GB2318818A

GB2318818A - A collapsible security grille

Info

Publication number: GB2318818A
Application number: GB9709367A
Authority: GB
Inventors: Timothy Michael Strawson
Original assignee: Bradbury Security Grilles Ltd
Current assignee: Bradbury Security Grilles Ltd
Priority date: 1996-11-02
Filing date: 1997-05-09
Publication date: 1998-05-06
Anticipated expiration: 2017-05-09
Also published as: GB9709367D0; GB2318818B

Abstract

A collapsible security grille comprises a plurality of pairs of channel-shaped elongate members (16) attached together at their ends and centre by means of rivets (11). Two tracks (17) are contained within the space between elongate members and their fastening means. The ends of the tracks are attached to a wall or frame (26) by brackets (not shown). The grill is mounted on the lower track by rollers (18) and the upper track serves as a guide. To allow the grille to collapse fully, the roller edges may enter into the space between adjacent pairs of elongate members. Pairs of elongate members are inter-connected by lattice members (21-25). Also disclosed is a bracket assembly comprising a pair of spaced apart plates suitable for attachment to elongate members and provided with bores through which a bolt may be passed to secure the plates to an attachment member (see figures 5 and 6). Also disclosed is a locking mechanism comprising a pair of slidably mounted bolts, a corresponding pair of bolt receiving members and a spring to bias each bolt into locking engagement (see figures 12 and 13).

Description

Collapsible Grilles Field of the Invention This invention relates to collapsible grilles, and in particular to collapsible grilles used to secure windows, doors, etc..

Background to the Invention Collapsible grilles are often used to render doorways and windows more secure.

Historically, business premises other than banks and retail outlets have not held large amounts of valuable goods which could be easily removed and subsequently sold by a thief. Most businesses installing collapsible security grilles have done so to deter the opportunist thief, and vandals.

However, the increasing use of computers and other electronic communications equipment in business means that now most businesses have very valuable equipment on their premises. This equipment is not only valuable in terms of it being saleable, but computers also have a value in terms of the information stored on them. This value can of course only be recognised by the owner of the computer, not a thief who merely wants to sell the parts of the computer. As more and more businesses have invested in computers and electronic communications equipment there has been a steady increase in the number of thefts from premises, and there is now a thriving market for parts from such stolen goods.

It has been found that many of the collapsible grilles on the market are relatively easy to break through, and serve only to hinder burglary rather than prevent it. Whilst only a few premises have such grilles across their windows and doors, the grilles may well prevent burglary simply because the thief will move on to the next premises which does not have such grilles. However, as the number of thefts increases, more owners of premises which may be seen as targets invest in collapsible grilles to secure their premises. This leads the thief to attempt to break through the grille.

Known grilles comprise pairs of elongate spaced apart members, each elongate member of the pair being connected to the other, each pair of elongate members being inter-connected by connecting members so as to move in concertina fashion, the extreme ends of the elongate members being slidably mounted on tracks. Experiment has shown that by inserting a lever between a pair of elongate spaced apart members, the connection therebetween can be broken with relative ease. Also, again with the use of a lever, the elongate members of a pair can be splayed so that the grille can be lifted off the guides on which it is mounted, or the ends of the connecting members can be dislodged. Furthermore, the connection of the tracks to the window surrounds, and the locking mechanisms which lock the grilles shut have proved to be points of weakness.

Attempts to improve such grilles have focused on increasing the strength of the parts of the grille, and hence increasing its weight. However, experiment has shown that even with stronger components, by twisting pairs of elongate members, the length thereof can be decreased to such an extent that the grille simply falls off its tracks.

There is therefore a need to provide a collapsible grille which is significantly more difficult to break through than those presently on the market.

Summary of the Invention The invention provides a collapsible grille comprising a plurality of pairs of elongate members, the ends of the elongate members of each pair being fastened one to another by fastening means to provide a space therebetween extending in a first direction, wherein the pairs of elongate members are interconnected and slidably mounted on at least one track extending in a second direction so that the pairs of elongate members may move in the second direction towards and away from adjacent pairs of elongate members, wherein the first and second directions are substantially perpendicular to each other, and wherein the or each track is located within the said space and between the said fastening means.

Preferably, the elongate members of each pair are fastened one to another by at least one additional fastening means at a point between the ends of the elongate members.

