GB2169343A - High security padlock - Google Patents

Abstract

A lock body 1 contains a shackle 8 and a locking mechanism 29 which is mounted in a removable cartridge 15, said cartridge 15 being connected to the lock body 1 by means of a screw 42 which is accessible only when the shackle 8 is in an open position, said screw 42 having a core 43 which is formed of hard material. <IMAGE>

Description

SPECIFICATION High security padlock The present invention relates to an improvement in high security padlocks wherein the lock cylinder may be easily removed and replaced while the physical strength of the lock remains unaffected.

For economic and ease of supply reasons, it is desirable that the components which form a lock can be obtained separately so that if it becomes necessary to replace a part of a lock it is not necessary to replace the whole lock, only the part which is to be replaced. A It has previously been proposed to provide a padlock with a removable lock mechanism which is retained within the body of the padlock by means of a threaded retaining screw which passes through a locating hole in the padlock body and engages a threaded base provided in the lock mechanism. This pin is only accessible when the padlock is open, removal of the pin allowing removal and replacement of the lock mechanism.

Conventional (i.e. non-high security) padlocks are often forced open, by means of levering open the shackle or by attacking the structure of the lock with a heavy hammer or by drilling out either the lock mechanism or any screws holding the mechanism in place. Existing highsecurity padlocks have sought to overcome these methods of attack by increasing the physical strength of the padlock and manufacturing it in such a shape that it is difficult to attack by the methods indicated previously.

However, if it is desired to produce a high security padlock having an easily removed lock mechanism using the technique described above in relation to conventional padlocks, a weakness is introduced into the padlock in the form of the retaining screw. This screw is vulnerable either to attack using a heavy hammer which may break the screw or by drilling of the screw and consequent release of the lock mechanism. It is the object of the present invention to provide a high security padlock having an easily removable lock mechanism which is not vulnerable to the methods of attack described previously.

According to the present invention there is provided a high security padlock comprising a removable lock mechanism within a lock body and a lockable shackle which can form a closed loop with the lock body, said lock mechanism being releasably retained within the lock body by screw threaded means which comprise a retaining screw and a coacting threaded bore, the screw threaded means embodying a retaining screw provided with a hardened pin fixed within a bore extending in the direction of the longitudinal axis of the retaining screw.

The arrangement is preferably such that said retaining screw is only accessible from the exterior of the padlock when said shackle is in its open position and conveniently the lock mechanism is mounted in a cartridge which is secured within the lock body by the aforesaid retaining screw.

In a preferred embodiment the padlock is provided with hardened plates between the lock body and the lock mechanism as further protection against drilling.

It is also preferred that the retaining screw passes through a plain locating hole provided in the lock body and engages a threaded bore provided in the lock mechanism or a cartridge which contains the lock mechanism.

The locking mechanism preferably comprises a key-operable angularly movable cylinder which may be disposed within a sleeve adaptor. Furthermore, where a cartridge is provided as above-mentioned all the components therein may conveniently be held together by means of a removable resilient clip. Moreover, the shackle may be so shaped that it can be removed from the lock body after the locking mechanism has been removed.

In the accompanying drawings Figure 1 is a sectioned elevation of an embodiment of the present invention.

Figure 2 is a sectioned elevation of the embodiment shown in Figure 1, viewed at 90" to the elevation shown in Figure 1.

Figure 3 is a sectioned elevation of the lock body of the embodiment shown in Figure 1.

Figure 4 is a side elevation of a cartridge.

Figure 5 is a sectioned elevation of the cartridge shown in Figure 4.

Figure 6 is a plan view of the cartridge shown in Figure 4.

Figure 7 is an end view of the cam arrangement of Figure 1, Figure 8 is an exploded view of an alternative embodiment in accordance with the invention, and Figure 9 is a sectional elevation of the embodiment (when fully assembled) seen in Figure 8.

