GB2391583A

GB2391583A - Gear driven closing locking mechanism

Info

Publication number: GB2391583A
Application number: GB0317262A
Authority: GB
Inventors: Nigel Ridgway
Original assignee: MILLENCO HARDWARE Ltd; Rostance & Co Ltd
Current assignee: MILLENCO HARDWARE Ltd; Rostance & Co Ltd
Priority date: 2002-07-24
Filing date: 2003-07-24
Publication date: 2004-02-11
Also published as: GB0217098D0; GB0317262D0

Abstract

A closure locking mechanism for a casement window or a sliding patio door has a casing (10,11) with a faceplate, the casing containing a handle operated follower (42) which has gear teeth (56) which directly mesh with gear teeth on a first pivoted hook bolt (37) and which indirectly mesh, via a reversing pinion (40), with gear teeth on a second pivoted hook bolt (36). The hook bolts retract and extend through respective openings (45, 44) in the faceplate on operation of the handle (72) and their gear teeth mesh with gear teeth on respective drive racks (48, 49) slidable at the rear of the faceplate. In their respective retracted states, the bolts lie wholly behind the faceplate. Each drive rack can have an extension part fitted thereto to extend its length for different sash rebate sizes.

Description

it' 2391 583

-1 CLOSI}RE LOCKING MECHANISIM

This invention relates to a locking mechanism for a closure, such as a casement window, pivotally mounted in a frame. However the mechanism could alternatively be used with a sliding patio door to lock it into its frame in its dosed position.

With known casement window locks used with PVC windows it has been found that due to expansion of the PVC material, cam locks are unreliable.

Moreover linear bolts have been found relatively easy to jemmy, whilst other proposed mechanisms have required an unacceptably large casement.

An object of the invention is to provide a locking mechanism in an effective yet convenient form.

According to a first aspect of the present invention there is provided a locking mechanism comprising a casing having a faceplate, a follower angularly movably mounted in the casing and connectable, in use, to an operating member disposed externally of the casing, the follower having gear teeth meshing or arranged to mesh with gear teeth on a bolt angularly movably mounted in the casing, said gear teeth on the bolt meshing or being arranged to mesh with an elongate member mounted for sliding movement at an inside face of the faceplate, and said faceplate having an opening for passage therethrough of a hook part of said bolt, the arrangement being such that, in use, with the operating member in a first position corresponding to a unactuated state of the mechanism, the bolt is in a retracted position in the casing, and the elongate member is a retracted state relative to the casing, whilst with the operating member in a second position corresponding to an

-2 actuated state of the mechanism, the bolt is in an extended position where it passes through said faceplate opening and has its hook part disposed beyond an outer face of the faceplate, and the elongate member has slidably moved to an extended state relative to the casing.

Preferably in its retracted position, the bolt is wholly behind the faceplate.

More preferably gear teeth on the follower mesh or are arranged to mesh with a pinion angularly movably mounted in the casing, which pinion has gear teeth meshing or arranged to mesh with gear teeth on a further bolt angularly movably mounted in the casing and arranged to pass through a further faceplate opening when the operating member is in its second position, with a hook part thereof disposed beyond said outer face of the faceplate. Desirably in said first position of the operating member, said further bolt is in a retracted position in the casing, fully behind the faceplate. Conveniently the pinion is a reversing pinion so that angular movement of the follower in one direction effects angular movement of the bolt and the further bolt in opposite angular directions respectively. Advantageously the gear teeth of the bolt and the further bolt respectively mesh with gear teeth on said elongate member and a further slidable elongate member respectively which move in opposite directions when the operating member is pivoted from its first to its second position or vice versa.

