprise two continuous rails and two switch rails. The switch rails terminate at the junction. A change in direction of a rail mounted vehicle, such as a train, is effected by moving the two switch rails, such that one rail engages the continuous rail of the non-required direction, and the other switch rail moves away from engagement with the continuous rail of the required direction. [0003] An alternative method of directing a rail vehicle uses switch rails fixed in position such that passages are defined of just sufficient size to permit the wheel flanges to pass on either of the switch rails. With this arrangement, the rail vehicle is directed not by movement of the switch rails, but by the provision of a force on the inner face of the wheel of the rail vehicle, namely the face nearest the centre line. An example of such a system is disclosed in WOOO/75429. The wheels are connected to each other by solid axles and, therefore, the distance between the inner faces of the wheels remains constant. [0004] The geometry of the passage between the continuous rails and the switch rails is critical, and the support of the rail vehicle depends on the rail head widths, rail wear, wheel widths, wheel wear, head stability and the required minimum vertical load bearing contact area between rail and wheel. The possibility exists that excessive wear on the rail and wheel flange could cause a wheel to have insufficient contact with the supporting rail. Disclosure of Invention [0005] According to one aspect of this invention, there is provided a rail junction assembly for directing first and second rail vehicle wheels of a wheel arrangement, the rail junction assembly comprising: first and second main rails and first and second switch rails; a first flange receiving passage defined between the first switch rail and the first main rail, and a second flange receiving passage defined between the second switch WO 2014/135852 PCT/GB2014/050625 2 rail and the second main rail; the first flange receiving passage being configured to receive a flange of the first wheel, and the second flange receiving passage being configured to receive a flange of the second wheel; and a wheel control arrangement for controlling the first wheel on the first main rail when the second flange is received in the second flange receiving passage, and for controlling the second wheel on with the second main rail when the first flange is received in the first flange receiving passage. [0006] According to another aspect of this invention, there is provided a rail junction assembly for directing first and second rail vehicle wheels of a wheel arrangement, the first and second wheels having respective first and second flanges, the rail junction assembly comprising: first and second main rails; first and second switch rails; a first flange receiving passage being defined between the first switch rail and the first main rail, and a second flange receiving passage being defined between the second switch rail and the second main rail, wherein the first flange receiving passage is configured to receive the first flange, and the second flange receiving passage is configured to receive the second flange; and a wheel control arrangement for controlling the first wheel on the first main rail and on the first switch rail when the second flange is received in the second flange receiving passage, and for controlling the second wheel on with the second main rail and on the second switch rail when the first flange is received in the first flange receiving passage. [0007] According to another aspect of this invention, there is provided a rail junction assembly for directing first and second rail vehicle wheels of a wheel arrangement, the first and second wheels having respective first and second flanges, the rail junction assembly comprising: first and second main rails; first and second switch rails; a first flange receiving passage being defined between the first switch rail and the first main rail, and a second flange receiving passage being defined between the second switch rail and the second main rail, wherein the first flange receiving passage is configured to receive the first flange, and the second flange receiving passage is configured to receive the second flange; and wheel directing arrangement for controlling the first wheel on the first main rail and on the first switch rail when the second flange is received in the second flange receiving passage, and for controlling the second wheel on with the second main rail and on the second switch rail when the first flange is received in the first flange receiving passage. [0008] In the embodiments described herein, the provision of the wheel directing ar rangement advantageously has the effect of ensuring that the bearing areas provided to the first wheel by the first main and switch rails or by a combination of the first main rail and the first switch rail, and between the second wheel and the second main and switch rails or by a combination of the second main rail and the second switch rail, are WO 2014/135852 PCT/GB2014/050625 3 sufficient to provide the necessary support to the first and second wheels even where the rails and/or the wheels are worn. [0009] The rail junction assembly may be a facing only rail junction assembly, in which the first and second main rails diverge from each other in the direction of travel of the rail vehicle, a trailing only rail junction assembly in which the first and second main rails converge towards each other in the direction of travel of the rail vehicle, or a junction assembly through which the rail vehicle can travel in both directions. [0010] According to another aspect of this invention, there is provided a method of directing first and second rail vehicle wheels having respective first and second flanges, comprising: providing first and second main rails, and first and second switch rails, the first switch rail being spaced from the first main rail to define a first flange receiving passage therebetween, and the second switch rail being spaced from the second main rail to define a second flange receiving passage therebetween; providing a wheel control arrangement, and, with the wheel control arrangement, controlling the first wheel on the first main rail and on the first switch rail when the second flange is received in the second flange receiving passage, and controlling the second wheel on the second main rail and on the second switch rail when the first flange is received in the first flange receiving passage. [0011] According to another aspect of this invention, there is provided a method of directing first and second rail vehicle wheels having respective first and second flanges, comprising: providing first and second main rails, and first and second switch rails, the first switch rail being spaced from the first main rail to define a first flange receiving passage therebetween, and the second switch rail being spaced from the second main rail to define a second flange receiving passage therebetween; providing a wheel directing arrangement, and, with the wheel directing arrangement, controlling the first wheel on the first main rail and on the first switch rail when the second flange is received in the second flange receiving passage, and controlling the second wheel on the second main rail and on the second switch rail when the first flange is received in the first flange receiving passage. [0012] In the use of the embodiments described herein, the first wheel may transfer between the first main rail and the first switch rail when the second flange is received in the second flange receiving passage, and the second wheel may transfer between the second main rail and the second switch rail when the first flange is received in the first flange receiving passage. [0013] The wheel directing arrangement may control the first wheel when the first wheel transfers between the first main rail and the first switch rail. The wheel directing ar rangement may control the second wheel when the second wheel transfers between the second main rail and the second switch rail.
