Technical Field

This invention broadly relates to a lock assembly for a door. The invention particularly relates to a lock assembly including a lock cylinder for a roller type door and a replaceable cam. Also, the invention relates to a spacing means for roller type doors and a latching means for mounting a fascia of a lock assembly onto a door. Fuithermore, the present invention relates to a lock assembly including a first mechanism adapted to provide an indication of the orientation of a lock cylinder in which a key can be retrieved and/or a second mechanism adapted to provide an indication of the orientation of a rotatable knob operatively connected to the lock cylinder.

Background of the Invention

Most conventional garage doors such as roller type and sectional doors operate on an upward-acting mechanism.. These types of doors commonly include a lock assembly having arms controlled by a scalloped internal turn for unlocking from the inside of the door and a keyway for unlocking with a key from the outside.

The lock assembly described above is capable of enabling deadlocking and/or free latching/unlocking. It however has a disadvantage that it typically includes a mechanism with a cam which can easily be removed with the assistance of a tool such as a screw driver, even when the lock assembly is in a locked state. Once the cam is removed, unauthorised turning of the turn can be effected to unlock the door. This means that the mechanism only offers a relatively low level of security.

Also, the lock assembly described above has another disadvantage that after it has been mounted onto a roller type door with a plurality of folding panels, the panels are likely to be nibbed against the housing of the lock assembly often resulting in the surface of the panels being scratched or the housing being damaged.

Furthermore, it is generally recognised that maintaining a fascia of the lock assembly described above in position for coupling with a corresponding housing containing a lock cylinder is a challenge as the fascia falls off easily and quickly while the user is getting to the other side of the door to complete installation of the housing.

Furthermore, the lock assembly described above involves a design which allows retrieval of a key only when the lock barrel is at a certain orientation. Some designs provide a lock assembly with a stopper which functions to let the user know when the key can be retrieved. Other designs however do not facilitation provision of a stopper. In such cases, the user has to rely merely on the feel of the barrel wafers within the lock barrel to determine whether the lock barrel is in an orientation in which the key can be retrieved. This has the disadvantages of the lock assembly being not very user-friendly and having a shorter than normal life expectancy due to frequent wear and tear.

It is an object of the present invention to provide a lock assembly, a cam, and/or a spacing means which may overcome or at least ameliorate the above disadvantages and difficulty or which may at least provide a useful alternative.

Summary of the Invention

According to a first aspect of the present invention there is provided a lock

assemblyincluding:

a housing adapted to receive a lock cylinder operable between a lock position and an unlocked position;

a knob being rotatable with respect to the housing;

a cam removably attached to the lock cylinder and capable of being locked in position with respect to the lock cylinder,

wherein the cam is configured with respect to the knob so that removal of the cam is prevented when the lock cylinder is in the locked position.

Acconiing to second aspect of the present invention there is provided a lock assembly including:

a housing adapted to receive a lock cylinder operable by a key between a lock position and an unlock position;

a knob being rotatable with respect to the housing;

a first or second cam removably attached to the lock cylinder and capable of being locked in position with respect to the lock cylinder;

wherein one of the first or second cam is replaceable by another of the first or second cam, the first cam being configured with respect to the knob so that in use when the lock cylinder is in the locked position and the key removed, the knob is restricted from rotating, the second cam being configured with respect to the knob so that in use when the lock cylinder is in the locked position and the key removed, the knob is rotatable.

Preferably, the (first) cam is configured with respect to the knob such that when the lock cylinder is moved to the unlocked position by the key, the cam is removable.

In a preferred embodiment, the lock cylinder includes two interlocking means. The interlocking means are in the form of recesses. The two recesses are preferred to be in different shapes.

It is preferred that the (first) cam includes an annular wall on one side with two engaging means. The two engaging means are in the form of protrusions of different shapes. The shapes of the two protrusions are preferred to be complementary to the shapes of the two recesses, respectively. This enables the user to identify the orientation in which the cam is to engage the lock cylinder. The (first) cam is also preferred to include two opposing flanges located around its periphery.

In a preferred embodiment, the knob is in the shape of a ring having two opposing retaining means. Preferably, the retaining means are configured and located such that when the lock cylinder is in a locked position, they overlap at least part of the flanges of the cam. As a result, the cam cannot be removed from the lock assembly.

