WO2004022891A1

WO2004022891A1 - A lock for a sliding door

Info

Publication number: WO2004022891A1
Application number: PCT/AU2003/001148
Authority: WO
Inventors: John Henry Hoogendoorn
Original assignee: Lockwood Security Products Pty Limited
Priority date: 2002-09-05
Filing date: 2003-09-05
Publication date: 2004-03-18
Also published as: AU2002951205A0; NZ538095A

Abstract

A lock for a sliding door, the lock comprising: a. a base plate, b. a hook bolt which can be moved between an unlocking position and a locking position, c. a rotatable drive member which rotates about a first angle upon movement of the hook bolt between the unlocking position and the locking position, and which is able to rotate about a second angle when the hook bolt is in the locking position, d. a locking cam which rotates with the rotatable drive member about the first angle, and which is depressed by the rotatable drive member when the rotatable drive member moves through the second angle, e. engagement means to engage the locking cam with the base plate when the locking cam is in the depressed position, thereby preventing rotation of the rotatable drive member thereby preventing rotation of the hook bolt, thereby deadlocking the hook bolt in position, and f. means to rotate the rotatable drive member about the second angle.

Description

A LOCK FOR A SLIDING DOOR

FIELD OF THE INVENTION This invention is directed to a lock for a sliding door which can be a sliding glass door. The invention need not be limited to a lock for a sliding door and may encompass a lock for other types of sliding members such as windows, panels and the like.

One embodiment of the invention is directed to a novel lock mechanism which has a depressible locking cam to allow the lock to be deadlocked. BACKGROUND ART

A lock for a sliding door typically comprises a lock body. The lock body supports a hook bolt. The hook bolt can rotate or pivot between an unlocked position and a locked position. When the sliding door is closed, the hook bolt can be moved to the locked position where it engages with a striker or keeper. The hook bolt can be attached to, or form part of an external handle, snib, turn knob and the like. This type of lock is extremely well known.

It is known to provide a lock where a key can operate the hook bolt between the unlocked position and the locked position. It is also known to provide a lock for a sliding door which allows the hook bolt to be deadlocked in position. A number of different mechanisms are known to allow the hook bolt to be deadlocked. Most known mechanisms use some form of lever which is positioned next to the hook bolt and which can be moved to engage with the hook bolt to deadlock the hook bolt. The movement can be a pivoting movement or a sliding movement.

A disadvantage with the lever type deadlocking mechanism is that the mechanism is subject to inadvertent displacement which means that it may be possible to inadvertently undeadlock the hook bolt. For instance, a strong blow to the lock may be sufficient to undeadlock the hook bolt. Alternatively, the hook bolt can be accidentally deadlocked which can result in a person being accidentally locked in a room. Clearly, there is a great advantage in being able to provide a strong reliable deadlocking mechanism for a sliding door lock and which does not accidentally deadlock. Another type of known deadlocking mechanism is known in a lock apparatus which is used on a hinged door. The lock apparatus comprises an external handle which can be turned, a rose, and a reciprocating latch tongue. The deadlocking mechanism comprises a small flat locking plate which sits under the rose. The external handle, contains a central snib which can be turned, causing the flat locking plate to engage against a shoulder in the rose. This type of lock is widely used on front doors. A disadvantage with the deadlocking mechanism is that the locking plate is quite small to allow it to fit in the lock apparatus and it is possible to force the lock into the undeadlocking position, and to damage the lock apparatus upon attempts to turn the locked handle.

It will be clearly understood that, if a prior art publication is referred to herein, this reference does not constitute an admission that the publication forms part of the common general knowledge in the art in Australia or in any other country.

OBJECT OF THE INVENTION

The present invention is directed to a lock which can be used on a sliding door and which can be locked and deadlocked using a particularly designed mechanism. The lock and particularly the deadlocking mechanism can be made robust and less susceptible to inadvertently moving it to the undeadlocked or deadlocked position.