Advantageously, the elongate members are channel shaped in section.

Preferably two spaced apart tracks are provided, and more preferably the two tracks are spaced apart vertically. Even more preferably, at least one pair of elongate members is provided with a slider, which may be a roller or a skid, mounted in the said space. Most preferably, the slider is so mounted that it rests upon upper surface of a track. Advantageously, the ends of each track are attached to a substantially immovable object, for example a building, preferably by means of brackets.

One aspect of the invention provides a bracket assembly suitable for attaching a grille of the invention to an immovable object, the said bracket assembly comprising a pair of spaced apart plates, each plate being attachable to one elongate member of a pair so as to permit the track to pass between the said plates, and an attachment member securable to an immovable object, wherein the plates are securable to the attachment member.

Preferably, the plates are releasably securable to the attachment member. More preferably, the plates are attached to elongate members by means of welding.

Each plate may be provided with at least one aperture.

Each plate may be provided with at least one means to facilitate securing of the plate to the attachment member, and at least one means to facilitate attachment of the track to the pair of plates, which means may be an aperture. Preferably, the track is provided with an elongate slot, and more preferably the track is provided with elongate slots at each of its ends. The attachment member may be provided with bores which may be through bores. A pin or bolt may be passed through the aperture in each plate and into or through the bores of the attachment member to secure the plates to the said attachment member.

The attachment member may be provided with a slot at one or both of its ends, the or each slot being adapted to receive a pair of spaced apart plates.

The attachment member may be provided with a reinforcement member, which may be in the form of a plate, and is preferably in the form of an angled profile. The reinforcement member may be provided with at least one bore, which may be a through bore.

Where the grille comprises two spaced apart tracks, a pair of plates is provided for each track The bracket assembly may be provided at each end of the grille.

Another aspect of the invention provides a locking mechanism comprising a pair of slidably mounted bolts and a corresponding pair of bolt receiving members, biasing means to bias each bolt of the pair into locking engagement with the bolt receiving members, and means to move both the bolts of the pair against the biasing force and out of engagement with the bolt receiving members.

Preferably, each bolt may slide independently of the other, and more preferably each bolt is provided with a biasing means. The biasing means may be a spring, and advantageously is a coil spring.

The means to move both the bolts of the pair against the biasing force and out of engagement with the bolt receiving members suitably comprises a rotatable cam, which is preferably operated by a key, and more preferably is part of a "Europrofile Cylinder". The bolts are suitably brought out of engagement with bolt receiving members by turning the cam through less than 60 degrees.

Advantageously, the bolts are mounted between plates. A sleeve may be provided to encase the plates and bolts located therebetween.

Preferably, the bolt receiving members are mounted on a plate.

Another aspect of the invention provides a collapsible grille having a locking mechanism according to the invention.

The bolt receiving members may be in the form of hasps or other suitably shaped brackets. Alternatively, the bolt receiving members may be bores which may be located in a wall, floor, ceiling, door frame or similar.

The bolt receiving members and/or the pair of bolts may be attached to an endmost pair of elongate members of the said grille. Alternatively, the pair of bolts may be attached to an endmost pair of elongate members and the bolt receiving members may be attached to an object such as the attachment member, or the bolt receiving members may be attached to an endmost pair of elongate members and the pair of bolts may be attached to an object such as the attachment member.

The fastening means preferably extends between the elongate members and may be in the form of a rivet, one end of which is advantageously welded to an elongate member. Alternatively, the fastening means may be in the form a rod each end of which is attached, suitably by welding, to an elongate member. In one embodiment, the fastening means comprises a nut and bolt, the bolt preferably being passed through apertures in the elongate members. The fastening means is advantageously sufficiently strong to withstand a tensile force of greater than 1 tonne being applied thereto, without failing. Desirably, each fastening means is sufficiently strong to withstand a tensile force of greater than 1. 3 tonnes being applied thereto, without failing.

The fastening means preferably further comprises a spacer which advantageously slides over the body of the rivet, rod or bolt, and extends between the elongate members to space them apart.

The pairs of elongate are suitably inter-connected by lattice members. Preferably two lengths of lattice member are used, one being sufficiently long to connect two adjacent pairs of elongate members, and the other being sufficiently long to connect together three pairs of elongate members.

