GB2406610A - Lock with handle which variably moves levers - Google Patents

Abstract

A lock includes a bolt (4) movable between a locked position and an unlocked position, a plurality of levers (5) movable between blocking positions in which they prevent movement of the bolt from the locked position to the unlocked position and clear positions in which they allow movement of the bolt from the locked position to the unlocked position, and a keyhole into which a key is able to be inserted to move the levers (5) from the blocking positions to the clear positions and to move the bolt (4) from the locked position to the unlocked position. The amounts of movement of the levers (5) that are required to move the levers from the blocking positions to the clear positions vary from one lever to another. The lock further comprises a handle (6) which is movable from a first position to a second, releasing position, the handle (6) being arranged, upon movement from its first position to its second position when the bolt (4) is in the locked position and the levers (5) are in the blocking positions, to move the levers by the varying amounts required to move them from the blocking positions to the clear positions and to move the bolt from the locked position to the unlocked position. A latch member (9) when locked prevents movement of the handle (6) from the first position to the second position.

Description

- 1 - 2406610 Locks The invention relates to locks.

Whilst it is very desirable for locks to be secure it may also be important that a user of a lock can readily unlock it, for example to escape from a building in the case of a fire. It is therefore desirable to provide a lock which is secure but which can also be unlocked from the inside without the use of a key.

A particular issue arises in the case of what is commonly referred to as a lever lock, a lever lock being a lock including a plurality of "levers" and levers being defined herein as members shiftable when a key is turned in a lock to selected relative positions in which they collectively permit retraction of the bolt from its locked position to its unlocked position. The levers are commonly pivotable but may for example be slidable. The bolt may be a member of any form suited in a particular application and shiftable from a locked to an unlocked position. The drawings referred to below show a common form of bolt. In the case of a lever lock, if a quick release handle arrangement is to be provided in addition to the key system, then the handle arrangement is required to lift the levers to the same positions as the key. That can be accomplished by providing a lever lock in which the levers are of varying shapes which complement the key so that they are all shifted by equal amounts when the key is turned; it is then a relatively straightforward matter to arrange for - 2 there also to be a handle which, via another mechanism, can shift the levers as a block by the same amount as when the key is turned. Thus the bolt can be retracted quickly by operation of the handle which may be provided for example on the inside of an exterior door. Such an arrangement is, however, not especially secure since careful inspection of the levers through the keyhole can reveal the shapes of the levers, enabling the lock to be read and subsequently opened by illicit means.

A security issue arises if a handle is provided to allow retraction of the bolt without a key, especially but not only if there is a letterbox or breakable glass panel allowing an intruder to gain access to the handle. Thus, a conflict can arise between security considerations and safety considerations.

It is an object of the invention to provide a lever lock that is able to be secure but with a handle providing an alternative to a key for retracting the bolt.

It is a further object of the invention to provide a mortise lock with a bolt that can be retracted by operation of a key or a handle and yet can be secure.

According to a first aspect of the invention there is provided a lock including a bolt movable between a locked position and an unlocked position, a plurality of levers movable between blocking positions in which they prevent movement of the bolt from the locked position to the unlocked position and clear positions in which they allow movement of the bolt from the locked position to the unlocked position, a keyhole into which a key is able to be inserted to move the levers from the blocking positions to the clear positions and to move the bolt from the locked position to the unlocked position, the amounts of movement of the levers that are required to move the levers from the blocking positions to the clear positions varying from one lever to another, wherein the lock further comprises a handle which is movable from a first position to a second, releasing position, the handle being arranged, upon movement from its first position to its second position when the bolt is in the locked position and the levers are in the blocking positions, to move the levers by the varying amounts required to move them from the blocking positions to the clear positions and to move the bolt from the locked position to the unlocked position.

By making the amounts of movement of the levers that are required to move the levers from the blocking positions to the clear positions vary from one lever to another and arranging for the handle to move the levers by those varying amounts, it becomes possible to provide a lever lock that maintains its security but in which the bolt can be retracted by the handle.

In the United Kingdom, lever locks are most commonly mortise locks, although the invention may also be applied to rim locks.