According to a second aspect of the invention there is provided a locking mechanism comprising a casing having a faceplate, a follower angularly movably mounted in the casing and connectable, in use, to an operating member disposed externally of the casing, the follower having gear teeth meshing or arranged to mesh, directly or indirectly, with gear teeth on first

-3- and second bolts respectively angularly movably mounted in the casing, the faceplate having respective openings for passage therethrough of respective hook parts of said first and second bolts when the operating member is moved, in use, to a position corresponding to an actuated state of the mechanism, each bolt being disposed wholly in the casing and behind the faceplate when the operating member is in a position corresponding to an unactuated state of the mechanism.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which; Figure 1 is an exploded front perspective view of a locking mechanism of the invention, in a locking state, Figure 2 is a view like Figure 1, but shows an exploded rear perspective view, Figures 3 and 4 are respective perspective views of the interior of two halves of a casing of the locking mechanism, Figures 5 to 7 are a perspective view, a plan view and a side view of a hook bolt of the locking mechanism, Figures 8 to 10 are a plan view, a side view and a perspective view of a follower of the locking mechanism,

Figures 11 to 13 are a plan view, a side view and a perspective view of a pinion of the locking mechanism, Figure 14 is a perspective view of a drive rack of the locking mechanism, Figure 15 is a schematic view of the mechanism showing two adjusted positions of a drive rack extension, Figure 16 is an underneath plan view of a clamp button used with the drive rack extension, Figures 17 and 18 are respectively an assembled and exploded view of the clamp button with a drive rack extension in a track, Figure 19 is a section of a window and its frame with which a locking mechanism of the invention can be used, Figures 20 and 21 are respectively a front view and a sectional view on line 21-21 of Figure 20 of the locking mechanism in an unlocked state, and Figures 22 and 23 are respectively a front view and a sectional view on line 23-23 of Figure 22, of the locking mechanism in a locked state.

Whilst the locking mechanism shown in Figures 1 and 2 can generally be used with many forms of closure between a pivoted or sliding wing and its frame, it is particularly intended for use with a casement window which is pivotally mounted in its associated frame. An alternative likely use,

) -s- however, is with a sliding patio door in order to lock this to its frame when the door is slid to its closed position.

The locking mechanism shown in Figures 1 and 2 includes a casing made up of a male casing part 10 and a female casing part 11 which interfit to form the complete casing, as will be described. These two parts are also shown in Figures 3 and 4 respectively. Both parts can be made of any suitable material, but are preferably of plastics material.

The male casing part 10 is of generally rectangular form having at one end of its front longitudinal face a small rectangular locating projection 12. In its inner surface, are provided a pair of upstanding cylindrical pivot pins 13,14 respectively, the centres of these pivot pins lying in a corrunon plane parallel to the front face of the casing part and spaced slightly rearvvardly therefrom. Around each pivot pin is a concentric recess 15,16 respectively with raised areas 17,18 respectively adjacent Me recesses 15,16 towards the respective opposite ends of the casing part. These areas 17,18 are raised relative to the recesses lS,16, but are still recessed relative to the outer surface of this inner side of the casing part, as shown best in Figure 3. As can be seen from that Figure, the recess 15 is open to the longitudinal front face of the casing part whilst for the recess 16 the front surface of the casing part is at the level of the raised area 18.

Disposed centrally in the inner face of the casing part 10 is a further part-circular recess 19, which is in communication with the recess 15, the recess 19 extending to the outer longitudinal face of the casing part 10 where it is closed thereby. The centre of the recess 19 is provided with a circular

-6 opening 20. Finally at opposite sides of the recess 19 in a common plane parallel to the outer longitudinal face of the part 10 are two upstanding cylindrical spigots 21 with respective circular holes therethrough.