WO 2014/135852 PCT/GB2014/050625 4 [0014] The controlling of the first wheel on the first main rail and on the first switch rail may comprise controlling the first wheel during said transfer of the first wheel between the first main rail and the first switch rail. The controlling of the second wheel on the second main rail and on the second switch rail may comprise controlling the second wheel during said transfer of the second wheel between the second main rail and the second switch rail. [0015] The rail junction assembly and the method of directing a first and second rail vehicle wheels described and claimed herein are particularly suitable for use with any rail mounted vehicle, including locomotives, maintenance equipment, passenger or freight vehicles, as well as for use in any other type of rail system, for example trams, toys, models, metro, light rails or main line rails of any size or type. [0016] The first switch rail may have a first terminating region adjacent the first main rail. The first switch rail and the first main rail may define a first transition region. The first transition region may comprise a region of the first main rail and a region extending from the point at which the first rail vehicle wheel begins to move laterally away from the first main rail to be supported by the first switch rail. The first transition region may terminate at the point at which the rail vehicle wheel is fully supported by the first switch rail. [0017] The second switch rail may have a second terminating region adjacent the second main rail. The second switch rail and the second main rail may define a second transition region. The second transition region may comprise a region of the second main rail and a region extending from the point at which the second rail vehicle wheel begins to move laterally away from the second main rail to be supported by the second switch rail. The second transition region may terminate at the point at which the rail vehicle wheel is fully supported by the second switch rail. [0018] The wheel directing arrangement may guide the flange of the first wheel of the wheel arrangement into, or out of, the first flange receiving passage, and may guide the flange of a second wheel of the wheel arrangement into, or out of, the second flange receiving passage. The wheel directing arrangement may guide the flange of the first wheel at least partially through the first flange receiving passage. The wheel directing arrangement may guide the flange of the second wheel at least partially through the second flange receiving passage. [0019] In the embodiments described herein, in which the rail junction assembly comprises a facing rail junction assembly or a junction assembly through which the rail vehicle can travel in both directions, the provision of the guide arrangement is advantageous. [0020] The guiding of the flange of the first wheel into, or out of, the first flange receiving passage may comprise guiding the second wheel during the transfer between the second main rail and the second switch rail. The guiding of the flange of the second WO 2014/135852 PCT/GB2014/050625 5 wheel into, or out of, the second flange receiving passage may comprise guiding the first wheel during the transfer between the first main rail and the first switch rail. [0021] The wheel directing arrangement may be moveable to a first guide condition for guiding the flange of the first wheel into, or out of, the first flange receiving passage as aforesaid. The wheel directing arrangement may be moveable to a second guide condition for guiding the flange of the second wheel into, or out of, the second flange receiving passage as aforesaid. [0022] The wheel directing arrangement may be configured to engage the wheel ar rangement to maintain the first wheel in engagement with the first main rail as the first wheel transfers between the first main rail and the first switch rail when the guide ar rangement is in the second guide condition. The wheel directing arrangement may be configured to engage the wheel arrangement to maintain the second wheel in en gagement with the second main rail as the second wheel transfers between the second main rail and the second switch rail when the guide arrangement is in the first guide condition. [0023] The wheel directing arrangement may comprise a wheel control arrangement for effecting the aforesaid control of the first and second wheels. The wheel directing ar rangement may further include a separate guide arrangement for effecting the aforesaid guiding of the first and second wheels. [0024] The guide arrangement may be rotationally moveable, laterally moveable and/or lon gitudinally moveable relative to the first main rail to guide the flange of the first wheel as aforesaid. The guide arrangement may be rotationally moveable, laterally moveable and/or longitudinally moveable relative to the second main rail to guide the flange of the second wheel as aforesaid. Where the guide arrangement is longitudinally moveable, the guide arrangement may slide along the first and second main rails between the first and second guide conditions. [0025] The wheel control arrangement may be configured to engage the wheel arrangement to maintain the first wheel in engagement with the first main rail as the first wheel transfers between the first main rail and the first switch rail when the guide ar rangement is in the second guide condition. The wheel control arrangement may be configured to engage the wheel arrangement to maintain the second wheel in en gagement with the second main rail as the second wheel transfers between the second main rail and the second switch rail when the guide arrangement is in the first guide condition. [0026] The method may further include providing a guide arrangement, guiding a flange of a first wheel of the wheel arrangement into, or out of, the first flange receiving passage, and guiding the flange of a second wheel of the wheel arrangement into, or out of, the second flange receiving passage. The method may include guiding the flange of the WO 2014/135852 PCT/GB2014/050625 6 first wheel at least partially through the first flange receiving passage. The method may include guiding the flange of the second wheel at least partially through the second flange receiving passage. [0027] The guiding of the flange of the first wheel may comprise moving the guide ar rangement to a first guide condition to guide the flange of the first wheel as aforesaid. The guiding of the flange of the second wheel may comprise moving the guide ar rangement in a second direction towards the second main rail to a second guide condition to guide the flange of the second wheel as aforesaid. [0028] The guiding of the flange of the first wheel may comprise moving the guide ar rangement in a first direction towards first main rail to the first guide condition. The guiding of the flange of the second wheel may comprise moving the guide arrangement in a second direction towards second main rail to the second guide condition. [0029] The maintaining of the first wheel on the first main rail during transfer of the first wheel between the first main rail and the first switch rail may comprise maintaining the first wheel on the first main rail when the flange of the second wheel is received in the second flange receiving passage. The maintaining of the second wheel on the second main rail during transfer of the second wheel between the second main rail and the second switch rail may comprise maintaining the second wheel on the second main rail when the flange of the first wheel is received in the first flange receiving passage. [0030] The maintaining of the first wheel on the first main rail in the first transition region may comprise effecting engagement of the wheel control arrangement with the wheel arrangement, desirably with the first wheel of the wheel arrangement, when the guide arrangement is in the second guide condition. [0031] The maintaining of the second wheel on the second main rail in the second transition region may comprise effecting engagement of the wheel control arrangement with the wheel arrangement when the guide arrangement is in the first guide condition. Desirably, the wheel control arrangement engages the first wheel of the wheel ar rangement. [0032] The first and second main rails are desirably fixed rails. The first and second switch rails are desirably fixed rails. [0033] The first and second transition regions may include respective first and second end regions of the first and second switch rails. In the embodiments described herein, the first and second transition regions include respective regions of the first and second switch rails where the second wheel engages the second main rail and the second switch rail when the guide arrangement is in the first position, and where the first wheel engages the first main rail and the first switch rail, when the guide arrangement is in the second guide condition. [0034] The wheel control arrangement may be configured to engage the second wheel when WO 2014/135852 PCT/GB2014/050625 7 the guide arrangement is in the first guide condition. The wheel control arrangement may be configured to engage the first wheel when the guide arrangement is in the second guide condition. [0035] The wheel control arrangement may have a first control surface for engaging the