In one embodiment of the invention, a lattice member is pivotally mounted on a fastening means so as to have at least one free end. Preferably, the or each free end of the lattice member is slidably mounted in the space between the elongate members of an adjacent pair of elongate members. Advantageously, a free end of the lattice member is apertured and a pin is located in the aperture, the length of the pin preferably being such that each end thereof can slide in the channel shaped elongate members.

The pin may be formed in two parts, and is suitably formed from an elongate rod having a head, and a cap. The cap is preferably apertured so that the rod can pass through the aperture. Means to fasten the cap to the rod are advantageously provided, and the most preferably the means comprises sizing the aperture in the cap so that the fitting of the rod to the cap is a press fit.

The pair of elongate members at one end of the grille is suitably provided with a locking means.

When the grille is installed, the pair of elongate members at one end of the grille is preferably immovable, the other pairs of elongate members being moveable with respect thereto.

A further embodiment of the invention provides a bracket comprising an angled profile having a plurality of apertures, at least one aperture passing through one face of the angled profile, and at least one aperture passing through another face of the angled profile, the apertures providing for attachment of the bracket to a substantially immovable object and a track, so that when fixed in position the fixing of the bracket to the wall and the track to the bracket are covered by the bracket.

The collapsible grille of the invention provides a substantial improvement over grilles of the prior art, in that it utilises the strength of the tracks upon which the grille is mounted to make breaking through the grille a much more onerous task for a thief. Furthermore, the mounting of the grille to the wall is immensely strong.

The locking mechanism of the invention is particularly advantageous when compared to existing locking mechanisms, because whilst turning a key through only part of a complete rotation brings both bolts out of engagement with the bolt receiving members, if one of the bolts is destroyed by an attacker, the other bolt will remain in the locking position.

The term "grille" used in this application shall be understood to encompass the use of the grille of the invention as a gate.

Brief Description of the Drawings In the drawings, which illustrate a known collapsible grille and an exemplary embodiment of the invention: Figure 1 illustrates a collapsible grille of the prior art; Figure 2 is a front view of the collapsible grille according to the invention; Figure 3 is an end view of a collapsible grille shown in Figure 2; Figure 4 is a plan view of a portion of the collapsible grille shown in Figure 2; Figure 5 illustrates a connecting device; Figure 6 illustrates a fastening means; Figure 7 illustrates another fastening means; Figure 8 illustrates a bracket suitable for mounting the track; Figure 9 is an exploded view of an alternative bracket arrangement for mounting the track; Figure 10 shows the mounting of an upper track to a wall using the bracket arrangement shown in Figure 9; Figure 11 shows the mounting of a lower track to a wall using the bracket arrangement shown in Figure 9; Figure 12 is a schematic representation of the components of a lock according to one aspect of the invention; and Figure 13 is an exploded view of one of the components of the lock shown in Figure 12.

Detailed Description of the Preferred Embodiment Figure 1 illustrates a collapsible grille 1 comprising elongate members 2 which are arranged in pairs so as to be spaced apart. Elongate members 2 are channel shaped in section. Adjacent pairs of elongate members 2 are inter-connected by lattice members 6, 7. Lattice members 6 are connected to three different pairs of elongate members 2. The elongate members 2 of the pair are connected one to another by rivets 8 which pass through both elongate members 2 and a spacer which separates the said elongate members. Lattice members 6 are rotatably mounted on the rivets between the elongate members 2. Free ends of the lattice members 6 are slidably mounted by means of pins and bushes 9 in the channel shaped elongate members 2. As the grille 1 is collapsed, the lattice members 6, 7 rotate about rivets 8, and the free ends thereof move either upwardly or downwardly so that the grille collapses in concertina fashion.

Between the elongate members 2 of a pair, there is mounted a roller 5, which rests upon a track 3. A guide 4 is arranged between the upper ends of the elongate members to maintain the grille in the desired position.

In Figure 2, a collapsible grille according to the invention is shown.

Upper and lower tracks 17 are attached at their ends to a substantially immovable object, such as a wall or frame at 26. The grille shown comprises six pairs of elongate members 16. The endmost pair of elongate members 16 is also attached to the substantially immovable object at 26.