Referring now to the drawings, the high security padlock according to one embodiment of the present invention comprises a lock body 1 made from silicon bronze defining a lock compartment 2 (see Figure 3) having an open end 3 at one end of the body and two shackle locating holes 4 at the other end of the body 1. The end of the body 1 in which the shackle locating holes 4 are situated has a radiussed channel 5 defined by the body 1 between the holes 4, and two pairs of projections 6, the projection of each pair being situation on opposite sides of one of the holes 4.

A lock locating lug 7 having a concave surface is provided on the inside of the body 1 which projects a short way into the lock com partment 2.

A hardened steel shackle 8 of generally cir cular cross section having a long depending arm 9 and a short depending arm 10, connected by a radiussed section 11 is releasably mounted in the body 1, the depending arms 9 and 10 projecting through the holes 4. A pair of grooves 12 is provided in the inner side of the arms 9 and 10 such that the grooves 12 are opposite each other. a flat surface is machined on the portion 13 of the long depending arm 9 projecting beyond the groove 12 and a circumferential groove 14 is provided in the end region of this arm. The arms 9 and 10 of the shackle 8 can be locked within the lock body 1 by the locking means described below.

A brass lock cartridge 15 is releasably retained within the lock cavity 2. The cartridge 15 has a bore 16 provided through its central portion, a groove 17 being provided along the length of the bore 16. A key aperture 18 communicating with the bore 16, is provided at one end 19 of the cartridge 15, the bore 16 opening onto the other end 20 of the cartridge 15. A radiussed shackle locating channel 21 is provided to receive the long depending arm 9 of the shackle 8, on a first side 22 of the cartridge 15 and a threaded bore 23 opening into the bore 16 is provided in the channel 21. The second side 24 of the cartridge 15 is adapted at its upper portion to receive the end portion of the short depending arm 10 of the shackle 8.Below this portion there is a further lock locating lug 25 having a concave outer surface which combined with the concave surface of the locating lug 7 to provide a plain bore 26. Immediately below the further locating lug 25 is a threaded bore 27 which extends downwardly away from the lugs 7 and 25 coaxial with the plain bore 26.

Recessed faces 28a are provided on the remaining sides 28 of the cartridge 15, in which hardened steel plates 45 are positioned.

A retaining screw-42 serves to retain the cartridge 15 and hence the locking means within the body 1. The screw 42 has a hardened steel pin 43, fixed within a bore 44 in the screw 42. The bore 44, and pin 43 extend for substantially the whole length of the screw 42 and are coaxial therewith. The threaded portion 42a of the screw 42 engages with the threaded bore 27 and the screw head 42b engages the locating lugs 7 and 25 so that cartridge removal may only be effected after removal of the retaining screw 42.

A pin-tumbler lock mechanism 29 is provided within the bore 16, a key-hole 30 being adjacent the key aperture 18. A slotted, hardened steel disc 31 having a flange 32 around its circumference is provided within the aperture 18, a slot 33 being provided in the disc 31 so that it is in alignment with the keyhole 30. In the present embodiment the lock mechanism 29 is prevented from rotating by means of a portion 34 of the lock mechanism 29 projecting into the groove 17.However, in the case of a cylindrical lock casing the cooperation of a locating hole provided in the lock casing and a grub screw provided in the threaded bore 23 prevents rotation of the lock mechanism within the bore 15 or alternatively a separate part (known in the industry as a "bible") can be attached to a cylindrical lock casing to prevent rotation thereof as is described later with reference to the embodiment shown in Figures 8 and 9.

A slot 35 is provided in the end of the lock mechanism 29 which engages with a ridge 36 provided in a hardened cam 37 which is located in the open end of the bore 16. The cam 37 has a lobe 38 of generally rectangular cross-section. However, opposite sides 39 of the lobe 38 are slightly radiussed to allow a smoother cam action and reduce the possibility of jamming. The radiussed sides 39 of the lobe 38 act upon a pair of hardened steel cam followers 40. The portions 41 of the cam followers 40 acted upon by the lobe 38 are flat.

