AU2023201126B1

AU2023201126B1 - A Lock

Info

Publication number: AU2023201126B1
Application number: AU2023201126A
Authority: AU
Inventors: Rakesh Murali
Original assignee: Allegion New Zealand Ltd
Current assignee: Allegion New Zealand Ltd
Priority date: 2023-02-24
Filing date: 2023-02-24
Publication date: 2024-05-02
Anticipated expiration: 2043-02-24

Abstract

A problem is that when the lock is used with a door requiring greater extension of the deadbolt, it takes more than one rotation of a key in a cylinder to return the deadbolt to its fully retracted position. It is an object of a preferred embodiment of the invention to go at least some way towards addressing this. The invention is a lock comprising a casing 1, a deadbolt 3, a cam 5, and a cam follower 6 having a first leg 7 and a second leg 8. The cam 5 can be moved rotationally so that it passes beneath the first leg 7 to drive the deadbolt 3 from a start position to an extended position. The cam 5 can then turn away from the second leg 8 in the same rotational direction to engage the first leg 7 to drive the deadbolt 3 to a more extended position. The cam 5 can then be moved by hand force in an opposite rotational direction so that it turns away from the first leg 7 to come around to engage and push against the first leg 7 to drive the deadbolt 3 back to the start position.

Description

TITLE

A Lock

FIELD OF INVENTION

This invention relates to a lock, and preferably to a mortice lock.

BACKGROUND

It is known to use mortice locks having both a latch and a deadbolt to secure a door. It is also known for these to provide for more than one extension position for the deadbolt so as to accommodate door jambs of greater or lesser depth. A problem is that when the lock is used with a door requiring greater extension of the deadbolt, it takes more than one rotation of a key in a cylinder to return the deadbolt to its fully retracted position. It is accordingly an object of a preferred embodiment of the invention to go at least some way towards addressing this problem. However, it should be understood that the object of the invention per se is not so specific and is simply to provide the public with a useful choice.

DEFINITIONS

The term "comprises" or "has", if and when used in this document in relation to one or more features, should not be seen as excluding the option of there being additional unmentioned features. The same applies to derivative terms such as "comprising" and "having".

Orientational terms such as those conveying upwards or downwards positions or movement apply to the normal in use disposition of the lock.

SUMMARY OF THE INVENTION

According to a first aspect, the invention is a lock comprising: • a casing; * a deadbolt; * a cam; and * a cam follower having a first leg and a second leg; the lock being such that the cam can be moved by hand force in a rotational direction so that:

o the cam passes beneath first leg to engage and push against a side of the second leg to drive the deadbolt from a start position to an extended position; and o the cam then turns away from the second leg in the same rotational direction until it engages the first leg to drive the deadbolt to a more extended position; the lock also being such that the cam can then be moved by hand force in an opposite rotational direction so that: o the cam turns away from the first leg to come back around to reengage and push against the first leg to drive the deadbolt back to the start position.

Optionally the lock has a key cylinder that incorporates the cam, the cylinder having a neutral disposition which allows a key to be inserted into the cylinder, wherein starting with the cylinder in the neutral disposition the key can be turned in the cylinder by one, or by less than one, revolution to drive the cam to move the deadbolt from its more extended position to its start position.

Optionally the key turn that moves the deadbolt from its most extended position to its start position involves less than a % revolution of the key and cam.

Optionally the key turn that moves the deadbolt from its most extended position to its start position involves a 2500- 270° turn of the key and cam.

Optionally, starting with the cylinder in the neutral disposition, the key can be turned in the cylinder about 1% revolutions to drive the cam to move the deadbolt from its start position to its more extended position.

Optionally the key turn that moves the deadbolt from its start position to its most extended position involves a 540°- 570 turn of the key and cam.

Optionally the cam follower is spring biased downwards.

Optionally the cam follower is adapted to move as least partially within the deadbolt.