The female casing part 11, shown best in Figure 4, is a very similar form to the male casing part 10 having a rectangular locating projection 22 at one end of its front face, this however being at the opposite end of the casing to the projection 12 of the male casing part 10. Like the male casing part 10, the female casing part 11 has a pair of upstanding cylindrical pivot pins 23,24 respectively positionally matching the pivot pins 13,14, so that when the two halves are fitted together the pins 13 and 23, and 14 and 24, are axially aligned and can be arranged to abut at their respective ends or terminate just short of one another. Similarly the casing part 11 has recesses 25,26 respectively matching the recesses 15,16, and raised areas 27,28 respectively matching me raised areas 17,18. Moreover the recess 26 is open to the longitudinal front surface of the casing part, while both recess 25 and 26 communicate with a further partcircular recess 29 having a central circular opening 30. The recess 29 is disposed centrally of the casing part 11 at the rear face Hereof which closes said recess 29 in the same way as the rear longitudinal face closes the recess 19 for the casing part 10. However instead of the spigots 21, the casing part 11 is provided wim complementary circular bores 31 which at the outer surface of the casing part 10 are provided with respective countersinks 31a, as shown in Figures 1 and 2. When the two halves of the casing are fitted together, respective countersunk screws can be received through the countersinks 31a and bores 31 to be received in He spigots 21. These screws can eider engage with respective screw threads in the spigots 21, or could be arranged to cut Weir own threads as they are

engaged therein. In either event, the screws fix together the two casing parts to form the casing of the locking mechanism.

Also shown in Figures 3 and 4, are respective openings 32,33 in the parts 10 and 11, these being formed adjacent respective part-circular recesses 34,35 in I upstanding inner walls of the recesses 15,25 adjacent the junction of these recesses I with the further recesses 19 and 29. The openings 32, 33 are in alignment when the casing parts are fitted together.

As shown in Figures 1 and 2, respective hook bolts 36,37 are pivotally mounted in the locking mechanism, the hook bolt 36 being pivotally mounted on the pivot pins 13 and 23, whilst the hook bolt 37 is pivotally mounted on the pivot pins 14 and 24.

Pivotally mounted in the locking mechanism with its respective cylindrical ends 38,39 received in the openings 32,33 is a reversing pinion 40 having longitudinally extending gear teeth 41. Pivotally disposed in the further recesses 19 and 29 is a follower 42 which, as will be described, receives therethrough a spindle connected to an operating handle at an exterior side of the locking mechanism, the spindle extending through the respective openings 20 and 30 in the casing parts 10 and 11.

As will be explained, angular movement of the handle, and thus the spindle, effects corresponding angular movement of the follower, resulting in associated angular movement of the hook bolts.

From Figures 1 and 2 it can be seen that the front of the locking mechanism is formed with a faceplate 43 defining an inwardly facing rectangular channel. The faceplate has a pair of longitudinally spaced centrally disposed rectangular slots 44,45 through which respective parts of the hook bolts can

-8 extend or retract, as will be described. Figures 1 and 2 show these hooks in their respective extended positions where respective parts thereof extend through said slots 44,45. Moreover it can be seen that below and above said slots 44,45 respectively are further smaller rectangular slots 46,47 which receive the locating I projections 12 and 22 respectively of the casing parts 10 and 11 so as to secure the j assembled casing to said faceplate. From Figures 1 and 2 it can also be seen that extending from opposite ends of the faceplate are respective drive racks 48,49. As will be explained, each of these is provided with gear teeth which mesh with gear teeth on a respective associated one of the hook bolts, so that when there is angular movement of the hook bolts there is corresponding sliding movement of the drive racks within Me channel defined by the faceplate 43, and as best shown for the drive racks in Figure 2.

Turning now to the individual components, it will be noted that although the hook -

bolt 36 is shown in Figures 5 to 7, the hook bolt 37 is identical therewith, the only Z difference being that when these bolts are disposed within the locking mechanism casing they are mutually reversed so that their hook parts face one another. As can; be seen from Figures 5 to 7, the hook bolt 36 is formed at one end with a cylindrical portion 50. Extending generally radially from the centre of the periphery of the cylindrical portion 50 is a leg part 51 which is formed with a finger 52 at its free end, this being turned through 90 to form a hook part. As best shown in Figures 5 and 7, the opposite side of the leg part at the end of the bolt where the cylindrical portion 50 is provided, is formed generally as part cylindrical, but with the outer surface of this part 53 being formed with gear teeth 54, the gear teeth extending around the whole of the part 53 which extends for approximately

