GB2511800B - Latch releasing mechanism - Google Patents

Description

Latch releasing mechanism

This invention relates to a mechanism for releasing latches on a door assembly comprising a pair of doors and to a door assembly comprising such a mechanism.

It is well known to provide what is commonly referred to as a "panic" latching arrangement on a door, to allow people to open the door outwardly by pressing on an activation bar mounted across the inside of the door. The door may be latched in a closed position by locking bars extending vertically from the region of the activation bar to or towards the top and bottom of the door and providing latching bolts at their ends and/or along their lengths. A mechanism is provided to cause the pressing of the bar to release the latches.

An issue arises in the case where such a "panic" arrangement is required on a double door. The double door may consist of two doors which abut one another along adjacent rebated edges when they are closed or they may consist of two doors whose neighbouring sides are separated by a fixed upright frame member forming a mullion. In that case it is of course possible to provide the same kind of arrangement as for a single door but it is undesirable that releasing the latches on one door does not release the latches on the other door. That is especially a problem if the doors are arranged such that one door cannot be opened until the other door has been opened.

Various attempts have been made to interconnect latching arrangements on adjacent doors so that if one is released the other is automatically released but these have tended to be complex and/or unreliable.

It is an object of the invention to provide an improved mechanism for releasing latches on one door when a latching release mechanism on a neighbouring door is activated.

According to the invention there is provided a door assembly comprising a pair of doors arranged with a first side edge of a first door neighbouring a second side edge of a second door, and a latch releasing mechanism comprising a first elongate latch assembly extending along the first side edge of the first door and arranged for longitudinal movement between a first latching position and a second releasing position, the first elongate latch assembly including an engageable part arranged for longitudinal movement with the first elongate latch assembly and projecting laterally outwardly, a second elongate latch assembly extending along the second side edge of the second door and arranged for longitudinal movement between a first latching position and a second releasing position, the second elongate latch assembly including an actuating part arranged for longitudinal movement with the second elongate latch assembly and projecting laterally outwardly, the first and second elongate latch assemblies being arranged such that, when the doors are closed and the first and second elongate latch assemblies are in their latching positions, longitudinal movement of the second elongate latch assembly into the second releasing position causes the actuating part of the second elongate latch assembly to move longitudinally, to drivingly engage the engageable part of the first elongate latch assembly and thereby to move the first elongate latch assembly longitudinally into the second releasing position.

By providing such an arrangement in which release of the second latch assembly on the second door causes release of the first latch assembly on the first door through a straightforward longitudinal driving engagement it becomes possible to provide a simple and reliable system for releasing the latching of the first door when the latching of the second door is released.

It should be understood that the engagement need not necessarily operate in the same way when the longitudinal movement is in the opposite direction, namely from a releasing position to a latching position and in an embodiment of the invention described below it does not do so. Because the mechanism is intended for use when the doors are opened in an emergency, it is the releasing step that needs to be driven from the second door to the first door. It is acceptable for the doors to be put back in latched states independently of one another.

As already indicated the invention is of particular advantage in a case where the second door cannot be opened unless the first door is opened, for example in the case where the confronting side edges of the doors are rebated, but it is also of wider application and can for example be used in a case where there is a fixed frame member, for example a vertical mullion, between the doors. Thus the first side edge of the first door neighbouring the second side edge of the second door may be spaced from the second side edge of the second door for allowing a fixed elongate frame member to be interposed between them. In that case, the actuating part of the second elongate latch assembly and the engageable part of the first elongate latch assembly preferably engage through a recess in the fixed frame member when the first elongate latch assembly is moved longitudinally into the second releasing position.

The recess preferably allows the actuating part and/or the engageable part to pass freely out of the recess when one or both of the doors are opened so as not to impede the opening of the doors. Preferably, the actuating part of the second elongate latch assembly extends through the recess in the fixed frame member and engages the engageable part of the first elongate latch assembly outside the recess, when the first elongate latch assembly is moved longitudinally into the second releasing position.

One of the actuating part and the engageable part may comprise a cylindrical member whose axis is approximately perpendicular to the first side edge of the first door.

The cylindrical member is preferably a roller which may be rotatably or non-rotatably mounted. The other of the actuating part and the engageable part preferably comprises an arm projecting laterally outwardly from the side edge of the door and having a distal end for engaging the cylindrical member to provide the driving engagement for moving the first elongate latch assembly longitudinally into the second releasing position. The outwardly projecting arm is preferably a moulded member. The length of the outwardly projecting arm can preferably be adjusted by cropping the arm.