Optionally the lock has a locking lug adapted to move at least partially within the deadbolt and which is spring biased downwards, the locking lug having a first arm adapted to be moved by the cam to as a consequence move a second arm of the lug between steps of a castellation in the casing, wherein at least some of the steps correspond with and assist in retaining the deadbolt in its extended and start positions respectively.

Optionally the deadbolt comprises a ramp (eg a second ramp) which, as the deadbolt moves to either of its extended positions, pushes a locking bar into a recess of the latch to lock the latch in an extended position, but wherein movement of the deadbolt into the start position causes the locking bar (which is preferably spring loaded) to withdraw from the recess to unlock the latch (eg and return to its bottom position).

Optionally the lock comprises a hub engaged with both a spindle and a hub plate, the spindle also being engaged with a door handle, the lock being such that when the latch is unlocked the handle can be turned by hand to cause the spindle to rotate such that a cam of the hub plate drives the latch inwards with respect to the casing.

Optionally the latch is spring biased towards an extended position corresponding to the position it would have when in use extending into a doorjamb.

Optionally the lock comprises a locking bar (eg a second locking bar) having a protrusion (eg a stud) arranged to ride along a ramp of the deadbolt as the deadbolt moves between its starting and extended positions to move this locking bar between upper and lower positions, wherein when in the upper position that locking bar can be driven by the cam to retract the latch and, when in the lower position, that locking bar is out of the rotational path of the cam.

Optionally the lock comprises a plate having a ramped recess, wherein a further protrusion (eg a stud) of the deadbolt is arranged to run along the ramped recess to cause the plate to assume raised and lowered positions when the deadbolt is in its start and extended positions respectively, the arrangement being such that when the plate is in its raised position it is adapted to be moved further upwards by a hand day latch handle to lock the hub against rotational movement.

According to a second aspect, the invention is a lock comprising: • a casing; * a latch; * an upper connector comprising a threaded portion, a gear rack and a magnet; * an upper shoot bolt comprising a threaded portion and a magnet; * a lower connector comprising a threaded portion, a gear rack and a magnet; * a lower shoot bolt comprising a threaded portion and a magnet; * a hub; * a gear wheel;

* at least one handle associated with the hub; the lock being formed such that if during its installation:

o the upper shoot bolt is manoeuvred proximate the upper connector then the magnets of each of these parts will cause their threaded portions to come together in at least substantial alignment such that subsequent rotation of the upper shoot bolt causes those threaded portions to engage in a screw fit;

o the lower shoot bolt is manoeuvred proximate the lower connector then the magnets of each of these parts will cause their threaded portions to come together in at least substantial alignment such that subsequent rotation of the lower shoot bolt causes those threaded portions to engage in a screw fit;

the lock being further formed such that when installed in a door the handle is able to be turned by hand to cause rotation of the hub to move one of the connectors between thrown and retracted positions such that the rack of that connector causes the gear wheel to rotate to in turn cause the rack of the other connector to move that other connector between thrown and retracted positions respectively, wherein such movement of the connectors causes the shoot bolts to move simultaneously, vertically, between thrown and retracted positions to respectively lock and unlock the door.

Optionally the gear wheel is mounted o, and is able to rotate with respect to, the hub.

Optionally the lock is formed such that when in use rotation of the handle is adapted to cause the hub (eg a cam thereof) to bear against one of the connectors (preferably the lower connector) to move that connector between its retracted and thrown positions and this causes the gear wheel to rotate to move the other connector between its retracted and thrown positions. Preferably this causes the connectors to assume their thrown positions.

Optionally the lock is formed such that when in use rotation of the handle is adapted to cause the hub to rotate a plate (eg a cam thereof) mounted on the hub to bear against one of the connectors (preferably the lower connector) to move that connector between its retracted and thrown positions and this causes the gearwheel to rotate to move the other connector between its thrown and retracted positions. Preferably this causes the connectors to assume their retracted positions.