Preferably, the first cam has a different configuration from the second cam, although they both have a pair of engaging means and a pair of flanges. In a preferred embodiment, both the first and second cams include a pair of impeding means in the form of tags. The lugs of the fust cam are preferred to be positioned such that when the lock cylmder is in the locked position and the key removed, the knob is restricted from rotating. As such, deadlocking is achieved as the lock cylinder cannot be rotated without the key and the knob cannot be rotated being restricted by the lugs.

Preferably, the impeding means of the second cam are positioned in such a way that when the cam is engaged with the lock cylinder, the lock cylinder in the locked position and the key removed, the knob is still rotatable as the lugs of the cam are not abutting the retaining means of the knob.

In a preferred embodiment, the key is retrievable from the lock cylinder only when the lock cylinder is in a selected orientation. The housing preferably also includes or is operatively associated with a latching mechanism adapted to engage a corresponding part of the lock cylinder so as to provide an indication that the lock cylinder is in the selected orientation.

Preferably, the latching mechanism includes a pivotal arm with an enlarged portion, the pivotal arm being adapted to be biased by a biasing means.

The corresponding part of the lock cylinder is preferred to include an indent configured in use to at least partially receive the enlarged portion of the biased pivotal arm when the lock cylinder is in the selected orientation.

In a preferred embodiment, the lock cylinder is in the selected orientation when the key is disposed in a horizontal position.

In a more preferred embodiment, the housing further includes or is operatively associated with an engaging mechanism adapted to engage a first selected part of the rotatable knob so as to provide an indication that the knob is in a first selected orientation.

The lock cylinder is preferably movable by the rotatable knob via the first or second cam. It is preferred that the engaging mechanism is configured and arranged to engage a second selected part of the knob to provide an indication that the knob is in a second selected orientation.

In a preferred embodiment, the engaging mechanism includes an engaging means adapted to be biased by a biasing means supported by the housing. The engaging means is preferred to be a spherical ball.

Each of the first and second selected parts of the knob is preferred to be a recess adapted in use to at least partially receive the ball.

According to a third aspect of the present invention there is provided a cam as defined above.

According to a fourth aspect of the present invention there is provided a lock assembly including:

a housing adapted to receive a lock cylinder rotatable between a lock position and an unlock position, the lock cylinder adapted to receive one or more locking elements movable to a projection position, the or each locking element having a profile adapted to in the projection position prevent the lock cylinder from rotating with respect to the housing; and

one or more removable inserts adapted to be received within the housing;

wherein the or each insert is so configured as to facilitate use of one or more replacement locking elements having a different profile or size.

The locking elements are preferred to be in the form of L-shaped wafers. Each wafer includes a profile in the form of a blade. Preferably, each replacement locking elements has a blade shorter than mat of the (original) locking elements.

Each insert is preferred to be in the form of a rod with an extension. Each insert is accommodated within a compartment forming part of the housing. The compartment is preferably in communication with another compartment adapted to receive the lock cylinder. The extension of each insert is configured to abut the blade of the replacement locking means so as to restrict rotational movement of lock cylinder when the wafer is in the projection position.

According to a fifth aspect of the present invention there is provided a locking element as defined above.

According to a sixth aspect of the present invention there is provided a lock assembly for a roller type door having a plurality of panels adapted in use to fold onto one another, the lock assembly being adapted to be mounted onto one of the panels and including:

a housing; and

spacing means adapted to form an integral part of or be attached to the housing;

wherein the spacing means is configured so that it prevents the housing from contacting another panel.

Preferably, there are two spacing means located diagonally to one another at the corners of the housing. Each spacing means is preferred to be located in a seat Each spacing means is made of non-abrasive or rubbery material. Alternatively, the spacing means includes a raised portion located on each of the two lateral sides of the housing.

According to a seventh aspect of the present invention there is provided a spacing means as defined above.

According to a eighth aspect of the present invention there is provided a lock assembly for a door with a cut-out partially defined by upper and lower borders, the lock assembly including:

a fascia adapted to cover the cut-out; and

a resilient latching means forming an integral part of or being connected to the fascia, the latching means having a length longer than a distance between the upper and lower borders;

wherein the latching means is configured and arranged such that it is capable of flexing whilst being forced through the cut-out and subsequently returning to its original shape immediately after passing through the cut-out to, in combination with part of the fascia abutting me upper and lower borders of the cut-out, prevent the fascia from falling off

The resilient latching means are preferred to be made of a flexible metal. The resilient latching means preferably include a flat portion and two wings disposed at an angle to the flat portion, respectively. The flat portion may be releasably joined to the fascia via a fixing means.