It is an object of the invention to provide a lock which may at least partially overcome the above-mentioned disadvantages or provide the consumer with a useful or commercial choice. In one form, the invention resides in a lock for a sliding door, the lock comprising:

1. a base plate,

2. a hook bolt which can be moved between an unlocking position and a locking position, 3. a rotatable drive member which rotates about a first angle upon movement of the hook bolt between the unlocking position and the locking position, and which is able to rotate about a second angle when the hook bolt is in the locking position, 4. a locking cam which rotates with the rotatable drive member about the first angle, and which is depressed by the rotatable drive member when the rotatable drive member moves through the second angle,

5. engagement means to engage the locking cam with the base plate when the locking cam is in the depressed position, thereby preventing rotation of the rotatable drive member thereby preventing rotation of the hook bolt, thereby deadlocking the hook bolt in position, and

6. means to rotate the rotatable drive member about the second angle. In an embodiment, the hook bolt can initially be moved to the locked position to lock the sliding door to a door jamb. In this locked position, the hook bolt can be moved to the unlocked position by either turning the hook bolt from the inside or by key from the outside of the door. To deadlock the lock, the rotatable drive member is further turned through its second angle which causes the locking cam to be pushed against and become locked to the base plate. In the embodiment, the locking cam, the rotatable drive member and the hook bolt are all operatively connected together such that if the locking cam is unable to rotate, the rotatable drive member is also unable to rotate and the hook bolt is also unable to move to the unlocked position. Typically, a lock barrel is used as the means to rotate the rotatable drive member which means that a key inserted into the lock barrel can be turned about the first angle to rotate the hook bolt into the locked position and can then be further turned (if desired) to deadlock the hook bolt. If the key is then removed from the lock barrel, the hook bolt cannot be rotated to the unlocked position when in the deadlocked position.

As mentioned above, the lock can be used in respect of a sliding door which will typically be a sliding glass door but the invention need not be limited to this particular use of the lock.

The lock has a base plate. The base plate may be formed with projections, apertures, shoulders, abutments and the like to hold, support various parts of the lock. The lock typically has a pull handle attached to the base plate. The base plate may be formed with an aperture which may be a central aperture, the reason for which will be described in greater detail below. The central aperture is preferably circular and may have a threaded internal wall. At least one further recess may be provided adjacent the central aperture, or may form part of the central aperture to assist in engagement of the locking cam with the base plate. The lock has a hook bolt. The hook bolt can be moved between an unlocking position and a locking position. It is typical for the hook bolt to pivot or rotate between these positions. The lock may contain one hook bolt or a plurality of hook bolts. The hook bolt typically comprises a forward portion formed with a hook/shoulder/abutment to engage with the keeper, and a rear portion. The rear portion may at least partially project out of the lock body to allow the rear portion to be pushed upwardly or downwardly to rotate the hook bolt.

The hook bolt may be length adjustable to accommodate the variations in the spacing between the lock and the keeper. In one form, the hook bolt may comprise a plurality of parts to allow the hook bolt to be length adjustable. In a preferred form the hook bolt may comprise two parts which may be a hook bolt carrier and a parrot beak. The beak may comprise the above-mentioned hook/shoulder/abutment and the rear portion which can at least partially project out of the lock. The hook bolt carrier may comprise a rotatable member in the lock body and to which the beak can be adjustably attached. Typically, the beak may be provided with a length of serrations which can mate with a similar set of serrations on the hook bolt carrier. This allows the length of the beak projecting from the lock body to be varied. Of course, other length adjusting means can be provided. The hook bolt carrier and the beak may be attached together via a faster. The fastener may comprise a screw or bolt. Other types of attachments are envisaged. To further secure the beak to the hook bolt, one of the beak or the hook bolt may be provided with at least one projection which passes into a corresponding recess on the other of the beak or hook bolt. In an embodiment, the serrations on the beak can be made wider than the thickness of the beak which means that the serrations can project below the bottom wall of the beak. The hook bolt carrier may be provided with a channel or groove into which the projecting serrations can pass when the two parts are attached together to better attach the two parts to each other. The hook bolt carrier may comprise a relatively large and typically centralised aperture to accommodate the rotatable drive member and the locking cam as will be described in greater detail below. The lock is provided with a deadlocking means. The deadlocking means can comprise the rotatable drive member and the locking cam. The rotatable drive member preferably comprises a drive stud. The drive stud typically contains a passageway extending therethrough. The drive stud may comprise a lower cylindrical portion and an upper portion. The upper portion may comprise at least one upwardly extending projection. The projection may be in the form of a lug. Preferably, a pair of diametrically opposed extending lugs are provided on the upper portion. These lugs can act on the locking cam to depress the locking cam into locking engagement with the base plate. The lower cylindrical portion may be rotatably coupled to, or relative to, the base plate. In one form this can be achieved using a circlip. Other attachment means can be used. This allows the drive stud to be rotatably held to the base plate. The lower cylindrical portion typically has a diameter which is less than the central aperture in the hook bolt carrier.

