GB2622472A

GB2622472A - Cylinder lock

Info

Publication number: GB2622472A
Application number: GB2310597.6A
Authority: GB
Inventors: O'sullivan Mark; O'Sullivan Marcus
Original assignee: Brisant Secure Ltd
Current assignee: Brisant Secure Ltd
Priority date: 2022-07-15
Filing date: 2023-07-11
Publication date: 2024-03-20
Also published as: GB202210454D0

Abstract

A double cylinder lock comprising and body 110 and first and second key operated cylinders 120 each with a plunger (drive member/actuator) 190 engageable with a rotator 170 of a cam. When no key is inserted into first and second cylinders the first and second plungers are in a first, neutral, position wherein they both engage the rotator/cam and at least one of the plungers is engaged with the body 110 preventing rotation of both cylinders and cam. When a key is inserted into a cylinder the plunger is axially moved to a second position permitting rotation of the rotator/cam. The plungers may have radially projecting protuberances/wings (260) engaging in slots in the cylinder to rotationally couple the plungers with the cylinder, the lock body may include T-slots in which radial protuberance engage providing selective blocking of rotation of the plunger depending on its axial position. Preferably the first and second plungers are equally biased toward the cam by springs 210. Preferably each plunger 190 has axial protrusions/pins to releasably engage axial recesses in rotor to transmit rotational torque. The rotator may include axial displaceable anti-tamper radial pins which engage upon snapping the cylinder.

Description

CYLINDER LOCK

[0001] This invention is a cylinder lock, and in particular a cylinder lock with an additional locking mechanism.

[0002] Cylinder locks are a type of lock commonly used to secure doors and the like and comprise a cylinder rotatable within a lock body upon insertion of a correct key. The locking mechanism which prevents rotation of the cylinder relative to the lock body includes a series of pins and springs, which extend into the cylinder from the lock body until the correct key is inserted. Upon insertion of the correct key, the pins are aligned to permit rotation. The cylinder is engaged with a rotator and cam which is engaged with a bolt mechanism on a door. When the cylinder is rotated, the rotator and cam actuate the door mechanism to unlock the door from a door frame. Whilst a single cylinder may be provided for one-way access to a door, generally cylinder locks will incorporate two opposed locks, one either side of the door to enable locking and unlocking from either side. Such locks may be referred to in the art as full or double Euro cylinder locks. Alternatively, one side of the lock may include a thumb-turn lock in place of a keyed lock.

[0003] Cylinder locks have the disadvantage that they can be picked by placing a series of levers into the keyhole thereof to depress the pins in the locking mechanism to the correct position to unlock the cylinder. Furthermore, the cam of the lock can be accessed by snapping the cylinder out of the lock using pliers or similar. Once accessed, the cam can be actuated with a lever such as a screwdriver to unlock the door's bolt mechanism. Attempts have been made to block access to the cam if the cylinder has been snapped off. In particular, the cylinder may include a break point so that the place where the cylinder is snapped can be controlled, and prevent access to the cam. However, the cam can sometimes still be accessed after the cylinder has been broken.

[0004] The present invention addresses shortcomings with cylinder locks, and in particular provides a locking mechanism that is secure against attempts to pick the locking mechanism or snapping off a cylinder.

[0005] Therefore, according to the present invention there is provided a cylinder lock comprising a body, the cylinder lock further comprising: opposed first and second cylinders comprising respectively first and second keyholes disposed in opposite ends thereof for receiving a key to actuate a door mechanism, the first and second cylinders being rotatable relative to the body when actuated by a correctly-fitting key inserted into the first or second keyhole; a rotator and cam being rotatable relative to the body when actuated by the key inserted into the first or second keyhole, the cam being disposed to engage, in use, the door mechanism; a first plunger disposed in the body between the rotator and first cylinder and a second plunger disposed between the rotator and second cylinder; wherein the first and second plungers are, when no key is inserted into the first or second keyhole, disposed in a first position whereby the first and second plungers are engaged with the rotator and at least one of the first and second plungers are engaged with the body to prevent rotation of the first and second cylinders and wherein when a key is inserted into the first or second cylinder, the first or second plungers are pushed by the key to a second position enabling rotation of the cylinder containing the key, the rotator and the cam.

