AU1473499A - Lock bolt assembly - Google Patents

Description

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AUSTRALIA

Patents Act 1990 COMPLETE

SPECIFICATION

FOR A STANDARD

PATENT

ORIGINAL

Name of Applicant: Actual Inventor: Address for Service: Invention Titie: TECHNOSEARCH PTY. LIMITED Ladislav Stephan

KARPISEK

Robert G. Halliday 44 Ashley Street, Hornsby NSW 2077 LOCK BOLT ASSEMBLY Details of original application of which this application is a divisional: Application number 45708/96, filed 20th February, 1996 The following statement is a full description of this invention, including the best method of performing it known to me:

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IMPROVEMENTS IN LOCK BOLT ASSEMBLIES.

This invention relates to lock bolt assemblies of the remote type to supplement the protection given by primary locks on security doors. Security doors comprised of a rectangular frame made from aluminium extrusions with an infill of expanded metal mesh are those with which the present invention is particularly (but not exclusively) intended to be used. Primary locks for the above purpose desirably have several characteristics including, an ability to be used in right hand or left hand opening doors, (ii) a sliding tongue which normally has a short bolt projection condition so that only a small force acting on the closing door will cause the bolt to retract as the nose of the bolt engages the striker plate on a door jamb, this facilitates the fitment of an automatic door closer to the door, (iii) an automatic change to a long bolt projection condition when the tongue is aligned with the aperture in the striker plate on a door jamb, (iv an automatic return of the bolt to its short bolt projection S 20 condition on retraction of the bolt back into the lock body by a lock operating handle, provision of deadlock means to deadlock the bolt but only when in the long bolt projection condition, (vi) multiple means to both activate and deactivate the deadlock -2- Smeans, including a manual means operational from what would be the inside of the door and key operated means operable from both sides of the door and which will over-ride the manual j means, (vii) a latch means to retain the deadlock means in its operative position to thereby prevent unauthorised release of the deadlock means.

This invention provides a lock assembly which supplements the security provided by a primary lock of a door and adds to the desirable qualities of primary locks by providing in the primary lock actuation means for the lock assembly, where the actuation is limited to certain conditions of use of the primary lock.

Broadly the invention can be said to provide a lock 15 assembly including a housing, a lock bolt receiving cavity in said housing, an opening in the housing providing access to said cavity, a lock bolt aligned with said opening and forming part of a lever arm mounted in said cavity, a pivot pin fixed to said housing and engaged in a slot in said. 1v'l arm located intermediate said lock bolt and a connection point oh said lever arm for coupling to a lever arm moving means, pivoting movement of said lever arm causes movement of said lock bolt between retracted condition when it lies substantially completely in said cavity and 3 an extended condition where said bolt projects from said housing through said opening, a toothed zone on said lever arm and a complementarily shaped toothed zone in said cavity, said toothed zones being spaced apart when said pivot pin is in engagement with one end of said slot and said slot having a length such that force applied to said lock bolt when in the extended condition to promote rotation of the lever arm about the pivot pin and retraction of said lock bolt will allow planar movement of said lever arm sufficient to caus- engagement of the teeth of said zones thereby locking said lever arm against arcuate bolt retracting movement.

Embodiments of the invention, including a particularly preferred embodiment of a remote lock assembly, and the interaction of remote lock assemblies with a primary lock will now 15 be described with reference to the accompanying drawings in which: Fig.l is a view of a general type of primary lock as before generally described with the lock bolt in the retained intermediate projection condition, Fig.2 is a view similar to Fig.l with the lock bolt in the fully o: 20 extended condition, Fig.3 is a view similar to Fig.2 with the lock bolt engaged by a deadlocking bar 'snib, operated, Fig.4 is a view similar to Fig.2 with the lock bolt engaged by a deadlocking bar 'key' operated, Fig.5 is a view similar to Fig.l showing a first form of remote 1; rc- i