In the lock defined above, it is stated that when the levers are in the blocking positions they prevent movement of the bolt from the locked position to the unlocked - 4 - position. In accordance with conventional design, the levers when in the blocking positions also preferably prevent movement of the bolt from the unlocked position to the locked position. Similarly, in accordance with conventional design, a key is preferably also able to move the levers from the blocking positions to the clear positions and to move the bolt from the unlocked position to the locked position. On the other hand, the handle need not be arranged to be able to move the bolt from the unlocked position to the locked position and in an embodiment of the invention described below it is not able to do so.

Where reference is made herein to a "handle" it should be understood that the term is to be construed widely as referring to any member that may be engaged by a user's hand to effect movement of it. The handle may therefore be a sliding member or a rotatable member. In a case where it is a rotatable member it may have a round part arranged to be grasped by a user's hand to rotate it, but preferably it is of generally lever form and is pivotable, preferably through an acute angle, to move it from its first position to its second position. Preferably the handle is resiliently biased into its first position.

In a preferred embodiment of the invention described below, the handle is mechanically coupled to the levers via a camming arrangement that engages the levers at locations spaced from the locations at which the levers are engaged when a key is operated. In an embodiment of the invention - 5 described below, the levers are pivotally mounted and the two sets of locations are angularly spaced apart around the axis of pivoting by about a right angle. Preferably the angular spacing is more than 45 . Preferably the handle is mechanically coupled to the levers via an intermediate member, one portion of which is able to be engaged by the handle and another portion of which is able to engage the levers. The intermediate member is preferably pivotally mounted. In order that the engagement of the camming arrangement, for example the intermediate member, with the levers results in varying amounts of movements of the levers, either the profile of the camming arrangement needs to vary or the lever profiles need to vary to vary their proximity to the camming arrangement. Since it is preferable to use the same camming arrangement regardless of the key that operates the lock, it is preferred that the lever profiles vary in order to vary the proximity of the levers to the camming arrangement such that the camming arrangement engages the levers at different stages during movement of the handle from its first position to its second position.

In a preferred embodiment of the invention described below, the handle is mechanically coupled to the bolt via an arrangement that engages the bolt at a location spaced from the location at which the bolt is engaged when a key is operated to move the bolt from the locked position to the unlocked position. More particularly, the handle is mechanically coupled to the bolt via a pivotally mounted - 6 - link, one portion of which is engaged by the handle or a member moving with the handle and another portion of which is able to engage the bolt to move it from the locked position to the unlocked position.

In accordance with an especially preferred feature of the first aspect of the invention, the lock further includes a locking arrangement which in a locked condition prevents movement of the handle from the first position to the second position. Such a locking arrangement further enhances the security of the lock because, when the locking arrangement is in the locked condition, even a person who gains access to the handle is unable to move the bolt from the locked position to the unlocked position by that means.

Preferably the locking arrangement includes a locking latch member which, when in a latching position, is able to prevent movement of the handle from the first position to the second position. The locking latch member is preferably resiliently biased into the latching position and movable away from the latching position against the resilient bias. Preferably the locking latch member is pivotally mounted.

An actuator for locking the locking arrangement in the locked condition is preferably provided on the forend of the lock. The "forend" is that part of the lock through which the bolt passes when it moves from the unlocked position to the locked position and is usually inaccessible when the door is closed and when the lock is in use. For example, in the case of a door, the "forend" of the lock is - 7 aligned with the side edge face of the door and is disposed adjacent to and confronting the door frame when the door is locked shut. In such a case, therefore, the actuator is inaccessible when the door is locked shut making it difficult or impossible to release the locking arrangement from its locked condition.

Whilst many different arrangements may be employed for preventing the handle from moving from the first position to the second position, it is preferred that the handle is movable from the first position into a third position in which it can be locked to prevent it moving to the second position. Preferably the handle is moved into the third position from the first position by moving it in a direction opposite to the direction in which the handle moves from the first position to the second position.

The feature of providing a locking arrangement to prevent movement of the handle is of particular advantage in a lever lock according to a first aspect of the invention but may also be employed in other applications.

Thus according to a second aspect of the invention there is provided a lock comprising a bolt movable between a locked position and an unlocked position, a keyhole into which a key is able to be inserted to move the bolt from the locked position to the unlocked position, a handle which is spaced apart from the keyhole and movable from a first position to a second position for moving the bolt from the locked position to the unlocked position, and a locking arrangement which in a locked condition prevents movement - 8 of the handle from the first position to the second position.

