WO2005106164A1

WO2005106164A1 - Improvements in latches/locks

Info

Publication number: WO2005106164A1
Application number: PCT/GB2005/001565
Authority: WO
Inventors: Colin Sidney Middleton
Original assignee: Colin Sidney Middleton
Priority date: 2004-04-27
Filing date: 2005-04-25
Publication date: 2005-11-10
Also published as: GB2413590B8; GB2413590B; GB0409383D0; GB2413590A; TW200602544A; GB2413590A8; TWI293350B; GB0508312D0

Abstract

A latch has means for enabling a latch bolt (22) to be reversed without having to open the casing (1) and without having to remove the casing from a door in which the casing has been fitted. A preferred means for achieving this object comprises a latch bolt lath (34) having a projection (18) which is arranged to extend out of the inner forend (26) through an aperture when the outer forend (29) is removed. The latch bolt (6) is rotatably mounted on the latch bolt lath (34) and a spring (24) serves to urge the latch bolt (6) out of the casing (1) by acting on the latch bolt lath (34). Thus, when the outer forend (29) is removed, the latch bolt (22) is clear of the inner forend (26) and can be turned through 180° to reverse the latch bolt. The outer forend (29) can then be re-fitted by means of screws (28).

Description

Title: IMPROVEMENTS IN LATCHES/LOCKS

This invention relates to latches or the latch portions of combined locks and latches and is concerned with the problem of reversing the latch bolt of latches and the latch portions of combined locks and latches.

With conventional mortise locks, it is necessary to open the casing in order to reverse a left hand latch bolt to a right hand latch bolt or vice versa. This is not only time consuming but can also lead to the loss or misplacement of some of the latch components. It has been proposed to provide a latch with means for reversing the latch bolt without opening the casing but access to the casing is still necessary to achieve this. This means that the casing has to be taken out of a door to reverse the latch bolt if the lock is in a factory fitted door. Factory made doors with fitted locks are increasing in popularity and it is necessary to specify whether left hand or right hand doors are needed. If an incorrect door is supplied or if there is a shortage of, say, left hand doors, right hand doors have to be supplied and then the lock casing has to be taken out of the door and the latch bolt reversed.

The present invention seeks to provide a solution to this problem by providing a latch with means to enable the latch bolt to be reversed without having to open the casing or to take the casing out of a door.

According to the invention, there is provided a latch or a combined lock and latch including a casing having a latch bolt and means for enabling the latch bolt to be reversed without having to open the casing and without having to remove the casing from a door in which the casing has been fitted.

Preferably, the means for enabling the latch bolt to be reversed comprise a latch bolt lath having a projection which is arranged to extend out of the front face of the inner forend of the lock casing through an aperture in said inner forend, a latch bolt rotatably mounted on the latch bolt lath and a spring acting on the latch bolt lath to urge the latch bolt and the projection out of the casing whereby the latch bolt is clear of the inner forend and is free to rotate with respect thereto.

The latch bolt head can therefore be adjusted for left hand or right hand as desired. This is done while the outer forend has been removed from the casing. If the outer forend is re-fitted to the casing, it will engage the projection on the latch bolt lath and force the projection back into the casing against the action of the spring. This in turn will force the latch bolt lath away from the inner forend and the latch bolt, which is connected to the latch bolt lath, will be drawn back so that a portion of it is located in an aperture in the inner forend and the latch bolt is no longer free to rotate. Thus, the latch bolt can be reversed simply by removing the outer forend from the casing, turning the latch bolt through 180° and re-fitting the outer forend.

The latch bolt lath preferably has a projection which is arranged to be acted on by an arm of a follower, a further spring being provided which is arranged to act on the follower in such a manner as to move the follower to a position in which the follower arm engages the projection on the latch bolt lath.

The follower may be provided with a series of teeth which are engageable with a toothed rack, said toothed rack being slidably mounted in a guide mounted in the casing and said further spring being arranged to act on the toothed rack.

