This invention relates to positioning devices for positioning wall members of an article. More particularly, but not exclusively, this invention relates to positioning devices for positioning wall members of rail receiving shells. The invention also relates to rail assemblies comprising rails and rail receiving shells. The invention also relates to lids for rail receiving shells. The invention also relates to lid assemblies comprising rail receiving shells and lids.

In the railway industry, embedded rails are installed into shells that support the rail and hold it in place. Two parallel shells can be provided at a required distance apart e.g. for a railway gauge. The shells can be mounted in elongate troughs, and are fastened in place by a fixing medium, e.g. grout, concrete or asphalt. The shells have upstanding opposite walls defining a channel therebetween in which the rail is received. When the shells are installed in the trough, it is necessary to ensure that the arms are maintained substantially vertical, and that the walls are spaced from each other along their full height by a predetermined distance. This allows the shell to be held in the appropriate position to allow it to be fastened in place and receive the rail.

According to a first aspect of this invention, there is provided a positioning device for positioning opposite first and second wall members of an article, the positioning device comprising: a first holding formation to hold the first wall member of the article; a second holding formation to hold the second wall member of the article; a spacing member extending between the first and second holding formations; and a fastening system for fastening the positioning device to the first and second walls.

The fastening system may comprise a first fastening arrangement for fastening the positioning device to the first wall member. The fastening system may further include a second fastening arrangement for fastening the positioning device to the second wall member. Thus, the first and second wall members may be held in a spaced position relative to each other by the spacing member. In the embodiments described herein, the first and second holding formations provide the advantage of holding the rail receiving shell in the correct position for grouting. In the embodiments described herein, the first and second holding formations provide the further advantage that they ensure the first and second wall members are spaced by the correct distance to receive a rail therebetween and hold the rail in an appropriate position for its use.

The combined effect of the first and second holding portions and the first and second fastening portions is that they may provide the advantage of holding the rail receiving shell up for alignment and grouting, and holding the rail receiving shell down against uplift when the rail receiving shell is arranged in wet medium, such as concrete.

According to a second aspect of the invention, there is provided a positioning assembly comprising: a positioning device as described above; and an article having first and second wall members; wherein the first holding formation holds the first wall member, and the second holding formations holds the second wall member; and wherein the fastening system fastens the positioning device to the first and second wall members.

The first fastening arrangement may fasten the positioning device to the first wall member. The second fastening arrangement may fasten the positioning device to the second wall member.

The first and second wall members may extend upwardly from the support member. The first and second wall members may be arranged opposite each other.

The first wall member may define an inwardly facing first fastening recess. The second wall member may define an inwardly facing second fastening recess.

The article may be a shell, such as a rail receiving shell for receiving a rail. The shell may comprise an elongate support member and elongate upstanding first and second wall members supported by the support member.

The first holding formation may comprise a first holder. The second holding formation may comprise a second holder.

According to a third aspect of this invention, there is provided a positioning device for positioning opposite first and second wall members of an article, the positioning device comprising: first and second holders; a spacing member extending between the first and second holders; and a fastener engageable with the first wall member.

In use, the first holder may hold the first wall, and the second holder may hold the second wall.

The fastener may comprise a detent for engaging one of the first and second walls. The positioning device may comprise first and second of the fasteners. The first fastener may be engageable with the first wall member. The second fastener may be engageable with the second wall member.

The first fastener may comprise a first detent. The second fastener may comprise a second detent.

According to a fourth aspect of this invention, there is provided a shell for receiving a rail, the shell comprising: an elongate support member; and elongate upstanding first and second wall members extending upwardly from the support member, the first and second wall members being arranged opposite each other; wherein the first wall member defines an inwardly facing first fastening recess, and the second wall member defines an inwardly facing second fastening recess.

The shell may comprise a rail receiving shell. According to a fifth aspect of this invention, there is provided a rail assembly comprising a shell described above, and a rail received between the first and second wall members of the shell.

According to a sixth aspect of this invention, there is provided a lid for a rail receiving shell having elongate upstanding first and second wall members, the lid comprising: a spacing member to extend between the first and second wall members, the spacing member having opposite edges; first and second holding formations extending from the edges for engaging upper edges of the wall members.

According to a seventh aspect of the invention, there is provided a lid assembly comprising: a lid as described above; and a rail receiving shell having first and second wall members, each wall member having a respective upper edge; wherein the first holding formation portion engages the upper edge of the first wall member, and the second holding formation engages the upper edge of the second wall member.

The first holding formation may comprise a first lip portion. The second holding formation may comprise a second lip portion.

The wall members may extend along the support member.

The first wall member may have an inwardly facing surface. The first fastening recess may be defined in the inwardly facing surface of the first wall member. The first fastening recess may cooperate with the first fastening arrangement to fasten the positioning device to the first wall member.

The second wall member may have an inwardly facing surface. The second fastening recess may be defined in the inwardly facing surface of the second wall member. The second fastening recess may cooperate with the second fastening arrangement to fasten the positioning device to the second wall member.

The first fastening recess may be defined in an upper region of the first wall member. The second fastening recess may be defined in an upper region of the second wall member.

The first wall member may be taller than the second wall member. Alternatively, the first wall member may be the same height as the second wall member.

Each of the first and second wall members may define a respective inwardly facing locking recess to lock the rail to the shell. The inwardly facing locking recesses may receive respective locking projections on the rail. The locking recesses may be defined at lower regions of the first and second wall members.