As will be understood, a lock according to the second aspect of the invention may have any of the features of a lock according to the first aspect of the invention.

By way of example, a lock embodying the invention will now be described with reference to the accompanying drawings, in which: Fig. 1 is a side sectional view of the lock with a bolt of the lock in the locked position and a handle of the lock in a released condition, Figs. 2a, 2b, 2c and 2d show the lock changing from the state shown in Fig. 1 to a state in which the bolt has been moved to the unlocked position by the handle, Figs. 3a, 3b and 3c show the lock changing from the unlocked state shown in Fig. 2d to a locked state through operation of a key, Figs. 4a, 4b and 4c show the handle being moved from a released condition to a locked condition, and Figs. 5a, 5b and 5c show the handle being moved back from a locked condition to a released condition.

In the interests of clarity, reference numerals are not included in all the drawings where the referenced parts are shown.

Referring first to Fig. 1, it should first be noted that the lock shown is in many respects conventional. It is a lever-operated mortise lock and includes a lock case 1, a bolt thrower 2, a bolt thrower spring 3 which 9 - engages a recess in the bolt thrower to bias it against movement away from the correct position for insertion of a key, a bolt 4 and a plurality of levers 5. The number of levers would commonly be five but there may be more or fewer levers. The interaction of those parts is entirely conventional. The bolt thrower 2 and spring 3 are unchanged from a conventional lever lock and the levers 5 and the bolt 4 are unchanged apart from the addition of a top flange on the bolt 4 to form an undercut 4a and the addition of lugs 5a on the levers 5. The levers 5 are resiliently biased in an anticlockwise direction (as seen in Fig. 1) by respective springs 5b, one of which is visible in Fig. 1.

The lock additionally includes extra parts in an upper region. A follower operated by a handle is rotatably mounted in the lock case. The handle includes a lever arm (not shown) on the exterior of the lock case projecting from the face that will be the interior face of the lock when it is installed. The combination of the handle and follower is designated by reference numeral 6 in the drawings and is referred to herein simply as the "handle".

Intersecting chain dotted lines in Fig. 1 mark the axis of rotation of the handle 6. A pivotally mounted link or rocker 7 is mounted in the case 1 and mechanically couples the handle 6 to the levers 5, as will be described below.

The link 7 is pivotally mounted on a post lb fixed in the case and is resiliently biased by a torsion spring 7b in a clockwise direction (as seen in Fig. 1). Another pivotally 10 mounted link or arm 8 is mounted in the case 1 and mechanically couples the handle 6 to the bolt 4, as will be described below. The link 8 is pivotally mounted on a post la fixed in the case and is resiliently biased by a spring 8a in a clockwise direction (as seen in Fig. 1). Also, a locking latch member 9 including an integral thumb actuator 9a is pivotally mounted in the case 1 about the same axis as the link 8. The locking latch member 9 is pivotally mounted on the post la fixed in the case and is resiliently biased by a spring (not shown) in a clockwise direction (as seen in Fig. 1). Its purpose will also be described below.

As will be understood, starting from the position of the parts shown in Fig. 1, the lock can be operated by a key in an entirely conventional manner. Thus, a key can be inserted into the thrower 2 and rotated about 360 clockwise (as seen in Fig. 1). During a first phase of rotation the key engages the undersides of the levers 5 which in this embodiment are pivotally mounted on a pivot lc of the case. The engagement of the key with each lever causes the lever to pivot clockwise (as seen in Fig. 1) about the pivot lo by an amount determined principally by the profile of the key. Thus once the first phase of movement of the key is complete, the amount of pivoting of the levers 5 will have varied, but the levers 5 are arranged in a manner known per se such that after such varied amounts of movement they are all aligned in clear positions to allow passage of a part of the bolt through their aligned openings. During a second phase of movement - 11 of the key, the levers 5 remain in their clear positions and the thrower 2 effects movement of the bolt 4 from the locked position shown in Fig. 1 to the unlocked or retracted position.

The operation described immediately above is entirely conventional.