The follower may also be provided with means for operating a dead bolt. These means may comprise a lug on the follower on which a lever is pivotally mounted and a pin on a dead bolt lath of the dead bolt, the lever having a slot in which the pin on the dead bolt lath is located and the arrangement being such that, when the dead bolt is in the thrown or extended position and the follower is moved to move the latch bolt to the retracted position, the lever is effective to free the dead bolt and to move said dead bolt to the withdrawn or retracted position. According to another embodiment of the invention, a latch or a combined lock and latch has an outer forend and an inner forend and the means for enabling the latch bolt to be reversed comprise a spindle mounted in the casing, said spindle being normally engaged at one end by the outer forend; a latch bolt lath slidably mounted in the casing, the latch bolt being rotatably mounted on the latch bolt lath; a spring arranged to act on the latch bolt lath to urge the latch bolt out of the casing and a follower pivotally mounted in the casing; the follower having an arm which is engageable with a projection on the latch bolt lath and the arm of the follower being normally held against the other end of the spindle.

The invention will now be described in detail, by way of example, with reference to the drawings, in which: -

Fig. 1 is a front view of one embodiment of a latch according to the invention;

Fig. 2 is a part-sectioned side elevation of the latch shown in Fig. 1 ;

Fig. 3 is a section taken on the line III-III in Fig. 1 ;

Fig. 4 is a side elevation of a second embodiment of a latch according to the invention with the casing cover removed and showing the latch in the withdrawn or retracted position and a dead bolt in the thrown position;

Fig. 5 is a side elevation of the latch shown in Fig. 4 but with the outer forend removed and with the dead bolt in the withdrawn or retracted position; and

Fig. 6 is a side elevation of a third embodiment of a latch according to the invention again with the cover removed but showing both the latch and the dead bolt in the thrown positions.

In the drawings, like parts are denoted by like reference numerals. Reference will first be made to Figs. 1 to 3 of the drawings in which a combined latch and lock according to the invention comprises a casing 1 to one side of which is mounted an inner forend 26 which is secured to a side wall 2 of the casing 1. The casing is arranged to be closed by a cover plate 4 which is secured to the casing 1 by screws 5. Part of the cover plate 4 is cut away in Fig. 2 to show part of the latch mechanism.

A deadbolt 6 is slidably mounted in the casing and is arranged to extend through guides in the side wall 2 of the casing and in the inner forend 26. The deadbolt is arranged to be operated by a cylinder lock 7 which extends through the casing 1.

A handle follower 8 extends through the casing 1 and is adapted to receive the spindle of a door handle (not shown). An arm 9 of the follower 8 carries a peg 10 which is arranged to engage with a lever 11 pivotally mounted on a pillar 12 in the casing 1. The lever 11 carries, adjacent its end remote from the pillar 12, a peg 13 which is engageable in an inclined slot 15 in a latch bolt lath 14 which is slidably mounted in the casing 1. The latch bolt lath 14 has a central slot 16 which is located over a guidance peg 17 secured to the casing 1. Further guidance of the latch bolt lath 14 is achieved by a projection 18 which extends through an aperture in the side wall 2 of the casing 1 into an aperture 27 in the inner forend 26.

The latch bolt lath 14 is provided with a flange 19 at its front end and a spindle 21 is rotatably mounted in an aperture in the flange 19. A latch bolt head 22 is secured to one end of the spindle 21 by a salop pin 23 and the other end of the spindle is shaped to locate one end of a latch bolt spring 24. The other end of the spring 24 engages with a shaped protrusion 25 which can either extend from the casing 1 or be formed on the guidance peg 17. When installed, the latch bolt head 22 projects from the casing through aligned apertures in the side wall 2 and inner forend 26.

The latch bolt spring 24 is suitably sized to allow the recommended 6-12 NT's end pressure on the latch bolt head 22. It is also suitably sized to push the latch bolt head 22 out of engagement with the inner forend 26 when the projection 18 on the latch bolt lath 14 projects through the aperture 27 in the inner forend 26.

The inner forend is further provided with a series of screw-threaded bores for the reception of screws 28 which serve to secure an outer forend 29 to the inner forend. The outer forend is provided with apertures to permit the deadbolt 6 and latch bolt head 22 to pass therethrough but no aperture is provided in the vicinity of the projection 18. Therefore, when the outer forend 29 is secured to the inner forend 26 by the screws 28, the projection 18 and hence the latch bolt lath 14 is forced back into the casing 1. This has the effect of moving the latch bolt head 22 into engagement with the inner forend 26. The combined latch and lock will normally be supplied in this condition and the inner forend 26 is provided with further bores 30 by means of which the inner forend can be secured to a door by screws 31 passing through said bores.