[0006] In addition to the plunger being engaged with the body of the lock when in the first position to prevent rotation of the cylinder, the cylinder may also include a standard pin and spring mechanism to further lock the cylinder.

Advantageously, this would mean that only a specific key could unlock the lock. Furthermore, a lock picker, even if they are able to overcome the pin and spring mechanism, would not know to also slide the plunger, which would be hidden from view, to the second position.

[0007] The first and second cylinders and first and second plungers may be coaxial, and the first and second plungers may be slidable in a channel defined by the body along the axis between the first and second positions.

[0008] The first and second plungers may each further comprise a central, axial pin that extends into a central, axial aperture extending the length of the rotator, wherein the axial pins remain in the axial aperture when the first and second plungers move between the first and second positions. Such axial pins may be cylindrical to enable the plungers to rotate relative to the rotator. The axial pin could extend form the plunger or could be a shaft on which the plunger is slidably mounted, the shaft comprising an abutment to retain the shaft within the plunger.

[0009] A slidable drive member, such as a cylindrical rod, may be disposed in the axial aperture between respective ends of the axial pins of the first and second plungers, so when the first or second plunger is pushed by the key, the other plunger is pushed along the axial aperture by the slidable drive member.

[0010] The first and second plungers may each further comprise at least one engagement member that extends into an aperture on the rotator when the first and second plungers are in the first position, to prevent rotation of the rotator relative to the first or second plunger. The engagement member may be shorter than the axial pin and comprise one or more further pin that extends into a corresponding aperture in the rotator, so that the axial pin may remain engaged with the rotator, but the further pin or pins may be engaged or disengaged with the rotator. Two further pins may be provided either side of the axial pin, but other arrangements are envisaged. Alternatively the engagement member may comprise a profile extending from the plunger which is wider than the axial pin and which engages with a corresponding recess in the axial aperture, so that the profile may disengage from the recess but the axial pin in retained in the axial aperture.

[0011] When the first plunger is in the second position, the second plunger may be in a third position whereby the at least one engagement member is disengaged from the rotator, to permit rotation of the rotator relative to the second plunger, and when the second plunger is in the second position, the first plunger may be in a third position whereby the at least one engagement member is disengaged from the rotator, to permit rotation of the rotator relative to the first plunger. When the first or second plunger is pushed into the second position by the key, the slidable drive member between the respective ends of the axial pins of the plungers, if present, will push the other of the first or second plungers into the third position. When the plungers are in the respective second/third positions, the plunger in the second position is unlocked permitting the cylinder containing the key to be rotated, and the plunger in the third position is locked by engagement to the lock body, but the at least one engagement member of the locked plunger is disengaged from the rotator permitting the rotator to rotate relative to the locked plunger.

[0012] The first and/or second plungers may comprise a generally circular cross section and further comprise opposed engagement ears on the circumference thereof to engage with corresponding slots on the body of the cylinder lock, whereby the engagement ears and slots permit coaxial movement of the first and second plungers between the first, second and third positions, and permit rotation of the plunger only when in the second position. The slots may be generally "T" shaped permitting lateral movement of the plungers along the axis between the first, second and third positions, but preventing rotation when in the first or third positions, and permitting rotational movement when in the second position. Alternative means of engaging the plunger to the lock may be envisaged.

[0013] The first and second plungers may be biased to the first position by a biasing member. Therefore, the plungers and the cylinders revert to being locked when a key is removed and, if present, the further pins on the plungers are engaged with the rotator to prevent rotation.