The drive stud is typically able to rotate relative to the hook bolt carrier about the first angle and about the second angle. The hook bolt carrier may be provided with a stop means to limit rotation of the drive stud about these angles. The stop means may be in the form of a raised curved wall of the hook bolt carrier.

The locking cam may comprise a short member which has an internal passageway. It is preferred that the internal passageway of the member is cylindrical. The internal diameter of the member is preferably slightly larger than the outer diameter of the lower cylindrical portion of the drive stud which allows the drive stud to pass through the internal passageway and allows the drive stud to rotate relative to the locking cam. Suitably, the locking cam contains means to engage with the at least one projection of the drive stud. The means may comprise a recess in an upper portion of the locking cam into which the projection/lug of the drive stud can locate. The recess preferably contains at least one ramped surface to act as a cam wall. The arrangement is preferably such that rotation of the drive stud will cause corresponding rotation of the locking cam however if the locking cam is held against further rotation, further rotation of the drive stud will now cause the lug to ride up the cam wall to cause the locking cam to be pushed 5 downwardly into locking engagement with the base plate.

The locking cam preferably sits within the central aperture of the hook bolt carrier. Suitably, the locking cam is prevented from rotating relative to the hook bolt carrier. Thus, it is preferred that the locking cam can only rotate with the hook bolt carrier. In one form, this can be achieved by 0 providing an irregular shape to the locking cam such that it cannot rotate relative to the hook bolt carrier.

The lock contains engagement means to engage the locking cam with the base plate when the locking cam is in the depressed position. In a preferred form, the engagement means comprises a projection on the 5 locking cam which engages in a recess on the base plate. Suitably, a plurality of such projections are provided.

A means is provided to rotate the rotatable drive member about the second angle (where the drive member depresses the locking cam). The means may comprise a lock barrel. The lock barrel typically has a pin which o extends in the rotatable drive member such that actuation of the lock barrel causes rotation of the rotatable drive member. The pin may be arcuate in shape.

BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the invention will be described with reference 5 to the following drawings in which:

Figure 1. Is a side view of the lock in the locked [ but not deadlocked] position.

Figure 2. Is a side view of the lock in an unlocked position. o Figure 3. Is an exploded view of the lock from the top.

Figure 4. Is an exploded view of the lock from the bottom. Figure 5. Is a close up view of some of the lock components. Figure 6. Is a side view of the lock in a deadlocked position. BEST MODE

Referring to the drawings and initially to figure 3 and 5 there is illustrated an exploded view of a lock for a sliding door and according to an embodiment of the invention. Briefly, the lock contains a cover member 10 containing a central aperture 11 through which the face of a lock barrel 12 can pass to allow a key to be inserted into the lock barrel 12. A base plate 13 is provided which is formed with various projections, ribs, abutments, shoulders, openings and the like to accommodate the various components of the lock, provide strength etc. A pull handle 14 is part of the base plate 13 to assist in opening and closing of the sliding door. The main internal components of the lock include the lock barrel 12, a hook bolt which comprises a parrot beak 15 attached to a hook bolt carrier 16 in a length adjustable manner, a screw 17 to attach beak 15 to carrier 16, a rotatable drive member in the form of a drive stud 18, and a locking cam 19.