Optionally the threaded portion of the upper connector is male threaded, and the threaded portion of the upper shoot bolt is female threaded.

Optionally the threaded portion of the lower connector is male threaded, and the threaded portion of the lower shoot bolt is female threaded.

Optionally the magnet of the upper connector is substantially flush with the most outer part of that connector's threaded portion.

Optionally the magnet of the upper shoot bolt is substantially flush with the most inner part of that shoot bolt's threaded portion.

Optionally the magnet of the lower connector is substantially flush with the most outer part of that connector's threaded portion.

Optionally the magnet of the lower shoot bolt is substantially flush with the most inner part of that shoot bolt's threaded portion.

Optionally the features of the locks of the first and second aspects of the invention are combined in one lock.

DRAWINGS Some preferred embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, of which

Figure 1a is a front side view of a mortice lock with its deadbolt retracted and its key cylinder in a neutral disposition;

Figure lb is a front side view of the lock when its deadbolt is about to be driven to an extended position;

Figure 2a is a further front side view of the lock when its deadbolt is about to be driven to the extended position;

Figure 2b is a front side view of the lock when its deadbolt is moving to a first extended position;

Figure 3a is a front side view of the lock when its deadbolt has reached the first extended position;

Figure 3b is a front side view of the lock when its deadbolt has reached a second extended position;

Figure 4 is a front side view of the lock when its deadbolt is about to be moved to a fully retracted position;

Figures 5-6 are isometric and end views showing detail of the deadbolt, cam follower and locking lug which form part of the lock;

Figure 7 is an isometric view showing detail of the locking lug;

Figure 8 illustrates the manner in which the locking lug engages a castellation in the lock's casing;

Figure 9 illustrates detail of the deadbolt, including a ramp thereof for moving a first locking bar;

Figure 10 illustrates detail of a latch retracting mechanism from the front side of the lock;

Figure 11 illustrates detail of the latch retracting mechanism from the rear side of the lock;

Figures 12-13 are isometric views showing a hub and hub plate forming part of the latch retracting mechanism;

Figures 14-15 are isometric views showing detail of the latch retracting mechanism and nearby parts;

Figures 16-26 are isometric views showing the lock when fitted with components for operating it with shoot bolts;

DETAILED DESCRIPTION

Referring to Figure 1a the lock is a mortice variety for use with a door or the like and has a casing 1, a latch 2, a deadbolt 3, and a key cylinder 4. The cylinder 4 has a cam 5 and the deadbolt is integral with or otherwise connected with a cam follower 6. Although the cam 5 is shown in Figure 1 for ease of reference, when in that rotational position it would be out of view. As also illustrated, the cam follower 6 has a first leg 7 and a second leg 8 with a recess between them.

A key (not shown) can be inserted into and turned in the cylinder 4 by hand when the lock is in the Figure 1 neutral position to rotate the cam 5 anti-clockwise towards the cam follower 6 as shown in Figure 1b. The purpose of this is to drive the deadbolt bolt 3 to an extended position. As illustrated in Figure 2a, the anticlockwise rotation causes the cam to swing under the first leg 7 to contact and push against the inner side of the second leg 8. This pushing continues until the deadbolt 3 is driven to its first extended position. Figure 2b shows the deadbolt on its way to the first extended position, and Figure 3a shows the deadbolt when at that position.

To move the deadbolt to a second position where it is fully extended, the anticlockwise movement of the cam continues under key turning to bring the cam 5 back around to its position shown in Figure 3a, to then contact and push against the outside of the cam follower's first leg 7. This pushing drives the deadbolt 3 to its fully extended position shown in Figure 3b. Therefore, from the neutral Figure 1 position the key is rotated through just over 1% turns (between about 540°- 570) to get the deadbolt 3 from a fully retracted position to a fully extended position. The key may then be turned clockwise to cause the cam 5 to assume its neutral Figure 1 disposition and removed.

