GB2383078A

GB2383078A - Latchbolt with deadlock

Info

Publication number: GB2383078A
Application number: GB0302843A
Authority: GB
Inventors: Kevin Leslie Burrows
Original assignee: Security Products UK Ltd
Current assignee: Security Products UK Ltd
Priority date: 2003-02-07
Filing date: 2003-02-07
Publication date: 2003-06-18
Anticipated expiration: 2023-02-07
Also published as: GB2383078B; GB0302843D0

Abstract

A nightlatch having an extendable and retractable spring loaded latchbolt (15) includes a deadlocking spindle (33) axially slidably movable in a bore in a part (32) of a handle (29) at the exterior of a casing (10) of the nightlatch. The spindle is operated by a push button (36) at the interior side of the door to which the nightlatch is filled, in use, and to release the deadlocking from the interior a double action of pushing the push button and additionally turning the handle is required. From the exterior side of the door key operated lock means are provided for operating a backplate cam assembly (44) to deactivate a trigger (41) which holds the spindle in a position where it deadlocks the latchbolt. Axial movement of the spindle during latchbolt retraction and extension is controlled by the spindle interacting with a configurated slot (31) in the latchbolt lath (22).

Description

LOCK This invention relates to a lock for a movable wing, and particularly to a socalled nightlatch intended to be fitted to a domestic entrance door.

A nightlatch is a rim or mortice lock/latch with a bevelled latchbolt which shoots when the wing, e. g. the door, to which it is fitted is closed, but can be withdrawn from the outside by a key and from the inside by a knob or lever handle. A snib is usually provided in order to hold the latchbolt retracted.

An object of the invention is to provide a lock for a movable wing which has increased security.

According to a first aspect of the invention a lock for a wing movable between respective open and closed positions relative to a frame comprises a casing, a latchbolt operable to extend from or retract into said casing and being biased towards its extended position, an operating member arranged to be operable at one side of the wing, in use, to effect retraction of the latchbolt, lock means arranged, in use, for key operation at the other side of the wing for retracting the latchbolt, and a deadlocking element which is automatically actuated when the wing is closed into its frame, in use, with the latchbolt other than retained in its fully retracted state, such actuation of the deadlocking element deadlocking the latchbolt by holding it in its fully extended state against movement thereof towards its retracted position, retraction of the latchbolt from its deadlocked position requiring, at said one side of the wing, a double action of effecting movement of said deadlocking element generally normally to the direction of latchbolt movement to a

release position, and additionally operating said operating member whilst said deadlocking element is at said release position.

According to a second aspect of the invention a lock for a wing movable between respective open and closed positions relative to a frame comprises a casing, a latchbolt operable to extend from or retract into said casing and being biased towards its extended position, the latchbolt having a head and a lath secured thereto, an operating member arranged to be operable at one side of the wing, in use, to effect retraction of the latchbolt, lock means arranged, in use, for key operation at the other side of the wing for retracting the latchbolt, a deadlocking element which is automatically actuated when the wing is closed into its frame, in use, with the latchbolt other than in its fully retracted state, such actuation of the deadlocking element deadlocking the latchbolt by holding it in its fully extended state against movement thereof towards its retracted position, and the latchbolt lath having a configurated aperture therein to control movement of the deadlocking element during latchbolt retraction and extension.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a cut-away, inside perspective view of components of a lock of the present invention, with a latchbolt held partly extended, Figure 2 is a perspective interior view of the casing of the lock of Figure 1, with the latchbolt fully retracted,

Figure 3 is a view similar to Figure 2, with the latchbolt fully extended,

Figure 4 is a longitudinal cross-section through the casing of Figure 2, 1 Figure 5 is an enlarged fragmentary perspective view of a trigger engaging a deadlocking element of the lock, as in Figure 3, Figure 6 is a view like Figure 5 showing the trigger disengaged from the deadlocking element, Figure 7 is a view like Figure 4, but with the latchbolt in its fully extended position, as in Figure 3, and a push-button of the lock depressed, and Figure 8 is an enlarged fragmentary perspective view, like Figures 5 and 6, showing a lock means component for preventing release of the deadlocking element.