The lock shown in the drawings may also be operated by the handle 6 which may be used in place of a key to retract the bolt 4, as will now be described with reference to Figs. 2a to 2d. In Fig. 2a the handle 6 is shown in the same position as in Fig. 1, namely the position into which it is resiliently biased by a torsion spring (not shown).

As shown in the drawings, the part of the handle within the case 1 includes a radially projecting portion that carries a peg 6a and also, on the other side of its axis of pivoting a protruding cam part 6b against which a part of the link 7 is resiliently biased.

In order to retract the bolt using the handle 6, a user rotates the handle clockwise (as seen in the drawings). The rotation of the handle 6 rotates the cam part 6b which engages the pivotally mounted link 7, pivoting the link in an anticlockwise direction (as seen in the drawings). The anticlockwise pivoting of the link 7 causes the lower end 7a of the link 7 to engage the lugs 5a of the levers 5. As can be seen from Fig. 2a, the lugs 5a are engaged by the link 7 at different stages during the rotation of the handle. In Fig. 2a, the lugs of two levers are shown and are marked as 5a' and 5a'' respectively: it can be seen that the lug 5a'' is engaged by the link 7 before the lug 5a'. Other levers will be engaged at stages determined by the shape of their lugs 5a.

Fig. 2b shows the position of the handle once a first stage of rotation is complete, after about 30 of rotation.

It can be seen that the lug 5a'' has been moved a significant distance by the engagement of the link 7 and that the lever 5 having the lug 5a'' has therefore rotated a relatively large amount clockwise (as seen in the drawings). On the other hand the lug 5a' has only just made contact with the link 7 and has therefore not moved so that the lever 5 having the lug 5a' has not rotated. The varying movements of the levers 5, determined by the shapes of the lugs 5a are designed to match the movements of the levers when the correct key is operated to move them. Thus in the positions of the parts shown in Fig. 2b, the levers 5 are all rotated by selected and varying amounts into clear positions where they allow free movement of the bolt 4 between the locked and unlocked positions.

It may be noted that, during the initial rotation of the handle 6 described above; the peg 6a travels around a radiused surface of the link 8 and does not effect any movement of the link 8. When the handle 6 reaches the position shown in Fig. 2b, the peg 6a comes into contact with a projecting part 8b on the link 8.

As the handle is rotated further in a clockwise direction (as seen in the drawings) a constant radius portion of the cam part 6b comes into contact with the - 13 link 7 which therefore remains in the same position, holding the levers 5 in the same clear positions. At the same time the peg 6a engages the projecting part 8b on the link 8 which causes the link 8 to pivot anticlockwise (as seen in the drawings) about the post la. The bottom end 8c of the link 8 is therefore caused to move to the right (as seen in the drawings) and engages the undercut 4a of the bolt 4 moving the bolt to the right (as seen in the drawings).

Fig. 2c shows the position of the handle 6 once this second stage of rotation is complete, after about 50 of rotation overall. It can be seen that the levers are still in the clear positions shown in Fig. 2b and that the bolt 4 has been moved from the locked position to the unlocked (retracted) position.

The handle 6 is then returned to its original position which it naturally returns to as a result of the resilient bias previously referred to. That rotation of the handle 6 returns the link 8 to its original position but does not move the bolt 4; the bottom end 8c of the link 8 simply moves away from the undercut 4a of the bolt 4. The return rotation of the handle also causes the link 7 to return to its original position by virtue of its resilient bias and as it rotates clockwise so the resiliently biased levers 5 return to their original, blocking, positions. Fig. 2d shows the positions of the parts after this movement and it can be seen that the levers 5 are in the same position as in Fig. 2a. - 14

As will be clear from the description above the

handle 6 can be used to retract the bolt into an unlocked position but not to move it into a locked position.

Locking has to be carried out using a key. Figs. 3a, 3b and 3c show that process, which as already explained is entirely conventional. Fig. 3a shows the positions of the parts after a correct key has been inserted in the lock and rotated about 150 . At that stage the key has engaged the undersides of the levers 5 and lifted them by varying selected amounts according to the shape of the key. Thus the lever 5 having the lug 5a'' has been lifted a considerable distance whereas contact has only just been made with the lever 5 having the lug 5a'. In the position shown in Fig. 3a the levers 5 have all been pivoted to their clear positions, namely the same positions as shown in Fig. 2b. As the key is rotated further the bolt thrower 2 begins to move the bolt 4 to the left (as shown in the drawings). Fig. 3b shows the positions of the parts partway through this movement and it may be noted that the positions of the levers 5 have not changed significantly because the shapes of the undersides of the levers are curved to provide that result. Fig. 3c shows the positions of the parts after more than sufficient rotation from the thrower 2 to move the bolt 4 into its extended position.