To fully retract the deadbolt, starting in the Figure 1 position, the key is inserted and rotated clockwise initially away from (eg moving right of) the first leg 7 but then comes around to contact and push against the inside of the cam follower's first leg 7 as shown in Figure 4. This pushing continues to drive the deadbolt 3 to the fully retracted position shown in Figure 1b. Therefore, from the Figure 1a neutral position, the key only needs to be rotated clockwise about %of a full turn, or less (eg about 250° - 270°) to fully retract the deadbolt. The key can of course be further rotated clockwise to get it back to the Figure 1a position from which it can be removed. The lock is therefore such that the deadbolt 3 can be fully retracted from either of its extended positions and/or the key removed by one, or less than one, full key/cam rotation via the lock cylinder.

Referring to Figures 5 and 6, the cam follower 6 is spring biased downwards, eg towards the cylinder 4. Therefore, as the cam 5 pushes against the cam follower 6 it is able to move up and down a little but is retained in the deadbolt so that ultimately it cannot drop out of the deadbolt in use. This spring bias serves to keep the cam follower 6 in the optimal position for contact with the cam 5 when such contact is needed for driving the deadbolt.

Still with Figure 6, and also with reference to Figure 7, the deadbolt is fitted with a locking lug 9 set next to the cam follower 6. The lug 9 is also spring biased downwards and has a first arm 10 and a second arm 11. As illustrated, the second arm 11 is above and at right angles to the first arm 10. The arrangement is such that rotational movement of the cam 5 causes it to contact the lug's first arm 10 to move both arms 10, 11 vertically.

Referring to Figure 8, as the cam 5 causes the deadbolt 3 to move laterally between its retracted and extended positions, the second arm 11 of the lug moves through the steps of a castellation 12 formed in the casing. When the lug's second arm 11 is against castellation steps 13, 14 and 15, the deadbolt is in the fully retracted, first extended and second extended positions respectively. These castellation steps help to retain the deadbolt in the respective positions. As an alternative to step 14, the lug's second arm 11 may sit in step 14a for the first extended position.

Still with Figure 8, to move the deadbolt 3 laterally out of either of its extended positions 14, for return to the deadbolt's retracted position 13, the lug's second arm 11 must be raised out of the castellation steps corresponding to the extended positions. This is achieved by the cam 5 which pushes upwards on the lug's first arm 10 as the cam rotates. The cam 5 also serves to lift the lug in the same way out of the castellation step corresponding to the deadbolt's retracted position 13 when the cam is rotated in the opposite direction to extend the deadbolt.

Referring to Figure 9, and also to Figure 5, the end of the deadbolt 3 that remains inside the casing has an upwardly extending ramp 16. As the deadbolt 3 is driven to either of its extended positions, the ramp 16 engages the lower end of a latch locking bar 17 which rides along the ramp to an elevated position. This has the effect of placing an upper end of the locking bar 17 into a locking recess 18 (see Figure 11) of the latch 2 to prevent the latch from retracting. Therefore, whenever the deadbolt is thrown, the latch 2 is automatically deadlocked. However, as the deadbolt moves back to its fully retracted position the lower end of the locking bar 17 (which is preferably spring loaded) rides down the ramp 16 (preferably under the bias from the spring loading) to take up a lower position and free the latch 2 for retraction into the lock casing so that the door it is used with can open.

Referring to Figures 10-13, the lock comprises a hub 19 and a hub plate 20 arranged in parallel. When the lock is in use a spindle connected to a door handle (not shown) passes through a central aperture in the hub 19, and the hub plate 20 fits around and can partially rotate on a boss 19a (see Figure 12) of the hub.