-9- 225 of arc. Extending centrally through the whole of bolt, concentrically with the aligned axes of the cylindrical portion SO and part 53 is a circular bore 55 into which the respective aligned pivot pins 13 and 23 or 14 send 24 respectively project so as pivotally to mount the hook bolt in the casing. As can be appreciated from I Figures 1 and 2, the hook bolt 36 is mounted with its part 53 received in the recess i 15 of the casing part 10, whilst its cylindrical portion 50 is received in the recess 25 1 of the casing part 11. Its gear teeth 54 thus lie in the casing part 10 where they are in engagement/mesh with the gear teeth 41 on the reversing pinion 40. The hook bolt 37 is, as described, reversed relative to the hook bolt 36, so that, as can be seen in Figures 1 and 2, it is arranged with its cylindrical portion in the recess 16 of the casing part 10 whilst its part with the gear teeth 54 is received in the rPress 26 in the casing part 11. Since the leg part 51 extends from the centre of the pivoted end of the hook bolt, as shown best in Figure 7, it will be appreciated that despite the i mutual reversing of the two bolts, the respective leg parts 51 thereof lie in the same i plane and thus can extend through the aligned slots 44,45 of the faceplate, as shown Z in Figures 1 and 2, when the bolts are 'thrown'. It will be appreciated than' when retracted, for example as shown in Figure 21, the leg parts S1 with the hook-like fingers 52, are received in the respective recesses defined together between the raised areas 17 and 27 or 18 and 28 respectively.

The follower 42 shown in Figures 8 to 10 has a part cylindrical surface around the whole of which, but across only half of which, are provided gear teeth 56 which, as will be described, are arranged to mesh with the gear teeth 54 on the hook bolt 37, as shown in Figure 1. The gear teeth 56 are also arranged to mesh with the gear teeth 41 on the reversing pinion 40, these

-10 gear teeth 41 meshing with the gear teeth 54 on the hook bolt 36, again as shown in Figures 1 and 2. As mentioned, and as shown in Figures 1 and 2, the follower 42 is arranged to be angularly movable in the locking mechanism with its gear teeth in the further recess 29, whilst the part cylindrical portion which is without gear teeth is received in the further recess 19. This ensures that the level of the gear teeth is at the same level as the gear teeth 54 of the hook bolt 37 as shown in Figure 1. As shown in Figures 8 and 1O, the follower has therethrough a twelve-sided opening 57 for the tight engagement therein of a spindle (not shown). As mentioned, an operating handle, also not shown, has its spigot and bearing bush fitted at an external side of the locking mechanism in the opening 20 or 30, with the spindle being received in said spigots, in the normal manner, and extending through the locking mechanism by way of being received through the opening 57 in the follower. Accordingly in this way angular movement of the operating handle is converted into angular movement of the follower.

It will be appreciated from Figures 1 and 2 that anticlockwise movement of the follower shown in Figure 1 will cause clockwise movement of the hook bolt 37 which will thus retract into the locking mechanism casing. However since the follower is in mesh with the gear teeth on the reversing pinion, this anticlockwise movement of the follower will cause clockwise movement of Me pinion, which in turn, as it is in mesh with the gear teeth 54 on the hook bolt 36, will effect anticlockwise movement of this hook bolt 36 which will similarly be retracted into the casing. Thereafter, clockwise angular movement of the follower will move the hook bolts in the opposite directions respectively, thereby extending them out of the faceplate to their Figure 1 and 2 positions, i.e. from the unlocked to the locked state of the locking mechanism.

-11 Figures 11 to 1 3 show the reversing pinion in detail, and in particular its opposite I cylindrical ends 38 and 39 which are received in the respective aligned openings 32 and 33 in the male and female casing parts 10,11 so as pivotally to mount the reversing pinion in the casing. As described the function of this pinion is to reverse the direction of rotation provided by the follower, so that the hook bolt 36 moves in i the opposite direction to that of the hook bolt 37 so that the two hook bolts are either extended together or retracted together.