The engageable part preferably comprises the cylindrical member. It should be understood, however, that engagement can also be achieved effectively if the actuating part comprises the cylindrical member.

At least one of the first and second latch assemblies preferably comprises an elongate bar slidably mounted for longitudinal movement along the side edge of the door, and one or more latches which are mounted on the bar and engaged in a neighbouring keep when the bar is in a latching position and the doors are closed but which are moved to a disengaged position when the latch assembly is moved to a disengaged position. At least one of the latches may be a shootbolt provided for latching the door above the top or below the bottom of the door. At least one of the latches may be a roller, for example a mushroom roller, which is movable longitudinally between a latching position in which it engages in a keep and a releasing position in which it is clear of the keep. Each of the first and second latch assemblies are preferably as defined in this paragraph, but it should be understood that it is within the scope of the invention for the second latch assembly not to effect any latching of the second door; that may in particular apply in the case where the second door is held closed by the first door when the first door is latched in a closed condition.

Each of the first and second latch assemblies preferably comprises an elongate bar, the elongate bar of the first latch assembly mounting the engageable part and the elongate bar of the second latch assembly mounting the actuating part, the door assembly further including a first faceplate mounted on the first side edge of the first door and a second faceplate mounted on a second side edge of the second door, the elongate bar of each of the first and second latch assemblies being disposed on the inside of the first and second faceplates respectively, the engageable part projecting through a slot in the faceplate of the first elongate bar and the actuating part projecting through a slot in the faceplate of the second elongate bar. The actuating part is preferably fixedly mounted on the elongate bar of the second latch assembly extending laterally outwardly, the first and second elongate latch assemblies being arranged such that, when in use the doors to which they are fitted are closed and the first and second elongate latch assemblies are in their latching positions, longitudinal movement of the second elongate latch assembly into the second releasing position causes the actuating part of the second elongate latch assembly to move longitudinally, to drivingly engage the engageable part of the first elongate latch assembly and thereby to move the first elongate latch assembly longitudinally into the second releasing position.

Preferably, at least the first latch assembly comprises a pair of elongate bars extending longitudinally in opposite directions from a gear mechanism and arranged with the gear mechanism such that movement of one of the bars in a first longitudinal direction causes movement of the other bar in a longitudinal direction, longitudinal movement of the second elongate latch assembly into the second releasing position causing the actuating part of the second elongate latch assembly to move longitudinally, to drivingly engage the engageable part of the first elongate latch assembly and thereby to move both the first elongate bar and the second elongate bar of the first latch assembly longitudinally into the second releasing position. Such gear mechanisms are well known per se; in some arrangements the first and second elongate bars are moved in opposite directions (both retracted or both extended) and in other arrangements they are moved in the same directions.

In an embodiment of the invention described below with reference to the drawings, the first and second elongate latch assemblies are arranged such that, when the doors are closed and the first and second elongate latch assemblies are in their unlatched positions, longitudinal movement of the first elongate latch assembly into the first latching position causes the engageable part of the first elongate latch assembly to move longitudinally, to drivingly engage the actuating part of the second elongate latch assembly and thereby to move the second elongate latch assembly longitudinally into the first latching position.

The invention has been defined above with reference to a door assembly; it will be understood that the doors themselves can be of conventional construction and that it is the latch releasing mechanism that introduces the special features of the present invention. That latch assembly can be made and sold separately and subsequently fitted to doors. Accordingly the invention further provides a latch releasing mechanism suitable for use in a door assembly as defined above, the mechanism comprising a first elongate latch assembly for extending along a first side edge of a first door and arranged for longitudinal movement between a first latching position and a second releasing position, the first elongate latch assembly including an engageable part arranged for longitudinal movement with the first elongate latch assembly and projecting laterally outwardly, a second elongate latch assembly for extending along a second side edge of a second door and arranged for longitudinal movement between a first latching position and a second releasing position, the second elongate latch assembly including an actuating part arranged for longitudinal movement with the second elongate latch assembly and projecting laterally outwardly, the first and second elongate latch assemblies being arranged such that, when in use the doors to which they are fitted are closed and the first and second elongate latch assemblies are in their latching positions, longitudinal movement of the second elongate latch assembly into the second releasing position causes the actuating part of the second elongate latch assembly to move longitudinally, to drivingly engage the engageable part of the first elongate latch assembly and thereby to move the first elongate latch assembly longitudinally into the second releasing position.