If it is desired to reverse the latch bolt head 22, it is merely necessary to remove the outer forend 29 by undoing the screws 28. The spring 24 will then be effective to urge the projection 18 through the aperture 27 in the inner forend 26 and to move the latch bolt head 22 out of engagement with the inner forend. The latch bolt head can then be reversed simply by turning it through 180° because the spindle 21 on which the latch bolt head is mounted is rotatably mounted in the latch bolt lath 14. The outer forend 29 can then be re-fitted and its engagement with the projection 18 will force the projection back into the casing 1 and the latch bolt head 22 back into engagement with the inner forend 26.

The latch bolt lath 14 can be operated for normal door operation by turning a handle attached to a spindle (not shown) extending through the follower 8. This has the effect of moving the follower arm 9 so that the peg 10 engages the lever 11 to cause the lever to pivot about the pillar 12. The peg 13 on the lever 11 moves up the inclined slot 15 in the latch bolt lath 14 and causes the latch bolt lath to move to the right as viewed in Fig. 2 which causes the latch bolt head 22 to be retracted into the casing 1 against the action of the spring 24. Release of the handle will allow the spring 24 to re-exert itself and return the latch bolt head 22 to its latched position in which it projects from the outer forend 29.

Turning now to Figs. 4 and 5 of the drawings, this embodiment has a latch bolt lath 34 which is similar to the latch bolt lath 14 shown in the embodiment of Figs. 1 to 3 except that the slot 15 is replaced by an upstand 35 which extends perpendicularly to the plane of the latch bolt lath 34 at the end remote from the latch bolt head 22. The upstand 35 is engaged by an arm 37 extending from a handle follower 36. The follower 36 has a square bore 38 for the reception of a spindle (not shown) on which handles (not shown) may be mounted. The follower 36 is further provided on its periphery with a series of teeth 39 which are arranged to engage with a toothed rack 41 which is slidably mounted in a guide 42 in the casing 1. The guide 42 is secured to the base of the casing 1. A follower spring 43, located on a screw 44 mounted on a plate 45 extending from the base of the casing 1, is arranged to act on one end of the toothed rack 41 to urge the follower 36 to a position in which the follower arm 37 is in the position "A" in Fig. 4 of the drawings. The upstand 35 on the latch bolt lath 34 will normally be held in engagement with the follower arm 37 by the action of the latch bolt spring 24 in which position the latch bolt head 22 will extend through the inner forend 26. This position is not shown in the drawings.

If a handle mounted on a spindle located in the bore 38 of the follower 36 is turned, the follower will pivot in a clockwise direction as viewed in Fig. 4 to move the toothed rack 41 to the left as viewed in Fig. 4 to compress the spring 43. At the same time, the engagement of the follower arm 37 with the upstand 35 will cause the latch bolt lath 34 to move to the right as viewed in Fig. 4 until the upstand 35 engages a nib 46 extending upwardly from the base of the casing 1. In this position, the latch bolt head 22 is fully withdrawn or retracted into the casing to the position shown in Fig. 4 of the drawings and the follower arm 37 is in the position marked "B" in Fig. 4. If the handle is now released, the follower spring 43 will re-exert itself to move the toothed rack 41 to the right as viewed in Fig. 4 which, by virtue of the teeth 39 on the follower 36, will cause the follower to pivot in an anti-clockwise direction as viewed in Fig. 4 to return the follower arm 37 to the position marked "A" in Fig. 4. At the same time, the latch bolt spring 24 will return the latch bolt head 22 to the thrown or extended position and the upstand 35 on the latch bolt lath 34 will be held in engagement with the follower arm 37.

As with the embodiment shown in Figs. 1 to 3 of the drawings, the latch bolt lath 34 is provided with a projection 18 which can pass through an aperture 27 in the inner forend 26 and which normally engages the outer forend 29 to limit the extension of the latch bolt head 22 from the casing. The latch bolt head can be reversed in a similar manner to the embodiment shown in Figs. 1 to 3 of the drawings by unscrewing the screws 28 to remove the outer forend 29. The projection 18 will then extend through the inner forend 26, as shown in Fig. 5 of the drawings, and the latch bolt head 22 will be clear of the inner forend so that the latch bolt head can be reversed simply by turning it through 180° because the spindle 21 on which the latch bolt head 22 is mounted is rotably mounted in the latch bolt lath 34. The outer forend 29 can then be refitted and its engagement with the projection 18 will force the projection back into the casing 1 and the latch bolt head 22 will then be located in an aperture in the inner forend 26 to prevent rotation of the latch bolt head.