Figure 14 shows me drive rack 48, it being understood that the drive rack 49 is identical, the two merely being mutually inverted, when arranged to slide relative to the faceplate 43, and as shown best in Figure 2. Each drive rack has a main end portion 58 provided with a hole threaded 59 for connection of an extension to be described in relation to Figure 15. This main end portion 58 has a width substantially corresponding to the inner width of the channel defined by me faceplate 43, so that, as can be seen from Figure 2, each drive rack is guided by the sides of the channel for longitudinal sliding relative thereto. It can be seen that away from this main end portion 58, the rack is cut away to provide space for movement of a latch bolt, this narrower longitudinally extending part 60 being formed with a gear rack 61 at its end on its inner surface. Accordingly it will be appreciated that with the two drive racks 48 arranged in mutually inverted form as shown in Figure 2, for sliding in the faceplate 43, with the respective main end portions outside of the faceplate 43 as shown, each rack engages with respective gear teeth 54 of a hook bolt. For example as shown in Figure 2, the gear rack 61 of drive rack 48 engages with the gear teeth 54 of hook bolt 37, whilst the gear rack

-12 61 of drive rack 49 is in engagement with the gear teeth 54 of hook bolt 36. In this way, it will be appreciated that, in use, as the hook bolts are angularly moved by I operation of the operating handles, the gear teeth 54 on the hook bolts cause the gear racks 61, and thus the respective drive racks 48 to move towards or away from one another so as, as will be described, to extend or retract locking extension rods connected to the drive racks 48,49 respectively. i Figure 15 shows how the end of one of the drive racks 48,49 is connected to a locking extension rod 62 through the intermediary of a lipped channel shaped extension part 63. As shown in Figure 15, the hole 59 at the end of the drive rack is utilised to connect the drive rack to said extension rod, for example as shown in Figures 16 to 18. Here it is shown how a clamp button 64 has a countersunk screw 65 fitted therein, the shank of the screw passing through the hole 59 and thereby clamping this end of the drive rack 48 or 49 in the channel provided by the extension part 63, as shown in Figure 17. Figure 16 shows the underside of the damp button, namely that it has a series of gripping projections 66 on its surface, to engage with the respective outer surfaces of the lips of the channel in the part 63, with further gripping projections 67 to engage tightly at the interior of the opening in the part 63 defined between its opposite lips. It will thus be appreciated that with the end of the drive rack 48 or 49 received in the end of the extension part 63 as shown in Figures 15 and 17, the clamp button 64 is positioned so that the screw 65 can be tightened with its shank extending through tile opening 59, until the Figure 17 position is reached whereby the button tightly clamps down onto the part 63 and the end of the drive rack is securely fastened to the extension part 63. As shown in Figure 15, the length of the extension to Me

-13 drive rack can be varied to cater for a range of sash rebate sizes, for example from 300 rum up to 1175 mm. This is accomplished by havmg a locking rod 68 mounted in the extension part 63 beyond the position where the drive rack is secured to Me extension part 63. Figure 15 shows an upper position where the locking rod 68 is fixed to the extension part 63 so that only a very small part of it extends from the part 63, this corresponding to the smallest sash rebate size. The lower part of Figure IS shows the arrangement to cater for the largest sash rebate size where the locking rod 68 extends to its maximum degree out of the extension part 63. It will be appreciated that these variations are accomplished by arranging for a series of spaced openings between the lips of the extension part 63 to allow the screw fastening to be effected at any one of these positions thereby controlling the amount of extension of the locking rod out of the end of the extension part 63.

Alternatively, however, there could be stepless adjustability by providing a continuous slot between the lips of the part 63 and fastening the locking rod in position by means of the screw 65 being passed through an opening in the Arid of the rod 68 and clamping the screw down onto the base of the extension part 63.