Referring initially to the hook bolt , in the embodiment this is formed in two parts being beak 15 attached to carrier 16. However, the hook bolt may also comprise a single structure. Beak 15 comprises a forward portion formed with a hook 19A to allow the beak to hook into a striker or keeper on the door jamb. This type of arrangement is known. Beak 15 has a rear portion 20 which extends out of the lock body. The end of rear portion 20 is attached to a handle 21 to allow a person to pivot beak 15 between an open unlocked position and a closed locked position. Beak 15 is formed with a length of serrations 22. The serrations 22 extend downwardly below the lower wall of beak 15. This allows the serrations to lock into a corresponding groove on the hook bolt carrier 16 as will be described in greater detail below. Hook bolt carrier 16 has a relatively complex configuration. The carrier is relatively squat and mainly disk like in configuration and contains a large centralised aperture 23. The aperture is generally cylindrical except that a pair of diametrically opposite inserts 24, 25 are provided to accommodate locking cam 19 and to prevent locking cam from rotating relative to carrier 16 as will be described in greater detail below. A relatively prominent arcuate wall 26 extends above carrier 16. Wall 26 extends only partway about carrier 16 and functions as an anti tamper feature . Carrier 16 is formed with a flat land portion 27 on which beak 15 can be placed. Land portion 27 is formed with a small boss 28 containing a threaded insert (not illustrated). Beak 15 can be placed on land portion 27 with boss 28 extending through an elongate slot 29 in beak 15. Slot 29 is elongate to provide a degree of length adjustment of beak 15 on carrier 16. Land portion 27 meets with an internal upstanding wall 28A (just visible in figure 3). This upstanding wall 28A is formed with serrations which mate with the serrations 22 on beak 15. Thus once the length of beak 15 has been adjusted and screw 17 has been tightened, the serrations on the beak mate with the serrations on the carrier to make it almost impossible for the beak to be inadvertently adjusted in length. As further strengthening, serrations 22 on beak 15 extend into a small groove 30 on carrier 16. Part of groove 30 is visible in figure 4 and the groove extends immediately below upstanding wall 28. Referring to drive stud 18, drive stud 18 comprises a lower substantially tubular portion 31 and an upper collar 32. Collar 32 is formed with a pair of diametrically opposed outwardly extending lugs 33. Lugs 33 form part of a camming action to depress locking cam 19 into engagement with base plate 13 as will be described in greater detail below. The bottom of tubular portion 31 passes through aperture 35 on base plate 13 and is rotatively held in place by a circlip ( not illustrated). This allows drive stud 18 to rotate clockwise and anticlockwise by a certain amount while still being engaged to base plate 13. The tubular portion 31 has a diameter which is substantially less than the internal diameter of aperture 23 in hook bolt carrier 16 and which is slightly less than the internal diameter of the aperture in locking cam 19 such that in use the tubular portion 31 of drive stud 18 is positioned inside the aperture in locking cam 19 into such a way that tubular portion 31 can under certain circumstances rotate relative to locking cam 19. This will be described in greater detail below. Locking cam 19 comprises a squat tubular or collar like member having a large aperture 37 which is cylindrical. The aperture 37 has a diameter which is slightly more than the external diameter of the tubular portion 31 of drive stud 18 which allows the drive stud to be supported by the locking cam 19. Locking cam 19 has a top face which has a particular profile to facilitate the camming action. The top face is provided with a pair of diametrically opposed recesses 38 which accommodate the lugs 33 on drive stud 18. Each recesses 38 is provided with one sidewall which is substantially at right angles to the bottom wall of the recess, and another sidewall which is ramped and therefore contains a camming surface. Finally, locking cam 19 is provided with a pair of diametrically opposed vertical projections 39 which function as part of the engagement means to lock locking cam 19 to base plate 13 and as a stop for the key when the locking 0 cam 19 is in the deadlocking position. The vertical projections 39 have a substantially rectangular cross-section . Locking cam 19 is designed to slide up and down inside hook bolt carrier 16. This is achieved by sliding engagement of the vertical projections 39 in the inserts 24 in hook bolt carrier 16. The arrangement is that locking cam 19 sits within aperture 23 in hook 5 bolt carrier 16, but locking cam 19 cannot rotate independently of carrier 16 because of engagement of the vertical projections 39 in inserts 24. Thus, locking cam 19 can only slide up and down within hook bolt carrier 16 but upon rotation of hook bolt carrier 16, locking cam 19 must rotate with the hook bolt carrier. 0 A locking cam return spring 40 sits between the bottom of locking cam 19 and base plate 13 to naturally bias locking cam 19 upwardly and into engagement with the lugs 33 on drive stud 18.

Finally, the vertical projections 39 ( see fig 5) on locking cam 19 extend below the lower face of locking cam 19 (best illustrated in figure 4) and 5 can pass into corresponding recesses 41 extending adjacent each side of aperture 35 in plate 13. Thus, the pressure of locking cam 19 will cause the vertical projections 39 to pass into recesses 41 to lock the locking cam 19 against further rotation.

Hook bolt carrier 16 is spring biased by a return spring 42 to o adopt either the unlocked position or the locked position.