The spacing member may have first and second engaging portions for engaging the respective first and second wall members of the article. The first holding formation may be provided at the first engaging portion of the spacing member. The second holding formation may be provided at the second engaging portion of the spacing member.

The first and second engaging portions may be provided at respective first and second opposite edge regions of the spacing member.

The fastening system may comprise a detent arrangement. The fastening system may be provided on the spacing member. The fastening system may be provided at the first engaging portion of the spacing member. The first fastening arrangement may be directed outwardly from the spacing member.

The first fastening arrangement may comprise a first detent arrangement. The first fastening arrangement may be provided on the spacing member. The first fastening arrangement may be provided at the first engaging portion of the spacing member.

The first fastening arrangement may be directed outwardly from the spacing member in a first direction. The second fastening arrangement may be directed outwardly from the spacing member in a second direction. The first direction may be an opposite direction to the second direction.

The spacing member may comprise a central portion arranged between the first and second engaging portions. The central portion may extend obliquely between the first and second engaging portions. The engaging portions may extend laterally from the central portion.

The fastening system may comprise a fastening member. The fastening member may engage the first wall member of the article. The fastening member may comprise a detent member.

Each of the locking recesses may receive a respective one of the first and second detent members.

The fastening member may be movable laterally outwardly from the spacing member to a fastening position of the fastening member. In the fastening position of the fastening member, the fastening member may be received in the first fastening recess, thereby fastening the positioning device to the first and second wall members.

The first fastening arrangement may comprise a first fastening member. The first fastening member may engage the first wall member of the article. The first fastening member may comprise a first detent member.

The first fastening member may be movable laterally outwardly from the spacing member to a fastening position of the first fastening member. The first fastening member may be movable outwardly from the spacing member in a first direction to the fastening position of the first fastening member. In the fastening position of the first fastening member, the first fastening member may be received in the first fastening recess, thereby fastening the positioning device to the first wall member.

The second fastening arrangement may comprise a second detent arrangement.

The second fastening arrangement may be provided on the spacing member. The second fastening arrangement may be provided at the second engaging portion of the spacing member.

The second fastening arrangement may comprise a second fastening member. The second fastening member may engage the second wall member of the article. The second fastening member may comprise a second detent member.

The second fastening member may be movable laterally outwardly from the spacing member to a fastening position of the second fastening member. The second fastening member may be movable outwardly from the spacing member in a second direction to the fastening position of the second fastening member.

In the fastening position of the second fastening member, the second fastening member may be received in the second fastening recess, thereby fastening the positioning device to the second wall member.

The fastening system may comprise an urging arrangement. The urging arrangement may be configured to urge the fastening member to the fastening position of the fastening member. The urging arrangement may urge the fastening member outwardly from the spacing member.

The urging arrangement may comprise an urging member to urge the fastening member to the fastening position of the fastening member. The urging member may urge the fastening member outwardly from the spacing member. The urging member may be resilient. The urging member may comprise a spring. The spring may be a leaf spring.

The urging arrangement may be configured to urge the first and second fastening members to the fastening positions of the first and second fastening members. The urging arrangement may urge the first and second fastening members outwardly from the spacing member.

The urging arrangement may urge the first and second detent members to respective fastening positions of the first and second detent members.

The urging arrangement may comprise a first urging member to urge the first fastening member to the fastening position of the first fastening member. The first urging member may urge the first fastening member outwardly from the spacing member.

The first urging member may urge the first detent member to the fastening position of the first detent member. The second urging member may urge the second detent member to the fastening position of the second detent member.

The first urging member may be resilient. The first urging member may comprise a first spring. The first spring may be a first leaf spring.

It will be appreciated that the first spring may be any other suitable spring, such as a coil spring. The first urging member may be attached to the first fastening member.

The urging member may be attached to the spacing member. The urging member may be integral with the spacing member. The spring may be integral with the spacing member. The detent member may be integral with the urging member.

The urging member may be configured to extend from the spacing member to the first fastening recess. Alternatively, the urging member may be configured to extend from the spacing member to the first locking recess. The urging member may extend from the spacing member. The urging member may extend downwardly from the spacing member.

The urging member may comprise a resilient portion. The resilient portion may extend from the spacing member. The resilient portion may have a free edge region. The detent member may be provided at the free edge region of the resilient portion.

The free edge region of the resilient portion may be a lower edge region, detent member may be provided at the lower edge region of the resilient portion. The detent member may be received in the respective first locking recess.

The urging arrangement may include a bracing member to brace the fastening member. The bracing member may be resilient. The bracing member may comprise a leaf spring.

The bracing member may comprise a gripping portion at the ends of the bracing member. The gripping portion may grip the resilient portion. The gripping portion may grip a lower end of the resilient portion.

The bracing member may include a raised portion to provide resilience to the bracing member. The raised portion may extend from the gripping portion.

The resilient portion may further include a curved region. The curved region may be provided at the upper edge of the resilient portion. The curved region may enhance the resilience of the resilient portion.

The urging member may comprise inner and outer resilient portions.

The detent member may be attached to the urging member. The detent member may be integral with the urging member. The inner resilient portion of the urging member may be attached to the spacing member. The inner resilient portion of the urging member may be integrally attached to the spacing member.

The outer resilient portion of the urging member may be attached to the inner resilient portion. The outer resilient portion of the urging member may be integrally attached to the inner resilient portion.

The outer resilient portion of the urging member may extend from the inner resilient portion towards the spacing member. The outer resilient portion may have a free edge region. The free edge region may be an upper edge region of the outer resilient portion.