The levers 5 are just beginning to return to their blocking positions which they reach once the key is further rotated anticlockwise (as seen in the drawings) from the position shown in Fig. 3c.

Whilst the handle 6, which would typically be provided with a single actuating lever arm on the inside of an exterior door provides a quick way of unlocking the lock without requiring a key, it is desirable for improved security to be able to disable the handle function. That is possible in the case of the lock shown in the drawings as will now be described with reference to Figs. 4a, 4b and 4c.

The part of the handle 6 within the case 1 includes a radially projecting backstop 6c which interacts with a projecting post 9b of the locking latch member 9 as will now be described.

As can be seen from, for example, Fig. 1, the degree of anticlockwise movement of the handle is usually limited by engagement of the backstop 6c of the handle with the projecting part 9b of the locking latch member 9 which is resiliently biased into engagement with the handle. The projecting part 9b can, however, be moved away from the handle by pivoting the latch member 9 anticlockwise (as seen in the drawings) and this can be accomplished by a user pressing downwardly on the thumb actuator 9a which projects from the forend of the casing 1, through an opening in the casing. Fig. 4a shows the latch member pivoted in this way and it can be seen that as a result it is possible for a user to rotate the handle anticlockwise beyond its usual end position and against its resilient bias into the position shown in Fig. 4b. The user can then release the actuator 9a, allowing the projecting part 9b to - 16 move back into contact with the handle and engage the other side of the backstop 6c. That position is shown in Fig. 4c and represents the condition in which the handle function is disabled, since the handle 6 is unable to rotate clockwise (as seen in the drawings).

With the parts in the positions shown in Fig. 4c the lock is especially secure. The bolt can only be moved to the unlocked position by use of a key. Furthermore access to the actuator 9a is prevented in ordinary applications because the actuator is situated between the confronting faces of the door edge and the doorway (in the case of a door lock).

To reinstate the handle action the thumb actuator 9a must be depressed to the position shown in Fig. 5a, the handle turned clockwise (as seen in the drawings) to the position shown is Fig. 5b and then the thumb actuator 9a released allowing the parts to return to the positions shown in Fig. 5c, those also being the positions of the parts shown in Fig. 4a.

Whilst in Figs. 4a to 4c and in Figs. 5a to 5c the bolt 4 is shown in a locked position it should be understood that the disabling and reinstatement of the handle action can also be carried out when the bolt 4 is in an unlocked (retracted) position. Indeed, since access is required to the forend of the lock to disable or reinstate the handle action, it will commonly be the case that the actions are carried out when the bolt 4 is retracted.

From the description above, it will be seen that the lock described is able to exhibit a high degree of security and yet can be set in a manner that allows a single movement of a handle to effect unlocking. Thus, for example, if the lock were used on an exterior door of a building it could be locked with the handle function disabled when the building was left unoccupied and locked with the handle function reinstated when the building was occupied.

Whilst one particular form of lock has been described by way of example, it will be understood that the lock may take a wide variety of forms. For example, although the lock shown is a single bolt deadlocking mortise lock, it could be some other kind of lock such as a sashlock. - 18

Claims (23)