The latch shown in Figs. 4 and 5 of the drawings also has a dead bolt 6 which is arranged to be operated by a cylinder lock 7. The dead bolt 6 is slidably mounted in the casing 1 and extends through aligned apertures in the side wall 2 of the casing 1, the inner forend 26 and the outer forend 29. The dead bolt has a dead bolt lath 61 provided with a guidance slot 62 and a pair of notches 65 and 66. A pair of posts 67 and 68 extend upwardly from the base of the casing 1 and are located in the guidance slot 62 of the dead both lath 61 for the purpose of guiding the sliding action of the dead bolt 6. A plate 72 is slidably mounted in the casing 1 and is provided with slots 73 and 74 and an arcuate surface 75. The post 68 extends through one of the slots 73 and a further post 69 mounted on the base of the casing 1 extends through the other slot 74. When installed in the casing, the arcuate surface 75 will be located at the lower edge of the plate 72 which plate further has an upstand 76 which is engageable in the notches 65 and 66 in the dead bolt lath 61. The upstand 76 engages in the notch 65 in the thrown or extended position of the dead bolt 6 shown in Fig. 4 and in the notch 66 in the withdrawn or retracted position of the dead bolt shown in Fig. 5 of the drawings. The plate 72 is urged in a downwards direction by a coil spring 78 bearing at one end against the plate 72 and at the other end against the guide 42 for the toothed rack 41. The spring 78 is located in a socket 79 in the guide 42 and on a peg 77 on the plate 72. A lever 81 is pivotally mounted on a post 82 in the casing and is arranged to engage a rear surface of the dead bolt 6. The cylinder lock 7 (not shown in Fig. 5) is held in position in the casing 1 by a screw 83 which passes through apertures in the inner forend 26 and side wall 2 of the casing and engages with a screw threaded bore in a block 84 which is secured to the base of the casing 1.

The dead bolt can be moved from the withdrawn or retracted position shown in Fig. 5 of the drawings to the extended or thrown position shown in Fig. 4 by inserting a key into the cylinder lock 7 and turning the key in an anti-clockwise direction as viewed in the drawings. This has the effect of turning a cam 71 of the cylinder lock in an anti-clockwise direction and the cam 71 will initially engage the plate 72 and move said plate upwards against the force of the spring 78. This movement will cause the upstand 76 to move out of the notch 66 in the dead bolt lath 61. At the same time, the cam 71 enters a recess 70 in the dead bolt lath 61 and continued rotational movement of the cam 71 will move the dead bolt lath 61 to the left as viewed in Fig. 5 of the drawings. The cam 71 also engages the lever 81 which pivots about the post 82 and is effective to move the dead bolt 6 from the withdrawn position shown in Fig. 5 of the drawings to the thrown position shown in Fig. 4 of the drawings. As the dead bolt 6 reaches the thrown position, the cam 71 moves out of engagement with the plate 72. The spring 78 then re- exerts itself to move the upstand 76 on the plate 72 into the notch 65 to lock the dead bolt in the thrown position.

The dead bolt 6 can be moved from the thrown position shown in Fig. 4 of the drawings to the retracted position shown in Fig. 5 of the drawings by inserting a key into the cylinder lock 7 and turning the key in a clockwise direction as viewed in the drawings. This has the effect of turning the cam 71 in a clockwise direction and the cam will again engage the plate 72 and move the plate upwards against the action of the spring 78. This movement will cause the upstand 76 to move out of the notch 65 in the dead bolt lath 61. Continued turning of the key will move the cam 71 into the recess 70 in the dead bolt lath 61 and continued rotation of the cam 71 will move the lath bolt lath 61 to the right as viewed in Figs. 4 and 5 of the drawings. As the dead bolt 6 reaches the withdrawn position shown in Fig. 5 of the drawings, the cam 71 moves out of the recess 70 and out of contact with the plate 72. The spring 78 re-exerts itself to move the upstand 76 on the plate 72 into the notch 66 to lock the dead bolt in the retracted position.