The detent member may be provided at said free edge region of the outer resilient portion. The outer resilient portion of the urging member may extend upwardly from the inner resilient portion. The detent member may be provided at the upper edge region of the outer resilient portion.

The detent member may be received in the first fastening recess. the urging member comprises a resilient portion extending from the spacing member, the resilient portion having a free edge, and the detent member being provided at the free edge region of the resilient portion.

The first and second urging members may be attached to the spacing member. The first and second urging members may be integral with the spacing member. The first and second springs may be integral with the spacing member.

The first and second urging members may be configured to extend from the spacing member to the first or second fastening recess. Alternatively, the first and second urging members may be configured to extend from the spacing member to the first or second locking recess. The first and second urging members may extend from the spacing member. The first and second urging members may extend downwardly from the spacing member. Each of the first and second urging members may comprise inner and outer resilient portions.

The first detent member may be attached to the first urging member. The second detent member may be attached to the second urging member.

The first detent member may be integral with the first urging member. The second detent member may be integral with the second urging member.

The inner resilient portion of each of the first and second urging members may be attached to the spacing member. The inner resilient portion of each of the first and second urging members may be integrally attached to the spacing member.

The outer resilient portion of each of the first and second urging members may be attached to the respective inner resilient portion. The outer resilient portion of each of the first and second urging members may be integrally attached to the respective inner resilient portion.

The outer resilient portion of each of the first and second urging members may extend from the respective inner resilient portion towards the spacing member. The outer resilient portion of each of the first and second urging members may have a free edge region. The free edge region may be an upper edge region of the outer resilient portion of each of the first and second urging members.

A respective one of the detent member may be provided at said free edge region of the outer resilient portion of each of the first and second urging members.

The outer resilient portion of each of the first and second urging members may extend from the respective inner resilient portion. The outer resilient portion of each of the first and second urging members may extend upwardly from the respective inner resilient portion. Each of the first and second outer resilient portions may have a free edge region. The first and second detent members may be provided at the free edge region of the respective outer resilient portion.

The free edge region of each of the first and second outer resilient portions may be an upper edge region. The first and second detent members may be provided at the upper edge region of the respective outer resilient portion.

The first detent member may be received in the first fastening recess. The second detent member may be received in the second fastening recess.

Each of the first and second urging members may comprise a respective resilient portion. Each resilient portion may extend from the spacing member.

The resilient portion may have a lower edge region. A respective one of the first and second detent members may be provided at the lower edge region of each of the resilient portions. The first and second detent members may be received in the respective first and second locking recesses.

The urging arrangement may include a bracing member to brace the first and second fastening members. The bracing member may be resilient. The bracing member may comprise a leaf spring.

The bracing member may comprise engaging portions at the opposite ends of the bracing member. Each engaging portion may comprise a gripping portion.

Each of the engaging portions may engage a respective one of the resilient portions. Each of the engaging portions may engage a lower end of a respective one of the resilient portions. In the embodiment described herein, the bracing member may further urge the detent members outwardly.

Each engaging portion may comprise a gripping portion. Each of the gripping portions may grip a respective one of the resilient portions. Each of the gripping portions may grip a lower end of a respective one of the resilient portions. The bracing member may include a raised portion to provide resilience to the bracing member. The raised portion may extend between the gripping portions.

Each resilient portion may have an attached edge region at which the respective resilient portion is attached to the spacing member. Each of the resilient portions may further include a curved region. Each curved region may be provided at the attached edge region of the respective resilient portion. The attached edge region may be an upper edge region

Each curved region may extend convexly towards the opposite resilient portion. The curved region of each resilient portion may enhance the resilience of the respective resilient portion.

Each urging member may include a connecting member connecting the resilient portion to the detent member. The detent member of each detent arrangement may comprise a curved end portion. The curved end portion may be received in a respective one of the fastening recesses. The detent member may be convexly curved, having a convex region. The convex region may face outwardly.

The urging arrangement may comprise a second urging member to urge the second fastening member to the fastening position of the second fastening member. The second urging member may urge the second fastening member outwardly from the spacing member.

The second urging member may be resilient. The second urging member may comprise a second spring. The second spring may be a second leaf spring.

It will be appreciated that the second spring may be any other suitable spring, such as a coil spring. The second urging member may be attached to the second fastening member. The urging arrangement may include a bracing member to brace the first and second fastening members. The bracing member may be resilient. The bracing member may comprise a leaf spring.

The first and second urging members provide the advantage that they allow the force applied on the first and second fastening members to be varied to suit the varying circumstances e.g. the different weight of rail receiving shell, changes of friction coefficient at the interface between the first and second detent members and the first and second fastening members, and the outdoor temperature. The use of the first and second urging members allows the manufacturer to engineer desired properties into the first and second detent arrangements, such as desired forces applied by the urging members.

The spacing member may define a housing portion in which the fastening system is housed. The housing portion may be provided at the first engaging portion of the spacing member.

The urging member may be housed in the housing portion. The fastening member may be housed in the housing portion. The detent member may be housed in the first housing portion.

The housing portion may define a chamber for receiving the fastening system.

The spacing member may define a first housing portion in which the first fastening arrangement is housed. The first housing portion may be provided at the first engaging portion of the spacing member.

The first urging member may be housed in the first housing portion. The first fastening member may be housed in the first housing portion. The first detent member may be housed in the first housing portion.