1. Claims 1. A lock including a bolt movable between a locked position and an

   unlocked position, a plurality of levers movable between blocking positions in which they prevent movement of the bolt from the locked position to the unlocked position and clear positions in which they allow movement of the bolt from the locked position to the unlocked position, a keyhole into which a key is able to be inserted to move the levers from the blocking positions to the clear positions and to move the bolt from the locked position to the unlocked position, the amounts of movement of the levers that are required to move the levers from the blocking positions to the clear positions varying from one lever to another, wherein the lock further comprises a handle which is movable from a first position to a second, releasing position, the handle being arranged, upon movement from its first position to its second position when the bolt is in the locked position and the levers are in the blocking positions, to move the levers by the varying amounts required to move them from the blocking positions to the clear positions and to move the bolt from the locked position to the unlocked position.
2. 2. A lock according to claim 1, in which the lock is a mortise lock.
3. 3. A lock according to claim 1 or 2, in which the levers when in the blocking positions prevent movement of the bolt from the unlocked position to the locked position. - 19
4. 4. A lock according to any preceding claim, in which a key is also able to move the levers from the blocking positions to the clear positions and to move the bolt from the unlocked position to the locked position.
5. 5. A lock according to any preceding claim, in which the handle is not able to move the bolt from the unlocked position to the locked position.
6. 6. A lock according to any preceding claim, in which the handle is mounted for pivotal movement.
7. 7. A lock according to claim 6, in which the handle is arranged to pivot through an acute angle when it moves from its first position to its second position.
8. 8. A lock according to any preceding claim, in which the handle is resiliently biased into its first position.
9. 9. A lock according to any preceding claim, in which the handle is mechanically coupled to the levers via a camming arrangement that engages the levers at locations spaced from the locations at which the levers are engaged when a key is operated.
10. 10. A lock according to claim 9, in which the levers are pivotally mounted and the two sets of locations are angularly spaced apart around the axis of pivoting by more than 45 .
11. 11. A lock according to claim 9 or 10, in which the handle is mechanically coupled to the levers via an intermediate member, one portion of which is able to be engaged by the handle and another portion of which is able to engage the levers. - 20
12. 12. A lock according to claim 11, in which the intermediate member is pivotally mounted.
13. 13. A lock according to any of claims 9 to 12, in which the lever profiles vary in order to vary the proximity of the levers to the camming arrangement such that the camming arrangement engages the levers at different stages during movement of the handle from its first position to its second position.
14. 14. A lock according to any preceding claim, in which the handle is mechanically coupled to the bolt via an arrangement that engages the bolt at a location spaced from the location at which the bolt is engaged when a key is operated to move the bolt from the locked position to the unlocked position.
15. 15. A lock according to any preceding claim, in which the handle is mechanically coupled to the bolt via a pivotally mounted link, one portion of which is engaged by the handle or a member moving with the handle and another portion of which is able to engage the bolt to move it from the locked position to the unlocked position.
16. 16. A lock according to any preceding claim, further including a locking arrangement which in a locked condition prevents movement of the handle from the first position to the second position.
17. 17. A lock according to claim 16, in which the locking arrangement includes a locking latch member which, when in a latching position, is able to prevent movement of the handle from the first position to the second position. - 21
18. 18. A lock according to claim 17, in which the locking latch member is resiliently biased into the latching position and movable away from the latching position against the resilient bias.
19. 19. A lock according to claim 17 or 18, in which the locking latch member is pivotally mounted.
20. 20. A lock according to any of claims 16 to 19, in which an actuator for locking the locking arrangement is provided on the forend of the lock.
21. 21. A lock according to any of claims 16 to 20, in which the handle is movable from the first position into a third position in which it can be locked to prevent it moving to the second position.
22. 22. A lock according to claim 21, in which the handle is moved into the third position from the first position by moving it in a direction opposite to the direction in which the handle moves from the first position to the second position.
23. 23. A lock substantially as herein described with reference to the accompanying drawings.

    23. A mortise lock comprising a bolt movable between a locked position and an unlocked position, a keyhole into which a key is able to be inserted to move the bolt from the locked position to the unlocked position, a handle which is spaced apart from the keyhole and movable from a first position to a second position for moving the bolt from the locked position to the unlocked position, and a locking arrangement which in a locked condition prevents movement of the handle from the first position to the second position. - 22

    24. A lock according to claim 23, in which the locking arrangement includes a locking latch member which, when in a latching position, is able to prevent movement of the handle from the first position to the second position.

    25. A lock according to claim 24, in which the locking latch member is resiliently biased into the latching position and movable away from the latching position against the resilient bias.

    26. A lock according to claim 24 or 25, in which the locking latch member is pivotally mounted.

    27. A lock according to any of claims 23 to 26, in which an actuator for locking the locking arrangement is provided on the forend of the lock.

    28. A lock according to any of claims 23 to 27, in which the handle is movable from the first position into a third position in which it can be locked to prevent it moving to the second position.