The latch releasing mechanism may include any of the features of the latch releasing mechanism of the door assembly defined above. For example: one of the actuating part and the engageable part may comprise a cylindrical member whose axis is approximately perpendicular to the length of the latch assembly of which it is part; the cylindrical member may be a roller; the other of the actuating part and the engageable part may comprise an arm projecting outwardly and having a distal end for engaging the cylindrical member, the distal end being engageable with the cylindrical member to provide the driving engagement for moving the first elongate latch assembly longitudinally into the second releasing position; the engageable part may comprise the cylindrical member; at least one of the first and second latch assemblies may comprise an elongate bar slidably mounted for longitudinal movement along the side edge of the door, and one or more latches which are mounted on the bar and engageable in a neighbouring keep when the bar is in a latching position and the doors are closed but which are moved to a disengaged position when the latch assembly is moved to a disengaged position; each of the first and second latch assemblies may comprise an elongate bar, the elongate bar of the first latch assembly mounting the engageable part and the elongate bar of the second latch assembly mounting the actuating part, the latch releasing mechanism further including a first faceplate mounted on the first side edge of the first door and a second faceplate mounted on a second side edge of the second door, the elongate bar of each of the first and second latch assemblies being disposed, in use, on the inside of the first and second faceplates respectively, the engageable part projecting through a slot in the faceplate of the first elongate bar and the actuating part projecting through a slot in the faceplate of the second elongate bar; at least the first latch assembly may comprise a pair of elongate bars extending longitudinally in opposite directions from a gear mechanism and arranged with the gear mechanism such that movement of one of the bars in a first longitudinal direction causes movement of the other bar in a longitudinal direction, longitudinal movement of the second elongate latch assembly into the second releasing position causing the actuating part of the second elongate latch assembly to move longitudinally, for drivingly engaging the engageable part of the first elongate latch assembly thereby to move both the first elongate bar and the second elongate bar of the first latch assembly longitudinally into the second releasing position.

By way of example an embodiment of the invention will now be described with reference to the accompanying schematic drawings, of which:

Fig. 1 is a front view of a pair of doors fitted with a panic latching arrangement, including a latch releasing mechanism;

Fig. 2 is a view of the parts of the latch releasing mechanism; and

Fig. 3 is a view to a larger scale than Fig. 2 of part of the latch releasing mechanism.

Fig. 1 shows a door assembly comprising a first door 1 and a second door 2. In most respects, the door assembly is conventional and some of the conventional aspects of the assembly will be described first. The first door 1 is fitted with an activation bar 3 and the second door 2 is fitted with a similar activation bar 4. The activation bars 3 and 4 are pivotally mounted at their ends and can be pressed downwards as illustrated by the arrow on the second door 2 in order to open the doors, especially in the case of an emergency.

The doors 1 and 2 are of generally rectangular shape and a second edge 5 of the second door 2 is next to a first edge 6 of the first door 1. As can be seen in Fig. 1 the first and second edges of the doors are in this case spaced apart by a small distance to allow an upright fixed frame member (not shown) to be interposed between the doors.

The doors 1 and 2 are fitted with latch releasing mechanisms that are shown in Fig. 2. It should be noted that in Fig. 2 the mechanism fitted to the first door 1 is shown on the left hand side of Fig. 2 while the mechanism fitted to the second door 2 is shown on the right hand side of Fig. 2. Referring first to the mechanism fitted to the first door 1 and shown on the left hand side of Fig. 2 that mechanism is of a kind generally known per se and includes a faceplate 7 on which casings 8, 9 and 10 are mounted. As will be understood the faceplate is fitted along the side edge of the door 1 with the casings 8, 9 and 10 accommodated internally within the door. Mounted immediately behind (inside) the faceplate 7 is a slidable locking bar 11. The locking bar 11 extends from the casing 8 to the casing 10. It should be understood that, as is again conventional, another locking bar (not shown) would be provided extending between the casing 8 and the casing 9. The locking bars are mounted for sliding longitudinal movement behind the faceplate. In the example shown, the longitudinal movement of the bars controls pivoting of hook bolts in the casings 8, 9 and 10. Furthermore, there may be further locking bars, or extensions of the locking bars already referred to, extending from the opposite ends of the casings 9 and 10 for driving shootbolts and/or other latching members, as is conventional. The casing 8 is shown with a chamfered latch member 12 which is movable between latching and releasing positions upon longitudinal movement of the locking bars. A facility for key operation of the mechanism may also be provided and a key hole 13 is shown in the casing 8.