[0014] The first and second plungers may be attached respectively to the first and second cylinders with the one or more biasing member, wherein the biasing member is a spring. Such springs may be arranged to bias the plungers to the first position, and also secure the plungers to their respective cylinder, so that when the cylinders are rotated by a key the plungers rotate as well. The plungers may also comprise a recess to engage with the key to aid rotation of the plunger.

One or more spring permits the plungers to be pushed or pulled back to the first position from the second or third positions. Alternative biasing means may be provided.

[0015] The rotator may comprise at least one abutment member located in an aperture extending from the axial aperture, wherein the at least one abutment member is covered by the axial pin of the first or second plunger, the abutment member arranged such that if the axial pin of the first or second plunger is removed from the rotator, the abutment member moves to block the axial aperture. The abutment member or members provide a security mechanism whereby if a cylinder is snapped off and the plunger is removed, the abutment member will block the central aperture of the rotator to prevent access to the cam and/or the other plunger. Should one of the plungers be removed, the other plunger will remain in or revert to the first position and thus lock the rotator, to prevent the rotator from rotating and actuating the door mechanism. The abutment members may be a pin, ball bearing, shutter or similar.

[0016] The first and second plungers may be attached to the body of the lock via a circlip which will still permit lateral and rotational movement, but when the cylinder is snapped off will ensure that the plunger is also removed and not left in the rotator.

[0017] A break point, sometimes known in the art as a break slot, may be provided in the lock body and aligned with one or both of the first and second cylinder, so that if the cylinder is broken off it will break at a specified point so 15 that the rotator and cam cannot be accessed.

[0018] One way in which a door mechanism may be accessed after breaking a lock is by inserting a lever, such as a screwdriver, under the lock body and forcing it upwards. The cylinder lock may further comprise a pin extending from the underside of the lock body which engages with a door when the lock is installed, and which prevents access to the lever and movement of the lock within the door.

[0019] Embodiments of the present invention will now be described in detail, but by way of example only, with reference to the following drawings in which: [0020] Figure 1A shows an end view of a cylinder lock according to the present application; [0021] Figure 1B shows a cross-sectional view of the cylinder lock shown in Figure 1A through line A-A; [0022] Figure 1C shows a cross-sectional view of the cylinder lock shown in Figures 1A and 1B through line B-B.

[0023] Figure 2A shows a side view of a plunger as shown in Figures 1B and 1C; [0024] Figure 2B shows an underside view of the plunger of Figure 2A; [0025] Figure 2C shows an upper side view of the plunger shown in Figures 2A and 2B; [0026] Figure 2D shows a cross-sectional view of the plunger shown in Figure 2C through line A-A; [0027] Figure 3A shows a side view of a rotator as shown in Figure 1B and 1C; [0028] Figure 3B shows an end view of the rotator as shown in Figure 3A; [0029] Figure 3C shows a cross-sectional view of the rotator shown in Figure 3B through line A-A; [0030] Figure 3D shows a cross-sectional view of the rotator shown in Figure 3B through line B-B; [0031] Figure 4A shows an end view of a lock body as shown in Figures 1A-1C; [0032] Figure 4B shows a side view of the lock body as shown in Figure 4A; [0033] Figure 4C shows an underside view of the lock body as shown in Figures 4A and 4B; [0034] Figure 5A and 5B show exploded views of a lock mechanism according to an alternative embodiment of the present invention; and [0035] Figure 5C shows a close up of the plunger of the lock mechanism of Figures 5A and 5B.

[0036] As best shown in Figures 1A-1C, there is shown a cylinder lock generally indicated 100 comprising a body generally indicated 110. The body 110 of this example is generally symmetrical along a vertical axis and comprises two locks, which in use may be provided on either side of a door.