The form of nightlatch shown in the drawings can have its casing 10 of any suitable form to allow it to be rim or mortice mounted at a wing, such as a door. In this regard it will be seen from the drawings that with the casing in the form illustrated there are provided front countersunk screw holes 11, and as shown in Figures 3 and 4, an associated keep 12 is intended to be fitted, in use, at a frame of the door. The generally square casing 10 shown in the drawings accommodates, in this embodiment, all the main components of the nightlatch and the open side of the casing 10 is closed by a backplate (not shown) which is secured by fixing screws passing through three respective openings therein which align with upstanding internally threaded spigots 13

so as to receive the fixing screws respectively to hold the backplate to the casing 10. Additionally the backplate can have a tongue which is tightly received in an opening L4 in a front face of the casing through which a head 15 of a latchbolt of the nightlatch extends and retracts, in use, the tongue of the backplate being held securely in the slot defined at a side of the opening 14 between the bolt head and the casing. As can be seen from the drawings, the bolt head is chamfered at 16 in the normal manner so that, as will be described hereinbelow when freely movable inwards, the latch bolt will be forced inwards into the casing 10 when the door is closed, by virtue of the chamfered face of the bolt head engaging the keep in the normal manner, the bolt head thereafter, in its fully extended position, being received in the keep in the normal manner so as to hold the door closed and, as will be hereinbelow described, also deadlocked. From the drawings it can be seen that Figure 3 shows the latchbolt in its fully extended position, where the head 15 is nearly fully out of the casing 10, whilst Figure 4 shows the latchbolt in its fully retracted position with the bolt head 15 substantially fully received within the casing. Figure 1 shows an intermediate position where the bolt head is partly extended out of the casing, being held against full extension.

In connection with movement of the bolt, it will be noted that the front face of the casing 10 is provided with a rectangular slot, and at the inner one of the narrower edges thereof is pivoted an auxiliary bolt 17 which is biased by a coiled torsion spring 18 on one of the spigots 13 so as normally to have its head 19 extended out through the slot in the front of the casing 10, as shown in Figures 1 and 2, one straight end part of the spring 18 bearing on the auxiliary bolt 17 to create said biasing, whilst the opposite, straight end of

the spring bears against an interior side surface of the casing 10. From the Figures, it can be seen that the part of the bolt 17 which lies within the casing 10, and thus extends from the head 19 is in the form of a tail 20 for holding the latchbolt in its intermediate position, as shown in Figure 1, as will be described hereinafter.

There is also shown in Figures 1 and 2 a spring loaded snib 21 which is of conventional form, namely a push button operable from the exterior of the main face of the casing 10 to hold the latchbolt in its fully retracted state shown in Figure 2. Generally, when the snib is pushed in to the casing, it forms an abutment against which a forwardly biased lath 22 of the latchbolt engages, thereby preventing forward movement of the lath, and thus of the latchbolt head 15. However the snib forms no part of the present invention and will thus not be described further.

As can be seen from the drawings, the latchbolt lath 22 is of generally platelike form, having a tongue or the like at its front end welded or otherwise secured to the latchbolt head so that there is a single latchbolt assembly comprising the head and lath. As can be seen from the drawings, a cylindrical column 23 is upstanding in the casing 10, and around this is received a coiled torsion spring 24 which is considerably stronger than the spring 18 which biases the auxiliary bolt 17. One elongated end of this spring 24 bears upon the bolt head 15, whilst the other end of the spring 24 bears against the interior of a side of the casing, with the result that this spring 24 biases the latchbolt assembly towards its fully extended position shown in Figure 3. Accordingly in its fully retracted position shown in

Figure 2, the force of the spring 24 is acting on the bolt head 15 to urge the latchbolt assembly to its Figure 3 position.

Although, as stated, the bolt lath 22 is of generally plate-like form, its end remote from the bolt head 15 is formed with a respective pair of perpendicularly disposed feet 25,26 at opposite sides of the lath 22, the feet extending to and engaging with respective guideways 27,28 formed on the interior surface of the part of the casing 10 which forms the main outer side of the nightlatch, in use, these guideways being linear so that the engagement of the feet 25,26 therewith serve to guide the linear movement of the latchbolt assembly as its head 15 extends out of and retracts into the casing 10 as described above. Moreover, as will be described, retraction of the bolt . assembly into the casing is by way of operation of an exterior handle 29 causing movement of a handle cam 30 which engages one or other of the feet, thereby retracting the latchbolt assembly.

As can be seen from the Figures, the plate-like part of the lath 22 has a central longitudinal slot 31, with the respective sides and end of the slot being configurated as will be described.