The spacing member may define a second housing portion in which the second fastening arrangement is housed. The second housing portion may be defined at the second engaging portion of the spacing member. The second urging member may be housed in the second housing portion. The second fastening member may be housed in the second housing portion. The second detent member may be housed in the second housing portion.

The first housing portion may define a first chamber for receiving the first fastening arrangement. The second housing portion may define a second chamber for receiving the second fastening arrangement.

The first holding formation may hold the upper region of the first wall member of the article. The second holding formation may hold the upper region of the second wall member of the article.

The first holding formation may comprise a first receiving formation for receiving the first wall member of the article. The first receiving formation may define a first cavity for receiving the first wall member of the article.

The first receiving formation may open downwardly. Thus, the first receiving formation may be arranged to receive an upper end region of the first wall member.

The second holding formation may comprise a second receiving formation for receiving the second wall member of the article. The second receiving formation may define a second cavity for receiving the second wall member.

The second receiving formation may open downwardly. Thus, the second receiving formation may be arranged to receive an upper end region of the second wall member.

The first holding formation may be provided on the spacing member. The second holding formation may be provided on the spacing member.

The first holding formation may comprise first guide means to guide the first holding formation onto the first wall member. The first guide means may taper inwardly towards the first cavity. The first guide means may comprise converging guide elements of the first holding formation. The converging guide elements may comprise an inner guide element and an outer guide element.

The fastening system may extend into the first holding formation. The fastening system may be arranged between the inner guide element and an upper region of the first holding formation.

The first fastening arrangement may extend into the first holding formation. The first fastening arrangement may be arranged between the inner guide element and an upper region of the first holding formation.

The second holding formation may comprise second guide means to guide the second holding formation onto the second wall member. The second guide means may taper inwardly towards the second cavity. The second guide means may comprise converging guide elements of the second holding formation.

The second guide means may comprise converging guide elements of the second holding formation. The converging guide elements may comprise an inner guide element and an outer guide element.

The second fastening arrangement may extend into the second holding formation. The second fastening arrangement may be arranged between the inner guide element and an upper region of the second holding formation.

The first and second holding formations may be offset relative to each other. The spacing member may be inclined between the first and second holding formations. The first and second fastening arrangements may be offset relative to each other.

The positioning device may have a lifting arrangement to allow the positioning device to be lifted from the article or lowered onto the article. The lifting arrangement may be provided on the spacing member. The lifting arrangement may comprise a projecting member to allow the lifting arrangement to be engaged by a suitable lifting device.

The projecting member may comprise a connecting portion. The projecting member may further include a contact portion extending across the connecting portion.

The contact portion may be gripped by suitable gripping elements of a lifting device.

The lifting arrangement may include a magnetically sensitive element on the contact portion to allow the contact portion to be engaged magnetically by a magnetically operated lifting device.

Alternatively, the lifting arrangement may comprise a magnetically sensitive region of the spacing member which can be magnetically engaged by the lifting device.

The spacing member may comprise a cover.

The lid may comprise first and second clip members. Each clip member may depend from a respective one of the edges of the spacing member. The clip members may be engageable with the first and second wall members to fasten the lid to the rail receiving shell.

The first clip member may engage the first wall member. The second clip member may engage the second wall member.

Each of the first and second clip members may be resilient. The first clip member may have an outwardly extending first sprung formation for engaging the first wall member. The second clip member may have an outwardly extending second sprung formation for engaging the second wall member. The first sprung formation may be received in the first fastening recess. The second sprung formation may be received in the second fastening recess.

Each of the clip members may have a respective connecting portion extending from the first or second sprung formation to the spacing member. The first and second sprung formations may extend in opposite directions from each other.

The lip portions may extend laterally from the edges of the spacing member. The first and second lip portions may extend in opposite directions from the spacing member.

Each of the first and second lip portions may be arranged in engagement with a respective one of the first and second wall members. Each of the first and second lip portions may engage the upper edge of a respective one of the first and second wall members.

The lid may include a lifting arrangement to allow the lid to be lifted from the article or lowered onto the article. The lifting arrangement of the lid may be provided on the spacing member. The lifting arrangement of the lid may comprise a projecting member to allow the lifting arrangement to be engaged by a suitable lifting device.

The projecting member of the lid may comprise a connecting portion. The projecting member of the lid may further include a contact portion extending across the connecting portion.

The contact portion of the lid may be gripped by suitable gripping elements of a lifting device.

The further lifting arrangement may include a further magnetically sensitive element on the further contact portion to allow the further contact portion to be engaged magnetically by a magnetically operated lifting device. Alternatively, the lifting arrangement of the lid may comprise a further magnetically sensitive region of the spacing member which can be magnetically engaged by the lifting device.

At least one embodiment of the invention will now be described by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a sectional view of a rail system;

Figure 2 is perspective view of a positioning assembly;

Figure 3 is a side view of the positioning assembly shown in Figure 2;

Figure 4 is a close up view of the region marked IV in Figure 3;

Figure 5 is an end view of a rail assembly for use as part of the rail system;

Figure 6 is perspective view of a lid assembly; and

Figure 7 is a side view showing the lid assembly;

Figure 8 is perspective view of another positioning assembly;

Figure 9 is an exploded view of the positioning assembly shown in Figure 8;

Figure 10 is a side view of the positioning assembly shown in Figure 8;

Figure 11 is perspective view of another lid assembly;

Figure 12 is a side view of the lid assembly shown in Figure 11 ;

Figure 13 is a side view of a further positioning assembly; and

Figure 14 is a side view of a still further positioning assembly. Figure 1 shows an embedded rail system 10 comprising a rail 12 held within a trough 14 by a rail receiving shell 16. The rail system 10 further includes a resilient pad 18 between the rail 12 and the rail receiving shell 16.