[0037] The cylinder lock 100 comprises two opposed cylinders generally indicated 120a,120b each having a keyhole 130a,130b, the walls of the cylinder 120a,120b and keyholes 130a,130b defining a channel 140a,140b extending the length of the cylinder 120a,120b for insertion of a key to operate the locks. The cylinders 120a,120b are housed within and are rotatable relative to the body 110 when unlocked. A lower section 380 of body 110 beneath the cylinders 120a,120b houses a series of pins and springs 150 which extend into respective apertures 160 at the base of the cylinders 120a,120b when locked. These pins and springs 150 prevent rotation of the cylinders 120a,120b relative to the body 110 when locked, and can be unlocked by insertion of a correct key which aligns the pins. The pins and springs 150 are a standard locking mechanism for a cylinder lock and will not be discussed in any further detail.

[0038] Disposed in the body 110 between the cylinders 120a,120b is a rotator generally indicated 170 connected to a cam 180 which in use engages with a door mechanism such as a bolt to lock and unlock a door to a door frame.

[0039] Plungers generally indicated 190a,190b are disposed in a cavity 200a,200b between the cylinders 120 and the rotator 170. The plungers 190a,190b are attached to an end of respective cylinders 120a,120b with springs 210.

[0040] Figures 2A-2D show the plungers 190a,190b in more detail. Plungers 190a,190b comprise a body 220 having a generally circular cross section. The body 220 comprises a base 230 which comprises a recess 240 for receiving a key during use and two apertures 250 to which springs 210 are attached and retained. Extending from the base 230 are opposed circumferential engagement ears or wings 260 which in use engage with the body 110 of the cylinder lock in the cavities 200a,200b. An upper surface 270 of the plungers 190a,190b comprises a cylindrical central pin 280 and two shorter side pins 290.

[0041] As shown best in Figures 3A-3D, rotator 170 comprises a generally cylindrical body 300 with a central aperture 310 extending the full length through the body 300. Two further pairs of apertures 320 and 330 extend partially into the body 330 of the rotator 170.

[0042] As shown in Figure 1B and 1C, the central aperture 310 receives the central pins 280 of plungers 190a,190b and the further pair of apertures 320, 330 receive the side pins 290 of plungers 190a,190b respectively.

[0043] Turning back to Figure 3A, the outer surface of body 300 comprises two circumferential grooves 340 to locate the rotator 170 in the body 110 of the cylinder lock 100.

[0044] As best shown in Figure 3D, guard pins 350 are provided in the body 300 of the rotator 170 in an aperture. The end of the guard pins 350 are flush with the central aperture 310 extending through the centre of the rotator 170. The guard pin 350 are placed so that, as best shown in Figure 1B, they are covered by the central pins 280 of plungers 190a,190b when the central pins 280 are in the central aperture 310. Further apertures 360 are provided in line with the guard pins 350 to receive the guard pins 350 as will be described later.

[0045] Figures 4A-4C show the body 110 of the cylinder lock 100 in more detail. The body 110 comprises a cylindrical, substantially tubular upper section 370 and a lower section 380. The upper section 370 defines a central channel 390 for receiving the cylinders 120a,120b and an opening 400 for receiving the rotator 170 and cam 180. The lower section 380 comprises a screw hole 410 for affixing the cylinder lock 100 to a door and a series of openings 420 which receive the springs and pins 150. The body 110 comprises two break points 430 which are provided as a security mechanism. If the cylinder lock were broken with a pair of pliers to gain access to the rotator 170 and cam 180 to actuate the locking mechanism of the door, the body 110 will break at the break points 430 and, as will be described later, in so doing will actuate a security mechanism to prevent access to the rotator 170 and cam 180. A central part of the body between the break points may be constructed from steel or alternatively the entire body could be made of brass.

[0046] An axis is defined from keyhole 130a to 130b along channels 140a and 140b of cylinders 120a and 120b and through the central pins 280 of plungers 190a and 190b and through the central aperture 310 of rotator 170. As shown in Figure 1B and 1C, a slidable drive member 440 is disposed in the central aperture 310 of rotator 170 between the ends of the central pins 280 of the plungers 190a,190b.