When the shackle 8 is in the position shown in Figure 1 and the cam mechanism is operated via the lock mechanism 29 by means of a key, the cam followers 40 are forced into the recesses 12 on the arms 9 and 10 of the shackle 8 and prevent withdrawal of the shackle 8 from the lock body 1.

The parts 41a of the cam followers 40 are forced into the recesses 12 on the arms 9 and 10 of the shackle 8 and prevent withdrawal of the shackle 8 from the lock body 1.

The parts 41a of the cam followers 40 which engage the recesses 12 have a shape corresponding to that of the recesses 12. This provides a closed loop defined by the lock body 1 and the radiussed portion 11 of the shackle 8. This closed loop is generally too small to allow a iever to be inserted when the lock is located in place. As can be seen, when the shackle 8 is locked in this position and the key is removed, the retaining screw 42 is totally inaccessible and it is only possible to remove the cartridge when the shackle is opened. Unlocking the lock mechanism 29 rotates the cam mechanism and allows the cam followers 40 to fall out of the recesses 12.

Physical protection is afforded to this padlock by means of the strength of the components, especially the lock body 1 and the shackle 8; the hardened steel plates 45 provided in the recesses 28a; the hardened steel slotted disc 31 and the retaining pin, all of these components being constructed so that they can withstand physical attack by means of a hammer and/or drill as mentioned previously.

In the alternative embodiments seen in Figures 8 and 9 the construction of the padlock shown therein is generally similar in many respects to the embodiments described above with reference to Figures 1-7 that is to say there is a lock body 1 a hardened steel shackle 8 and a removable brass lock cartridge 15 which is connected to the body 1 by means of a retaining screw 42 having a hardened steel pin insert 43, said screw only being accessible when the shackle 8 is in its open position. Opposite sides of the removable cartridge 15 are similarly protected by hardened steel plates (such as plate 45 seen in Figure 8) as before each of such plates being connected to the cartridge itself by means of a pop rivet indicated by reference numeral 50.

There is also provided as before a pair of separate bolts 51 which are each provided with a flat inner surface 52 and a rounded nose or outer surface 53, such surfaces 53 being arranged in the locked position of the padlock to engage with the recesses or grooves 12 formed in the inner surfaces of the arms of the shackle 8. Extending between said flat surfaces 52 of the bolt 51 is a projection 54 extending from one end of an angularly movable bolt operating member 55 which at its other end is formed with a further outwardly extending projection 56 which is adapted to engage in a corresponding groove formed at one end 57 of the cylinder 58 of a key operated locking mechanism 59.

The bolts 51 in this embodiment are however held in position against a platform or ledge 60 formed in the lock body 1 beneath the radiussed surface 5 thereof by means of a spring retaining plate indicated in Figures 8 and 9 by reference numerals 61. Said bolts 51 are however free to slide inwardly and outwardly relative to each other under the control of the projection 54 of the bolt operating member 55. Said projection 54 is of generally rectangular configuration in crosssection so that in the position of said projection shown in Figure 9 the two bolts 51 are, as previously explained, forced relatively outwardly in order to engage the recesses of grooves 12 of the shackle 8.If however said projection 54 is turned, through operation of said locking mechanism 59, through 90" then the narrower cross-sectional dimension of the projection 54 will lie between the bolts 51 which will enable the shackle 8 to be pulled outwardly, the rounded grooves 12 acting on the curved nose portions of the bolts 51 then pushing the bolts inwardly out of engagement with said grooves.