According to a ninth aspect of the present invention there is provided a latching means as describe above.

According to a tenth aspect of the present invention, there is provided a lock assembly including:

a housing having or being operatively associated with a latching mechanism and being adapted to receive a lock cylinder rotatable by a key which is retrievable only when the lock cylinder is in a selected orientation;

wherein the latching mechanism is configured and arranged to engage a corresponding part of the lock cylinder so as to provide an indication that the lock cylinder is in the selected orientation.

Preferably, the latching mechanism includes a pivotal arm with an enlarged portion, the pivotal arm being adapted to be biased by a biasing means.

The corresponding part of the lock cylinder is preferred to include an indent configured in use to at least partially receive the enlarged portion of the biased pivotal arm when the lock cylinder is in the selected orientation.

In a preferred embodiment, the lock cylinder is in the selected orientation when the key is disposed in a horizontal position.

According to an eleventh aspect of the present invention, there is provided a lock assembly mcluding:

a housing having or being operatively associated with an engaging mechanism and being adapted to receive a lock cylinder movable by a rotatable knob;

wherein the engaging mechanism is configured and arranged to engage a first selected part of the knob so as to provide an indication that the knob is in a first selected orientation.

The lock cylinder is preferably movable by a rotatable knob via a cam operatively connected to the lock cylinder.

Preferably, the engaging mechanism is configured and arranged to engage a second selected part of the knob to provide an indication that the knob is in a second selected orientation.

In a preferred embodiment, the engaging mechanism includes an engaging means adapted to be biased by a biasing means supported by the housing. The engaging means is preferred to be a spherical ball.

Each of the first and second selected parts of the knob is preferred to be a recess adapted in use to at least partially receive the ball.

Brief Description of the Drawings

The invention may be better understood from the following non-limiting description of the present invention, in which:

Figure 1 is a rear view of a lock assembly with a deadlock cam in a locked position in accordance with a preferred embodiment of the present invention;

Figure 2 is a front view of the lock assembly of Figure 1 ;

Figure 3 is a rear view of the lock assembly of Figure 1 with a deadlock cam in an unlocked position;

Figure 4 is a front view of the lock assembly of Figure 3;

Figure 5 is an exploded view showing the arrangement of the cam, knob and lock cylinder of the lock assembly of Figure 1 from the front;

Figure 6 is an exploded view showing the arrangement of Figure S from the back; and

Figure 7 is a rear view of the lock assembly of Figure 1 with a free latching cam in a locked position; Figure 8 is a front view of the lock assembly of Figure 7;

Figure 9 is a rear view of the lock assembly of Figure 1 with a free latching cam in a unlocked position;

Figure 10 is a front view of the lock assembly of Figure 9;

Figure 11 is an exploded view showing the cam and lock cylinder from the front; Figure 12 is an exploded view of (he arrangement of Figure 11 from the back;

Figure 13 is an exploded view of the lock assembly of Figure 1 with a lock cylinder;

Figure 14 is an exploded view of the lock assembly of Figure 13 with a lock cylinder having wafers of a different profile and size;

Figure 15 is an exploded view of the lock assembly of Figure 14 showing two inserts; Figure 16 is a perspective view of an assembled lock assembly of Figure 15;

Figure 17 is a perspective view of the lock assembly of Figure 1 with spacing means;

Figure 18 is a perspective view of a fascia the lock assembly of Figure 1 with a latching means;

Figure 19 is a front view of the lock assembly of Figure 1 after installation onto a roller type door,

Figure 20 is a cross sectional view of the lock assembly of Figure 19 taken along A-A; Figure 21 is a perspective view of the lock assembly of Figure 20 showing an installed fascia;

Figure 22 is a cross sectional view of the lock assembly of Figure 21 ;

Figure 23 is a cross sectional view of the lock assembly of Figure 1 being fully installed including the fascia;

Figure 24 is a perspective of a lock assembly in accordance with another embodiment of the present invention illustrating a latching mechanism installed in the housing;

Figure 25 is a partial plan view of the lock assembly of Figure 24;

Figure 26 is an exploded front perspective view of the lock assembly of Figure 24 with a knob and an engaging mechanism; and

Figure 27 is an exploded rear perspective view of the lock assembly of Figure 26. Detailed Description of the Drawings

Referring to Figures 1 to 6, a lock assembly 10 for a roller type door (not shown) includes a housing 12, a knob 14, a lock cylinder 16, a cam 18 and two arms 44 and 46.