Elongate members 16 of a pair are attached together at their ends and centre by fastening means which comprise rivets 11, and a sleeve 10, the rivet 11 passing through apertures in the elongate members 16 and the sleeve. The length of sleeve 10 determines the space between the elongate members. One end of rivet 11 has a head 12, whilst the other end is welded 13 to an elongate member 16.

Two pairs of elongate members are provided with rollers 18. Roller 18 is mounted in the space between the elongate members 16 of a pair on a spindle 19 which passes through apertures in the said elongate members 16. The grille is slidably mounted on lower track 17 by the rollers 18, so that the grille can be collapsed and extended. Upper track 17 serves to guide the grille as it is collapsed and extended. When the grille is collapsed, the edges of rollers 18 enter into the space between elongate members 16 of adjacent pairs of elongate members, thereby allowing the grille to collapse fully. Clearly, if smaller rollers of a diameter less than or equal to the width of the elongate members 16 are used, then each pair of elongate members 16 may be equipped with a roller whilst still enabling the grille to close properly.

Pairs of elongate members 16 are inter-connected by means of lattice members 21, 22, 23, 24, 25. Each of lattice members 22 and 23 is provided with three apertures, two being at opposite ends and the third being at the centre thereof, and are connected to three pairs of elongate members 16. Lattice members 21 and 24 are provided with four apertures, two being at opposite ends, a third being at the centre of the lattice member, and the fourth being between an endmost aperture and the central aperture.

Lattice members 25 are connected to only two pairs of elongate members 16. One end of each lattice member 25 is pivotally connected to rivet 11, whilst the other is connected to a lattice member 22 to 23 for sliding in a pair of elongate members 16. The lattice member 25 has an aperture between its ends, and is connected to a lattice member 21 or 24 by means of a rivet 34 passing through the said aperture, and a corresponding aperture in lattice member 21 or 24. This connection ensures that the grille remains square each time it is collapsed and extended.

Referring now to Figures 2 to 6, it can be seen the lattice members 21 and 24 are pivotally connected at their centres to a pair of elongate members 16 by means of a rivet 11 which passes through the apertures at the centres of the lattice members and spacer 10. Lattice members 21 and 24, are spaced apart by a spacer 15. The free ends of lattice members 21 and 24 are slidably connected to adjacent pairs of elongate members 16 by pins 36 which slide in the elongate members 16.

Figure 5 illustrates pin 36 which comprises a shank 35 having a head 32 at one end. Cap 31 is fastened onto the shank 35. Aperture 33 is smaller in diameter than shank 35, so it is necessary to exert a large amount of force on the cap 31 and the head 32 to press the cap 31 onto the shank 35. Alternatively, cap 33 may be welded onto shank 35, or pin 36 may comprise a bolt and cap 31 a nut, the nut and bolt each being threaded so that one may be secured to the other.

In Figure 6 there is shown rivet 11 which passes through sleeve 10.

Head 12 of rivet 11 comes into abutment with the outer surface of an elongate member 14, and when in situ, as shown in Figure 2, the free end of rivet 11 is welded to the other elongate member of a pair, thereby joining the two elongate members 16 of the pair together.

In Figure 7, there is shown the fastening means used to join elongate members 16 of a pair together, and to connect lattice members 20, 24 to the said pair of elongate members. The fastening means comprises a rivet 11 having a head 12. Rivet 11 is passed through an aperture in elongate member 16, and two sleeves 20 and a spacer 15 are slid onto the rivet. The free end of rivet 11 is passed through an aperture in the opposite elongate member 16 of the pair, and then welded thereto.

Figure 2 shows (in broken lines) pins 36 slidably mounted within the elongate members 16.

A lock (not shown) is suitably provided on the movable endmost pair of elongate members 16 so that the collapsible grille can be locked to a frame, or another collapsible grille.

Referring now to Figure 8, bracket 41 is connectable to track 17 and a substantially immovable object, such as wall or door frame. The bracket 41 is provided with threaded apertures 42, 43. Track 17 can be attached to bracket 41 by passing a threaded bolt through aperture 46 in plate 45 and aperture 40 in track 17, the threads of the bolt engaging with the threaded aperture 42, 43. The provision of four threaded apertures 42, 43 and a square aperture 40 which is larger than apertures 42, 43 allows for different lengths of track to be used with the same bracket. Bracket 41 is provided with apertures 44, through which a bolt or similar may be passed to attach the bracket to a wall.