wheel arrangement when the guide arrangement is in the second guide condition, thereby maintaining the first wheel of the rail vehicle on the first main rail during transfer of the first wheel between the first main rail and the first switch rail. The wheel control arrangement may have a second control surface for engaging the wheel ar rangement when the guide arrangement is in the first guide condition, thereby maintaining the second wheel of the rail vehicle on the second main rail during transfer of the second wheel between the second main rail and the second switch rail. [0036] The first control surface may be disposed to engage the first wheel when the guide arrangement is in the second guide condition. The second control surface may be disposed to engage the second wheel when the guide arrangement is in the first guide condition. The method may comprise effecting engagement of the first control surface with the first wheel when the guide arrangement is in the second guide condition. The method may comprise effecting engagement of the second control surface with the second wheel when the guide arrangement is in the first guide condition. [0037] The wheel control arrangement may comprise a first wheel control member for engaging the first wheel, and a second wheel control member for engaging the second wheel. The first wheel control member may be provided with the first wheel control surface, and the second wheel control member may be provided with the second wheel control surface. The first and second wheel control members may be elongate and may extend along the first and second transition regions respectively. [0038] The wheel control arrangement may be fixed or moveable. Where the wheel control arrangement is moveable, the wheel control arrangement may be moveable to a first wheel control position to engage the wheel arrangement when the guide arrangement is in the second guide condition, and to a second wheel control position to engage the wheel arrangement when the guide arrangement is in the first guide condition. [0039] Where the junction assembly is a trailing junction assembly, the wheel control ar rangement may be fixed. If desired, the trailing junction assembly may be devoid of the guide arrangement. [0040] The wheel control arrangement may be moveable to the first wheel control position to engage the first wheel, when the guide arrangement is in the second guide condition. The wheel control arrangement may be moveable to the second wheel control position to engage the second wheel, when the guide arrangement is in the first guide condition. [0041] The method may comprise moving the wheel control arrangement to the first wheel control position to engage the first wheel, when the guide arrangement is in the second WO 2014/135852 PCT/GB2014/050625 8 guide condition. The method may comprise moving the wheel control arrangement to the second wheel control position to engage the second wheel, when the guide ar rangement is in the first guide condition. [0042] The guide arrangement may comprise a first guide member for guiding the first wheel into the first flange receiving passage, and a second guide member for guiding the second wheel into the second flange receiving passage. The first and second guide members may be elongate, and may extend alongside the first and second main rails. [0043] The first guide member may be configured such that, when the guide arrangement is in the first guide condition, the first guide member can engage the first wheel. The second guide member may be configured such that, when the guide arrangement is in the second guide condition, the second guide member can engage the second wheel. The method may comprise moving the first guide member to the first position to engage the first wheel. The method may comprise moving the second guide member to the second position to engage the second wheel. [0044] In one embodiment, the wheel control arrangement may be part of the guide ar rangement. In this embodiment, the first wheel control member may constitute a portion of the first guide member, and the second wheel control member may constitute a portion of the second guide member. Desirably, in this embodiment, the first wheel control member may constitute an end portion of the first guide member, and the second wheel control member may constitute an end portion of the second guide member. [0045] In another embodiment, the first and second wheel control members may be separate from the guide arrangement. The first wheel control member may be moveable sub stantially horizontally relative to the region of the first switch rail in the first transition region. The second wheel control member may be moveable substantially horizontally relative to the region of the second switch rail in the second transition region. [0046] In a further embodiment, the first and second wheel control members may be moveable substantially vertically relative to the first transition region of the first switch rail. The second wheel control member may be moveable substantially vertically relative to the second transition region of the second switch rail. [0047] In the above embodiments, the first and second wheel control members may be moveable towards and away from the respective first and second transition regions. When the first wheel control member is moved towards the first transition region, the second wheel control member is moved away from the second transition region. When the second wheel control member is moved towards the second transition region, the first wheel control member is moved away from the first transition region. In a fourth embodiment, the first and second wheel control members may be fixedly mounted adjacent the first and second transition regions respectively.
WO 2014/135852 PCT/GB2014/050625 9 [0048] The wheel control arrangement may be connected to the guide arrangement so that movement of the guide arrangement effects movement of the wheel control ar rangement, and movement of the wheel control arrangement effects movement of the guide arrangement. [0049] In yet another embodiment, the first and second wheel control members may be fixed relative to the first and second main rails respectively. [0050] In the embodiments described herein, the transition regions of the switch rails are regions during use along which the rail vehicle wheel engages the switch rail and the main rail at the same time when the flange of the wheel passes along the flange receiving passage. [0051] In the embodiments described herein, the first transition region may be a region in which the extent of engagement of the first wheel with the first main rail reduces, and the extent of engagement of the first wheel with the first switch rail increases, as the first wheel moves through the first transition region and transfers from the first main rail to the first switch rail. [0052] Also in the embodiments described herein, the second transition region may be a region in which the extent of engagement of the second wheel with the second main rail reduces, and the extent of engagement of the second wheel with the second switch rail increases, as the second wheel moves through the second transition region and transfers from the second main rail to the second switch rail. [0053] The extent of the vertical engagement of a rail vehicle wheel with a rail is sometimes referred to as the bearing area. In the embodiments described herein, the aggregate bearing area on the first wheel provided by the first main rail and the first switch rail should remain sufficient so that the rail is not over stressed. The aggregate bearing area on the first wheel provided by the first main rail and the first switch rail desirably remains substantially constant as the first wheel transfers between the first main rail and the first switch rail. Also, the aggregate bearing area on the second wheel provided by the second main rail and the second switch rail remains substantially constant as the second wheel transfers between the second main rail and the second switch rail. [0054] It will be understood by those skilled in the art that the gauge of the first and second main rails widens in the first and second transition regions. [0055] The rail junction assembly may include a wheel urging member to selectively urge the flange of the first and second wheels along the first flange receiving passage or along the second flange receiving passage. [0056] The rail junction assembly may further include detection means to detect the direction the rail vehicle will take or has taken. The provision of the detection means is particularly suitable where the junction assembly is a trailing only junction assembly. [0057] According to another aspect