The housing 12 receives the lock cylinder 16 which is operable between a lock position (as shown in Figures 1 and 2) and an unlocked position (as shown in Figures 3 and 4). When a key (not shown) is inserted in the keyway 20, the knob 14 is freely rotatable with respect to the housing 12.

As best shown in Figures 5 and 6, the cam 18 is removably attached to the lock cylinder 16 and is capable of being locked in position with respect to the lock cylinder 16. The cam 18 includes two opposing flanges 32 and 34 located around its periphery 36. The lock cylinder 16 includes two interlocking means in the form of recesses 22 and 24. Recess 22 is semi-circular in shape whereas recess 24 is triangular in shape. The cam 18 includes an annular wall 26 on one side with two engaging means which are in the form of protrusions 28 and 30. The protrusion 28 is triangular in shape whereas protrusion 30 is semi-circular in shape. The shapes of the two protrusions 28 and 30 are complementary to the shapes of the two recesses 22 and 24, respectively, This enables a user to identify the orientation in which the cam 18 is to engage the lock cylinder 16 during installation.

The knob 14 is in the shape of a ring having two opposing retaining means 38 and 40. The knob 14 has two internally threaded tubes 48 and SO (see Figure 6) for receiving two screws 52 and 54. The arms 44 and 46 are associated with the tubes 48 and 50. As the knob 14 rotates, the tubes 48 and 50 move along tracks 56 and 58 respectively. As such, the movement of the arms 44 and 46 is dictated by the knob 14 which may be driven directly by a user or via the cam 18.

The retaining means 38 and 40 are configured and located such that when the lock cylinder 16 is in a locked position, they overlap part of the flanges 32 and 34 of the cam 18. As a result, the cam 18 cannot be removed from the deadlock assembly 10. It will be appreciated that the cam 18 is retained in the deadlock assembly 10 when the arms 44 and 46 are in the outwards (locking) position and the key removed and lock cylinder 16 in a locked position. In the deadlocked position, the knob 14 cannot be rotated due to the design of the geometry of the cam 18. The only way to override this would be to remove the deadlocking cam 18 or manipulate the lock cylinder 16 from the inside. To ensure that the deadlocking function cannot overridden by removing the cam 18, even if the screws 40 and 42 are removed, the cam 18 cannot be rotated due to the protrusions 28 and 30 of the cam 18 being interlocked with the recesses 22 and 24 and the flanges 32 and 34 of the cam 18 sitting under the retaining means 38 and 40 of the knob 14.

However, when the lock cylinder 16 is moved to the unlocked position by a key (see Figure 3), the deadlocking cam 18 is also turned accordingly. This results in the flanges 32 and 34 of the deadlocking cam 18 no longer sitting under the retaining means 38 and 40. As such, after removal of the screws 40 and 42, the cam 18 is removable, which in turn allows for easy removal of the lock cylinder 1 .

The cam 18 also includes a pair of impeding means in the form of lugs 62 and 64. The lugs 62 and 64 of the cam 18 are positioned such that when the lock cylinder 16 is in the locked position and the key removed, the knob 14 is restricted from rotating. As such, deadlocking is achieved as the lock cylinder 16 cannot be rotated without the key and the knob 14 cannot be rotated being restricted by the lugs 62 and 64.

In operation, to lock a door (not shown) when the deadlock cam 18 is in a locked position, the lock cylinder 16 is rotated anticlockwise by 180 degrees. This rotates the knob 14 anticlockwise by 90 degrees and hence driving the arms 44 and 46 outwards. In this state, the deadlocking cam 18 cannot be removed even after the screws 40 and 42 are removed. To retrieve the arms 44 and 46 when the deadlock cam 18 is in an unlocked position, rotate the key and hence the lock cylinder 16 clockwise by 180 degrees, which will rotate the knob 14 clockwise by 90 degrees. The cam 18 can now be removed after removing the screws 40 and 42.

Turning now to Figures 8 to 12, a second cam 60 replacing the first cam 18 is attached to the lock cylinder 16 and is locked in position with respect to the lock cylinder 16. The second cam 60 is configured with respect to the knob 14 so that when the lock cylinder 14 is in the locked position and the key removed, the knob 14 is rotatable.