The hub plate 20 has a lower cam 21a and an upper cam 21b, and the hub 19 has a single cam 22 arranged to move between these. The arrangement is such that when the door handle is turned, the spindle rotates in sympathy to initially cause only the hub 19 to rotate so that its single cam 22 rotates. This continues until a lug 23 part-way along the single cam 22 makes contact with the hub plate 20, to cause it to also rotate. The result is that the upper cam 21b of the hub plate swings against an inner wall of a recess 24 of the latch 2 to draw the latch into the lock's casing 1. In this way the door that the lock is used with can be opened with the turn of the handle, plus with a push or pull of the handle, depending on which side of the door one is on.

With further reference to Figures 10 and 11, the lock comprises a plate 25 arranged alongside the deadbolt 3. The plate has an internal ramped groove 26 which is engaged by a pin 27 extending outwards in the side of the deadbolt 3 (see Figures 6 and 10). As the deadbolt 3 moves to its extended positions the pin 27 rides along the groove from a position where the pin starts lower down in the plate and finishes higher up the plate. This causes the plate 25 to drop as the deadbolt 3 is extended. The plate 25 therefore has both raised and lowered positions.

Referring to Figures 14 and 15, when the plate 25 is in its raised position it can be slid further upwards by a hand operated day latch handle (not shown) protruding from the lock on the inside of the door. This upwards sliding causes an upstand 25a of the plate to block rotation of the hub 19. More particularly, when raised by the day latch handle, the upstand a sits in the path of rotation of a wing 19b of the hub 19 so that the hub cannot rotate to retract the latch 2 to open the door from the outside. This applies even when the deadbolt 3 is in its retracted position. To enable this, the day latch handle passes through an aperture in the lock's casing and fits into an aperture 25b of the plate. Further, the upward sliding of the plate 25 also drives the locking bar 17, which is preferably spring loaded, into its upward position, which puts the latch 2 into its locked state.

Referring again to Figures 14 and 15, the side of the deadbolt 3 opposite to the plate 25 has a downwards ramp 28 (see also Figure 5) which is engaged by a second locking bar 29 as the deadbolt 3 is extended. More specifically, As illustrated a pin 30 of the locking bar 29 sits on the top of the deadbolt 3 when the deadbolt is in its fully retracted position. After the cam 5 extends the deadbolt 3 to its first extended position, the cam continues rotation and contacts the top surface of leg 31 of the locking bar 29. Further rotation of the cam 5 moves the locking bar 29 into the lower position which is out of the cam's way for the next rotation to extend the deadbolt to the second extended position. The ramp 28 is for use when the deadbolt is retracted, in that it aids to lift the locking bar 29 into the path of the cam 5 so that further rotation of the cam (after retracting the deadbolt 3) allows the latch 2 to be retracted by the key. For the avoidance of doubt, as the locking bar does this it only moves vertically, not laterally. Subsequent retraction of the deadbolt 3 causes the pin 30 to ride back up the ramp 28 to restore the locking bar 29 to the position it had before being lowered.

The purpose of lowering the locking bar 29 is to place its lower end clear of the arc of the cam 5 as it swings, i.e. when the deadbolt 3 is in its extended positions. However, when the deadbolt is in its fully retracted position the locking bar 29 is in its higher position, being in the path of the cam 5 as it swings. Referring to Figure 15, when the locking bar is in this position, rotation of the cam 5 causes it to come around and up against the underside of a foot 31 of the locking bar 29 to drive the entire locking bar upwards. Referring to Figure 10, what this does is cause an upper ledge 32 of the locking bar 29 to push up against the lower cam 21a of the hub plate 20 to cause it to rotate. This rotational movement causes that hub plate's upper cam 21b to drive the latch 2 to a retracted position. Therefore, when the deadbolt 3 is in its retracted position, the latch 2 can be readily retracted for opening the door by a simple key turn, without having to grasp and turn the door handle. This may be particularly useful if for example there is no door handle on the outside of the door.

As illustrated in various of the above drawings, including Figures 14 and 15, the lock cylinder 4 is preferably of a type that can be turned by a key from the outside of the door, and in equivalent fashion by a turn handle 33 from the other side of the door inside a room or building.