Basically at its inner closed end, which is nearest the bolt head 15, the slot is semi-circular as at 31a, leading to a pair of spaced parallel short edge surfaces 31b, 31c, at respective opposite sides of the slot. At the end of these surfaces 31b, 31c, the lath is provided with a pair of normal short cuts 31d, 31e, to permit respective curved edge surfaces 3lf, 31g at opposite sides of the slot to be displaced out of the general plane of the lath in a direction towards the interior surface of the casing on which the guideways 27,28 are

formed. The surfaces 31f, 31g, are curved inwardly away from the semicircular part 3 la of the slot 31, so that the parallel sided slot defined at and between the respective opposite narrower parts of the surfaces 31f, 31g, is of a width which is less than the slot 31 defined by the semi-circular part 31a and the remainder of the surfaces 31f, 31g. This parallel sided slot 31h is defined between respective opposite lath side surfaces 31j, 31k, the sides of this slot 31h forming a ramp from the level of the surfaces 31f, 31g to a level at the opposite side of the plane of the plate-like lath where the slot 31h widens at its respective opposite sides by way of a pair of respective arcuate edge surfaces 311.31m which lie at the open end of the slot 31 as best shown in Figures 2 and 3.

Figure 4 shows how the semi-circular slot 31a is in the plane of the lath 22 which plane is denoted generally by the level X marked in Figure 4. With reference to this level it can be seen that the surfaces 31f, 31g are above this level X, as viewed in Figure 4, for one of the sides, Figure 4 also showing how the ramp is formed by the slot 31h being angled downwardly, as viewed in Figure 4, from the surfaces 31f, 31g, so that with the end of the ramp being below the level X, the surfaces 311,31m (only one shown), are also below this level X. As will be explained, the configuration and orientation of the slot surfaces and sides, particularly the ramp, serve to guide and control a deadlocking element of the nightlatch.

As mentioned above, the casing has pivotally mounted thereto an operating member in the form of a handle 29 which is exterior to the casing at the main face thereof which is outermost in use and which is thus readily accessible to a user of the nightlatch at the inner face of the door at which the nightlatch is

disposed. The handle 29 has a generally cylindrical part 32 extending through the casing into the interior thereof, suitable bearing means being provided to allow for the handle 29 to be pivotally mounted to the casing as described. This cylindrical part 32 carries around part of its circumference the handle cam 30 previously mentioned, this being in the form of oppositely extending arms 30a, 30b respectively, these, as described, being arranged to face the feet 26,25 respectively, so that, as described, when the handle 29 is angularly turned in one direction or the other one of the arms 30a, 30b will engage its respective associated one of the feet so as to attempt to move the latchbolt assembly against its biasing spring 24 in a direction to retract the latchbolt head 15 into the casing 10.

Extending centrally axially through the cylindrical part 32 of the handle 29 which extends into the interior of the casing 10 is a push-button deadlocking spindle 33. As can be seen best from Figures 4 and 7, this spindle is axially movable within a circular-section bore 34 extending through the cylindrical part 32 of the handle 29. At its outer end, i. e. at the exterior operating part of the handle 29, the bore 34 has its largest diameter portion 34a, this portion leading via a step to a reduced diameter portion 34b. At the bottom of the portion 34b, as viewed in Figure 4, there is a further inwards step to the narrowest portion of the bore, this portion 34c being only slightly larger than the diameter of the spindle 33 passing therethrough. However respective opposite radial slots extend from portion 34c of the bore to allow passage therethrough of respective opposite ends of a circular pin 35 which extends radially through the spindle 33 with the opposite ends of the pin extending equally at opposite sides of the spindle. With the orientation shown in Figure 4, the bore 34 is stepped outwardly from the portion 34c to increase its

diameter up to that of the portion 34b, and this portion 34d extends to the open end of the bore 34 at the bottom of the cylindrical part 32 as viewed in Figure 4.

As described above, the spindle 33 is of generally constant circular crosssection, but does have two radially enlarged portions as will be described. At its one end it has fitted thereon a push button cap 36, this cap being secured on to the end of the spindle 33 and being slidable within the portion 34a of the bore 34 so that application of force to the cap 36 will move the spindle 33 downwardly in the bore 34 in the orientation viewed in Figure 4. At a position spaced slightly inwardly from its opposite end, the spindle 33 is formed with an annular radial extension or land 37 which all the way therearound has its upper and lower side surfaces chamfered at their outer periphery. Spaced inwardly along the spindle 33 from said land 37 is a further land 38 which extends radially outwardly for the same distance as the land 37 but which is of greater axial extent and is of outwardly cylindrical form so as to have its outer side surface straight. This land 38 has a diameter substantially matching that of the portion 34d in which it is slidably received.

As can be seen from Figures 4 to 7 and also partly from Figure 8, a coiled compression spring 39 is received around the spindle 33 in the portions 34a and 34b of the bore 34 between the cap 36 and the bottom surface of the portion 34b, with a further coiled compression spring 40 being received around the part of the spindle 33 within the portion 34d of bore 34, between the upper surface of the portion 34d and the further land 38. In this way the spindle is biased to a rest position shown in Figure 4, where the land 37 is at level X of the bolt lath as shown. When the spindle moves axially, as will be described, the end of one of the springs 39 or 40 adjacent the pin 35 is

engaged thereby, depending on the direction of spindle movement, to compress said one of the springs.