The resilient pad 18 is provided to cushion the forces between the rail 12 and the rail receiving shell 16 and is formed of a suitable resilient material, such as rubber.

The rail receiving shell 16 is secured in the trough 14 by a grouting material, such as concrete. In order to ensure that the rail receiving shell 16 is held in the correct position during grouting, a positioning assembly 22 shown in Figures 2, 3 and 4 is employed.

The positioning assembly 22 comprises a positioning device 24 and an article in the form of the rail receiving shell 16.

The rail receiving shell 16 comprises a lower elongate support member 26 and first and second upstanding wall members 28 supported by the support member 26. The wall members 28 extend upwardly from the support member 26, and are arranged opposite each other, with the support member 26 extending therebetween. The lower elongate support member 26 extends longitudinally along the bottom of the trough 14, and the wall members 28 extend along the support member 26. The wall members 28 extend substantially the whole length of the support member 26.

One of the wall members 28 is taller than the other. This is to allow the flange of the train wheel to pass across the shorter wall member 28. In some embodiments, the wall members 28 may have the same height, for example where the rail 12 extends a far enough distance above the rail receiving shell 16 for the flange to pass above the wall members 28.

Each wall member 28 has an inwardly facing surface 30. An inwardly facing first fastening recess 32 is defined in an upper region of the first wall member 28. An inwardly facing second fastening recess 32 is defined in an upper region of the second wall member 28. The fastening recesses 32 extend from the respective inwardly facing surface 30 into the first or second wall member 28.

The pad 18 has upstanding side portions 19 that extend between the rail 12 and the wall members 28 of the rail receiving shell 16. Each side portion 19 has an outwardly extending projection 33 that can be received in the respective fastening recess 32 of the adjacent wall member 28, thereby retaining the pad 18 in the rail receiving shell 16. Each of the projections 33 extend the whole length of the pad 18.

Each of the fastening recesses 32 extends substantially the whole length of the rail receiving shell 16. The purpose of the fastening recesses 32 is described below.

A first fastening recess 32 is defined in an upper region of the first wall member 28. A second fastening recess 32 is defined in an upper region of the second wall member 28.

Referring to Figures 1 and 5, an inwardly facing first locking recess 34 is defined in a lower region of the first wall member 28. An inwardly facing second locking recess 34 is defined in a lower region of the second wall member 28. The first and second locking recesses 34 lock the pad 18 to the rail receiving shell 16.

The locking recesses 34 receive respective locking projections 36 provided at lower regions of the pad 18 on opposite sides thereof. When the pad 18 is received by the rail receiving shell 16, the locking projections 36 of the pad 18 are received in the locking recesses 34, thereby locking the pad 18 to the rail receiving shell 16.

The positioning device 24 comprises a spacing member 38 for spacing the first and second wall members 28 from each other by a desired distance. The spacing member 38 comprises a central portion 40 and first and second engaging portions 42 at respective opposite edges of the central portion.

The positioning device 24 has a fastening system comprising first and second fastening arrangements. The first and second fastening arrangements are in the form of first and second detent arrangements 44 for fastening the positioning device

24 to the wall members 28.

Each of the detent arrangements 44 is provided at a respective one of the first and second opposite engaging portions 42. As shown in Figures 2 and 3, the central portion 40 extends obliquely between the engaging portions 42. The engaging portions 42 and the detent arrangements 44 extend laterally from the central portion 40 in opposite directions.

The engaging portions 42 are arranged parallel to each other. The central portion 40 extends diagonally between the engaging portions 42.

Figure 4 is a close up view of one of the engaging portions 42. The other engaging portion 42 has the same features. The engaging portions 42 are in the form of housing portions defining respective chambers 46. In the embodiment shown, the chambers 46 are elongate. The detent arrangements 44 are housed in the chambers 46. Each chamber 46 has a lateral outer opening 48 through which the detent arrangement 44 extends.

Each detent arrangement 44 comprises a detent member 50 and an urging member 52. The urging members 52 are provided to urge the detent members 50 outwardly.

Each of the detent members 50 is elongate and extends lengthwise along the respective chamber 46. Each detent member 50 has a convex leading region 54, providing the detent member 50 with substantially D shaped end profile. Each of the urging members 52 is in the form of a leaf spring.

A respective one of the urging members 52 and a respective one of the detent members 50 is retained within each chamber 46. Each of the detent members 50 has a convex leading region 54 that extends out of the chamber 46 through the outer opening 48. Each detent member 50 is urged by the respective urging member 52 outwardly of the first chamber 46 via the opening. Consequently, the convex leading region 54 of each detent member 50 is received in the fastening recess 32 defined in the respective wall member 28 when the positioning device 24 is arranged on the rail receiving shell 16.

The urging member 52 is selected so that the detent member 50 is urged by the urging member 52 to project from the chamber 46, and so that the detent member 50 can be moved into the chamber 46 by a predetermined force against the action of the urging member 52. The predetermined force is such that the urging member 52 allows the detent member 50 to be pushed into the chamber 46 when positioning device 24 is mounted on the rail receiving shell 16, or removed therefrom. During such mounting or removal, the detent member 50 slides over the upper region of the wall member 28.