of this invention, there is provided a wheel urging WO 2014/135852 PCT/GB2014/050625 10 member for use with a rail junction assembly as described above, the wheel urging member being configured to selectively direct the flange of the first and second wheels along the first flange receiving passage or along the second flange receiving passage. [0058] The wheel urging member may have a triangular top plan profile. Alternatively, the wheel urging member may have any other suitable top plan profile. In one em bodiment, the wheel urging member may be wedge shaped. In the embodiments described herein, the wedge shape of the wheel urging member provides the advantage that a single wheel urging member can be used selectively to direct the first wheel along the first flange receiving passage, and to direct the second wheel along the second flange receiving passage. [0059] The wheel urging member may be disposed in alignment with the first switch rail to direct the flange of the first wheel along the first flange receiving passage. Alter natively, the wheel urging member may be disposed in alignment with the second switch rail to direct the flange of the second wheel along the second flange receiving passage. [0060] The first switch rail may have a first wheel facing side surface which faces the first wheel when the flange of the first wheel passes along the first flange receiving passage. The wheel urging member may have a first side surface, which is disposed in alignment with the first wheel facing surface when the wheel urging member is disposed in alignment with the first switch rail. [0061] The second switch rail may have a second wheel facing side surface which faces the second wheel when the flange of the second wheel passes along the second flange receiving passage. The wheel urging member may have a second side surface, which is disposed in alignment with the second wheel facing surface when the wheel urging member is disposed in alignment with the second switch rail. [0062] The wheel urging member may comprise a main body, which may be an elongate wedge shaped main body. Alternatively, the wheel urging member may be any other suitable shape. The wheel urging member may further include connecting means to connect the wheel urging member to a rail. The connecting means may comprise at least one connecting element. The connecting means may comprise a pair of connecting elements, which may be spaced axially from each other along the length of the main body. The connecting elements may be attached to the lower face of the main body, and may extend downwardly therefrom. [0063] The wheel urging member may be mounted on the rail junction assembly, and may be movable between operating and non-operating positions. The wheel urging member may be moveable horizontally or vertically between the operating and non-operating positions. The wheel urging member may be moveable longitudinally between the operating and non-operating positions.
WO 2014/135852 PCT/GB2014/050625 11 [0064] The wheel urging member may be rotatably moveable between the operating and non-operating positions. The wheel urging member may be moveable longitudinally between the operating and non-operating positions. The wheel urging member may be slidable between the operating and non-operating positions. [0065] According to another aspect of this invention, there is provided a rail switching ar rangement for switching wheels of a rail vehicle at a rail junction assembly, the rail switching arrangement comprising: [0066] first and second wheel directing means; the first wheel directing means comprising a first guide member and a first wheel control member, and the first wheel directing means being movable between a first guiding position and a first control position, wherein in the first guiding position, the first guide member can engage a first wheel of a wheel arrangement, and in the first control position, the first wheel control member can engage the first wheel; [0067] the second wheel directing means comprising a second guide member and a second wheel control member, and the second wheel directing means being movable between a second guiding position and a second control position, wherein in the second guiding position, the second guide member can engage a second wheel of the wheel ar rangement, and in the second control position, the second wheel control member can engage the second wheel; and [0068] operating means to operable on the first and second wheel directing means to move the first and second wheel directing means between the respective first and second guiding positions and the first and second control positions; [0069] wherein the first and second wheel directing means are configured so that, when the first wheel directing means is in the first guiding position, the second wheel directing means is in the second control position, and when the second wheel directing means is in the second guiding position, the first wheel directing means is in the first control position. [0070] The first and second wheel directing means may comprise respective first and second rotary members. Each of the first and second rotary members may be elongate. [0071] The first and second guide members may be provided on the respective first and second rotary members. The first and second wheel control members may be provided on the respective first and second rotary members. [0072] Each of the first and second guide members may be elongate and may extend axially along the respective first and second rotary members. Each of the first and second wheel control members may be elongate and may extend axially along the respective first and second rotary members. [0073] Each of the first and second rotary members may be substantially cylindrical, and may have an elongate axially extending recess defined therein. Each axially extending WO 2014/135852 PCT/GB2014/050625 12 recess may be substantially V shaped. Each recess may be a cylindrical sector. Each axially extending recess may be defined by radially extending longitudinal surfaces. [0074] The first guide member and the first wheel control member may be provided on the surfaces defining the recess in the first rotary member. The second guide member and the second wheel control member may be provided on the surfaces defining the recess in the second rotary member. [0075] The first and second guide members may extend substantially radially outwardly from the respective first and second rotary members. [0076] The operating means may comprise first and second cranks attached to the respective first and second rotary members. The operating means may comprise first and second push/pull members capable of applying a pulling force or a pushing force to the cranks. [0077] The operating means may include a drive arrangement for driving the first and second push/pull members. The drive arrangement may comprise a drive member, which may be a rotatable drive member. The first and second push/pull members may be attached to the drive member. [0078] The drive arrangement may be movable between first and second operative conditions. In the first operative condition, the first rotary member is in the first guiding position and the second rotary member is in the second control position. In the second operative condition, the second rotary member is in the second guiding position and the first rotary member is in the first control position. [0079] When the drive arrangement moves to the first operative condition, the rotatable drive member pushes the first push/pull member, which pushes the first rotary member to the first guiding position. At the same time, the rotatable drive member pulls the second push/pull member, which pulls the second rotary member to the second control position. When the drive arrangement moves to the second operative condition, the rotatable drive member pushes the second push/pull member, which pushes the second rotary member to the second guiding position. At the same time, the rotatable drive member pulls the first push/pull member, which pulls the first rotary member to the first control position. [0080] Alternatively, the first and second guide members may be linearly movable between the first and second guiding positions. The first and second guide members may be movable vertically or horizontally between the first and second guiding positions. The first and second wheel control members may be linearly movable between the first and second control positions. The first and second wheel control members may be movable vertically or horizontally between the first and second control positions. [0081] In one embodiment, the first and second guide members may define a plurality of gaps. The first and second wheel