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t i 4 lock actuator, Fig.6 is a view similar to Fig.3 showing the first form of remote lock actuator as it will be for a 'snib' operated deadlocking bar condition, 5 Fig.7 is a view similar to Fig.4 showing the first form of remote lock actuator as it will be for a 'key' operated deadlocking bar condition, Fig.8 is a view similar to Fig.l showing a second form of remote lock actuator, Fig.9 is a view similar to Fig.3 showing the second form of remote lock actuator as it will be for a 'snib' operated deadlocking bar condition, is a view similar to Fig.4 showing the second form of remote lock actuator as it will be for a 'key' operated 15 deadlocking bar condition, Fig.11 is a view of a first form of remote lock assembly according to the invention, with the lock bolt retracted, Fig.12 is a view similar to Fig.ll with the lock bolt in the extended condition, Fig.13 is a view similar to Fig.ll showing an actuator bar connected to the lock bolt operating lever, Fig.14 is a view similar, to Fig.12 showing a spring loaded actuator bar connected to the lock bolt operating lever, is a view of a second form of remote lock assembly according to the invention, with the lock bolt retracted and the 5 lock bolt operating lever removed to facilitate the later detailed description, Fig.i6 is a view similar to Fig.15 with the operating lever in place, Fig.17 is a view of the lock of Fig.16 with the lock bolt in an extended condition but 'unlatched', Fig.18 is a view similar to Fig.17 with the lock bolt 'latched', and Fig.19 is a view of a third and preferred form of remote lock assembly according to the invention.

The following description provides substantial detail of a primary lock of a type with which the remote lock of this invention will usually be used, however it is to be understood that the remote lock assemblies hereinafter described and claimed can be used with primary locks of a type other than that hereinafter illustrated and described. The amount of detail provided about the primary lock is considered important to the understanding of the funtion of the invention.

In Fig.l there is shown a lock casing 1 having a mounting 20 plate 2 and a body 3. The body 3 is defined by walls 4,5,6 upstanding from a panel 7 such that the walls 4,5,6 and the mounting plate 2 enclose a cavity in which the lock working parts are housed. There are other lugs and walls upstanding from the panel 7 of a shape and size and for purposes as are hereinafter described.

-6 The principal operating member of the lock is the lock bolt 8 which is a substantially rectangular solid member with a nose 9 which is a rounded edge at the intersection of a pair of angled converging faces 10. The bolt 8 has in its upper edge a substantially central slot, shown in broken lines at 11, which extends from adjacent the end 9 to the back face 12 of the bolt 8.

The slot 11 has a side pocket 13 and a hole 14 through the floor with a blind end 15. A trigger 16 is mounted in a pivotal manner in the slot 11 by a pin 16a and the trigger is upwardly biased by a compression spring 17 in the hole 14. There is a lug 18 on the side of the trigger 16 and the lug 18 is aligned with the pocket 13.

The trigger can move up and down within the slot 11 and within a slot in the mounting plate 2 with the upward limit of the trigger movement determined by the engagement between the boss 22 on the top edge of the trigger 16 and the abutment face of the block 23 within the body cavity. There is a hole 19 into the bolt 8 from the back face 12 and a compression spring 20 housed in the ^J hole 19 and engaged over a peg 21 on the inner face of the wall biases the bolt 8 to an extended condition. The projection of the bolt 8 beyond the mounting plate 2 is limited by the engagement of the lug 18 against the inner face of the mounting plate 2, see Fig.l. As will be understood if the trigger 16 is depressed so as to enter into the slot 11 and the lug 18 enters the pocket 13 the bolt under the influence of the spring 20 will move from P -I 7 Sthe short bolt projection condition shown in Fig.l to the long bolt projection condition shown in Fig.2, where the limit of the bolt projection is determined by the engagement of the lug 24 on the bolt with the rear of the mounting plate 2.

Movement of the bolt 8 is achieved by the engagement between the control arm 25 having a boss 26 (below the arm 25) housed in a bearing hole in the panel 7. When a cover plate is fastened (as by screws on rivets at the locations 27) over the body cavity a hole in the cover plate will provide a bearing hole for the boss 1, 10 26 above the arm 25 thereby providing a stable pivotal mounting for the arm 25. There is a square hole through the bosses 26 to accept a square shaft engaged by a handle thereby allowing actuation of the bolt 8. The control arm is received into a recess 28 in the side of bolt 8.