The lock functions as follows. Initially, the lock can be in the open unlocked position illustrated in figure 2. In this position, beak 15 has been rotated such that hook 19A is retracted. Return spring 42 biases hook bolt carrier 16 to the position illustrated in figure 2. The rear of beak 15 can be rotated to adopt the locked position illustrated in figure 1 which is locked but not deadlocked. In this position, beak 15 can be moved to adopt the open position illustrated in figure 2. Beak 15 can be moved between these two positions either by manipulating beak 15 or by inserting a key into barrel 12 and turning the key through a first angle typically about 75°. Thus, beak 15 can moved between the locked and the open position either by insertion and partial turning of the key or by manipulation of the beak. If a key is inserted in lock barrel 12, the lock barrel pin 43 engages with an internal shoulder or apartment or profile inside drive stud 18 causing drive stud 18 to also rotate as the key is turned. Drive stud 18 is connected to locking cam 19 by virtue of lugs 33 being inside recesses 38 which means that locking cam 19 rotates with the drive stud upon turning of the key. As locking cam 19 sits inside and engages with hook bolt carrier 16 by virtue of the vertical projections 39 sitting inside inserts 24, the hook bolt carrier 16 is rotated upon turning of the key. As beak 15 is attached to hook bolt carrier 16, it can be seen that insertion and turning of the key by about 75° causes beak 15 to move between the open position illustrated in figure 2 and the closed position illustrated in figure 1. Once in the position illustrated in figure 1 , the lock can be deadlocked to adopt the position illustrated in figure 6. The deadlocking action occurs by turning the key through a second turning motion in excess of about 70° and typically between 70°-140°. Thus, further turning of the key will cause the lock to be deadlocked. This means that a person can choose between locking or deadlocking the lock simply by turning the key by an additional amount. The deadlocking action occurs as follows. Once the lock is in the locked position illustrated in figure 1 , drive stud 18 is sitting within locking cam 19 with the lugs 33 sitting within recesses 38. Locking cam 19 is sitting within hook bolt carrier 16. As mentioned above, locking cam 19 cannot rotate relative to hook bolt carrier 16 but can slide downwardly or upwardly relative to hook bolt carrier 16. As beak 15 is in the closed position, further rotation of the key in lock barrel 12 will force further rotation of drive stud 18 but locking cam 19 cannot rotate any further because of its attachment to hook bolt carrier 16 and hook bolt carrier 16 cannot rotate any further because beak 15 is in the closed position and cannot rotate downwardly any further. At this point, further rotation of the key in lock barrel 12 begins to force lugs 33 to ride up the ramped or camming sidewall of each recess 38 in locking cam 19. This action causes locking cam 19 to be forced downwardly through hook bolt carrier 16 until such time as the bottom of the vertical projections 39 engage in recesses 41. At this point locking cam 19 is locked against further rotation. In turn, this prevents any rotation of hook bolt carrier 16 which prevents any rotation of beak 15. The key can then be removed from lock barrel 12 and the lock is in the deadlocked position. Drive stud 18 is limited in its rotation by having lugs 33 abutting against the upright protrusions 39 on locking cam.

The process can be reversed by inserting the key into lock barrel 12 and turning the key the other way. It is possible to turn the key by a first amount to simply remove the deadlock. Specifically, if the key is turned the other way will cause drive stud 18 to rotate the other way which will cause lugs 33 to ride down the ramped or camming sidewall of each recesses 38. In turn, this will cause locking cam 19 to move out of engagement with recesses 41 by virtue of the locking cam return spring 40 biasing locking cam 19 in a naturally unlocking position. If the key is then removed or simply kept in the lock barrel but not turned any further, the beak 15 can be manipulated by a person's hand to the unlocking position illustrated in figure 2 or the locked (but not deadlocked) position illustrated in figure 1. Of course, the key can be further rotated to lift beak 15 to the unlocking position. The lock illustrated in the drawings is for the inside of the door.

On the outside of the door will be a small cover containing another key barrel which is operatively connected to a metal bar which passes through aperture 35, through the hook bolt carrier 16, through locking cam 19 and into the bottom of drive stud 18 to enable drive stud 18 to be rotated in a manner similar to that described above by insertion of a key in the "outside" key barrel.