[0047] As shown in Figures 1B and 1C, both locks of cylinder lock 100 are at rest in a locked state. This will be referred to as the "first position." The pins and springs 150, although not shown here, are engaged with apertures 160 in cylinders 120a,120b to prevent rotation of the cylinders 120a,120b relative to the body 110. Furthermore, plungers 190a,190b are partially engaged with the body 110 and the rotator 170. The engagement ears 260 of plungers 190a,190b are engaged with T-shaped slots (not shown) in the inside walls of central channels 390 of the body 110 within cavity 200. These slots provide for slidable movement of the plungers 190a,190b along the axis, but when the plungers 190a,190b are in the first position as shown in Figure 1B and 1C, rotation of the plungers 190a,190b relative to the body 110 is not permitted. Furthermore, since the plungers 190a,190b are attached to the cylinders 120a,120b with springs 260, engagement of the plungers 190a,190b to the walls of the body 110 also prevent rotation of the cylinders 120a,120b even if the pins and springs 150 are disengaged. The engagement of the plungers 190a,190b when in the first position therefore makes it much more difficult to pick the lock 100 and increases the security of the lock.

[0048] The central pins 280 of plungers 190a,190b and side pins 290 are engaged with central aperture 310 and other apertures 320, 330 of the rotator 170. Since the plungers 190a,190b are engaged with the walls of the body 110 in the first position, the side pins 290 prevent rotation of the rotator 170 relative to the body 110.

[0049] When a correctly fitting key is inserted into keyhole 130a and into channel 140a it will actuate two mechanisms. Firstly, the key will correctly position the pins and springs 150 to unlock this part of the lock as per a traditional cylinder lock. Furthermore, the end of the key will engage with the recess 240 of the plunger 190a and push plunger 190a to a so-called "second position" whereby the engagement ears 260 slide in the slots of the wall of the body 110 to the second position where the engagement ears 260 and slots permit rotational movement of plunger 190a. As plunger 190a is pushed into the rotator 170, central pin 280 of plunger 190a will push slidable drive member 440 along the central aperture 310 of rotator 170 and push the central pin 280 of plunger 190b.

Plunger 190b will be pushed away from rotator 170 into a so-called "third position" whereby side pins 290 are disengaged from the apertures 330 in rotator 170. When plunger 190a is in the second position and plunger 190b is in the third position, cylinder 120a and plunger 190a, rotator 170 and cam 180 can be rotated freely relative to the body 110.

[0050] When the key is released from cylinder 120a the springs 210 will bias both plungers 190a,190b back to the first position and lock both locks. The same mechanism would operate if the key were inserted into keyhole 130b.

[0051] As best shown in Figures 1B and 3D, the rotator 170 contains two guard pins 350 disposed in apertures within the body of the rotator 170. As shown in Figure 1B, the guard pins abut the central pins 280 of the plungers 190a,190b. Plungers 190a,190b are attached to the body 110 of the lock 100 with a circlip 450, which permits translational and rotational movement of the plungers 190a,190b. If one of the cylinders 120a or 120b is snapped off at a respective break point 430, the whole cylinder 120a or 120b and plunger 190a or 190b will be removed. When central pin 280 of the plunger 190a or 190b is taken out of the central aperture 310, the guard pin 350 will extend into the respective further aperture 360 and block the central aperture 310. This will prevent access to the other plunger to unlock it.

[0052] As show in Figure 1B, a pin 460 extends from the underside of the lock body 110. When the cylinder lock 100 is installed in a door, pin 460 prevents a lever being inserted between the lock and the door to raise the lock and access 15 the door mechanism.

[0053] An alternative embodiment of lock mechanism is shown in Figures 5A- 5C. There is shown an exploded view of an alternative lock mechanism generally indicated 500 comprising a cylinder, generally indicated 510, a plunger, generally indicated 520, a shaft, generally indicated 530, a spring generally indicated 540 and a rotator generally indicated 560. The lock 500 is an alternative to the cylinder 120a,120b, plunger 190a,190b and rotator 170 as shown in Figures 1-4, and both lock mechanisms can be used in one lock, as shown in Figures 5A-5C. Lock mechanism 500 sits within the same lock body 110 of Figures 1-4, so like numbers will be used where appropriate. Lock mechanism 500 is provided on one side of the rotator 560, and the lock mechanism of Figures 1-4 is provided on the other side of the rotator 560. The lock mechanism 500 may be an internal lock and the lock mechanism of Figures 1-4 may be an external lock.