The lock is of deadlocking type with a deadlock bar 29 Ij slidably housed between the mounting plate 2 and guides 30 and 32 S. against which the bar inner edge is urged by a spring loaded ball 37 housed in the bar 29. It is to be noted that the bar 29 is spaced from the guide 31. The bar 29 is retained in one of three S 20 possible axial movement positions by the ball 37 engagable in one of three depressions 38,39,40 in the inner face of the mounting plate 2. The upper end the bar 29 is reduced in thickness on its underface down to the line 33 enabling the tongue 34 so formed to pass over into the recess 28 when the bolt is in the long bolt projection condition shown in Fig.2 but not otherwise, see Fig.l.

The movement of the bar 29 can be achieved in two ways which involve actuators 41 and 42 co-operating with notches 35 and 36 in the bar 29. The actuator 41 is on an arm 43 having a boss 44 pivotally supported in holes in the panel 7 and in the cover plate (when applied) in the same manner as the boss 26. There is a square hole 45 through the boss 44 for a bar with an attached knob or the lie which is accessible from one side of the lock, which is the inside with respect to a door on which the lock is mounted.

The actuator 42 is key operated. There is a key in barrel assembly indicated 46 which is accessible from both sides of the door in which the lock is mounted.. The barrel assembly is retained in position in the body 3, where it is entered into 'keyhole' shaped openings in the panel 7 and the cover when fitted, by a screw 47 which enters through the mounting plate 2 and passes through a slot in the bar 29 and holes in the legs of the guide 31 and is threaded into the body of the barrel assembly 46. By rotation of t; he barrel 48 with a key the actuator 42 can be rotated between the extreme positions shown in Fig.l, where is has been used to pull the bar 29 to its release condition, and th position shown in Fig.4. where it has passed into the interior of the assembly 46 and in so doing has moved the tongue 34 in the bolt recess 28.

It will be noted in Fig.l when the actuator 42 is in the deadlock release position the actuator 41 is engaged deeply in the notch 35. As the key operated actuator 42 is moved to the Fig.4 position the actuator 41 is turned out of the notch 35 and overlies the face 49 of the lug 50 on the bar 29 with the limit of Srotary movement being determined by engagement between the leg 52 on the boss 44 with the pin 53 on the panel 7. When the reverse operation is performed the leg 51 adjacent the notch 35 will, in its downward movement, pick up the actuator 41 and return it to the notch 35. Thus it is clear that the operation of the key actuator 42 will override the actuator 41. Likewise it is clear Sthat if the actuator 41 has been used to position the deadlock bar in the 'half-on' position of Fig. 3 (to be explained) the key 1 10 operation of the actuator 42 will prevail and will return the deadlock bar to the Fig.l position. In the fully engaged and fully disengaged condition of the deadlock bar 29 the ball 37 will be respectively in the depressions 40 and 38. In the passage of the ball 37 from the depressions 40 to 38 and 38 to 40 it will pass through the depression 39. The operation of the deadlock bar 29 by the actuator 41 will only cause the ball 37 to move between he dep-essions 38 and 39 and when in the latter the deadlock bar will only have moved approximately half the travel obtained by the operation of the actuator 42, nevertheless, in this 'half-on' position the bar 42 will have sufficiently entered the recess 28 to deadlock the bolt 8, Fig.3. A further aspect to be noted is that in order for the actuators to operate as aforesaid the actuator 42 needs to be positively moveable by the key and at the same time there must he a degree of lost motion in the key operation to allow the actuator 42 to be moved between the positions of Figs. I and 4 by movement of the deadlocking bar 29 by the actuator 41.This is a feature inherent in the known barrel assembly used in this form of lock.

There is a further feature of the present lock and that is the retention of the deadlock bar 29 in the deadlocked condition.

As will be clear from the previous paragraph, if the deadlock bar 29 is in the Fig.3 *half-on' condition and some person was a.ble to access the end of the tongue 34 a downward movement of the deadlock bar would be possible due to the lost motion in the barrel assembly. This would then allow the bolt 8 to be retracted. The only resistance to the deadlock bar movement would be the prc~fression. of the ball 37 from the depression 39 to the depression 4D. This is not a serious problem for if the lock is in the 'half-on' position, which is effected by the turning of the knob on the inside of the door, it would mean that the area with the door is occupied. However, when the deadlock bar is moved by the key, either from the inside of the area having the door or outside that area, tbis is an action requiring absolute security and the above unauthorised operation of the deadlock bar 29 must he prevented.