Referring now to Figures 9 to 11, a bracket arrangement 50 is shown for connecting the upper and lower tracks 17 to a wall 64. An attachment member 57 in the form of a length of box section is attached to a wall by means of screws 66 which pass through apertures 65 in the attachment member 57. At each end of the attachment member 57 there is provided a slot 71 in which track locates. A bolt 51 passes through apertures 58 in the attachment member 57 and the apertures 60 in each plate 59 to secure the said plates 59 to the attachment member 57. Bolt 51 is held in place by a nut 52. At one end of track 17 there is an elongate slot 63.

Slots 63 may be provided at both ends of track 17. The purpose of the elongate slot is to provide a tolerance on the width of the grille. As can be seen from Figures 10 and 11, the track 17 passes between plates 59 and a bolt 51 passes through. Each plate 59 is attached to one of the elongate members 16, preferably by welding. Rivets 11 pass through the apertures 61 and 62 to secure the grille to the attachment member 57. A bolt 51 passes through apertures 72 in the elongate members 16, the aperture 73 in each plate 59 and the elongate slot 63 in track 17 to hold the track 17 in the required position. Bolt 51 is held in place by a nut 52.

Figures 10 and 11 show guide brackets 67 which are attached to upper or lower surfaces (not shown), and which serve to limit movement of the tracks 17. Screws 69 hold the bracket 67 in place.

Figure 9 shows a reinforcement member 53 in the form of an angled profile provided with a number of apertures 54, 55, and 56. Apertures 54 allow the passage of bolt 51, whilst apertures 55 allow screws 66 to pass through the reinforcement member 53 and into the wall 64. The provision of bracket 75 between the endmost pair of elongate members 16 thereby enables the grille to be attached to the wall 64 at an additional point thereby rendering removal of the grille from the wall much more difficult.

In Figure 11 it can be seen that at the end of the grille most distant from wall 64, there is an end piece 68 formed from box section, and comprising a lock.

In Figures 12 and 13 there is shown a lock suitable for use with a grille according to the invention.

The lock comprises a central assembly 100 which mounts a pair of bolts 102, the bolts being movable between a locking position in which they engage with the hasps 114 mounted on channel member 113 and release position where the tips 119 of the bolts move inwardly to disengage from the hasps 114. Central assembly 100 is mounted within case 109, slots 112 being provided therein to receive hasps 114. Case 109 is also provided with a slot shaped to receive the key operated lock 105, which is a "Europroffle Cylinder" available from Yale. A plate 111 is mounted on the case and provided with a slot shaped to receive the said lock 105. Plate 111 serves to strengthen the case in the region of lock 105.

Screw 108 passes through bore 110, which may be threaded, and into the threaded bore 136 in lock 105.

Figure 13 illustrates the components of central assembly 100. The central assembly 100 comprises a pair of spaced apart side plates 101, attached one to another by pins 103 which pass through apertures 133 in the said plates and an elongate slot 120 in the bolt 102. Pins 103 are held in place by deformable washers 135. Each bolt 102 has a protruding lip 119 which engages with hasp 114, a slot 120 and an aperture 121. The distance between the apertures 133 and hence pins 103 is less than the length of elongate slot 120, and therefore bolts 102 may slide.

At the end of the bolt opposite to the lip 119, there is provided an aperture through which a pin 122 passes. Pin 122 also passes through slot 134 in one of the side plates 101. As can be seen from Figure 12, pin 122 and the adjacent pin 103 are connected together by means of a spring 104. Spring 104 biases bolt 102 outwards so that the inner most end of slot 120 is in abutment with the innermost pin 103, and furthermore so that lip 119 is in engagement with hasp 114. As can be seen from Figures 12 and 13, each bolt 102 can move independently of the other. This feature is important, because if a thief succeeds in breaking one hasp/bolt, he will not be able to gain entry until he has broken the other.

Plates 107 and 117 work in combination with lock 105, lever 124, pins 122 and bars 128 to move bolts 102 out of engagement with hasps 114.