Details of the mechanism that may be employed in the casing 8 are not relevant to the present invention and will not be described further here. Many examples of suitable mechanisms may be found in commercial use and in published patent specifications. The latching mechanism on the second door 2 is generally similar to the mechanism on the door 1 and includes a faceplate 14 and a central casing 15. A locking bar 16 is shown extending from the lower end of the casing 15 and it should be understood that a similar locking bar may be provided extending from the top of the casing 15.

The invention is particularly concerned with release of the latches on the doors 1 and 2. As will be understood, the latch mechanisms are arranged so that upon pressing activation bar 4, the mechanism in the casing 12 causes the locking bar 11 to be retracted into the casing 12 (and the other locking bar extending from the top of the casing to be similarly retracted) and thereby to move all latches to a releasing position so that the second door is unlatched. The retraction of the two locking bars into the casing 12, which requires movement of the locking bars in opposite longitudinal directions can be achieved by providing by a suitable gear mechanism, for example a pinion gear engaging, at diametrically opposite locations, toothed racks at the ends of the locking bars, as shown in Fig. 9 of GB2466518. Similarly, pressing the activation bar 3 effects, via the mechanism in the casing 15, release of the operating bars and unlatching of the door 2.

The arrangement described above with reference to the drawings is conventional. A special feature of the invention is that a simple latch releasing mechanism is provided so that pressing of the activation bar 4 on the second door 2 not only releases any latches on the second door 2 but, also, releases latches on the first door 1. The construction that enables this to occur and the manner in which it does occur will now be described, referring also to Fig. 3.

An actuating arm 20, which may be moulded or cast, for example, from metal, is fixed in an opening 17 of the locking bar 16 and passes through a slot 21 in the faceplate 14. The actuating arm therefore moves when the locking bar moves longitudinally and in Figs. 1 to 3 the actuating arm is shown in the two extremities of its position. The actuating arm 20 extends across the space between the second edge 5 of the second door 2 and the first edge 6 of the first door 1. Mounted in an opening 18 of the locking bar 11 on the first door 2 is a roller 23 which similarly is fixed to the locking bar 11 for longitudinal movement therewith. As shown, the roller passes through a slot 25 in the faceplate 7. In Figs. 1 to 3 the roller 23 is also shown in its two extreme positions.

Thus it will be understood that a single actuating arm 20 and a single roller 23 are provided in the illustrated embodiment.

When the activation bar 4 is pressed the locking bar 16 is raised upwardly, causing the actuating arm 20 to engage the underside of the roller 23 and lift the roller upwardly. Lifting of the roller 23 in turn drives the locking bar 11 upwardly with the result that operating the activation bar 4 on the second door 2 causes all the latches on the first door 1 to be released so that both doors are able to be opened. The upright frame member has a recess on its outer face to accommodate the actuating arm 20 over its range of movement and to allow the actuating arm 20 to pass out of the recess when the second door 2 is opened.

The invention thus provides a very simple way in which operation of the activation bar on one door can release all the latches on the other door.

It may also be noted that if the first door 1 is closed when the door 2 is closed but not latched and the bar 3 on the first door is raised, then the roller 23 on the first door will engage the actuating arm 20 to press the arm 20 downwardly causing the latches on the second door to be latched.

In the arrangement shown, the first and second doors 1 and 2 are spaced apart but it should be understood that it is also within the scope of the invention for the doors 1 and 2 to overlap along rebated edges. In that case the second door 2 may be arranged to be held closed by the first door 1 and the second door 2 may itself have no latches. In a conventional arrangement of that kind the operation of the activation bar 4 on the second door 2 would not open any doors until the first door 1 was unlatched, but in the arrangement embodying the invention operation of the activation bar 4 releases all the latches on the first door 1 so that both doors are free to open together. In a case of the kind just described it will be understood that the actuating arm 20 would be replaced by a member that projected only a small distance outwardly from the side of the door. An alternative option to replacing the actuating arm 20 is to provide an arm that can be cropped to a desired length.

In the arrangement described above, the locking bars on opposite sides of the central casings 8 and 15 are arranged to be moved in opposite directions; that is both locking bars are retracted towards the casing 8 or 15, or they are both moved away from the casing 8 or 15. It should be understood, however, that it is also possible to employ the invention in an arrangement where that is not the case and the locking bars on opposite sides of the central casings 8 and 15 are moved in the same directions. Of course, casings such as those referenced 9 and 10 in the drawings may be provided with gearboxes etc. to convert a given longitudinal movement of a locking bar into a desired rotational or translational movement of a latching member.