In order to prevent the above manipulation of the deadlock bar 29 a latching means is provided. The latching action is *automatic in operation when the deadlock bar 29 is activated fully by the key in ther barrel assembly and there is an unlatching operation when the key is used to release the deadlock bar 29 from

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id \i 11 the bolt recess 28.

Referring to Figs.l and 3 it will be seen that in the off and 'half-on' condition of the deadlock bar the inner face of the deadlock bar is urged against the guides 30 and 32 by the action of the spring loaded ball 37 bearing against the inner face of the mounting plate 2. In Fig. 4, where the deadlock bar is fully the bar has moved upwardly beyond the guide 32 and under urging by the spring loaded ball 37 the bar 29 has moved laterally to boar on the guide 31 and place the end 54 of the bar 29 over the top edge of the guide 32. This condition is made possible by the actuator 42 retracting into the barrel assembly.

In this configuration it is clear that no amount of effort applied to the top of the tongue 34 can move the deadlocking bolt 29 downwardly. On the other hand, when the actuator 42 is moved anti-clockwise by the key the end of the actuator 42 will first enter the notch 36, then bear against the bottom of the notch 36 and in so doing move the deadlocking bar 29 laterally. The lateral movement is sufficient to allow the bar 29 to be moved to the 'off' condition, by engagement of the actuator 42 with the bottom lug 55 of the recess 36, into the Fig.l relationship with the guide 32. Having described the lock in its various modes of operation the interaction of the lock with a striker plate to effect the extension of the bolt 8 from the short bolt projection condition to the long bolt projection condition will be explained.

Referring to Pig.3 there is shown a door jamb 56 with an inset I -a 5 *e 5 r Irf

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Di: i 12 striker plate 57 with a bolt opening 58 behind which there is a bolt recess 59 in the door jamb. In known manner a door fitted with a lock will close with the bolt angled face 10 engaging a curved contact face of the striker plate this will cause the bolt 8 to retract into the housing and the bolt nose 9 will wipe across the striker plate face until the bolt is aligned with the striker plate bolt opening 58. At that instant the spring 20 will thrust the bolt forward into the opening 58 and the recess 59. In so doing the upper edge 60 of the opening 58 in the striker plate will come to bear on the ramped nose 61 of the trigger 16. As the bolt extends further into the recess 59 the contact between the opening edge 60 and the ramped nose 61 of the trigger will result in the trigger being depressed into the slot 11 in the bolt until the position is reached where the lug 18 enters the pocket 13. The means for limiting the projection of the bolt from the housing has now been removed and the bolt 8 will adopt its long bolt projection condition within the recess 59.

In a door opening procedure, when the handle is turned to move the arm 25 to retract the bolt 8 into the housing the spring 20 17 will be free to elevate the trigger 16. The lug 18 will now be in a position where it will engage the back of the mounting plate 2 when the handle is released and the bolt 8 is moved by the spring 20. Where the door with the lock as just described is in the open condition and some person accidentally depresses the trigger nose 61 the bolt 8 will adopt the long bolt projection r sc

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:r rr f i i i ;i-r li j ST~ 13 position. This will prevent a door closing procedure as described above as the bolt nose will be projecting too far to engage the ramped contact face of the striker plate. In this situation the bolt 8 can be simply reset to the short projection condition by pushing against the bolt nose 9. This will cause the top edge of the aperture in the mounting plate 2 through which the bolt 8 extends to bear on the ramped back of the lug If with the result the trigger will be pressed down into the slot 11. with continued pressure on the bolt nose 9 the lug 18 will pass under the top edge of the mounting plate aperture and pop up behind the mounting Splate to again hold the bolt in the short projection condition.

j The foregoing described lock is one of several forms of primary lock, in this case one having a two movement bolt, that could be used with the remote lock of the present invention.