Whilst a push button, such as cap 36, is a convenient means of axially depressing the spindle 33, other means could be employed to effect such axial movement thereof. For example a slidable button could cause axial sliding spindle movement, as could a squeezable member.

As best shown in Figures 5 and 6, the bolt lath 22 carries a bolt-lath trigger 41 at a position next to the area of foot 25 and adjacent the open end of the slot 31. Basically the trigger has a flat part 42 pivotally mounted to the platelike lath at the side thereof facing away from the interior surface of the casing at which the guideways 27,28 are formed. This flat part 42 has a leg 43 upstanding therefrom towards the backplate of the nightlatch, for engagement, in use, with a backplate cam assembly 44 movement of which is controlled by a lock mechanism associated with the nightlatch and disposed at the opposite, i. e. outer, face of the door to which the nightlatch is fitted. An extension from the flat part 42 extends through an opening in the lath to a plate 45 which pivots with the flat part 42 when this is moved by the leg 43 being engaged by the cam assembly 44. The plate 45 which is substantially parallel to the plane of the lath 22 has an ear 46 which upstands therefrom in a direction towards the backplate of the nightlatch, and which also extends in a direction outwardly from one edge of the plate 45. The plate 45 has a finger 47 on which is fitted one end of a coiled compression spring (not shown), the other end of which is engaged against the foot 25 so as to bias the trigger 41 to the position shown in Figure 5 where in the fully extended position of the latchbolt, the ear 46 engages against the one of the chamfered

surfaces of the land 37 which faces the further land 38, thereby holding the land 37 at the level of the surfaces 311,31m, at which level the land 37 cannot pass through the slot 31h, thereby deadlocking the latchbolt assembly in its fully extended position.

Figure 6 shows the effect of the backplate cam assembly 44 engaging the leg 43 and causing it to pivot against its spring bias. As can be seen from Figure 6, the pivoting of the part 42 causes corresponding pivoting of the plate 45 which moves the ear 46 from its engagement with the land 37 so that, as will be described hereinafter, the deadlocking is then removed.

Finally with regard to the structure of the nightlatch, it will be noted that Figures 5,6 and 8 show the backplate cam assembly 44. It can be seen that this comprises a cylindrical member 48 which has a circular opening 49 therethrough which has therein a pair of opposing triangular projections 50a, 50b to engage at respectively oppositely directed side faces thereof an operating bar (not shown) of lock means mentioned above and disposed in use at the opposite side of the door from that at which the operating handle 29 is located. Normally the operating bar will be at the end of a pin tumbler cylinder lock, so that key operation of the lock will turn the bar and thus rotate the cylindrical member 48 of the backplate cam assembly 44, thereby angularly moving a finger 51 fixed to the cylindrical member 48. As mentioned above, angular movement of this finger 51 in one direction will engage the leg 43 and pivot the part 42 of the trigger 41 thereby releasing the ear 46 from the land 37 of the spindle 33 to remove deadlocking. Further rotation of the cylindrical member 48 causes the end of the finger 51 to engage an associated upstanding end of a pair of upstanding ends 25a, 26a

respectively of the bolt lath, these lying at the opposite side of, but in the same plane as, the feet 25 and 26. Such rotation of the finger 51 thus effects movement of the latchbolt assembly and thus of the latchbolt head into the casing 10 to retract the bolt. Figure 8 shows an upstand 52 at the periphery of the member 48 which extends through the finger 51 and, as will be described, in a particular rotational position of the backplate cam assembly 44 lies over the end of the spindle 33 remote from its push button cap 36 thereby to prevent deadlocking of the nightlatch being disengaged from inside of the door.

Before describing operation of the nightlatch, some basic functions of the described components will firstly be referred to.

As far as the latchbolt assembly is concerned, it will be noted that this is biased towards its extended position by the spring 24. The auxiliary bolt 17 pivots around axis Z-Z shown in Figure 1 and is activated as the door is closed by the keep 12 pushing on the auxiliary bolt head 19, the auxiliary bolt being returned to its outwardly extended position by the bias of the spring 18.