The cam 60 also includes two opposing flanges 70 and 72 located around its periphery (see Figures 11 and 12). The cam 60 also includes an annular wall 76 (see Figure 12) on one side with two engaging means which arc in the form of protrusions 78 and 80. The protrusion 78 is semi-circular in shape whereas protrusion 80 is triangular in shape. The shapes of the two protrusions 78 and 80 are complementary to the shapes of the two recesses 22 and 24, respectively. This enables a user to identify the orientation in which the cam 60 is to engage the lock cylinder 16 during installation. It can be seen that compared with the geometry of the cam 16, the semi-circular and triangular protrusions have swapped positions.

Also, the cam 60 also includes a pair of impeding means in the form of lugs 66 and 68. The lugs 66 and 68 of the cam 60 are positioned differently from those of the cam 18 and in such a way that when the cam 60 is engaged with the lock cylinder 16, the lock cylinder 16 in the locked position and the key removed, the knob 14 is still rotatable as the lugs 66 and 68 of the cam 60 are not abutting the retaining means 38 and 40 of the knob.

In operation, when the (free latching) cam 60 is in a locked position, the arms 44 and 46 are moved into locking position by having the key in a rest position and rotating it anticlockwise by 90 degrees. This turns the knob 14 anticlockwise by 90 degrees. The key and lock cylinder 16 are rotated clockwise by 90 degrees back to the rest position before the key can be removed and lock cylinder 16 locked. With cam 60, the knob 14 can still be rotated anticlockwise to retrieve the arms 44 and 46 and unlock the door. Conversely, when the cam 60 is in an unlocked position, starting with the key in a rest position, and rotating it clockwise by 90 degrees would turn the knob 14 clockwise by 90 degrees accordingly. This moves the arms 44 and 46 into the locking position. The key and lock cylinder 16 can then be rotated anticlockwise by 90 degrees back to the rest position so that the key can be removed and lock cylinder locked. The knob 14 can still be rotated clockwise to extend the arms 44 and 46 and lock the door.

Referring to Figure 13 to 16, the housing 12 receives the lock cylinder 16 which is rotatable between a lock position and an unlock position. As best shown in Figures 14 and 16, the lock cylinders 16 and 82 carrying locking elements 84 and 86, respectively. The locking elements 84 and 86 arc both moved to a projection position. As shown in Figures 14 and 16, each locking element 84 or 86 has a profile 88 or 90. The profile 88, 90 is configured so as to prevent the lock cylinder 16 from rotating with respect to a cavity 92 of the housing 12. The housing 12 also includes two small compartments 94 and 96 which are in communication with the cavity 92 for receiving the lock cylinder 16 or 82.

Referring to Figure 15, the profile of each locking element 84 in the form of a wafer includes a flat end 98 in the form of a blade and an L-shaped end 100. Turning now to Figures 13 and 14, it can be observed that the blade of the replacement locking elements 84 is shorter than that of the locking elements 86. Removable inserts 102 and 104 are therefore provided as adaptors being received in compartments 94 and 96 to enable the housing 12 to operate with different lock cylinders carrying different locking elements having a different profile or size.

As best shown in Figure 14 and 15, each insert 102 and 104 is in the form of a rod with an extension 108. Each extension 108 is configured to abut the edge of the blade of the flat or L-shaped ends 98 or 100 of the projected locking elements 82 so as to restrict rotational movement of lock cylinder 16.

It should be noted that although the lock assembly 10 of the present invention may be applied to other types of doors, it particularly suits a roller type door 110 (see Figure 18) having a plurality of panels 112 which in use fold onto one another. Two spacing means 114 and 116 which are attached to the housing 12 are provided to prevent the housing 12, particularly its sharp corners, from contacting another panel. The two spacing means 114 and 116 are located diagonally to one another at the corners of the housing 12. Each spacing means 114, 116 is located in a seat 118, 120. The spacing means 114 and 116 are made of non-abrasive or rubbery material.

Referring to Figures 18 to 23, the door 110 has a cut-out 122 which is partially defined by upper and lower borders 124 and 126. The cut-out 122 is to be covered by a fascia 128 being part of the lock assembly 10. A resilient latching means 130 is connected to an arm 132 of the fascia 128. As best shown in Figure 20, the latching means 130 has a length B-B which is longer than the distance indicated by C-C between the upper and lower borders 124 and 126.

The resilient latching means 130 is made of a flexible metal including a flat portion 134 and two wings 136 and 138 disposed at an angle to the flat portion 134, respectively. The flat portion 138 is releasably joined to the fascia 128 by fixing means 140.