Figure 19 shows a section It [rough a casement 69 and a section through an associated frame 70, with a "EUROGROOVE" 71 in the casement section for reception of the locking mechanism of the invention. This EUROGROOVE" 71 is also shown schematically in Figure 18 to show the fitting therein of the extension rod arrangement 62 including the extension part 63 and its associated locking rod 68. It will be understood that the casing of the locking mechanism will normally be disposed generally centrally along the length of the " EUROGROOVE' with an operating

-it handle at one side of the casement window, or alternatively at respective opposite sides thereof, for example, where the" EUROGROOVE" is in a patio door section.

As shown in Figure 15, with the casement window, operation of the operating handle to 'lock' the mechanism will effect throwing of the hook boots from their retracted positions to their extended positions, as shown in this Figure. Similarly, as described, such throwing of the latch bolts will cause sliding of the respective drive racks in opposite directions away from one another and this will similarly cause sliding movement of the respective extension parts and the locking rods secured thereto. At each of their ends, the respective locking rods pass through respective guides on the casement window and when the hook bolts are thrown, the ends of these locking rods 68 respectively are moved slidably through the guides to extend outwardly therefrom into a keep or the like at the window frame. Accordingly not only do the hook bolts extend to engage in respective slots/keeps of the window frame, but the shoot bolts or locking rods 68 also extend to engage with the free, thereby tightly securing the casement window in its closed, locked position at the frame. Figures 20 to 23 show this arrangement, with Figures 20 and 21 showing a handle 72 in its unlocked position which would be horizontal in use, with the drive racks 48,49 in their most nested position behind the faceplate 43. In this open or unlocked state of the locking mechanism, it can be seen that each of the hook bolts is fully received/retracted into its casing. In other words unlike with other known arrangements, the whole of each hook bolt is received fully behind the faceplate so as to avoid any problem of engagement between a bolt and Me frame when the window is closed with the locking mechanism in its unlocked position. It can be seen that in this state the gear

-15 teeth on the follower are in mesh with the gear teeth on the one hook bolt and also on the reversing pinion, with the gear teeth on the reversing pinion being in mesh with the gear teeth on the other hook bolt. Moreover the gear teeth on the two hook bolts respectively are in mesh with the gear teeth on the respective drive racks extending outwardly at opposite ends of the faceplate.

Figures 1 and 23 show how, when the operating handle is angularly moved through 90 , for example downwardly, in use, the follower is similarly angularly moved through 90 so as to 'throw/extend' both of the hook bolts, with the angular movement of the bolts causing outwards sliding movement of each of the drive racks so that these cause their extension parts and associated locking rods to engage with the frame. As is well known, the hook bolts swing to engage in respective slots or the like keeps in the side surface of the frame. As designed, the hook bolts function as anti-separation members thereby to resist any attempt to force them back into their casing and thereby release the locking.

It will of course be appreciated that only a single hook bolt might be provided in some forms of locking mechanism of the invention, and moreover it is possible that the sliding of a locking rod may not itself function as a lock at the window Dame, it may alternatively itself operate some over form of bolt, such as a swing bolt to engage with the face of the frame in the same manner as with the hook bolts 36 and 37. Where only one drive rack is provided, it could be arranged that sliding movement of this is transmitted through further gearing to effect sliding movement of a second drive rack which is thus not directly engaged by a hook bolt or the like.

Claims

-16 CLMS 1. A locking mechanism comprising a casing having a faceplate, a

follower angularly movably mounted in the casing and connectable, in use, to an operating member disposed externally of the casing, the follower having gear teeth meshing or arranged to mesh with gear teeth on a bolt angularly moveably mounted in the casing, said gear teeth on the bolt meshing or being arranged to mesh with an elongate member mounted for sliding movement at an inside face of the faceplate, and said faceplate having an opening for passage therethrough of a hook part of said bolt, the arrangement being such that, in use, with the operating member in a first position corresponding to a unactuated state of the mechanism, the bolt is in a retracted position in the casing, and the elongate member is a retracted state relative to the casing, whilst with the operating member in a second position corresponding to an actuated state of the mechanism, the bolt is an extended position where it passes through said faceplate opening and has its hook part disposed beyond an outer face of the faceplate, and the elongate member has slidably moved to an extended state relative to the casing.
2. A locking mechanism as claimed in Claim 1, wherein in its retracted