When the auxiliary bolt is in the position shown in Figure 1, i. e. when the door is open, it prevents the latchbolt assembly fully extending. However when it has pivoted to its retracted position shown in Figure 3, it allows the latchbolt assembly to move to its fully extended position. This will be the case when the door is closed, so that the fully extended latch bolt is received within the keep 12. The deadlock spindle 33 is centrally biased by springs 39 and 40 acting on the spindle pin 35 when the spindle 33 is moved inwardly or outwardly from its Figure 4 position so that the land 37, if allowed, will always return to the level X of the latchbolt assembly. The bolt-lath trigger

41 is normally in the position shown in Figures 3 and 5 in which it is held by the trigger spring referred to. It is moved to its Figure 6 position by the finger 51 of the backplate cam assembly acting on leg 43 of the bolt-lath trigger. Finally the bolt-lath 22 is withdrawn to its fully retracted position shown in Figure 2 by rotating the handle 29 clockwise or counter clockwise, this rotating the handle cam 30 which engages an associated one of the feet 25,26 of the latchbolt lath, thereby pulling the latchbolt assembly rearwardly.

In operation, with the latchbolt fully thrown as in Figure 3, the deadlock spindle 33 will be positioned so that its land 37 will rest against the ear 46 of the trigger 41. This ear thus holds the spindle from returning to its Figure 4 position where the land 37 is at level X. Accordingly with the trigger 41 as described, the land 37 is held at the level of the surfaces 311,31m so that, as shown in Figure 3, the left side part of the annular land tightly engages against the arcuate surfaces 311,31m thereby preventing the latchbolt assembly from being pushed back, i. e. in its retraction direction.

Accordingly in this state shown in Figure 3 the latchbolt is deadlocked.

From this deadlocked position there are two ways of removing the deadlock and pulling back the latchbolt.

Firstly it is possible to depress the push button cap 36 from the interior of the door, this moving the spindle 33 to its Figure 7 position, thereby disengaging it from the surfaces 311,31m. With the push button cap 36 still depressed, the handle can then be turned clockwise or anticlockwise so as to pull back the latchbolt assembly as described above. This brings the side surfaces 31j,

31k of the ramp under the land 37, the surfaces being above the land 37 as viewed in Figure 7. Once this process begins, however, the push button cap 36 can be released in that the continued angular movement of the handle will now continue with the spring bias on the spindle 33 causing the land 37 to move along the ramp surfaces which face the backplate. The level of the land continues to move towards the level X shown in Figure 4 until this is reached at the bottom of the ramp surfaces, so that continued retraction of the latchbolt brings the land 37 to the semi-circular part 31a of the slot 31 as shown in Figure 4, with the latchbolt now fully retracted.

The other way of overcoming the deadlocking is by an operation from the opposite, i. e. the outer, side of the door. As described, key operation at said opposite outer side will angularly move the cylindrical member 48 of the backplate cam assembly 44, and angular movement of the member 48 in a clockwise direction will first cause the finger 51 to push on the leg 43, thereby rotating the trigger from its Figure 5 to its Figure 6 position. In the Figure 5 position the trigger holds the land 37 at the surfaces 311,31m as described above. When the trigger is released by the action of the finger 51 pressing on the leg 43, the ear 46 moves out of engagement with the land 37 thereby allowing the spring bias on the spindle 33 to move it to a position where the land 37 is disposed at the underside of the ramp surfaces which face away from the backplate. In this released position, the land is at the level X-X. However as the key rotation continues and the finger 51 draws back the latchbolt lath as described above, the ramp surfaces act on the land 37 to move the spindle in the opposite direction from that described above where the deadlock is released from the inside of the door, so that the push button cap 36 extends outwardly from its Figure 4 position as the spindle

moves upwardly as viewed in that Figure. As the backplate cam assembly angular movement continues, the latchbolt is withdrawn from the keep into its fully retracted state thereby allowing the door to open.

As this retraction of the latchbolt assembly continues, the land 37 runs along the ramp surfaces as described until the land reaches the part circular aperture defined by the sides 31f, 31g, at which point, since the aperture defined is larger than the diameter of the land 37, the spindle jumps back to level X shown in Figure 4, and remains at this level when it is received in the semi-circular slot part 31a upon full retraction of the latchbolt.

When the bolt assembly is released from its fully retracted state described above, i. e. whether the deadlock has been removed from the inside or the outside of the door, there are then two possible occurrences.

Firstly if the door is closed and the auxiliary bolt is depressed to its position shown in Figure 3, the latch bolt assembly will return to its fully extended Figure 3 position. As it does the land 37 will run along the ramp surfaces 31j, 31k and drop into the aperture defined between the arcuate surfaces 311, 31m, in an attempt to return to level X shown in Figure 4. However the trigger prevents it returning to this level and holds it in the position shown in Figure 3 which, as previously described, now again deadlocks the latchbolt and prevents it from being pushed back.