Plates 107 and 117 are connected together by lever 124, the lever being connected by pins 125 to bores 118 in the said plates 107, 117. Bars 128 are connected to the plate 107 by means of screws 129 which engage in apertures 130, the bars being spaced so as to leave sufficient room for the cam 106 of lock 105 to enter the said space and engage with the bars to move plate 107 upwardly. When the cam 106 is turned by a key (not shown), pin 122 which engages with slot 116 and aperture 121 is caused to move upwardly, thereby lifting lip 119 out of engagement with hasp 114.

The effect of rotating lever 124, which is rotatably mounted on pin 103, is to cause plate 117 to move downwardly pulling lip 119 of bolt 102 out of engagement with hasp 114. When the key is released, the springs 104 return the bolts 102 to their locking positions.

Deformable washers 132 hold pins 122 in place. Spacers 123 and 126, and washers 131 are provided to correctly orientate individual parts so that each lip 119 will engage a hasp 114.

Claims

1. A collapsible grille comprising a plurality of pairs of elongate members, the ends of the elongate members of each pair being fastened one to another by fastening means to provide a space therebetween extending in a first direction, wherein the pairs of elongate members are interconnected and slidably mounted on at least one track extending in a second direction so that the pairs of elongate members may move in the second direction towards and away from adjacent pairs of elongate members, wherein the first and second directions are substantially perpendicular to each other, and wherein the or each track is located within the said space and between the said fastening means.

2. A collapsible grille according to Claim 1, wherein the elongate members of each pair are fastened one to another by at least one additional fastening means at a point between the ends of the elongate members.

3. A collapsible grille according to Claim 1 or 2, wherein the elongate members are channel shaped in section.

4. A collapsible grille according to any preceding claim, wherein two spaced apart tracks are provided.

5. A collapsible grille according to Claim 4, wherein at least one pair of elongate members is provided with a slider mounted in the said space.

6. A collapsible grille according to Claim 5, wherein the slider is so mounted that it rests upon upper surface of one of the said at least one track.

7. A collapsible grille according to any preceding claim, wherein the ends of each track are attached to a substantially immovable object.

8. A collapsible grille according to Claim 7, wherein brackets are provided to attach the ends of each track to a substantially immovable object.

9. A collapsible grille according to Claim 8, wherein the fastening means is in the form of a rivet.

10. A collapsible grille according to Claim 9, wherein one end of the said rivet is welded to an elongate member.

11. A collapsible grille according to any of Claims 1 to 8, wherein the fastening means is in the form a rod each end of which is attached to an elongate member.

12. A collapsible grille according to Claim 11, wherein each end of the rod is attached to an elongate member by means of welding.

13. A collapsible grille according to any of Claims 1 to 8, wherein the fastening means comprises a nut and bolt.

14. A collapsible grille according to any of Claims 8 to 13, wherein the fastening means is sufficiently strong to withstand a tensile force of greater than 1 tonne being applied thereto, without failing.

15. A collapsible grille according to Claim 14, wherein each fastening means is sufficiently strong to withstand a tensile force of greater than 1. 3 tonnes being applied thereto, without failing.

16. A collapsible grille according to any of Claims 8 to 15, wherein the fastening means further comprises a spacer which slides over the body of the rivet, rod or bolt, and extends between the elongate members to space them apart.

17. A collapsible grille according to any preceding claim, wherein the pairs of elongate are inter-connected by lattice members.

18. A collapsible grille according to Claim 17, wherein two lengths of lattice member are used, one being sufficiently long to connect two adjacent pairs of elongate members, and the other being sufficiently long to connect together three pairs of elongate members.

19. A collapsible grille according to Claim 17 or 18, wherein a lattice member is pivotally mounted on a fastening means so as to have at least one free end.

20.A collapsible grille according to Claim 19, wherein the or each free end of the lattice member is slidably mounted in the space between the elongate members of an adjacent pair of elongate members.

21. A collapsible grille according to Claim 20, wherein a free end of the lattice member is apertured and a pin is located in the aperture, the length of the pin being such that each end thereof can slide in the channel shaped elongate members.

22. A collapsible grille according to Claim 21, wherein the pin is formed in two parts.

23. A collapsible grille according to Claim 22 wherein the pin is formed from an elongate rod having a head, and a cap.

24. A collapsible grille according to Claim 23, wherein the cap is apertured so that the rod can pass through the aperture, and means to fasten the cap to the rod are provided.