The latch bolt can also be operated by an extra turn of the key. A lever 85 is pivotally mounted on a lug 86 on the follower 36 and has an elongated slot 87 which is located on a pin 88 extending from the dead bolt lath 61. The lever 85 is provided at the end remote from its pivot point with an upstand 89. When the dead bolt has been moved by the cam 71 of the cylinder lock 7 to the retracted position and if the key is again turned in a clockwise direction, the cam 71 will engage the upstand 89 on the lever 85 and move the lever 85 upwards. The engagement of the pin 86 in the slot 87 serves to guide the lever and as the lever moves upwards it causes the follower 36 to rotate in a clockwise direction, as viewed in Fig. 5, which causes the follower arm 37 to move the latch bolt lath 34 to move to the right, by virtue of the engagement of the upstand 35 by the follower arm 37, and thus retract the latch bolt head 22. The key can then be turned back so that the cam 71 is disengaged from the upstand 89 and the follower 36 can be returned to its normal position under the action of the follower spring 43.

Handle operation of the follower 36 to retract the latch bolt head 22 has no effect on the dead bolt because as the follower 36 is pivoted, the lever 85 is free to move with the follower because the elongated slot 87 in the lever 85 is free to move along the pin 88. The embodiment shown in Fig. 6 of the drawings differs from the embodiments shown in Figs. 1 to 3 and in Figs. 4 and 5 in a number of respects. In this embodiment, the latch bolt lath 94 does not have a projection similar to the projection 18 of the other embodiments but it does have an upstand 95 which is engaged by a follower aπn 37 of a handle follower 36. The follower 36 is also provided with a series of teeth 39 arranged to engage with a toothed rack 41 which is slidably mounted in a guide 42 in the casing 1. A follower spring 43 acts on the toothed rack 41 as in the embodiment of Figs. 4 and 5. The spring 43 serves to act on the follower 36 to cause said follower to rotate in an anti-clockwise direction as viewed in Fig. 6, rotation of the follower being restricted by a spindle 98 which engages the follower arm 37.

The latch bolt head 22 can be moved from the extended position shown in Fig. 6 to the withdrawn or retracted position by turning a handle fitted to an end of a spindle (not shown) extending through a square bore 38 in the follower 36. This has the effect of causing the follower arm 37 to pivot to move the latch bolt lath 94 to the right as viewed in Fig. 6 by virtue of the engagement of the upstand 95 by the follower arm 37. Movement of the latch bolt 22 is continued until a shoulder 96 on the latch bolt lath 94 engages a post 97 projecting from the base of the casing 1. At the same time as the latch bolt is moved to the right, the toothed rack 41 is moved to the left as seen in Fig. 6 to compress the follower spring 43. Release of the handle enables the spring 43 to re-exert itself to return the follower 36 and the latch bolt to the positions shown in Fig. 6 of the drawings.

In this embodiment, the latch bolt head 22 can again be reversed simply by removing the outer forend 29. In this case, however, when the outer forend is removed, the spring 43 acting on the follower 36 via the toothed rack 41 will cause the follower arm 37 to move the spindle 98 partially out of the casing until the follower arm 37 is clear of the upstand 95 on the latch bolt lath 94. The spring 24 acting on the latch bolt is then effective to move the latch bolt head 22 clear of the inner forend 26. The latch bolt head 22 can then be reversed simply by turning it through 180° because the spindle 21 on which the latch bolt head is mounted is rotatably mounted in the latch bolt lath 94. The latch bolt head 22 must then be pushed back into the casing, against the force of the spring 24 and the outer forend 29 refitted so that the upstand 95 on the latch bolt lath 94 is again engaged by the follower arm 37 because the spindle 98 again engages the follower arm 37.

The latch shown in Fig. 6 of the drawings also has a dead bolt 6 which is arranged to be operated by a multi-detainer lock operated by a key. The dead bolt has a dead bolt lath 101 provided with a slot 102 through which a post 99 mounted on the base of the casing 1 extends to provide guidance for the deadbolt. A projection 103 extends from the dead bolt lath 101 and is engaged by a number of detainers 106 (only one shown in Fig. 6). The detainers are pivotally mounted on a post 112 in the casing and each is urged by a respective leaf spring 111 into contact with an arcuate member 113 surrounding a key hole slot 114. A lever 115, pivotally mounted on a post 116 which is secured to the base of the casing 1, is arranged to bear against a shoulder 105 on the dead bolt lath 101 and is arranged to be engaged by a key in a manner to be hereinafter described. A circular disc 117 surrounds the arcuate member 113 and has a peripheral depression 118 which is engaged by a curved end of a spring 121 which is mounted on a post 122 secured to the base of the casing 1, the other end of the spring 121 bearing against a side wall of the casing 1.