The positioning device 24 further includes first and second holders, in the form of first and second holding formations 56 for holding the respective first and second wall members 28. Each holding formation 56 is provided adjacent, and outwardly of, a respective one of the engaging portions 42 of the spacing member 38.

Each holding formation 56 comprises a receiving formation 58 defining a cavity 60 which opens downwardly to receive the upper edge region of the respective wall member 28. When the upper edge regions of both wall members 28 are received by the receiving formations 58, the limb portions are held by the holding formations 56 in the correct position to allow the rail receiving shell 16 to be grouted into the trough 14.

Each of the holding formations 56 further includes guide means 62 to guide the holding formations 56 onto the wall members 28, so that the wall members 28 are received in the cavities. Each of the guide means 62 is in the form of converging inner and outer guide elements 64, 66. This means that each of the guide means 62 tapers inwardly towards the respective cavity 60. Each detent arrangement 44 is arranged between the inner guide element 64 and the cavity 60 of the respective holding formation 56. Thus, when the wall members 28 are received by the cavities, the detent members 50 are urged by the urging member 52 partially across the cavities to engage the wall members 28.

The detent arrangements 44 ensure that both wall members 28 are fastened to the positioning device 24, whereas the holding formations 56 to hold the wall members 28 in the correct spaced orientation from each other by the spacing member 38 to allow the grouting to occur.

In the embodiment shown, the holding formations 56 are offset relative to each other, so that the spacing member 38 is inclined between the first and second holding formations 56. The offset holding formations 56 means that the detent arrangements 44 are also offset relative to each other.

The offset holding formations 56 accommodate the rail receiving shell 16 having wall members 28 of different heights. However, in the embodiments where both wall members 28 are the same height, the holding formations 56 and the detent arrangements 44 are not offset.

The positioning device 24 includes a lifting arrangement 84 in the form of a magnetically sensitive element 102 (shown in broken lines in Figure 3) on the central portion 40 of the spacing member 38. The magnetically sensitive element 92 can be engaged magnetically by the magnetically operated lifting device to allow the positioning device 24 to be raised and lowered so that it can be removed from, or installed on, the rail receiving shell 16.

The positioning device 24 may be any suitable length. In one embodiment, the spacing member 38 may be a metre or more in length. A plurality of the positioning devices may then be arranged on the rail receiving shell 16 in abutment with one another. In this embodiment, the holding formations 56 may be the same length as the spacing member 38. In this embodiment, the positioning device 24 may comprise a plurality of detent arrangements 44 arranged intermittently on each of the edge regions. Each of the detent members 50 may be, for example, a few centimetres in length.

Alternatively, each detent arrangement 44 may comprise a single detent member 50 extending the length of the spacing member 38, and a plurality of urging members 52 arranged intermittently along each urging member 52.

In a further embodiment, the spacing member 38 may be only a few centimetres in length, for example 4 to 10 cm, wherein each detent member 50 is the same length as the spacing member 38. In this embodiment, each detent arrangement 44 has a single urging member 52.

With this embodiment, the positioning devices 24 are arranged intermittently along the rail receiving shell 16. A respective further positioning device in the form of a lid 68 is arranged between adjacent positioning devices 24.

The lids 68 and the positioning devices 24 exclude material, such as dust, dirt, grout, concrete and rain from the rail receiving shell 16.

An example of such a lid 68 is shown in Figures 6 and 7. These drawings show a lid 68 assembly comprising a lid 68 mounted on a rail receiving shell 16 described above.

The lid 68 comprises a spacing member in the form of a cover 70 to extend between the first and second wall members 28 of the rail receiving shell 16. The cover 70 has opposite edges and two detent arrangements in the form of resilient clip members 72. The clip members 72 are provided for engaging the first and second wall members 28.

Each clip member 72 is arranged on the cover 70 adjacent a respective one of the edges of the cover 70, and each clip member 72 depends from the cover 70 to engage the first and second wall members 28 of the rail receiving shell 16 to fasten the lid 68 to the rail receiving shell 16. Each clip member 72 is in the form of a detent arrangement comprising an outwardly extending sprung formation 74. The sprung formations 74 of the clip members 72 face away from each other, and are received in the fastening recesses 32 of the wall members 28 when the clip members 72 engage the wall members 28 of the rail receiving shell 16, thereby fastening the lid 68 to the rail receiving shell 16.

Each of the clip members 72 has a connecting portion 76 to connect the sprung formation 74 to the cover 70.

The lid 68 further includes first and second holding formations in the form offirst and second lip portions 78. The first and second lip portions 78 extend laterally in opposite directions from the opposite side edges of the cover 70. Each of the lip portions 78 is arranged in engagement with a respective one of the upper edges of the first and second wall members 28.

Thus, the lip portions 78 support the lid 68 on the rail receiving shell 16, and the clip members 72 fastener the lid 68 to the rail receiving shell 16.

The cover 70 is elongate. When a plurality of the positioning devices arranged intermittently on the rail receiving shell 16, the lid 68 is arranged between the positioning devices. The cover 70 of each lid 68 has a length to extend between the positioning devices. The clip members 72 and the lip portions 78 extend substantially the whole length of the cover 70.

As shown in Figures 5 and 6, the cover 70 has a central member 80, and first and second engaging members 82 which extend from respective opposite edges of the central member 80. The clip members 72 and the lip portions 78 are provided on the outer edges of the engaging members 82. The central member 80 extends obliquely between the first and second engaging members 82, thereby providing the lid 68 with a similar shape to the positioning device 24.