Thus, the door can be closed from the outside and beak 15 can be moved to the locked (but not deadlocked) position by turning a key in the outside key barrel. The lock can be deadlocked by further turning this key in the outside key barrel. Similarly, the lock can be locked or deadlocked by turning the key in the "inside" the lock barrel 12.

It should be appreciated that various other changes and modifications can be made to any embodiment described without departing from the spirit and scope of the invention.

Claims

1. A lock for a sliding door, the lock comprising: a. a base plate, b. a hook bolt which can be moved between an unlocking position and a locking position, c. a rotatable drive member which rotates about a first angle upon movement of the hook bolt between the unlocking position and the locking position, and which is able to rotate about a second angle when the hook bolt 0 is in the locking position, d. a locking cam which rotates with the rotatable drive member about the first angle, and which is depressed by the rotatable drive member when the rotatable drive member moves through the second angle, e. engagement means to engage the locking cam with the base 5 plate when the locking cam is in the depressed position, thereby preventing rotation of the rotatable drive member thereby preventing rotation of the hook bolt, thereby deadlocking the hook bolt in position, and f. means to rotate the rotatable drive member about the second angle. 0

2. The lock as claimed in claim 1 , wherein the hook bolt is moveable to the locked position to lock the sliding door to a door jamb, and in this locked position the hook bolt is moveable to the unlocked position by turning the hook bolt from the inside of the door or by a key from the outside 5 of the door and to deadlock the lock, the rotatable drive member is further turned through its second angle which causes the locking cam to be pushed against and become locked to the base plate.

3. The lock of claim 1 , wherein the locking cam, the rotatable drive o member and the hook bolt are all operatively connected together such that if the locking cam is unable to rotate, the rotatable drive member is also unable to rotate and the hook bolt is also unable to move to the unlocked position.

4. The lock of claim 2, wherein a lock barrel is used as the means to rotate the rotatable drive member whereby a key is inserted into the lock barrel and turned about the first angle to rotate the hook bolt into the locked position and is able to be further turned to deadlock the hook bolt.

5. The lock of claim 3, comprising a pull handle attached to the base plate.

6. The lock of claim 1 wherein the base plate is formed with a central aperture which is circular and has a threaded internal wall, and at least one further recess is provided adjacent the central aperture, or forms part of the central aperture to assist in engagement of the locking cam with the base plate.

7. The lock of claim 1 , wherein the hook bolt pivots between the locking and unlocking positions and comprises a forward portion formed with a hook/shoulder/abutment to engage with the keeper, and a rear portion which at least partially projects out of the lock body to allow the rear portion to be pushed upwardly or downwardly to rotate the hook bolt.

8. The lock of claim 1 wherein the hook bolt is length adjustable.

9. The lock of claim 1 , wherein the deadlocking means comprises the rotatable drive member and the locking cam.

10. The lock of claim 9, wherein the rotatable drive member comprises a drive stud which contains a passageway extending therethrough and comprises a lower cylindrical portion and an upper portion, the upper portion comprising at least one upwardly extending projection in the form of a lug which acts on the locking cam to depress the locking cam into locking engagement with the base plate.

11. The lock of claim 1 , wherein the drive stud is rotatable relative to the hook bolt carrier about the first angle and about the second angle and the hook bolt carrier is provided with a stop means to limit rotation of the drive stud about these angles.

12. The lock of claim 1, wherein the locking cam comprises a short member which has an internal passageway which is slightly larger than the outer diameter of the lower cylindrical portion of the drive stud to allow the drive stud to pass through the internal passageway and to allow the drive stud to rotate relative to the locking cam.

13. The lock of claim 10, wherein the locking cam contains means to engage with the at least one projection of the drive stud, the means comprising a recess in an upper portion of the locking cam into which the projection/lug of the drive stud locates, the recess comprising at least one ramped surface to act as a cam wall.

14. The lock of claim 13, wherein rotation of the drive stud will cause corresponding rotation of the locking cam, however if the locking cam is held against further rotation, further rotation of the drive stud will now cause the lug to ride up the cam wall to cause the locking cam to be pushed downwardly into locking engagement with the base plate.

15. The lock of claim 11 , wherein the locking cam sits within the central aperture of the hook bolt carrier and is prevented from rotating relative to the hook bolt carrier.

16. The lock of claim 1 containing engagement means to engage the locking cam with the base plate when the locking cam is in the depressed position.