The latching means 130 is capable of flexing whilst being forced through the cut-out 122 and subsequently returning to its original shape immediately after passing through the cut-out 122 to, in combination with the upper and lower parts 142 and 144 of the fascia 128, prevent the fascia 128 from falling off. Referring to Figures 26 and 27, the housing 12A has a latching mechanism with a curved pivotal arm 200 having an enlarged portion 202. The pivotal arm 200 is in constant contact and biased by a biasing means in the form of a resilient curved plate 204. The pivotal arm 200 is biased by the resilient plate 204 such that it is in constant contact with the lock cylinder 16. It should be noted that the lock cylinder 1 is rotatable by a key (not shown) which is retrievable only when the lock cylinder is in a selected orientation, ie. when a elongate key hole 206 is disposed in a horizontal position as shown in Figure 25. In operation, as the lock cylinder 16 rotates, the enlarged portion 202 slides against a circumferential surface 204 of the lock cylinder (see Figure 25). When the lock cylinder 16 is rotated to the orientation in which the elongate key hole 206 is disposed in a horizontal position, the enlarged portion 202 engages a

corresponding part of the lock cylinder 16 so as to provide an indication that the lock cylinder 16 is in the orientation in which the key (not shown) can be retrieved. The corresponding part of the lock cylinder is in the form of an indent 208 which partially receives the enlarged portion 202 of the biased pivotal arm 200 when the lock cylinder 1 is in the orientation in which the key is allowed to be retrieved. As the enlarged portion 202 drops into the indent 208, the key holder is able to fe l the engagement between the enlarged portion 202 and the indent 208, which is a positive indication that the key (and the lock barrel) is in a retrievable orientation.

Turning now to Figures 26 and 27, the housing 12A has an engaging mechanism including an engaging means in the form of a spherical ball and a biasing means in the form of a spring 211. The spring 211 in use is received within a cavity 212 provided in the housing 12A. The lock cylinder 16 being contained in the housing is movable by a rotatable knob 14A which is connected to the lock cylinder 16 via a cam. The knob 14A has two recesses 214 and 216 (see Figure 27) located at two selected positions in its internal surface 218. In use, the ball 210 is urged by the spring 211 to press against the internal surface 218 of the knob 14A. As the knob 14A is rotated the selected orientations, the ball 210 being urged by the spring 211 is partially received within the recesses 214 and 216, respectively. This offers two advantages, namely 1) allowing a knob user to receive a positive indication as to the orientation of the knob and 2) allowing a key holder who is operating the lock assembly via the lock cylinder 16 to receive a position indication as to when the stop turning the lock cylinder 16 which is connected to the cam (not shown) which in turn can be rotated by the rotatable knob 14A. Also, the knob 14A acts as a stop for the cam and the lock cylinder 16. In operation, when key hole 206 of the lock cylinder 16 is turned from a vertical (locked) position to the horizontal position for retrieval of the key, the key holder can feel the engagement between the ball 210 and the recess 214 thereby receiving a positive indication that the lock cylinder 16 is in a orientation in which the key can be retrieved. This enables the key holder to know that the key (and hence the lock cylinder 16) need not be turned any further.

It will be appreciated that the latching and engaging mechanisms may operate collaboratively or independently.

Now that preferred embodiments of the present invention have been described in some detail, it will be apparent to a person skilled in the art that the lock assembly of the present invention may offer at least the following advantages:

1. it prevents unauthorised removal of the deadlock cam from the lock assembly,

2. it allows replacement of a deadlock cam with a free latching cam;

3. it minimises the risk of scratching the surface of the panels of a roller type door,

4. it facilitates use of the housing with lock cylinders carrying locking elements of a different profile or size;

5. it prevents the fascia from falling off a roller type door during installation

6. it provides a positive indication as to the orientation of the lock barrel thereby enabling the user to identify when the key can be retrieved; and

7. it provides a positive indication as to the orientation of the knob thereby enabling the user to identify when to stop turning the knob by hand or turning the lock barrel by the key to get to the locked, unlocked and key retrieval positions.

Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. For instance, the engaging means may be in other desired shapes and forms with a curved surface to facilitate moving in and out of the recesses as the knob rotates. Also, the L-shaped wafers may be replaced by Z-shaped wafers or wafers in other shapes to suit different lock cylinder designs. All such variations and modifications are to be considered within the scope and spirit of the present invention the nature of which is to be determined from the foregoing description.

Industrial Applicability

The lock assembly of the present invention is industrially applicable as it prevents unauthorised removal of a deadlock cam from the lock assembly and allows replacement of a deadlock cam with a free latching cam.