control members may comprise a plurality of projecting portions, which can protrude through the gaps in the respective first and WO 2014/135852 PCT/GB2014/050625 13 second guide members when the first and second directing means are in the control positions. Brief Description of Drawings [0082] Embodiments of the invention will now be described by way of example only, with reference to the accompanying drawings, in which: [0083] Figure 1 is a plan view of a rail junction assembly, showing a guide arrangement in a first guide condition; [0084] Figure 2 is a view similar to Figure 1 showing the guide arrangement in a second guide condition; [0085] Figure 3 is an end sectional view of a rail junction assembly, with a rail vehicle wheel arrangement thereon showing a guide arrangement in a first guide condition; [0086] Figure 4 is an end sectional view of a rail junction assembly in which the main rails have become worn, with a rail vehicle wheel arrangement thereon showing a first wheel control arrangement; [0087] Figure 5 is a view similar to the views shown in Figures 3 and 4 but with a further embodiment of a wheel control arrangement and a guide arrangement; [0088] Figure 6 is a view similar to the views shown in Figures 3 and 4 with another em bodiment of a wheel control arrangement and a guide arrangement; [0089] Figure 7 is a top plan view of a wheel urging member; [0090] Figure 8 is a side view of a wheel urging member; [0091] Figure 9 is a side view of a wheel urging member; [0092] Figure 10 is a top plan view of a further embodiment of a rail junction assembly in which one of the wheel urging members shown in Figures 7 to 9 can be used. [0093] Figure 11 shows an embodiment of a rail switching arrangement; [0094] Figure 12 is a close up of a first rotary member in a first guiding position; [0095] Figure 13 is a close up of the first rotary member in a first control position; and [0096] Figure 14 shows a further embodiment of a rail junction assembly. Mode(s) for Carrying Out the Invention [0097] Figures 1 and 2 show a rail junction assembly 10 which can be used for directing rail vehicles travelling into the rail junction assembly in the facing direction, i.e. in the direction indicated by the arrow F in Figures 1 and 2 or in the trailing direction, i.e. in the directions indicated by the arrows G and H. [0098] The rail junction assembly 10 comprises a first fixed continuous main rail 12, a second fixed continuous main rail 14, a first fixed switch rail 16 having an end region terminating in close proximity to the first main rail, and a second fixed switch rail 18 having an end region terminating in close proximity to the second fixed main rail 14. [0099] A first flange receiving passage 17 is defined between the first main rail 12 and a WO 2014/135852 PCT/GB2014/050625 14 first terminating region 16A of the first switch rail 16. A second flange receiving passage 19 is defined between the second main rail and a second terminating region 18A of the second switch rail 18. The rail junction assembly 10 also includes a wheel directing arrangement comprising a guide arrangement 20. [0100] The guide arrangement 20 comprises a first moveable elongate guide member 22 and a second moveable elongate guide member 24. The first and second guide members 22, 24 may be laterally, longitudinally or vertically moveable. Alternatively, the first and second guide members 22, 24 may be moveable in directions which have components in two or more of the lateral, longitudinal and vertical directions. [0101] The guide arrangement 20 is movable between first and second guide conditions. In the first guide condition, shown in Figure 1, the first guide member 22 is in a first guiding position shown in solid lines and the second guide member 24 is in a first non guiding position, shown in broken lines. In the second guide condition, shown in Figure 2, the first guide member 22 is in a second non-guiding position, shown in broken lines, and the second guide member is in a second guiding position shown in solid lines in Figure 2. [0102] As explained in more detail below, the first terminating region 16A of the first switch rail 16 is a region in which a first wheel 42 of a wheel arrangement 40 engages the first main rail 12 and the first switch rail 16. Similarly, the second terminating region 18A of the second switch rail 16 is a region in which a second wheel 44 of the wheel ar rangement 40 engages the second main rail 14 and the second switch rail 18. [0103] The first and second wheels 42, 44 are connected to each other by a rigid axle 45, whereby movement of one of the first or second wheels 42, 44 is immediately transmitted to the other of the first or second wheels 42, 44 so that both wheels perform the same movement. Each of the wheels 42, 44 comprises a frusto-conical main portion in the form of a tread 46 and an outwardly extending circumferential flange 48 on the tread 46. The flange 48 extends radially outwardly from the tread 46. Each wheel 42, 44 has an inner face 50 extending across the tread 46 and the flange 48. [0104] The first elongate guide member 22 is disposed adjacent the first main rail 12 and guides rail vehicle wheels along the first main rail 12 so that the flanges of the rail vehicle wheels are received into the first flange receiving passage 17. The second elongate guide member 24 is disposed adjacent the second main rail 14 and guides rail vehicle wheels along the second main rail 14 so that the flanges of the rail vehicle wheels are received into the second flange receiving passage 19. The guide ar rangement 20 ensures that the wheels are guided in the desired direction. In the em bodiments described herein, the guide arrangement 20 does not control the extent of lateral movement of the rail vehicle wheels on the rails. [0105] The first and second elongate guide members 24 are fixedly attached to each other so WO 2014/135852 PCT/GB2014/050625 15 that when the guide arrangement 20 is moved to the first condition, both of the first and second elongate guide members 22, 24 move together to their respective guiding and non-guiding positions. Similarly, when the guide arrangement 20 is moved to the second condition shown in Figure 2, both of the first and second elongate guide members 22, 24 move together to their respective non-guiding and guiding positions. [0106] The wheel directing arrangement also includes a wheel control arrangement 30 comprising a first elongate wheel control member 32 and a second elongate wheel control member 34. The first wheel control member 32 is disposed adjacent the first switch rail 16, and overlaps the main rail 12 at a first transition region, which is the region comprising a main rail overlap region 12A of the first main rail 12, and the first terminating region 16A of the first switch rail 16. [0107] The first transition region 12A, 16A is a region from the point at which the flange 48 of the first wheel 42 begins to move laterally away from the first main rail 12 thereby allowing the tread 46 of the first wheel 42 to engage the first switch rail 16. The first transition region 12A, 16A terminates at, or beyond, the point at which the tread 46 of the first wheel 42 is fully supported by the first switch rail 16. [0108] The second wheel control member 34 is disposed adjacent the second switch rail 18, and overlaps the main rail 14 at a second transition region, which is the region comprising a main rail overlap region 14A of the second main rail 14, and the second terminating region 18A of the second switch rail 18. [0109] The second transition region 14A, 18A is a region from the point at which the flange 48 of the second wheel 44 begins to move laterally away from the second main rail 14 thereby allowing the tread 46 of the second wheel 44 to engage the second switch rail 18. The second transition region 14A, 18A terminates at, or beyond, the point at which the tread 46 of the second wheel 44 is fully supported by the second switch rail 18. [0110] The purpose of the wheel control arrangement 30 is to ensure that the rail vehicle wheels remain correctly aligned on the appropriate rails in order to provide sufficient wheel bearing during the transition of the first or second wheels 42, 44 from the first main rail 12 to the first switch rail 16, or from the second main rail 14 to the second switch rail 18, even when the rails are worn. [0111] The wheel control arrangement 20 stops excessive lateral movement of the wheels 42, 44 on the first and second main rails 12, 14 and on the first and second switch rails 16, 18, thereby ensuring adequate contact area between the wheels and the rail or rails supporting it. It is an advantage of the embodiments described herein that they