Also in the illustrated embodiment, the actuating arm 20 and the roller 23 are shown located below the central casings 8 and 15, but it is of course possible to locate them above the casings 8 and 15, if desired.

In the arrangement shown, whilst operation of the activation bar 4 on the second door 2 releases the latches on the first door 1, downward operation of the activation bar 3 on the first door 1 does not release any latches on the second door 2. If desired, a similar arrangement to that already described above and involving the actuating arm 20 and the roller 23 may be provided, so that operation of the activation bar 3 on the first door 1 releases the latches on the second door 2 via an actuating arm on the locking bar 11 and a roller on the locking bar 16.

Where in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present invention, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the invention that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims.

Claims (24)

Claims :

1. A door assembly comprising a pair of doors arranged with a first side edge of a first door neighbouring a second side edge of a second door, and a latch releasing mechanism comprising a first elongate latch assembly extending along the first side edge of the first door and arranged for longitudinal movement between a first latching position and a second releasing position, the first elongate latch assembly including an engageable part arranged for longitudinal movement with the first elongate latch assembly and projecting laterally outwardly, a second elongate latch assembly extending along the second side edge of the second door and arranged for longitudinal movement between a first latching position and a second releasing position, the second elongate latch assembly including an actuating part arranged for longitudinal movement with the second elongate latch assembly and projecting laterally outwardly, the first and second elongate latch assemblies being arranged such that, when the doors are closed and the first and second elongate latch assemblies are in their latching positions, longitudinal movement of the second elongate latch assembly into the second releasing position causes the actuating part of the second elongate latch assembly to move longitudinally, to drivingly engage the engageable part of the first elongate latch assembly and thereby to move the first elongate latch assembly longitudinally into the second releasing position.

2. A door assembly according to claim 1, in which the first side edge of the first door neighbouring the second side edge of the second door is spaced from the second side edge of the second door for allowing a fixed elongate frame member to be interposed between them.

3. A door assembly according to claim 2, in which the actuating part of the second elongate latch assembly and the engageable part of the first elongate latch assembly engage through a recess in the fixed frame member when the first elongate latch assembly is moved longitudinally into the second releasing position.

4. A door assembly according to claim 3, in which the actuating part of the second elongate latch assembly extends through the recess in the fixed frame member and engages the engageable part of the first elongate latch assembly outside the recess, when the first elongate latch assembly is moved longitudinally into the second releasing position.

5. A door assembly according to any preceding claim, in which one of the actuating part and the engageable part comprises a cylindrical member whose axis is approximately perpendicular to the first side edge of the first door.

6. A door assembly according to claim 5, in which the cylindrical member is a roller.

7. A door assembly according to claim 5 or 6, in which the other of the actuating part and the engageable part comprises an arm projecting outwardly from the side edge of the door and having a distal end for engaging the cylindrical member to provide the driving engagement for moving the first elongate latch assembly longitudinally into the second releasing position.

8. A door assembly according to claim 7, in which the outwardly projecting arm is a moulded member.

9. A door assembly according to claim 7 or 8, in which the length of the outwardly projecting arm can be adjusted by cropping the arm.

10. A door assembly according to any of claims 5 to 9, in which the engageable part comprises the cylindrical member.

11. A door assembly according to any preceding claim, in which at least one of the first and second latch assemblies comprises an elongate bar slidably mounted for longitudinal movement along the side edge of the door, and one or more latches which are mounted on the bar and engaged in a neighbouring keep when the bar is in a latching position and the doors are closed but which are moved to a disengaged position when the latch assembly is moved to a disengaged position.

12. A door assembly according to claim 11, in which each of the first and second latch assemblies comprises an elongate bar, the elongate bar of the first latch assembly mounting the engageable part and the elongate bar of the second latch assembly mounting the actuating part, the door assembly further including a first faceplate mounted on the first side edge of the first door and a second faceplate mounted on a second side edge of the second door, the elongate bar of each of the first and second latch assemblies being disposed on the inside of the first and second faceplates respectively, the engageable part projecting through a slot in the faceplate of the first elongate bar and the actuating part projecting through a slot in the faceplate of the second elongate bar.