25. A collapsible grille according to Claim 24, wherein the means to fasten the cap to the rod comprise sizing the aperture in the cap so that the fitting of the rod to the cap is a press fit.

26. A collapsible grille according to any preceding claim, wherein the pair of elongate members at one end of the grille is suitably provided with a locking means.

27. A collapsible grille according to any preceding claim, further comprising a bracket comprising an angled profile having a plurality of apertures, at least one aperture passing through one face of the angled profile, and at least one aperture passing through another face of the angled profile, the apertures providing for attachment of the bracket to a substantially immovable object and a track, so that when fixed in position the fixing of the bracket to the wall and the track to the bracket are covered by the bracket.

28. A bracket assembly suitable for attaching a grille according to any of Claims 1 to 27 to an immovable object, the said bracket assembly comprising a pair of spaced apart plates, each plate being attachable to one elongate member of a pair so as to permit the track to pass between the said plates, and an attachment member securable to an immovable object, wherein the plates are securable to the attachment member.

29. A bracket assembly according to Claim 28, wherein the plates are releasably securable to the attachment member.

30. A bracket assembly according to Claim 28 or 29, wherein the plates are attached to elongate members by means of welding.

31. A bracket according to any of Claims 28 to 30, wherein each plate is provided with at least one aperture.

32. A bracket according to any of Claims 28 to 31, wherein each plate is provided with at least one means to facilitate securing of the plate to the attachment member, and at least one means to facilitate attachment of the track to the pair of plates.

33. A bracket assembly according to any of Claims 28 to 33, wherein the track is provided with an elongate slot at one or each end thereof.

34. A bracket assembly according to Claim 32 or 33, wherein the attachment member and the plates are each provided with bores through which a pin or bolt may be passed to secure the plates to the said attachment member.

35. A bracket assembly according to any of Claims 28 to 34, wherein the attachment member is provided with a slot at one or both of its ends, the or each slot being adapted to receive a pair of spaced apart plates.

36. A bracket assembly according to any of Claims 28 to 35, wherein the attachment member provided with a reinforcement member.

37. A bracket assembly according to Claim 36, wherein the reinforcement member is in the form of a plate.

38. A bracket assembly according to Claim 37, wherein the reinforcement member is an angled profile.

39. A locking mechanism comprising a pair of slidably mounted bolts and a corresponding pair of bolt receiving members, biasing means to bias each bolt of the pair into locking engagement with the bolt receiving members, and means to move both the bolts of the pair against the biasing force and out of engagement with the bolt receiving members.

40. A locking mechanism according to Claim 39, wherein each bolt can slide independently of the other.

41. A locking mechanism according to Claim 39 or 40, wherein each bolt is provided with a biasing means.

42. A locking mechanism according to any of Claims 39 to 41, wherein the biasing means comprises a spring.

43. A locking mechanism according to any of Claims 39 to 42, wherein the means to move both the bolts of the pair against the biasing force and out of engagement with the bolt receiving members comprises a rotatable cam.

44. A locking mechanism according to any of Claims 39 to 43, wherein the bolts are brought out of engagement with bolt receiving members by turning the cam through less than 60 degrees.

45. A mechanism according to any of Claims 39 to 44, wherein the bolts are mounted between plates.

46. A locking mechanism according to Claim 45, wherein a sleeve is provided to encase the plates and bolts located therebetween.

47. A locking mechanism according to any of Claims 39 to 46, wherein the bolt receiving members are mounted on a plate.

48. A locking mechanism according to any of Claims 39 to 48, wherein the bolt receiving members are in the form of hasps, other suitably shaped brackets, or are bores located in a wall, floor, ceiling, door frame or similar.

49. A collapsible grille according to any of Claim 1 to 29, further comprising a locking mechanism according to any of Claims 39 to 48.

so. A collapsible grille according to Claim 49, wherein the bolt receiving members and/or the pair of bolts are attached to an endmost pair of elongate members of the said grille, or the pair of bolts is attached to an endmost pair of elongate members and the bolt receiving members are attached to an object such as the attachment member, or the bolt receiving members are attached to an endmost pair of elongate members and the pair of bolts is attached to an object such as the attachment member.

51. A collapsible grille substantially as shown in, or as described with reference to, the drawings.