ensure sufficient bearing of the wheel by the rail orrails to avoid damage to the rail head or lack of support to the wheel. [0112] The wheel control arrangement 30 is movable between first and second wheel control conditions. In the first wheel control condition, shown in Figure 2, the first wheel WO 2014/135852 PCT/GB2014/050625 16 control member 32 is in a first wheel control position to engage the first wheel 42, thereby inhibiting excessive lateral movement of the first wheel 42 away from the first main rail 12. [0113] In the second wheel control condition, shown in Figure 1, the second wheel control member 34 is in a second wheel control position to engage the second wheel 44, thereby inhibiting lateral movement of the second wheel 44 away from the second main rail 14. [0114] In use, the guide arrangement 20 can be moved in the first direction to the first position shown in Figure 1. A rail vehicle travelling in the direction indicated by the arrow X in Figure 1 along the first and second main rails 12, 14 is directed by the first guide member 22 so that the wheels travel along the first main rail and the second switch rail 18. Similarly, by moving the guide arrangement 20 in the second direction to the second position shown in Figure 2, a rail vehicle travelling in the direction indicated by the arrow X is directed by the second guide member 24 so that the wheels travel along the second main rail 14 and the first switch rail 16. [0115] Figure 3 shows an end sectional view of the junction assembly 10 in the condition shown in Figure 1, i.e. with the guide arrangement 20 in the first position. As would be understood by the skilled person, Figure 3 shows lower portions of a known wheel ar rangement 40, which comprises first and second wheels 42, 44. An axle (not shown) connects the first and second wheels 42, 44 to each other. [0116] Lateral movement of one of the first and second wheels 42, 44 across the rails causes the same lateral movement of the other wheel. The words "lateral" or "laterally" as used herein is intended to refer to movement in a substantially horizontal direction transverse to the longitudinal orientation of the rails. [0117] In Figures 1 and 2, the flange 48 is represented by an oval, and the tread 46 is indicated by a solid/broken line extending from the flange 48. A solid region of the solid/broken line indicates a region of the tread 46 supported by a rail. A broken region of the solid/broken line indicates an unsupported region of the tread 46. [0118] As shown in Figure 3, the first guide member 22 is in its guiding position and has an outer wheel engaging surface 52 to engage the inner face 50 of the first wheel 42. The second guide member 24 has an outer wheel engaging surface 52 for engaging the inner face 50 of the second wheel 44, but the second guide member 24 is in its non guiding position, and is not shown in Figure 3. [0119] In Figures 1 and 3, the guide arrangement 20 is in the first guide condition, with the first guide member 22 in its guiding position, and the wheel engaging surface 52 thereof in the appropriate position to engage the inner face 50 of the first wheel 42, thereby directing the first wheel 42 in a direction so that the flange 48 of the first wheel 42 passes into the first flange receiving passage 17.
WO 2014/135852 PCT/GB2014/050625 17 [0120] The first wheel 42 thus continues along the first main rail 12. The second wheel 44, being connected to the first wheel 42, is moved relative to the second main rail 14 in the same lateral direction as the first wheel 42. Consequently, the flange 48 of the second wheel 44 is moved away from the second main rail 14 to a position where the flange 48 of the second wheel 44 engages the left hand side 18B (as shown in Figure 3) of the second switch rail 18, thereby moving the second wheel 44 onto the second switch rail 18. [0121] Similarly, when the guide arrangement 20 is moved to the second condition shown in Figure 2, the second wheel 44 is urged by the second guide member 24 towards the second main rail 14 so that the flange 48 of the second wheel 44 passes into the second flange receiving passage 19. [0122] The second wheel 44 continues along the second main rail 14, and the first wheel 42 is moved laterally relative to the first main rail 12 towards the first guide member 22. As this occurs, the flange 48 of the first wheel 42 is moved away from the first main rail 12 to engage the right hand side 16B of the first switch rail 16. [0123] In the situation shown in Figure 1, the second wheel 44 moves away from the second main rail 14 to be supported by the second switch rail 18. This occurs in the second transition region 14A, 18A, and the effect of such movement is that the support provided by the second main rail reduces, and the support provided by the second switch rail increases. [0124] In circumstances where the wheels and the rails are unworn and the wheel treads are of sufficient width, having a rail vehicle wheel engage a main rail and move across to engage a switch rail should not create a problem. This is because both wheels are supported by sufficient surface area of the rail head by the wheel until it passes beyond the transition region, at which point, the load is borne fully by the switch rail. [0125] As the first wheel 42 moves across the first transition region 12A, 16A from the first main rail 12 to the first switch rail 16, the bearing area of the first main rail 12, on the first wheel 42 decreases as the bearing area of the first switch rail 16 on the first wheel 42 increases. [0126] Similarly, as the second wheel 44 moves across the second transition region 14A, 18A from the second main rail 14 to the second switch rail 18, the bearing area of the second main rail 14, on the second wheel 44 decreases as the bearing area of the second switch rail 18 on the second wheel 44 increases. [0127] Thus, at all times during the movement of the first or second wheels 42, 44 through the first or second transition regions, the wheel 42 or 44 engages either the first or second main rails 12, 14, or the first or second switch rails 16, 18 or both the respective main rail 12, 14 and the respective switch rail 16, 18. [0128] However, where the first and second main rails 12, 14, and/or the first and second WO 2014/135852 PCT/GB2014/050625 18 switch rail 16, 18 and/or the wheels 42, 44 are worn and the tread 46 is insufficiently wide, insufficient support of the wheels 42,44 is possible, and can present a significant risk. An example of this is shown in Figure 4 in which the hatched region 58 represents regions of wear of the first main rail 12 and the first wheel 42. [0129] Such worn regions can cause a problem if the rail vehicle wheels 42, 44 drift across the rails. In such circumstances, there is a danger of there being insufficient contact between the first or second wheel 42, 44 and the rail surfaces supporting it. This could result in significant damage to the rail and/or derailment of the rail vehicle, the effects of which could be catastrophic. [0130] In order to prevent such a problem, the wheel control arrangement 30 is provided. As shown in Figures 1 and 2 the first and second wheel control members 32, 34 are provided adjacent the first and second switch rail transition regions 16A, 18A of the first and second switch rails 16, 18. The first and second wheel control members 32, 34 are disposed between the first and second switch rails 16, 18 [0131] In Figure 4, as the wheel arrangement 40 moves to the left hand side, as indicated by the arrow C, the worn region of the first main rail 12 and the first wheel 42 creates a tendency for the wheel arrangement 40 to move further in the lateral direction indicated by the arrow C than would be the case if no wearing has occurred. In such a situation, during the transfer of the second wheel 44 from the second main rail 14 to the second switch rail 18, the combined wheel rail bearing area provided by the second rail 14 and the second switch rail 18 may be insufficient to safely support the rail vehicle. [0132] In order to prevent such excessive lateral movement, the second wheel control member 34 engages the inner face 50 of the second wheel 44 to maintain the tread 46 thereof on the second main rail 14, so that the second wheel 44 is sufficiently supported by the bearing areas between the second wheel 44 and the second main rail 14 and between the second wheel 44 and the second switch rail 18 until the second wheel 44 is fully supported on the second switch rail 18. [0133] Correspondingly, although not shown in Figure 4, the converse applies when the guide arrangement 20 is in the second guide condition and the flange 48 of the second wheel 44 is received in the