13. A door assembly according to any preceding claim, in which at least the first latch assembly comprises a pair of elongate bars extending longitudinally in opposite directions from a gear mechanism and arranged with the gear mechanism such that movement of one of the bars in a first longitudinal direction causes movement of the other bar in a longitudinal direction, longitudinal movement of the second elongate latch assembly into the second releasing position causing the actuating part of the second elongate latch assembly to move longitudinally, to drivingly engage the engageable part of the first elongate latch assembly and thereby to move both the first elongate bar and the second elongate bar of the first latch assembly longitudinally into the second releasing position.

14. A door assembly according to claim 13, in which the first elongate bar and the second elongate bar of the first latch assembly move longitudinally in opposite directions to move into the second releasing position.

15. A door assembly according to claim 13, in which the first elongate bar and the second elongate bar of the first latch assembly move longitudinally in the same direction to move into the second releasing position.

16. A door assembly according to any preceding claim, in which the first and second elongate latch assemblies are arranged such that, when the doors are closed and the first and second elongate latch assemblies are in their unlatched positions, longitudinal movement of the first elongate latch assembly into the first latching position causes the engageable part of the first elongage latch assembly to move longitudinally, to drivingly engage the actuating part of the second elongate latch assembly and thereby to move the second elongate latch assembly longitudinally into the first latching position.

17. A latch releasing mechanism suitable for use in a door assembly according to any preceding claim, the mechanism comprising a first elongate latch assembly for extending along a first side edge of a first door and arranged for longitudinal movement between a first latching position and a second releasing position, the first elongate latch assembly including an engageable part arranged for longitudinal movement with the first elongate latch assembly and projecting laterally outwardly, a second elongate latch assembly for extending along a second side edge of a second door and arranged for longitudinal movement between a first latching position and a second releasing position, the second elongate latch assembly including an actuating part arranged for longitudinal movement with the second elongate latch assembly and projecting laterally outwardly, the first and second elongate latch assemblies being arranged such that, when in use the doors to which they are fitted are closed and the first and second elongate latch assemblies are in their latching positions, longitudinal movement of the second elongate latch assembly into the second releasing position causes the actuating part of the second elongate latch assembly to move longitudinally, to drivingly engage the engageable part of the first elongate latch assembly and thereby to move the first elongate latch assembly longitudinally into the second releasing position.

18. A latch releasing mechanism according to claim 17, in which one of the actuating part and the engageable part comprises a cylindrical member whose axis is approximately perpendicular to the length of the latch assembly of which it is part.

19. A latch releasing mechanism according to claim 18, in which the cylindrical member is a roller.

20. A latch releasing mechanism according to claim 18 or 19, in which the other of the actuating part and the engageable part comprises an arm projecting outwardly and having a distal end for engaging the cylindrical member, the distal end being engageable with the cylindrical member to provide the driving engagement for moving the first elongate latch assembly longitudinally into the second releasing position.

21. A latch releasing mechanism according to any of claims 18 to 20, in which the engageable part comprises the cylindrical member.

22. A latch releasing mechanism according to any of claims 17 to 21, in which at least one of the first and second latch assemblies comprises an elongate bar slidably mounted for longitudinal movement along the side edge of the door, and one or more latches which are mounted on the bar and engageable in a neighbouring keep when the bar is in a latching position and the doors are closed but which are moved to a disengaged position when the latch assembly is moved to a disengaged position.

23. A latch releasing mechanism according to claim 22, in which each of the first and second latch assemblies comprises an elongate bar, the elongate bar of the first latch assembly mounting the engageable part and the elongate bar of the second latch assembly mounting the actuating part, the latch releasing mechanism further including a first faceplate mounted on the first side edge of the first door and a second faceplate mounted on a second side edge of the second door, the elongate bar of each of the first and second latch assemblies being disposed, in use, on the inside of the first and second faceplates respectively, the engageable part projecting through a slot in the faceplate of the first elongate bar and the actuating part projecting through a slot in the faceplate of the second elongate bar.

24. A latch releasing mechanism according to any of claims 17 to 23, in which at least the first latch assembly comprises a pair of elongate bars extending longitudinally in opposite directions from a gear mechanism and arranged with the gear mechanism such that movement of one of the bars in a first longitudinal direction causes movement of the other bar in a longitudinal direction, longitudinal movement of the second elongate latch assembly into the second releasing position causing the actuating part of the second elongate latch assembly to move longitudinally, for drivingly engaging the engageable part of the first elongate latch assembly thereby to move both the first elongate bar and the second elongate bar of the first latch assembly longitudinally into the second releasing position.