It will be apparent by comparing Figures 2 and 3 with Figures 6 and 7 that the central portion 40 of the positioning device 24 corresponds in size and position with the central member 80 of the lid 68, and that the engaging portions 42 of the positioning device 24 correspond in size and position with the engaging members 82 of the lid 68. This is to ensure that, when the lids 68 are mounted on the rail receiving shell 16 adjacent one of the positioning devices 24, there are no gaps between the lid 68 and the positioning device 24.

The lid 68 may include a lifting arrangement in the form of a magnetically sensitive element 92 (shown in broken lines in Figure 3) on the central portion 40 of the spacing member 38. The magnetically sensitive element 92 can be engaged magnetically by the magnetically operated lifting device to allow the lid 68 to be raised and lowered so that it can be removed from, or installed on, the rail receiving shell 16.

There is thus described positioning device 24, rail receiving shell 16 and lid 68 that allows the rail receiving shell 16 to be grouted in the correct position, for example in the trough 14. The invention has the following advantages.

The positioning device 24 maintains distance between the wall members 28 and holds up the rail receiving shell 16 for alignment and grouting. In addition, the weight of positioning devices 24 and, where used, the lids 68 hold down the rail receiving shell 16 against uplift when the rail receiving shell 16 is placed in wet medium, such as concrete.

The detent arrangements 44 enable the positioning devices 24 to be firmly fixed and removed from the rail receiving shell 16. Each fastening recess 32 receives a projection 33 on the pad 18 to retain the pad 18 the rail receiving shell 16.

The configuration of the positioning device 24 means that the cost is reduced compared to prior art devices. Similarly, the configuration of the rail receiving shell 16 means that the cost is reduced compared to prior art shells.

The provision of the detent arrangements 44 fastens the positioning device 24 firmly to the rail receiving shell 16. This overcomes criticality of manufacture tolerances prior art positioning devices. The positioning device 24 directs the rail receiving shell 16 into the correct configuration, e.g. if the rail receiving shell 16 is deformed during manufacture, transport, or handling. The positioning device 24 and the lid 68 can be mounted on the rail receiving shell 16 if it is twisted.

Friction at interfaces is not so critical as prior art devices. In the embodiment described herein, the detent arrangement 44 is mechanical, which can be engineered to alleviate problems associated with properties associated with prior art devices, such as friction.

Various modifications can be made without departing from the scope of the invention. For example, the lid 68 may not possess the clip members 72. Instead, the lid 68 may simply be placed on the upper edges of the first and second wall members 28. In this modification, the lip portions 78 may engage the upper edges of the first and second wall members 28.

In a further modification, the lid 68 may have some regions that have lip portions 78, without clip members 72. Other regions may have clip members 72, without lip portions 78.

The leading region 54 of each of the detent members 50 has a profile that is semi-circular, oval, trapezoidal or other suitable shape.

The drawings depict the fastening recesses 32 at the upper edge regions of the wall members 28. It will be appreciated that the fastening recesses 32 could be defined at any suitable distance from the upper edge of the wall members 28. In such cases, the detent arrangements 44 could be provided on the spacing member 38 at suitable distances therefrom so that the detent members 50 could be received by the fastening recesses 32. The positioning device 24 may have extensions attached to the spacing member 38. The extensions may extend down the wall members 28 to provide a plurality of contact points on the wall members 28 at a plurality of distances from the upper edges of the wall members 28. In Figure 1 , the rail system 10 comprises a trough 14 in which the rail 12 is embedded. It will be appreciated that the trough 14 could extend around both rails forming the railway line. Alternatively, the rail system 10 could be made without forming a trough. Shuttering could be provided, and one or both rails disposed between the shuttering. A fill medium, such as concrete, grout, asphalt, or bitumen, could then be arranged in the shuttering to hold the rails and the, or each, rail receiving shell 16 in place

Figures 8 to 10 show a modified positioning device, generally designated 124, forming part of the positioning assembly 22. The positioning device 124 shown in Figures 8 to 10 comprises many of the features of the positioning device 24 shown in Figures 2 to 4. These features have been designated in Figures 8 to 10 with the same reference numerals as the corresponding features shown in Figures 2 to 4.

In the positioning device 24 shown in Figures 2 to 4, the central portion 40 comprises an upper member 40A, and a lower member 40B spaced from each other (see Figure 3). Alternatively, as shown in Figures 8 to 10, the central portion 40 of the positioning device 124 comprises a single member instead of the upper and lower members 40A, 40B. In this embodiment, the first and second engaging portions 42 are arranged parallel to the central portion 40.

The positioning device 124 shown in Figures 8 to 10 includes a lifting arrangement 84, which comprises a projecting member in the form of an elongate T bar extending along the length of the positioning device 124. The lifting arrangement 84 comprises a connecting portion 86 and a contact portion 88 extending across the connecting portion 86.

Figure 9 shows an exploded view of the positioning device 124, in which the features of the first and second detent arrangements 44. The features of the first and second detent arrangements 44 of the positioning device 24 are the same as the features of the first and second detent arrangements 44 of the positioning device 24.

The contact portion 86 may be gripped by suitable gripping elements of a lifting device. Optionally, the lifting arrangement 84 may include a magnetically sensitive element 90 (shown in broken lines in Figure 10) around the contact portion 88 to allow the contact portion 88 to be engaged magnetically by a magnetically operated lifting device.