If however the door is open when the bolt assembly is released from its fully retracted position, the auxiliary bolt will be in the position shown in Figure 1. Accordingly a turned-down side portion of the lath 22 will contact the tail

of the auxiliary bolt thereby holding the bolt lath in the position shown in Figure 1 where the latchbolt is partly extended out of the casing. As this happens the land 37 will run along the ramp surfaces 31j, 31k but will stop short of dropping into the aperture defined by the arcuate surfaces 311,31m.

Accordingly in this state the latch bolt is still free to be pressed rearwardly, i. e. in its retracted direction, so that the bolt is not deadlocked. This allows the door to be slammed, whereupon the bolt will be pushed back by the keep, the keep also pivoting the auxiliary bolt, so that on full closing the latch bolt will fully extend out of the casing and the automatic deadlocking previously referred to will again become effective, this being releasable from either inside the door by operation of the push button within the handle, or by key operation from outside of the door so as angularly to move the cylindrical member 48.

A further feature of this nightlatch is the provision for the release of the deadlocking from the interior to be prevented, this facility being provided at the outside of the door in conjunction with the lock means previously mentioned.

Reference has been made above to angular movement of the cylindrical member 48 in one direction (clockwise) to cause the finger 51 associated therewith to engage the leg 43 to pivot the trigger and disengage the deadlocking. However if the plug of the lock cylinder is angularly moved by operation of the key from the outside of the door, through one full turn counter-clockwise, with the door closed, the handle push button to disengage the deadlocking from the inside of the door, will be disabled. As the lock plug is turned through one full turn counter-clockwise, the backplate cam

assembly revolves through 270 using lost motion between it and the lock plug. As the central axis of the cylindrical member 48 and the central axis of the spindle 33 are relatively offset, this rotation of the cylindrical member 48 as part of the backplate cam assembly angular movement lines up the upstand 52 with the free end of the deadlock spindle 33, thereby preventing the deadlock spindle 33 from being depressed from the inside of the door.

Accordingly this prevents the deadlocking from being disengaged from the interior. Accordingly an intruder cannot exit through a door protected by such a nightlatch with the interior deadlocking release means deactivated as described. To allow the counter-clockwise movement of the finger, it will be noted from the Figures that the upstanding end 26a of the bolt lath is of a lower height than end 25a. Accordingly the finger 51 can pass over it when it moves angularly, rather than engaging it, as it does with end 25a to retract the latchbolt.

This reverse turn deadlock release inhibition forms the subject of our copending UK Patent Application No. (Our Reference M071892PGB).

Accordingly with the embodiment described, improved security is provided by the double action required to release the deadlock, namely operation of both the push button and also the handle rotation. This is also a child safety feature against inadvertent opening of the door by rotation of the handle alone. As far as the deadlocking mechanism is concerned, it is considered that the use of a slot in the bolt lath interacting with a deadlocking spindle is a particularly convenient arrangement. With regard to the reverse turn deadlocking, i. e. deactivation of the deadlock release from the interior, it is considered that this has a distinct advantage over conventional reverse turn

deadlocking, in that it does not rely on the strength of the lock cylinder and employs the full strength of the deadlocking.

Claims

CLAIMS 1. A lock for a wing movable between respective open and closed positions relative to a frame comprising a casing, a latchbolt operable to extend from or retract into said casing and being biased towards its extended position, an operating member arranged to be operable at one side of the wing, in use, to effect retraction of the latchbolt, lock means arranged, in use, for key operation at the other side of the wing for retracting the latchbolt, and a deadlocking element which is automatically actuated when the wing is closed into its frame, in use, with the latchbolt other than retained in its fully retracted state, such actuation of the deadlocking element deadlocking the latchbolt by holding it in its fully extended state against movement thereof towards its retracted position, retraction of the latchbolt from its deadlocked position requiring, at said one side of the wing, a double action of effecting movement of said deadlocking element generally normally to the direction of latchbolt movement to a release position, and additionally operating said operating member whilst said deadlocking element is at said release position.
2. A lock as claimed in Claim 1, wherein the deadlocking element is an axially slidable spindle.
3. A lock as claimed in Claim 2, wherein the spindle has a radial enlargement along part of its length which is engaged by part of a lath of the latchbolt in the actuated state of the spindle, thereby deadlocking the latchbolt.