In the modern environment with house breaking a constant problem the use of multi-point locks has become popular. The primary lock just described lends itself to ready use as a driver: for a multi-point lock installation using one or more remote lock as will now be described.

As shown in Fig.5 there is a lateral lug 62 on the bar 29 which has the position shown when the bar 29 is in the non-deadlock condition. In this condition the lug 62 is in contact with a peg 63 in a remote control bar 64 for remote multi-point locking device to be explained later. The peg 63 slides in a slot 65 in the rear wall 5 of the lock case. The bar 64 is spring i

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4~ -14biased in tha 'up' direction as will be later explained and is restrained against such movement by two means. The engagement between the peg 63 and the lug 62 and by the leaf spring finger 66 engaging the stop 67, but principally the latter.

Fig.6 shows the lock in relationship to a door frame, as per Fig.3, with the deadlocking bar 29 engaged as a result of the operation of the snib actuator 41. In this condition the lug 62 has lifted away from the peg 63 and the bar 64 is retained in place by the finger 66 engaging the stop 67. From this configuration it is clear that deadlocking the bolt 8 does not involve the operation of the remote multi-point locks.

Fig.7 shows the relationship of the components when the deadlocking bar 29 is operated by the k ey operated actuator 42.

The tapered upper end face of the lug 62 has deflected the finger .66 thereby releasing the bar 64 which is moved upwardly by a spring to operate the remote locks. The result of the upward movement of the bar 64 brings the peg 63 against the under face of the lug 62. As will be clear, the reverse operation of the actuator 42 will lower the bar 29 and the lug 62 which will thereby draw the bar 64 clown to withdraw the remote locks and the finger 66 will relocate below the stop 67.

It is to be noted that in the locked condition the remote locks are not held closed by the deadlocking bar 29 and if~ a direct force were to be applied to the bar 64 in the opposite direction of the arrow in F.Lg.7 the bar 64 could be moved to the

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~t ,c if 15 position with the deadlock bar 29 remaining in the Fig.7 position. Referring now to Figs.11 to 14 which illustrate a first form of remote lock, these are usually in pairs with a remote lock above and below the primary or main lock. There is provided a housing 68 which is illustrated in Figs.lO and 11 with a cover plate removed, and inside the housing there is a lock bolt 69 with a leg 70 which is rebated at 71. In the rebate there is housed one leg 72 of a lever arm pivoted at 73 and on the leg 72 there is a peg 75 which runs in a slot 76 in the lock bolt 69. The other leg 77 of the lever is provided with a hole 78 and the bar 64 is connected to the hole 78.

It follows from the construction shown and the action of the lever and the lock bolt 69 in the Figs.ll to 13 that by applying a turning force to the lever through the leg 77 by means of the rod 64 the lock bolt 69 can be caused to move out of and back into the housing 68. The outward movement of the lock bolt 69 is caused S^by the spring 79 which is around the rod 64 and retained between the bracket lug 80 and the collar 81 on the rod 64, with the spring 7 9 becoming effective when the actuator 41 moves the deadlocking bar 29 to remove the leaf spring 66 from engagement with the stop 67, as hereinbefore described.

The lock bolt 69 is retracted by the reverse movement of the deadlocking bar 29 bringing the lug 62 into engagement with the peg 63 to force the rod 64 downwardly against the action of the spring 79. When the bar 64 moves sufficiently the leaf spring 66 A'7.

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-16with return to its normal position below the stop 67. As will be understood, by reversing the lock of Figs.ll to 13 in locations above and below the main lock a three point lock can be achieved for a door and the movement of the rod 64 in one direction can be made to cause the lock bolts 69 to move out of the housings 68 and move back into the housings 68 in unison. The foregoing description is of a preferred embodiment of the invention and it is to be understood that changes can be made to various components described with departing form the inventive concept hereinbefore disclosed. By way of example, reference to Figs.8 to 10 will show that there is an alternative to the peg 63 and leaf spring 66 previously described.