Figures 11 and 12 show a modified lid, generally designated 168. The lid 168 shown in Figures 11 and 12 comprises many of the features of the lid 68 shown in Figures 6 and 7. These features have been designated in Figures 11 and 12 with the same reference numerals as the corresponding features shown in Figures 6 and 7.

The lid 168 further includes two lip portions 178 which extend laterally in opposite directions from the opposite side edges of the cover 70. The lip portions 178 engage the inwardly facing surface 30 of each of the wall members 28.

Each of the lip portions 178 is directed downwardly on the upper edges of the rail receiving shell 16.

The lid 168 shown in Figures 11 and 12 includes a further lifting arrangement 94, which comprises a further projecting member in the form of an elongate T bar extending along the length of the lid 168. The further lifting arrangement 94 is similar to the lifting arrangement 84 described above.

The further lifting arrangement 94 comprises a further connecting portion 96 and a further contact portion 98 extending across the connecting portion 96. The further contact portion 86 may be gripped by suitable gripping elements of a lifting device. Optionally, the further lifting arrangement 94 may include a magnetically sensitive element 100 (shown in broken lines in Figure 12) around the further contact portion 98 to allow the further contact portion 98 to be engaged magnetically by a magnetically operated lifting device.

It will be appreciated that the lifting arrangements 84 or 94 could be provided on the central portion 40 of the positioning device 24 or on the cover 70 of the lid 68. It will also be appreciated that the magnetically sensitive elements 92 or 102 could be provided on the central portion 40 of the positioning device 124 or on the cover 70 of the lid 168. In another modification, the first and second fastening members may be in the form of balls. In a further modification, the first and second urging members 52 may be in the form of springs, such as coil springs, or a resilient material.

Further modifications are shown in Figures 13, 14 and 15. Figure 13 shows a positioning device 224. Figure 14 shows a positioning device 324. Figure 15 shows a positioning device 424.

Each of the positioning devices 224, 324 and 424 shown in Figures 13, 14 and 15 comprises many of the features of the positioning device 24 shown in Figures 2 to 4. These features have been designated in Figures 13, 14 and 15 with the same reference numerals as the corresponding features shown in Figures 2 to 4.

Each of the positioning devices 224, 324 and 424 comprise first and second detent arrangements 144 that are integral with the spacing member 38.

Referring to Figure 13, each of the urging members 152 comprises inner and outer resilient portions 154, 156. Each inner resilient portion 154 is integrally attached to the spacing member 38 and extends downwardly therefrom. Each outer resilient portion 156 is integrally attached to the inner resilient portion 154. A curved linking portion 158 extends between the inner and outer resilient portions 154, 156.

The outer resilient portion 156 extends upwardly from the linking portion 158. A respective one of the detent members 150 is provided at the upper edge region 160 of each outer resilient portion 156.

The detent members 150 of the positioning device 224 shown in Figure 13 are received in the first and second fastening recesses 32 in the rail receiving shell 16.

Referring to Figure 14, each of the urging members 152 comprises a resilient portion 162 extending downwardly from the spacing member 38. A respective one of the detent members 150 is provided at the lower edge region 164 of each of the resilient portions 162. The detent members 150 of the positioning device 324 shown in Figure 14 are received in the first and second locking recesses 34.

In addition to the resilient portions 160, the positioning device 324 comprises a resilient bracing member 168 extending between the detent members 150. The bracing member 168 comprises gripping portions 170 at the opposite ends of the bracing member 168. Each of the gripping portions 170 grips a respective one of the detent members 150, thereby further urging the detent members 150 outwardly.

The bracing member also has a raised portion 172 to provide resilience to the bracing member 168. The raised portion 172 extends between the gripping portions 170.

Each of the resilient portions 160 further includes a curved region 174 at the upper edge region 178 of each resilient portion 160. The curved regions 174 attach the resilient portions 160 to the spacing member 38.

The curved region 174 extends convexly towards the opposite resilient portion 160. The curved region 174 of each resilient portion 160 enhances the resilience of the respective resilient portion 160.

Referring to Figure 15, each of the urging members 152 comprises a resilient portion 180 extending downwardly from the spacing member 38. Each urging member 152 further includes a connecting member 182 connecting the resilient portion 180 to the detent member 150.

The detent member 150 of each of the detent arrangements 144 is in the form of a curved end portion that is received in a respective one of the fastening recesses 32. The detent member 150 is convexly curved, having a convex region facing outwardly.

Each of the detent arrangements 44, 144 functions by means of the urging member 52, 152 applying a force on the detent member 50, 150 to urge the detent member 50, 150 into the recess 32, 34 when the positioning device 24, 124, 224, 324, 424 is mounted on the rail receiving shell 16. As the detent member 50, 150 moves across the recess 32, 34, the urging member 52, 152 pushes the detent member 50, 150 into the recess 32, 34, thereby locking the detent member 52, 152 in the recess 32, 34.

Each of the recesses 32, 34 has sloping sides. Therefore, when the positioning device 24, 124, 224, 324, 424 is removed from the rail shell 16, the detent member 50, 150 slides over the side of the recess 32, 34. As this happens, the movement of the detent member 50, 150 over the sides creates a force on the detent member 50, 150 in the opposite direction to the force applied by the urging member 52, 152. This has the effect that the detent member 50, 150 moves inwardly, thereby allowing the detent member 50, 150 to be released from the recess 32, 34, so that the positioning device 24, 124, 224, 324, 424 can be removed from the rail shell 16.