[0054] The locking action of cylinder 510 operates in the same way as cylinder 120a,120b and comprises apertures 160 to bear a pin and spring locking mechanism as previously described. The end of 570 of the cylinder body 510 opposite from a keyhole 550 at keyhole end 580 is hollow and comprise slots 590, and a first internal area 600 adjacent a second internal area 610 at the end 570 of the cylinder 510. The plunger 520 is retained by the spring 540 inside the first internal area 600 of the cylinder 510 when in a first position where no key is inserted into the cylinder 510.

[0055] The plunger 520 comprises a substantially cylindrical body section 620 having a curved outer surface 630 and upper and lower surfaces 640, 650. The plunger 520 is slidably located upon cylindrical shaft 530. Plunger 520 further comprises a stepped projection generally indicated 660, which extends from the outer surface 630 and from the upper surface 640. The projection 660 is flush with the lower surface 650. The projection 660 includes a step 670 whereby the projection 660 extends in different levels from the outer surface 630 of the plunger 520. A first part 680 extends from the curved outer surface 630 and is level with both the upper and lower surfaces 640, 650, and a second part 690 which extends above the upper surface 640 and does not project from the curved outer surface 630 as far as the first part 680. The projection 620 is slidably located in a slot 590 of the cylinder 510 so that rotation of the cylinder 510 within the lock body also rotates the plunger 520.

[0056] Shaft 530 further comprises a flange 700 to abut the second part 690 of the rotator 520.

[0057] Rotator 560 comprises a first side 710 and a second side 720. Second side 720 of the rotator 580 operates with a locking mechanism as described in respect of Figures 1-4 (not shown) and comprises central aperture 310 and pair of apertures 320 to receive pins of a plunger 190a,190b as previously described. First side of the rotator 710 comprises a tubular extension 730 which comprises a slot 740 which may retain the second part 690 of the plunger 520 when in the first position. The tubular extension 730 is rotatably mounted in the second internal area 610 of the cylinder 510. Rotator 560 further comprises a break point 750 as previously described.

[0058] In a first position, when a key is not inserted into the cylinder 510, the plunger 520 is retained in both the tubular extension 730, with the second part 690 of the plunger 520 in the slot 740 and also the first internal area 600 of the cylinder 510, where the first part 680 of the plunger is in the slot 590 of the cylinder 510. The plunger 520 therefore locks the cylinder 510 to the rotator 560.

The first part 680 of the plunger 520 extends out of the slot 590 of the cylinder 510 to engage with T-shaped slots (not shown) in the inside walls of central channels 390 of the body 110 within cavity 200 as previously described. These slots provide for slidable movement of the plunger 520 along an axis, but when the plunger 520 is in the first position, rotation of the plunger 520 relative to the body 110 is not permitted. Furthermore, since the plunger 520 is attached to the cylinder 510 with spring 540, engagement of the plunger 520 to the walls of the body 110 also prevents rotation of the cylinder 510 even if the pins and springs 150 are disengaged. The engagement of the plunger 520 with the body 110 when in the first position therefore makes it much more difficult to pick the lock 100 and increases the security of the lock.

[0059] The rotator 560 is also locked from the other side 720 by a plunger (not shown) as previously described.