First, the leaf spring 66 and its stop 67 are replaced by a detent in the remote lock, as by a spring loaded ball in the casing 68 engaged with a dimple in the side of the tongue 69. In Figs.3 to 10 the peg 63 is housed in a slot 82 in an end enlargement 83 of the lug 62. in Fig. 8 the rod 64 is held in place by the detent in the remote lock being stronger than the biasing spring 79 of the remote lock. The peg 63 will be seen in Fig.8 to lie adjacent the top of the slot 82.

In Fi-g.9 the snib actuator 41 has moved the deadlocking bar 29 upward sufficiently to bring the peg 63 into proximity to the bottom of the slot 82. in Fig.1O the deadlocking bar has been moved by the key operated actuator 42 to the fully deadlocked position with the tongue 8 and in so doing the bottom of the slot 17 82 has raised the peg 63 sufficiently to release the detent in the remote lock. When this happens the remote lock actuating spring 79 becomes effective to drive the remote lock bolts 69 into suitably positioned recesses in the door jamb. When the actuator 42 is operated to undeadlock the bolt 8 the position of Fig.8 is re-established and the detent in the remote lock retains the bolts 69 retracted.

The arrangement just described removes some of the operating load from the actuator 42 and lightens the operation of a three point locking arrangement. Again it is to be noted that the three point remote locks are not held in the extended position by the deadlocking bar 29 and if a force was applied to the bar 64 in the direction opposite to the arrow in Fig.lO the lock bolts 69 could be retracted without releasing the deadlocking bar 29 from the tongue 8.

Another form of remote lock will now be described with reference to Figs.15 to 18, where the slot 76 in the lock bolt 69 is in the form of a track which is not straight but profiled. The slot profile is of Vee shape with first and second divergent track 20 parts 76a and 76c disposed one to either side of an apex froming intermediate track zone 76b, with the apex 76b further from the lock bolt outer operating end than end zones of the track parts 76a and 76c. The track 76 includes a first part 76a which is straight and is angled relative to the path traversed by the track apex 76b as the lock bolt 69 moves in and out of the casing 68, I I

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iia i i i .ti i t i c I UIIC--~ 18 and is directed away from the track apex 69 towards the outer operating end of the lock bolt. The movement of the track following peg 75 along the track first part 76a provides an extending movement of the lock bolt 69 which is greater than that than can be achieved with a transverse slot as shown in Fig.lO.

When the peg 75 passes over the apex 76b of the Vee slot and enters the second track part 76c and an end portion thereof, which lies i stantially transverse to the path traversed by the track apex as the lock bolt moves, it is latched or retained or deadlocked, all terms having the same significance. The latching prevents the lock bolt 69 from retracting into the casing as the end portion of the portion 76c then engaged by the peg 75 is substantially transverse to the direction of the lock bolt movement. The whole arrangement is such that when said track follower 75 is positioned in the end zone of the track first part 76a and at said track apex 76c and in the second track part 76b lock bolt 69 is respectively fully retracted, fully extended and in an extended operative and latched position.

As will be understood from the foregoing description and the 20 drawing Fig.18, force applied to the outer end of the lock bolt, as may occur if the lock bolt 69 was the subject of attempted forced retraction, will be unsuccessful. Lock bolt retraction can only be achieved by lever controlled movement of the track follower 75 along the lock bolt track.

Another, and preferred, form of remote lock bolt assembly is .rrr

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r 1 rr a i i' ili r i .:1 v I 19 shown in Fig.19, the remote lock 84 includes a housing 91 with a cavity to house a lever arm 92 having an end part shaped as a hooked lock bolt 85. The housing 91 has a wall opening 93 allowing the lock bolt 85 to move between a retracted position, where it lies at least substantially wholly within the housing cavity, and an extended condition. The extended position of the lock bolt 85 is determined (in the illustrated embodiment of the invention) by engagement of the lever arm 92 with an edge 94 of the housing opening 93.

There are teeth 86 on a curved end face 95 of the lever arm 92 and there are correspondingly shaped teeth 90 on an adjacent curved surface 89 of the housing cavity. There is a slot 87 in the lever arm 92 and there is a pin 86 engaged in the slot 87 and fixed to the housing. There is a hole 88 in the lever for engagement by a pull and push rod shown as a broken line and indicated 64 which is coupled (as previously described) to a main or primary lock assembly. Other forms of movement promoting means (other than the pull rod of the previously described units) may be coupled to the lever arm 92.