    29. A lock according to claim 28, in which the handle is moved into the third position from the first position by moving it in a direction opposite to the direction in which the handle moves from the first position to the second position.

    30. A lock according to any of claims 23 to 29, in which the lock includes a plurality of levers movable between blocking positions in which they prevent movement of the bolt from the locked position to the unlocked position and clear positions in which they allow movement of the bolt from the locked position to the unlocked position. - 23

    31. A lock substantially as herein described with reference to the accompanying drawings.

    Amendments to the claims have been filed as follows: - Li 1. A lock including a bolt movable between a locked position and an unlocked position, a plurality of levers movable between blocking positions in which they prevent movement of the bolt from the locked position to the unlocked position and clear positions in which they allow movement of the bolt from the locked position to the unlocked position, a keyhole into which a key is able to be inserted to move the levers from the blocking positions to the clear positions and to move the bolt from the locked position to the unlocked position, the amounts of movement of the levers that are required to move the levers from the blocking positions to the clear positions varying from one lever to another, wherein the lock further comprises a handle which is movable from a first position to a second, releasing position, the handle being arranged, upon movement from its first position to its second position when the bolt is in the locked position and the levers are in the blocking positions, to move the levers by the varying amounts required to move them from the blocking positions to the clear positions and to move the bolt from the locked position to the unlocked position.

    2. A lock according to claim 1, in which the lock is a mortise lock.

    3. A lock according to claim 1 or 2, in which the levers when in the blocking positions prevent movement of the bolt from the unlocked position to the locked position. - '16

    4. A lock according to any preceding claim, in which a key is also able to move the levers from the blocking positions to the clear positions and to move the bolt from the unlocked position to the locked position.

    5. A lock according to any preceding claim, in which the handle is not able to move the bolt from the unlocked position to the locked position.

    6. A lock according to any preceding claim, in which the handle is mounted for pivotal movement.

    7. A lock according to claim 6, in which the handle is arranged to pivot through an acute angle when it moves from its first position to its second position.

    8. A lock according to any preceding claim, in which the handle is resiliently biased into its first position.

    9. A lock according to any preceding claim, in which the handle is mechanically coupled to the levers via a camming arrangement that engages the levers at locations spaced from the locations at which the levers are engaged when a key is operated.

    10. A lock according to claim 9, in which the levers are pivotally mounted and the two sets of locations are angularly spaced apart around the axis of pivoting by more than 45 .

    11. A lock according to claim 9 or 10, in which the handle is mechanically coupled to the levers via an intermediate member, one portion of which is able to be engaged by the handle and another portion of which is able to engage the levers. - Lb

    12. A lock according to claim 11, in which the intermediate member is pivotally mounted.

    13. A lock according to any of claims 9 to 12, in which the lever profiles vary in order to vary the proximity of the levers to the camming arrangement such that the camping arrangement engages the levers at different stages during movement of the handle from its first position to its second position.

    14. A lock according to any preceding claim, in which the handle is mechanically coupled to the bolt via an arrangement that engages the bolt at a location spaced from the location at which the bolt is engaged when a key is operated to move the bolt from the locked position to the unlocked position.

    15. A lock according to any preceding claim, in which the handle is mechanically coupled to the bolt via a pivotally mounted link, one portion of which is engaged by the handle or a member moving with the handle and another portion of which is able to engage the bolt to move it from the locked position to the unlocked position.

    16. A lock according to any preceding claim, further including a locking arrangement which in a locked condition prevents movement of the handle from the first position to the second position.

    17. A lock according to claim 16, in which the locking arrangement includes a locking latch member which, when in a latching position, is able to prevent movement of the handle from the first position to the second position.

    - -

    18. A lock according to claim 17, in which the locking latch member is resiliently biased into the latching position and movable away from the latching position against the resilient bias.

    19. A lock according to claim 17 or 18, in which the locking latch member is pivotally mounted.

    20. A lock according to any of claims 16 to 19, in which an actuator for locking the locking arrangement is provided on the forend of the lock.

    21. A lock according to any of claims 16 to 20, in which the handle is movable from the first position into a third position in which it can be locked to prevent it moving to the second position.

    22. A lock according to claim 21, in which the handle is moved into the third position from the first position by moving it in a direction opposite to the direction in which the handle moves from the first position to the second position.