Fig. 6 shows the dead bolt 6 in the thrown or extended position. In order to withdraw the dead bolt 6 into the casing 1, it is necessary to insert a key into the key hole slot 114 and turn the key in a clockwise direction as viewed in Fig. 6. As the key is rotated, it will first engage the detainers 106 and lift them against the action of the detainer springs 111. The detainers are moved to a position in which the projection 103 on the dead bolt lath can enter a slot 107 in the detainer 106. At the same time, the key enters a recess 104 in the dead bolt lath 101 and engages the dead bolt lath 101. Further rotation of the key causes the dead bolt lath 101 to move to the right as viewed in Fig. 6, by virtue of the engagement in the recess 104 by the key, so that the projection 103 moves along the slots 107 in the detainers 106. This movement is continued until the outer end of the dead bolt 6 is flush with the outer forend 129 at which point the key breaks contact with the dead bolt lath 101 and the detainers 106. The slot 107 is provided with a notch 108 at its inner end and as the key breaks off engagement with the detainers 106, the springs 111 are effective to cause the detainers 106 to pivot downwardly so that the projection 103 on the dead bolt lath 101 engages in the notch 108 and the dead bolt is held in the withdrawn position. Rotation of the key is continued until the keyhole slot is returned to the position shown in Fig. 6 of the drawings when the key can be removed from the lock. Although only one detainer 106 is shown in Fig. 6, it will be appreciated that the lock will in fact be provided with more than one detainer, the usual member being five although more or less detainers may be provided as desired. In order to move the deadbolt to the thrown or extended position, the key must first be inserted into the key hole slot 114 and the key turned in an anti-clockwise direction as viewed in Fig. 6 of the drawings. The key will first engage the detainers 106 and lift them so that the notch 108 is moved clear of the projection 103. At the same time, the key enters the recess 104 in the dead bolt lath 101 and moves the lath and hence the dead bolt 6 to the left as viewed in Fig. 6. With continued rotation, the key engages the lever 115 which bears against the shoulder

105 of the dead bolt lath and increases the throw of the dead bolt. Further rotation of the key moves it out of engagement with the lever 115 and with the detainers 106. The springs 111 can therefore cause the associated detainers 106 to pivot downwardly to engage with the projection 103 and secure the dead bolt in its thrown position as shown in Fig. 6 of the drawings.

It will be seen that the latch/lock according to the invention can readily be fitted to a door at a factory and that the latch bolt head can easily be reversed on site without the necessity of removing the casing from the door. It is a very simple system and the latch bolt spring performs two functions without involving the use of other tools, devices or mechanisms. The invention is not restricted to the above-described embodiments but variations and modifications may be made without departing from the scope of the invention. For example, although Figs. 1 to 3 of the drawings show the projection 18 as being located below the latch bolt head 22, this is not essential and it could be located above or to either side of the latch bolt head. Further, instead of a cylinder lock, a lever lock could be fitted.

Moreover, instead of complete removal in order to reverse the latch bolt head, the outer forend could be fitted with a plate which could be slidably mounted in order to gain access to and free the projection 18 or spindle 98. Alternatively, the plate could be pivotally mounted on the outer forend and secured in a normally closed position by a screw or other suitable fastening means or the plate could be completely removable from the outer forend and secured in the normally closed position by screws or other suitable fastening means. Further possible alternatives are to provide a cap or disc which is screwed or fitted in the outer forend by means of a bayonet type connection. Removal of the cap or disc will allow the projection 18 or spindle 98 to protrude through the outer forend to allow the latch bolt head to be reversed in the manner above described.

Claims

1. A latch or a combined lock and latch including a casing having a latch bolt and means for enabling the latch bolt to be reversed without having to open the casing and without having to remove the casing from a door in which the casing has been fitted.

2. A latch or a combined lock and latch according to claim 1 having an outer forend and an inner forend, wherein the means for enabling the latch bolt to be reversed comprise a latch bolt lath having a projection which is arranged to extend out of the front face of the inner forend through an aperture in said inner forend, the latch bolt being rotatably mounted on the latch bolt latch and a spring being provided which is arranged to act on the latch bolt lath to urge the latch bolt and the projection out of the casing whereby when the latch bolt is clear of the inner forend it is free to rotate with respect thereto.