second flange receiving passage 19. In this circumstance, the first wheel control member 32 engages the inner face 50 of the first wheel 42 to maintain the tread 46 thereof on the first main rail 12. [0134] There is thus described above a rail junction assembly 10 that obviates the need for moveable switch rails, and allows rail vehicles to be switched from one track to another while ensuring that there is sufficient bearing area between the wheels and the rails throughout the transition between the tracks. The wheels are always supported by either a single rail or by one of the main rails 12, 14 and the corresponding switch rail WO 2014/135852 PCT/GB2014/050625 19 16, 18 the rail. The rail junction assembly 10 also provides a benefit that there will be less wear of the rail head and wheel flange 48. [0135] Various modifications can be made without departing from the scope of the invention. For example, as shown in Figures 5 and 6, the wheel control arrangement 30 can be moveable. In other embodiments, the wheel directing arrangement comprises first and second wheel directing means. The first wheel directing means may comprise a first guide member and a first wheel control member as a single unit. The second wheel directing means may comprise a second guide member and a second wheel control member as a single unit. [0136] For example, in Figure 5, the second guide member 24 and the second wheel control member 34 are shown and together form a second wheel directing means 60. [0137] The second wheel directing means 60 comprises an upper wheel directing element 62 which constitutes the second wheel control member 34. The upper wheel directing element 62 extends upwardly from a lower wheel directing element 64, which con stitutes the second wheel guide member 24. [0138] The lower wheel directing element 64 provides a shoulder 66 extending from the upper wheel engaging element 62. The second wheel directing means 60 is movable between raised and lowered positions. [0139] In the lowered position shown in solid lines in Figure 5, the second wheel control member 34 is in the second wheel control position to engage the inner face 50 of the second wheel 44. The second guide member 24 is in its non-guiding position and is below the second wheel 44, so that the second wheel 44 is not engaged by the second guide member 64. [0140] In the raised position, shown in broken lines in Figure 5 the wheel directing means 60 has been raised so that the second guide member 24 is in its guiding position to engage the second wheel 44 and thereby guide the flange 48 thereof into the second flange receiving passage 19. [0141] Although not shown in Figure 5, a first wheel directing means is provided adjacent the first main and switch rails 12, 16. The first wheel directing means comprises the first guide member 22 and the first wheel control member 32. [0142] When the second wheel directing means 60 is in the lowered position shown in solid lines in Figure 5, the first wheel directing means is in a raised position, in which the first guide member 22 can engage the first wheel 42. [0143] When the second wheel directing means 60 is in the raised position, shown in broken lines in Figure 5, the first wheel directing means is in a lowered position, in which the first wheel control member 32 can engage the first wheel. [0144] Figure 6 shows a further example of the wheel directing arrangement comprising first and second wheel directing means. In Figure 6, a single second wheel directing means WO 2014/135852 PCT/GB2014/050625 20 68 is shown. The second wheel directing means 68 comprises the second guide member 24 and the second wheel control member 34. [0145] [0146] The second wheel directing means is movable laterally between a its guiding position shown in broken lines in Figure 6, and a second wheel control position shown in solid lines in Figure 6. [0147] In the second guiding position, the second guide member 24 is in the appropriate position to guide the flange 48 of the second wheel 44 into the second flange receiving passage 19. In the second wheel control position, the second wheel control member 34 is in the appropriate position to engage the inner face 50 of the second wheel 44 and thereby control the position of the second wheel 44 on the second main rail 14. [0148] The embodiment shown in Figure 6 also includes a first wheel directing means, but this is not shown in Figure 6. The first wheel directing means comprises the first guide member 22 and the first wheel control member 32. [0149] The first wheel directing means is movable between a first guiding position and a first wheel control position. In the first guiding position, the first wheel directing means can guide the flange 48 of the first wheel 42 into the first flange receiving passage 17. In the wheel control position, the first wheel directing means can control the position of the first wheel 42 on the first main rail 12. [0150] When the first wheel directing means is in the first guiding position, the second wheel directing means 68 is in the second wheel control position. When the first wheel directing means is in the first wheel control position, the second wheel directing means 68 is in the second guiding position. [0151] Referring to Figures 7 to 10, there is shown a wheel urging member 80, which is intended for use on a rail junction assembly 110 (see Figure 10), which is similar to the rail junction assembly 10, but is devoid of the guide arrangement 20. The rail junction assembly 110 is constructed when rail vehicles travel only in the direction indicated by the arrow A in Figure 10. [0152] However, when the rail junction assembly 110 requires maintenance, it may be necessary to drive a maintenance vehicle in the opposite direction through the rail junction assembly 110. This can be achieved by the use of the wheel urging member 80. [0153] The wheel urging member 80 comprises an elongate wedge shaped main body 82 and a pair of connecting elements 84, 86 spaced axially from each other along the length of the main body 82. The connecting elements 84, 86 are attached to the lower face of the main body 82, and extend downwardly therefrom. [0154] In the embodiment shown in Figure 8, each of the connecting elements 84, 86 defines an aperture, through which a connector (not shown) can be inserted to secure the wheel WO 2014/135852 PCT/GB2014/050625 21 urging member 80 to the rail. [0155] The main body 82 has first and second side surfaces 90, 92, the purpose of which is explained below. [0156] Figure 9 shows a second embodiment of the wheel urging member 80, which is the same as the first embodiment shown in Figures 7 and 8, but differs in that the first and second connecting elements 84, 86 are in the form of shaped tabs, which have been configured to engage corresponding formations on the rail junction assembly 110. [0157] Figure 10 shows a plan view of the rail junction assembly 110. In order to drive a railway vehicle through the rail junction assembly 110 in the direction opposite to that indicated by the arrow A, the wheel urging member 80 is disposed in alignment either with the first switch rail 16 or with the second switch rail 18, depending upon which direction of travel is required. The wheel urging member 80 is shown in broken lines in both possible positions in Figure 10, the broken lines indicating that the two positions are alternatives. [0158] The first switch rail 16 has a flange facing side surface 116. When it is desired to direct the rail vehicle along the first main rail 12, the wheel urging member 80 is disposed at the position indicated as 80A in Figure 10, so that the first side surface 90 thereof is aligned with the first flange facing surface 116 of the first switch rail 16. Thus, the flange 48 of the first wheel 42 (not shown in Figure 10) is directed along the first flange receiving passage 17. [0159] Conversely, when it is desired to direct the rail vehicle along the second main rail 14 the wheel urging member 80 is disposed at the position indicated as 80B in Figure 10, so that the second side surface 92 thereof is aligned with the second flange facing surface 118 of the second switch rail 18. Thus, the flange 48 of the second wheel 44 (not shown in Figure 10) is directed along the second flange receiving passage 19. [0160] Figures 11 to 13 show a rail switching arrangement 210 for use in the rail junction assembly 10 described above. The rail switching arrangement 210 comprises a first directing means 212 comprising a first elongate cylindrical rotary member 214, mounted on supports 216, and held on the supports 216 by C shaped holders 218. The rail switching arrangement 210 further includes a second directing means 220 comprising a second