Referring to Figures 16-26, if desired the lock may be fitted with upper and lower connectors 34, 35 for screw fitting shoot bolts 36 (shown in Figure 18). Each connector 34, 35 has a vertically extending gear rack 37 engaged with a common gear wheel 38 that is fitted onto the hub 19.

Referring to Figures 22 and 23, as the hub 19 is driven manually by a door handle (clockwise in Figure 23), it rotates the hub's cam 22 down against a seat 35a of the lower connector 35. This serves to push the lower connector 35 downwards into its thrown position. Because the gear racks 37 of the connectors are both meshed with the gear wheel 38, it means that as the lower connector 35 shifts downwards it synchronously causes the upper connector 34 to be driven upwards to its thrown position. The gear wheel 38 is not keyed into the hub 19a and it does not need to be for the connectors to move as described here.

To get the lower shoot bolt connector 35 to its retracted position (as shown in Figure 22), the lower cam 21a of the hub plate 20 is caused to rotate counter-clockwise (in Figure 23) to push up on a ledge (not shown) of the lower connector 35. This drives the lower connector upwards to retract it. Given that both connectors 34, 35 are meshed with the gearwheel

38 at opposite sides of that wheel, this shift of the lower connector 35 causes the upper connector 34 to automatically move downwards to its retracted position. As will be appreciated, this counter-clockwise motion of the lower cam 21a is driven by counter clockwise movement of the hub 19 and its lug 23 via the door handle.

Referring to Figures 16-19, each shoot bolt connector 34, 35 has a male threaded stub 34a, 34b for respectively engaging the shoot bolts 36 in a screw fit. The shoot bolts extend to engage upper and lower jambs (not shown) in a door frame in the normal way for more securely locking the door. Turning the door handle 39 clockwise, or upwards, as shown in Figure 18, throws the shoot bolts into a reversible locking position.

Referring to Figures 17 and 19, each connector 34, 35 incorporates an internally fitted magnet 40. These have the opposite pole to magnets at the lock connecting ends of the shoot bolts 36. The magnets help a locksmith when installing the lock as they manipulate each long shoot bolt 36 into a door cavity to get it into position where it can be turned to engage the screw thread of the respective connector 34, 35. The magnetic attraction between the complimentary female threaded end of the shoot bolt and the male threaded stub 34a, 35a of the respective connector helps to bring the shoot bolt into the correct position for screw fastening it with the connector. In alternative embodiments the connectors 34, 35 may have a female thread and the shoot bolts 36 may have a complementary male thread.

Figures 20 - 24 show the shoot bolt connectors 34, 35 from the various alternative angles together with surrounding components. Figures 25-26 illustrate the lock when fitted with the shoot bolts 36 as above, including the way magnets 40 are arranged internally of the connectors and shoot bolts respectively. As illustrated, the magnets 40 of the connectors are preferably about flush with the ends of the connectors. The magnet of each shoot bolt 36 on the other hand is inset from the end of the respective shoot bolt to allow space for screw tightening against the corresponding connector. Preferably the magnets are arranged so that when the shoot bolts are fully screw tightened against the connectors the magnets are, or are just short of, butting against one another. As illustrated, the magnet of each shoot bolt is significantly larger, and stronger, than that of the connector to enable a good magnetic pull between the magnets even before the screw threads of the shoot bolt engage those of the connector.

An additional advantage of the magnetic connection is that if the screw fit between a shoot bolt and a connector 34, 35 is under force to unscrew, for example due to vibration, that magnets 40 serve to resist this because, for example, the magnetic attraction in the vertical direction is stronger than the rotational force. While some forms of the invention have been described by way of example, it should be appreciated that modifications and improvements can be made without departing from the scope of the following claims.