When a force is applied through the rod 64 to rotate the lever arm 92 to extend or retract the lock bolt 85 the pin 86 will bear against the upper end 96 and sides of the slot 87 as pivoting takes place and the teeth 86/90 will not engage.

The teeth 86 and 90 are intended to prevent forced retraction of the bolt 85 from its extended condition. Forced retraction 20 could be attempted by use of an external agency, such as a bar or lever, applied to the nose 97 of lock bolt 85. Force applied to the nose 97 of the lock bolt when extended to try to rotate the lever arm 92 will cause the lever 92 to move in a planar manner and rise (as permitted by the slot 87) and the teeth 86/90 will engage thereby preventing rotation of the arm 92 and retracting movement of the bolt In the particular form of the invention, as shown in Fig.19, when the lock bolt 85 is retracted the teeth 86 will lie opposite the untoothed portion of the surface 89 of the cavity and the untoothed curved portion of face 95 of the lever arm 92 between the teeth 86 and the nose of the lock bolt 85 will lie below the teeth 90. This arrangement ensures that engagement of the teeth 86 with the teeth 90 can only occar when the lock bolt 85 is to some extent extended.

:As will be understood, details of the arrangements described and illustrated herein may be changed without change to the inventive concepts disclosed.

Claims (3)

1. A lock assembly including a housing, a lock bolt receiving cavity in said housing, an opening in the housing providing access to said cavity, a lock bolt aligned with said opening and forming part of a lever arm mounted in said cavity, a pivot pin fixed to said housing and engaged in a slot in said lever arm located intermediate said lock bolt and a connection point on said lever arm for coupling to a lever arm moving means, pivoting movement of said lever arm causes movement of said lock bolt between retracted condition when it lies substantially completely in said cavity and an extended condition where said bolt projects from said housing through said opening, a toothed zone on said lever arm and a complementarily shaped toothed zone in said cavity, said toothed zones being spaced apart when said pivot pin is in engagement with one end of said slot and said slot having a length such that force applied to said lock bolt when in the extended condition to promote rotation of the lever arm about the pivot pin and retraction of said lock bolt will allow planar movement of said lever arm sufficient to cause engagement of overlying teeth of said zones thereby locking said lever arm against arcuate bolt S; retracting movement.

2. A lock assembly including a housing, a lock bolt receiving cavity in said housing, an opening in the housing providing access to said cavity, a lock bolt aligned with said opening and forming part of a lever arm mounted in said cavity, a pivot pin fixed to said housing and engaged in a slot in said lever arm located intermediate said lock bolt and a connection point on said lever -22- arm for coupling to a lever arm moving means, pivoting movement of said lever arm causes movement of said lock bolt between retracted condition when it lies substantially completely in said cavity and an extei'.ed condition where said bolt projects from said housing through said opening, a curved face of said lever arm, teeth on said curved face, a curved cavity surface, teeth on said curved surface, at least some of the teeth on the lever arm overlie teeth in said cavity but are spaced therefrom when said pivot pin is in engagement with one end of said slot, said slot has a length such that force applied to said lock bolt when in the extended condition to promote rotation of the lever arm about the pivot pin and retraction of said lock bolt will result in planar movement of said lever arm and separation of said pivot pin and said one end of said slot sufficient to cause engagement of teeth on said lever arm with teeth on said cavity surface thereby locking said lever arm against pivoting bolt retracting movement.

3. A lock assembly as claimed in claim 1 or claim 2 wherein the teeth on the lever and the teeth in the housing cavity are in overlying relationship only when the lock bolt is in its extended condition. A lock bolt assembly as claimed in any one of the claims 1 to 3 wherein the movement of the lever arm to place the lock bolt in its exeddconsition is lmtdby eggmn fsi ee arm with an edge of the opening in said housing. -23- A lock assembly substantially as herein before described with reference to Fig. 19 of the drawings. Dated this 31st day of January, 1999 TECHNOSEARCH PTY. LIMITED 'By its Patent Attorney Robert G Halliday