elongate cylindrical rotary member 222. [0161] The second elongate cylindrical rotary member 222 is also held on the supports 216 by C shaped members, but these are not visible in Figure 11. [0162] The rail switching arrangement 210 is mounted between first and second main rails 224 (see Figures 12 and 13, in which only the first main rail 224 is shown) in the form of embedded rails. The first rotary member 214 extends alongside the first main rail 224. The second rotary member 222 extends alongside the second main rail. [0163] The first main rail 224 and the second main rail are mounted within respective WO 2014/135852 PCT/GB2014/050625 22 elongate rail holding arrangements 226. In Figure 11, the first and second main rails are not shown, only the rail holding arrangements 226. Each of the rail holding ar rangements 226 comprise a pair of opposed rail holding members 228 between which the first and second main rails 224 are mounted. [0164] The first and second rotary members 214, 222 are rotatable about their main axes between respective first and second guiding positions and respective first and second control positions. [0165] The first and second rotary members 214, 222 are connected to each other by an operating means 230, which comprises a first elongate push/pull member 232 in the form of a first rod and a second elongate push/pull member 234 in the form of a second rod. [0166] One end of the first push/pull member 232 is connected to the first rotary member 214 by a first crank 236, and one end of the second push/pull member 234 is connected to the second rotary member 222 by a second crank (not visible in the drawings), [0167] At their opposite ends, the first and second push/pull members 232, 234 are connected to a shaft 238 via a central crank 240. A drive means 242 is drivingly connected to the shaft 238. The drive means 242 may comprise a motor which can rotate the shaft 238 about its main axis. [0168] When the shaft 238 is rotated by the drive means 242 in the direction indicated by the arrow R in Figure 11, the first and second push/pull members 232, 234 are moved to cause the first and second rotary members 214, 222 to rotate in the same direction. This moves the first rotary member 214 from its first guiding position to its first control position, and also moves the second rotary member 222 from its second control position to its second guiding position. [0169] When the shaft 238 is rotated by the drive means 242 in the opposite direction to that indicated by the arrow R in Figure 11, the first and second rotary members 214, 222 are rotated correspondingly by the movement of the push/pull members 232, 234. The first rotary member 214 is moved from its first control position to its first guiding position, and the second rotary member 222 is moved from its second guiding position to its second control position. [0170] Referring to Figures 12 and 13, there is shown a close up end view of the first rotary member 214. Figure 12 shows the first rotary member 214 in the first guiding position, and Figure 13 shows the first rotary member in the first control position. As can be seen from Figures 12 and 13, the first rotary member 214 defines a first elongate V shaped recess 250, which extends the length of the first rotary member 214, and has upper and lower surfaces 252, 254. [0171] Figures 12 and 13 also show a first wheel 264 of a wheel arrangement. A second wheel of the wheel arrangement travels along the second main rail.
WO 2014/135852 PCT/GB2014/050625 23 [0172] A first guide member 256 is mounted on the first rotary member 214 on the lower surface 254 of the first V shaped recess 250. The first guide member 252 extends from the recess 250 radially outwardly beyond the first rotary member 214. [0173] A first wheel control member 258 is mounted on the first rotary member 214 on the upper surface 254, and has an outer surface coplanar with the upper surface 254 of the first V shaped recess 250. [0174] It will be appreciated that the second rotary member 222 has a second elongate V shaped recess, which is substantially the same as the first elongate V shaped recess. A second guide member and a second control member are provided on the second rotary member 222. [0175] Figure 12 shows in broken lines a first switch rail 260, and a first flange receiving passage 262 is defined between the first main rail 224 and the first switch rail 260. In Figure 12, the first main rail 224 and the first switch rail 260 are shown as rectangular embedded rails, but they could be, for example, flat bottom rails and they may be, for example, surface mounted. The first rotary member 214 is in the first guiding position, in which the first guide member 256 engages the first wheel 264 thereby urging the first wheel 264 into the first flange receiving passage 262. [0176] When the first rotary member 214 is moved to the first guiding position, by movement of the first push/pull member 232 in the direction as shown by the arrow S in Figure 12, the second rotary member 222 is moved to the second control position. In the second control position, the second control member engages the second wheel to control the second wheel on the second main rail. [0177] When the first rotary member 214 is moved to the first control position, by movement of the first push/pull member 232 in the direction indicated by the arrow T in Figure 13, the second rotary member is moved to the second guiding position. In the second guiding position, the second guide member engages the second wheel to urge the second wheel into a second flange receiving passage. [0178] This has the effect moving the first wheel 264 in the direction indicated by the arrow U to the position of the first wheel 264 shown in Figure 13, in which the support on the first wheel 264 from the first main rail 224 is reduced. The first control member 258 engages the wheel 264, thereby preventing further movement of the first wheel 264 in the direction indicated by the arrow U. [0179] In a further modification, the first and second guide members may each define a plurality of gaps. The first and second control members may comprise a plurality of projecting portions, which can protrude through the gaps in the respective first and second guide members when the first and second guide members are arranged in their non-guiding positions. [0180] The embodiment of the rail junction assembly 10 shown in Figures 1 and 2, and WO 2014/135852 PCT/GB2014/050625 24 described above, includes the guide arrangement 20 to guide rail vehicles travelling in the directions indicated by the arrows X and Y. Rail vehicles can also travel through the rail junction assembly 10 in the directions opposite to the directions indicated by the arrows X and Y. [0181] Figure 14 shows a further embodiment of a rail junction, generally designated 210, which is intended to be used only by rail vehicles travelling in the trailing directions indicated by the arrows S and T. The rail junction assembly 210 includes many of the features of the rail junction 10, and these features have been designated with the same reference numerals, and function in the same way as the corresponding features shown in Figures 1 and 2. [0182] The junction assembly 210 differs from the junction assembly 10 in that the junction assembly 210 does not possess a guide arrangement. The junction assembly also possesses a fixed wheel control arrangement generally designated 230. The wheel control arrangement 230 comprises a fixed first control member 232 and a fixed second control member 234 he purpose of the wheel control arrangement 230. [0183] The first control member 232 is provided to control the position of the first wheels 42 as the wheel arrangements 40 travel in the direction of the arrow T and the first wheels 42 travel from the first switch rail 16 to the first main rail 12. The first control member 232 ensures that there is sufficient bearing area between the first wheels 42 and the first switch and main rails 16, 12 throughout the transfer of the first wheels 42 between the first switch rail 16 and the first main rail 12. [0184] The first wheels 42 are thus sufficiently supported by the bearing areas between the first wheels 42 and the first main rail 12 and between the first wheels 42 and the first switch rail 16 until the first wheels 42 is fully supported on the first main rail 16. [0185] The second control member 234 is provided to control the position of the second wheels 44 as the wheel arrangements 40 travel from the second switch rail 18 to the second main rail 14, thereby ensuring the second wheels 44 are sufficiently supported throughout the transfer of the second wheels 44 from the second switch rail 18 to the second main rail 14.