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4. A lock as claimed in Claim 3, wherein the spindle is biased to a rest position where its radial enlargement is at a level spaced from that at which it is at when it is engaged by the latchbolt lath and deadlocks the latchbolt.
5. A lock as claimed in Claim 4, wherein once said spindle has moved to its release position, retraction of the latch bolt at said one side of the wing, in use, takes place with a radially non-enlarged part of the spindle being received in a slot in the latchbolt lath.
6. A lock as claimed in Claim 5, wherein as said latchbolt is retracted said radial enlargement on the spindle travels along a ramp section, whereby the spindle moves axially towards its rest position.
7. A lock as claimed in Claim 6, wherein at the end of its travel along the ramp section, the spindle is in its rest position.
8. A lock as claimed in Claim 7, wherein in its rest position at the end of its travel along the ramp section the radial enlargement is received in a partly correspondingly shaped end portion of the slot in the latchbolt lath.
9. A lock as claimed in Claim 8, wherein an end of the ramp section nearest said end portion of the slot terminates at a slot section which is at the opposite side of the latchbolt lath from that at which the other end of the ramp section is disposed.

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10. A lock as claimed in any one of Claims 5 to 9, wherein in its actuated, deadlocking position, the spindle is prevented from moving to its rest position by said radial enlargement on the spindle engaging part of a trigger.
11. A lock as claimed in Claim 10, wherein the trigger is pivotally mounted on the latchbolt lath.
12. A lock as claimed in Claim 11, wherein the trigger is biased to a position where part thereof is in the path of axial sliding of said spindle.
13. A lock as claimed in any one of Claims 1 to 12, wherein the operating member has a part thereof joumalled in the casing for angular movement, and the deadlocking element is arranged for sliding movement along the axis of angular movement of the operating member.
14. A lock as claimed in Claim 13, wherein the deadlocking element is slidable within a bore extending through part of the operating member.
15. A lock as claimed in Claim 14, wherein the deadlocking element is biased to a rest position by respective coiled compression springs around respective cylindrical sections thereof at opposite sides of a peg extending radially from the element.
16. A lock as claimed in Claim 15, wherein in its rest position, the peg is within a stepped down part of said bore in the operating member, and each of the springs has one of its ends respectively engaging a respective one of the surfaces formed at opposite sides of the stepped down part of the bore.

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17. A lock as claimed in any one of Claims 13 to 16, wherein the operating member is a manually turnable handle and the deadlocking element is a spindle having on an end thereof a push button which is actuatable from the exterior of the handle.
18. A lock as claimed in Claim 17, wherein pressing the push button inwards of the handle moves the spindle to a release position thereof, so that with the button held depressed turning of the handle commences retraction of the latchbolt.
19. A lock as claimed in Claim 18, wherein once said retraction has begun, the push button can be released without affecting continued retraction of the latchbolt.
20. A lock as claimed in Claim 10, wherein in its actuated, deadlocking position, movement of the spindle to a release position where it no longer prevents latchbolt retraction is possible by moving the spindle inwardly so that it slides in a bore in part of the operating member, thereby then allowing angular movement of the operating member to retract the latchbolt.
21. A lock as claimed in Claim 12, wherein key operation of the lock means can effect release of the trigger, thereby allowing the deadlocking spindle automatically to slide to its rest position and allow retraction of the latch bolt from said other side of the wing.

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22. A lock as claimed in Claim 21, wherein said key operation of the lock means can effect angular movement of a cam assembly carried by a backplate of the casing, such angular movement effecting said release of the trigger and thereafter retraction of the latchbolt.
23. A lock as claimed in Claim 21 or Claim 22, wherein as the latchbolt is retracted with said spindle originally in its rest position, said radial enlargement travels along said or a ramp section to slide the spindle axially so that its radial enlargement reaches a level spaced from that at which it is at when the spindle is in its rest position, further retraction of the latchbolt allowing the spindle to spring to its rest position when it reaches a part of said slot in the latchbolt lath through which said radial enlargement can pass.
24. A lock as claimed in any one of Claims 1 to 23, wherein an auxiliary bolt is pivotally carried by the casing, the auxiliary bolt being biased so as normally to have a part thereof extending from the face of the casing at which a head of the latchbolt extends when the wing is in its open position, in use, so as to hold the latchbolt in a partly extended position.
25. A lock for a wing movable between respective open and closed positions relative to a frame comprising a casing, a latchbolt operable to extend from or retract into said casing and being biased towards its extended position, the latchbolt having a head and a lath secured thereto, an operating member arranged to be operable at one side of the wing, in use, to effect retraction of the latchbolt, lock means arranged, in use, for key operation at the other side of the wing for retracting the latchbolt, a deadlocking element which is automatically actuated when the wing is closed into its frame, in