In terms of disclosure, this document envisages and hereby posits any feature mentioned herein in combination with itself or any other feature or features mentioned herein, even if the combination is not claimed.

Claims

1. A lock comprising: • a casing; * a deadbolt; * a key cylinder comprising a cam; and * a cam follower having a first leg and a second leg; the lock being such that the cam can be moved by hand force in a rotational direction so that:

o the cam passes beneath first leg to engage and push against a side of the second leg to drive the deadbolt from a start position to an extended position; and

o the cam then turns away from the second leg in the same rotational direction until it engages the first leg to drive the deadbolt to a more extended position; the lock also being such that the cam can then be moved by hand force in an opposite rotational direction so that:

o the cam turns away from the first leg to come around to engage and push against the first leg to drive the deadbolt back to the start position;

the lock also being such that:

o the cylinder has a neutral disposition which allows a key to be inserted into the cylinder, wherein starting with the cylinder in the neutral disposition the key can be turned in the cylinder by one, or by less than one, revolution to drive the cam to move the deadbolt from its more extended position to its start position.

2. A lock according to claim 1, wherein the key turn that moves the deadbolt from its more extended position to its start position involves less than a % revolution of the key and cam.

3. A lock according to claim 1, wherein the key turn that moves the deadbolt from its more extended position to its start position involves a 2500 - 2700turn of the key and cam.

4. A lock according to claim 2 or 3, wherein starting with the cylinder in the neutral disposition the key can be turned in the cylinder about 1% revolutions to drive the cam to move the deadbolt from its start position to its more extended position.

5. A lock according to claim 4, wherein the key turn that moves the deadbolt from its start position to its more extended position involves a 540°- 570 turn of the key and cam.

6. A lock according to any one of the preceding claims, wherein the cam follower is spring biased downwards.

7. A lock according to any one of the preceding claims, wherein the cam follower is adapted to move at least partially within the deadbolt.

8. A lock according to any one of the preceding claims, comprising a locking lug adapted to move at least partially within the deadbolt and which is spring biased downwards, the locking lug having a first arm adapted to be moved by the cam to as a consequence move a second arm of the lug between steps of a castellation in the casing, wherein at least some of the steps correspond with and assist in retaining the deadbolt in its extended and start positions respectively.

9. A lock according to any one of the preceding claims, wherein the deadbolt comprises a ramp which, as the deadbolt moves to either of its extended positions, pushes a locking bar into a recess of a latch to lock the latch in a latch extended position, but wherein movement of the deadbolt into the start position causes the locking bar to withdraw from the recess to unlock the latch.

10. A lock according to claim 9, comprising a hub engaged with both a spindle and a hub plate, the spindle also being engaged with a door handle, the lock being such that when the latch is unlocked the handle can be turned by hand to cause the spindle to rotate such that a cam of the hub plate drives the latch inwards with respect to the casing.

11. A lock according to claim 9 or claim 10, wherein the latch is spring biased towards the latch extended position corresponding to a position it would have when in use extending into a doorjamb.

12. A lock according to any one of claims 9-11, comprising a second locking bar having a protrusion (eg a stud) arranged to ride along a downwards ramp of the deadbolt as the deadbolt moves between its starting and extended positions to move this second locking bar between upper and lower positions, wherein when in the upper position that second locking bar can be driven by the cam to retract the latch and, when in the lower position, that second locking bar is out of the rotational path of the cam.

13. A lock according to claim 12, comprising a plate having a ramped recess, wherein a further protrusion (eg a stud) of the deadbolt is arranged to run along the ramped recess to cause the plate to assume raised and lowered positions when the deadbolt is in its start and extended positions respectively, the arrangement being such that when the plate is in its raised position it is adapted to be moved further upwards by a hand day latch handle to lock the hub against rotational movement.

14. A lock according to any one of the preceding claims, formed such that when the cam comes around to engage and push against the first leg to drive the deadbolt from the more extended position back to the start position it does so without engaging the second leg.