3. A latch or combined lock and latch according to claim 2, wherein the projection is normally engaged by the outer forend when said outer forend is fitted to the inner forend.

4. A latch or a combined lock and latch according to claim 3, wherein the outer forend is provided with a plate with which the projection is engaged when the outer forend is fitted to the inner forend.

5. A latch or a combined lock and latch according to claim 4, wherein the plate is slidably mounted in the outer forend.

6. A latch or a combined lock and latch according to claim 4, wherein the plate is pivotally mounted on the outer forend.

7. A latch or a combined lock and latch according to claim 4, wherein the plate is detachably fitted to the outer forend.

8. A latch or a combined lock and latch according to any one claims 2 to 7, wherein the latch bolt lath has a projection which is arranged to be acted on by an arm of a follower, a further spring being provided which is arranged to act on the follower in such a manner as to move the follower to a position in which the follower arm engages the projection on the latch bolt lath.

9. A latch or a combined lock and latch according to claim 8, in which the follower is provided with a series of teeth which are engageable with a toothed rack, said toothed rack being slidably mounted in a guide mounted in the casing and said further spring being arranged to act on the toothed rack.

10. A combined lock and latch according to claim 8 or claim 9, wherein the follower is provided with means for operating a dead bolt.

11. A combined lock and latch according to claim 10, wherein the follower has a lug on which a lever is pivotally mounted and wherein the dead bolt has a dead bolt lath from which a pin extends, the lever having a slot in which the pin on the dead bolt lath is located and the arrangement being such that, when the dead bolt is in the thrown or extended position and the follower is moved to move the latch bolt to the retracted position, the lever is effective to free the dead bolt and to move said dead bolt to the withdrawn or retracted position.

12. A combined lock a latch according to claim 11, wherein the dead bolt is provided with a plate which is effective to lock the dead bolt in the thrown or extended position and wherein the lever mounted on the lug of the follower is provided with a projection which is arranged to engage with said plate to move it to a position in which the dead bolt is unlocked when the follower is moved to move the latch bolt to the retracted position.

13. A latch or a combined lock and latch according to claim 1 having an outer forend and an inner forend, wherein the means for enabling the latch bolt to be reversed comprise a spindle mounted in the casing, said spindle being normally engaged at one end by the outer forend; a latch bolt lath slidably mounted in the casing, the latch bolt being rotatably mounted on the latch bold lath; a spring arranged to act on the latch bolt lath to urge the latch bolt out of the casing and a follower pivotally mounted in the casing; the follower having an arm which is engageable with a projection on the latch bolt lath and the arm of the follower being normally held against the other end of the spindle.

14. A latch or a combined lock and latch according to claim 13, wherein a further spring is arranged to act on the follower to urge the arm of the follower against the said other end of the spindle.

15. A latch or a combined lock and latch according to claim 14, wherein the arm of the follower is urged by the further spring to hold the spindle against the outer forend, the arrangement being such that, if the outer forend is removed, the said further spring is effective to cause the follower arm to move the spindle partially out of the casing and out of engagement with the projection on the latch bolt lath whereupon the spring acting on the latch bolt lath is effective to move the latch bolt out of the casing and out of engagement with the inner forend so that the latch bolt is free to rotate with respect to said inner forend.

16. A latch or a combined lock and latch according to claim 14, wherein the arm of the follower is urged by the further spring to hold the spindle against a plate on the outer forend, the arrangement being such that, if the plate on the outer forend' is moved out of engagement with the spindle, the said further spring is effective to cause the follower arm to move the spindle partially out of the casing and out of engagement with the projection on the latch bolt lath whereupon the spring acting on the latch bolt lath is effective to move the latch bolt out of the casing and out of engagement with the inner forend so that the latch bolt is free to rotate with respect to said inner forend.

17. A latch or a combined lock and latch according to claim 16, wherein the plate is slidably mounted in the outer forend.

18. A latch or a combined lock and latch according to claim 16, wherein the plate is pivotally mounted on the outer forend.

19. A latch or a combined lock and latch according to claim 16, wherein the plate is detachably fitted to the outer forend.

20. A latch or a combined lock and latch according to any one of claims 13 to 19, wherein the follower is provided with a series of teeth which are engageable with a toothed rack, said toothed rack being slidably mounted in a guide mounted in the casing.

21. A combined latch and lock substantially as described herein with reference to Figs. 1 to 3 or Figs. 4 and 5 or Fig. 6 of the drawings.