[0060] When a key is inserted into the keyhole 550 and into the cylinder 510, the key pushes the shaft 530 into the rotator 560, causing it to push a drive member 440 in the rotator 560 and therefore disengage the second plunger (not shown) from the rotator and allow the cylinder 510 and rotator 560 to rotate in the lock and engage the door locking mechanism. The first part 680 of the plunger 520 is able to rotate within the T-shaped slot (not shown) in the body 110 of the lock 100 [0061] If a key is inserted into the other side of the lock, then the plunger will push the drive member 440 into the shaft 520. This will cause the flange 700 to engage with the plunger 520 and push it down into the first internal area 600 of the first end 570 of the cylinder 510. This will cause the second part 690 of the plunger 520 to disengage with slot 740 of the rotator and permit the other cylinder and rotator to rotate.

Claims

CLAIMS1. A cylinder lock comprising a body, the cylinder lock further comprising: opposed first and second cylinders comprising respectively first and 5 second keyholes disposed in opposite ends thereof for receiving a key to actuate a door mechanism, the first and second cylinders being rotatable relative to the body when actuated by a correctly-fitting key inserted into the first or second keyhole; a rotator and cam being rotatable relative to the body when actuated by 10 the key inserted into the first or second keyhole, the cam being disposed to engage, in use, the door mechanism; a first plunger disposed in the body between the rotator and first cylinder and a second plunger disposed between the rotator and second cylinder; wherein the first and second plungers are, when no key is inserted into the first or second keyhole, disposed in a first position whereby the first and second plungers are engaged with the rotator and at least one of the first and second plungers are engaged with the body to prevent rotation of the first and second cylinders and wherein when a key is inserted into the first or second cylinder, the first or second plungers are pushed by the key to a second position whereby rotation of the cylinder containing the key, the rotator and the cam is permitted.
2. A cylinder lock as claimed in claim 1, wherein the first and second cylinders and first and second plungers are coaxial, and the first and second plungers are slidable in a channel defined by the body along the axis between the first and second positions.
3. A cylinder lock as claimed in claim 1 or 2, wherein the first and second plungers each further comprise an axial pin that extends into an axial aperture extending the length of the rotator and, wherein the axial pins remain in the axial aperture when the first and second plungers move between the first and second positions.
4. A cylinder lock as claimed in claim 3, wherein a slidable drive member is disposed in the axial aperture between respective ends of the axial pins of the first and second plungers, so when the first or second plunger is pushed by the key, the other plunger is pushed along the axial aperture by the slidable drive member.
5. A cylinder lock as claimed in any preceding claim, wherein the first and second plungers each further comprise at least one engagement member that extends into an aperture on the rotator when the first and second plungers are in the first position, to prevent rotation of the rotator relative to the first or second plunger.
6. A cylinder lock as claimed in claim 5, wherein when the first plunger is in the second position, the second plunger is in a third position whereby the at least one engagement member is disengaged from the rotator, to permit rotation of the rotator relative to the second plunger, and wherein when the second plunger is in the second position, the first plunger is in a third position whereby the at least one engagement member is disengaged from the rotator, to permit rotation of the rotator relative to the first plunger.
7. A cylinder lock as claimed in any preceding claim, wherein the first and/or second plungers comprise a generally circular cross section and further comprise opposed engagement ears on the circumference thereof to engage with corresponding slots on the body of the cylinder lock, whereby the engagement ears and slots permit coaxial movement of the first and second plungers between the first second and positions, and permit rotation of the plunger only when in the second position.
8. A cylinder lock as claimed in any preceding claim, wherein the first and second plungers are biased to the first position by a biasing member.
9. A cylinder lock as claimed in claim 8, wherein the first and second plungers are attached respectively to the first and second cylinders with one or more biasing member, wherein the biasing member is a spring.
10. A cylinder lock as claimed in any preceding claim, wherein the rotator comprises at least one abutment member located in an aperture extending from the axial aperture, wherein the at least one abutment member is covered by the axial pin of the first or second plunger, the abutment member arranged such that if the axial pin of the first or second plunger is removed from the rotator, the abutment member blocks the axial aperture.
11. A cylinder lock as claimed in any claim, wherein the cylinder lock further comprises a pin extending from the underside of the lock body to engage with a door when the lock is installed.