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use, with the latchbolt other than in its fully retracted state, such actuation of the deadlocking element deadlocking the latchbolt by holding it in its fully extended state against movement thereof towards its retracted position, and the latchbolt lath having a configurated aperture therein to control movement of the deadlocking element during latchbolt retraction and extension.
26. A lock as claimed in Claim 25, wherein said aperture is a elongated slot.
27. A lock as claimed in Claim 26, wherein the slot is disposed centrally of the bolt lath.
28. A lock as claimed in Claim 26 or Claim 27, wherein the slot is open at its end remote from the head of the latchbolt secured to said latch.
29. A lock as claimed in Claim 28, wherein respective opposite edge surfaces of said slot at said open end thereof are shaped to engage corresponding edge surfaces respectively of a radial enlargement of a generally cylindrical shaft constituting said deadlocking element, thereby to deadlock the latchbolt.
30. A lock as claimed in Claim 29, wherein the other end of the slot is closed and at a level spaced from the level at which said open end of the slot is disposed.
31. A lock as claimed in Claim 30, wherein a parallel sided part of the slot extends from said edge surfaces at said open end of the slot, said part sloping

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from the level of said open end of the slot, which level is spaced from one side of a main part of the lath, to a level spaced from the opposite side of said main part of the lath, respective opposite side surfaces of said parallel sided slot defining a ramp section at both sides of said main part of the lath, and the width of said parallel sided slot preventing passage therethrough of said radial enlargement.
32. A lock as claimed in Claim 31, wherein at the end of said parallel sided slot part spaced from the open end of the slot, there is a slot portion having its respective opposite sides of corresponding shape to said radial enlargement and being wider than said parallel sided slot part, to allow passage of said radial enlargement therethrough to lie at said level of said closed end of the slot.
33. A lock as claimed in any one of Claims 29 to 32, wherein the radial enlargement is an annular collar on said shaft.
34. A lock as claimed in any one of Claims 29 to 33, wherein the shaft is biased to a rest position where its radial enlargement is at a level spaced from that at which it is disposed when it is engaged by said edge surfaces at the open end of the latchbolt lath.
35. A lock as claimed in Claim 34, wherein the shaft is axially slidably movable to a respective release position from its actuated deadlocking position from either side of the wing.

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36. A lock as claimed in Claim 35, wherein once the shaft has been moved to a release position from said one side of the wing, retraction of the latch bolt can take place, in use, with a radially non-enlarged part of the cylindrical shaft being received through said parallel sided part of the slot in the latchbolt lath.
37. A lock as claimed in Claim 36, wherein whilst the shaft is received in said parallel sided slot, said radial enlargement travels along said ramp section at one side of the latchbolt lath, whereby the shaft moves axially towards its rest position.
38. A lock as claimed in Claim 36, wherein at the end of its travel along said ramp section, the radial enlargement is at said level of the closed end of the slot and upon full retraction of the latchbolt is in engagement with said closed end, corresponding to the rest position of the shaft.
39. A lock as claimed in Claim 37, wherein in its actuated, deadlocking position, the shaft is prevented from moving to its rest position by said radial enlargement thereon engaging part of a trigger.
40. A lock as claimed in Claim 39, wherein the trigger is pivotally mounted on the latchbolt lath.
41. A lock as claimed in Claim 40, wherein the trigger is biased to a position where part thereof is in the path of movement of said shaft.

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42. A lock as claimed in any one of Claims 39 to 41, wherein movement

of the shaft to a release position from the other side of the wing can be t : l effected by key operation of the lock means to effect release of said trigger.
43. A lock as claimed in Claim 42, wherein said key operation can effect angular movement of a cam assembly carried by a backplate of the casing, such angular movement effecting release of the trigger and thereafter retraction of the latchbolt.
44. A lock as claimed in Claim 42 or 43, wherein as the latchbolt is retracted with said shaft originally in its released, rest position, said radial enlargement travels along said respective side surfaces of said ramp section at the opposite side of the latchbolt lath to slide the shaft so that its radial enlargement reaches a level spaced from that at which it is disposed when the shaft is in its rest position, further retraction of the latchbolt allowing the shaft to spring to its rest position when it reaches said slot portion wider than said parallel sided slot part, whereupon said radial enlargement passes therethrough to lie at said level of said closed end of the slot.
45. A lock as claimed in Claim 37, wherein from whichever side of the wing the shaft is moved to a release position and the latchbolt fully retracted, subsequent extension of the latchbolt to its fully extended position takes place with the shaft moving from its rest position to its deadlocked position, and the radial enlargement thus travelling along the respective side surfaces of the ramp section at said one side of the latchbolt lath.

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46. A lock as claimed in any one of Claims 25 to 45, wherein the operating member is a pivotable handle.
47. A lock as claimed in any one of Claims 25 to 46, wherein the deadlocking element is actuated by a push button.
48. A lock substantially as hereinbefore described, with reference to, and as shown in the accompanying drawings.