position, the bolt is wholly behind the faceplate.
3. A locking mechanism as claimed in Claim 1 or Claim 2, wherein gear teeth on the follower mesh with a pinion angularly moveably mounted in the casing, which pinion has gear teeth meshing or arranged to mesh with gear teeth on a further bolt angularly movably mounted in the casing and arranged to pass through a further faceplate opening when the operating member is in its second position, with a hook part thereof disposed beyond said outer face of the faceplate.
4. A locking mechanism as claimed in Claim 3, wherein in said first position of the operating member, said further bolt is in a retracted position in the casing, fully behind the faceplate.
-17 S A locking mechanism as claimed in Claim 3 or Claim 4, wherein the pinion is a reversing pinion so that angular movement of the follower in one direction effects angular movement of the bolt and the further bolt in opposite angular directions respectively.
6. A locking mechanism as claimed in any one of Claims 3 to 5, wherein the gear teeth of the bolt and the further bolt respectively mesh with gear teeth on said elongate member and a further slidable elongate member respectively which move in opposite directions when the operating member is pivoted from its first to its second position or vice versa.
7. A locking mechanism as claimed in any one of the preceding Claims, in which an end of the elongate member remote from the casing is connected to an extension part.
8. A locking mechanism as claimed in Claim 7, wherein the extension part is of lipped channel fond.
9. A locking mechanism as claimed in Claim 8, wherein the elongate member is slidably received in the extension part and secured thereto by locking means.
10. A locking mechanism as claimed in Claim 9, wherein the locking means comprise clamping means including a screw which passes through a threaded Opening in said end of the elongate member to clamp the extension part at one end thereof to said elongate member.
11. A locking mechanism as claimed in any one of Claims 7 to 10, wherein an extension element is adjustably connected to said extension part to provide different lengths of the elongate member.
12. A locldag mechanism as claimed in Claim 10, wherein an extension rod is slidably adjustably fitted in said extension part by clamping means including a

-18 screw which passes through a slot or a selected one of a plurality of openings between the lips of the extension part.
13. A locking mechanism composing a casing having a faceplate, a follower angularly movably mounted in the casing and connectable, in use, to an operating member disposed externally of the casing, the follower having gear teeth meshing or arranged to mesh, directly or indirectly, with gear teeth on first and second bolts respectively angularly movably mounted in the casing, the faceplate having respective openings for passage therethrough of respective hook parts of said first and second bolts when the operating member is moved, in use, to a position corresponding to an actuated state of the mechanism, each bolt being disposed wholly in the casing and behind the faceplate when the operating member is in a position corresponding to an unactuated state of the mechanism.
14. A locking mechanism as claimed in Clum 13, wherein the follower gear teeth mesh with gear teeth on a reversing pinion, which gear pinion teeth also mesh with gear teeth on said second bolt.
15. A locking mechanism as claimed in Claim 13 or Claim 14, wherein at least one of the bolts has its gear teeth in mesh with gear teeth on an elongate member mounted for sliding movement at an inside face of the faceplate.
16. A locking mechanism as chimed in Claim 15, wherein said elongate member is extended in length by an extension part connected to an end thereof.
17. A locking mechanism as claimed in Claim 16, wherein said extension part has an extension element adjustably connected thereto in order to provide different lengths of the elongate member.
18. A locking mechanism as claimed in Claim 16 or Claim 17, wherein said connection to the extension part is by clamping means including a clamping screw.

-l9-
19. A locldog mechanism substantially as herednbefore descnbed, with reference to, and as shown in the accompanying drawings.