Surrounding the aforesaid locking mechanism 59 is a split sleeve 62 having a longitudinally extending slot 63 through which a longitudinally extending projection 64 provided on the locking mechanism 59 will project, said projection 64 lying within a groove formed in the cartridge 15 so as to prevent rotation of the locking mechanism 59. It is envisaged that different kinds of locking mechanisms can be used in the padlock as may be required and where such locking mechanisms have different external dimensions then each particular kind of locking mechanism may be provided with its own form of sleeve or adaptor 62.Moreover when the locking mechanism is not provided with a projection such as projection 64 then a separately formed spigot or projection can be provided which can be connected in any convenient way, as by means of a screw, to the locking mechanism and arranged so that it will then project itself through the slot formed in the adaptor sleeve.

In Figures 8 and 9 there are also shown a pair of hardened (to stop drilling) stop plates indicated by reference numerals 65 and 66 each of said plates having a central aperture in which a cam slot 67 is formed and there being also provided a radially extending projection 68 which is adapted in use to enter into the groove formed in the cartridge which is adapted to receive the projection 64 of the locking mechanism 59. There is also provided a hardened key engageable rotor plate 69 which will lie, in the views seen in Figures 8 and 9 at the bottom of the cartridge 15.

Looking therefore at the "exploded" view seen in Figure 8 the completed cartridge is assembled by taking the cartridge body 15 and firstly dropping into it the key engageable rotor plate 69. This is followed by the lower member 66, then by the locking mechanism 59 on which the sleeve 62 has been mounted, next will come the upper member 65 and then the bolt operating member 55 the lower projection 56 of which will engage with the cam slot 67 formed in said member 65 in order to limit the rotation of the cylinder 58 when the key 70 is inserted into the key slot formed in said rotor plate 69 and turned to turn the aforesaid cylinder 58 and bolt engaging projection 54.All these components are then held together in the cartridge body 15 by means of a spring clip 71 which is of generally U-shaped configuration having in its bridge portion a central aperture 72 through which the aforesaid projection 54 extends.

The two legs of said spring clip 52 are each formed with an inwardly extending dimple 73, each dimple being arranged to engage in a corresponding recess or aperture 74 formed in the adjacent hardened steel plate 45. It will therefore be understood that all of the aforementioned cartridge components can very easily be assembled into the cartridge body 15 and thereafter held in position by the spring clip 7 1 and correspondingly the locking mechanism 59 can very readily be changed if desired by removing the spring clip 72 and taking out the abovedescribed components of the cartridge. Conveniently the base of the cartridge 15 is formed with drain holes 1 5a to permit the escape of any water or moisture that may enter the padlock.

The longer arm 9 of the shackle 8 is formed, as is the case with the previously described embodiment, with a flat inner surface 13 and a circumferential groove 14 is formed adjacent to the end of this arm, leaving a terminal portion, indicated by reference numeral 14a having an overall diameter which is greater than the cross-sectional width of that portion which includes the flat surface 13.

Whilst the bolt operating member 55 remains in position, the portion 1 4a of the shackle cannot pass outwardly past the bolts 51, even when the projection 54 has been turned to a position in which its narrower cross-sectional dimension lies between the bolts. If however the cartridge assembly (including the bolt operating member 55) is removed from the lock body, the bolts 51 can then move further inwardly towards each other to permit the portion 1 4a of the shackle arm 9 to pass the bolts and thus enable the shackle to be taken out of the lock body.Thus an alternative shackle such as is indicated by dotted lines 75 in Figure 9 can then be inserted, such a longer shackle providing in its locked position a somewhat larger aperture between the shackle and the lock body 1 than is the case with the shorter shackle indicated by reference numeral 8. In assembling the complete padlock the bolts 51 and retaining spring plate 61 are assembled first to the lock body 1 whereafter the appropriate shackle is inserted and then finally the fully assembled cartridge is put in position and, with the shackle in the open position the cartridge can be secured to the body by means of the screw 42. A ball bearing 15b can be inserted beneath screw 42 at base of tapped hole to prevent drilling out of retaining screw by means of a "hollow" drill.

The padlock therefore provides the facility of not only being able to have alternative lengths of shackle but also different kinds of locking mechanisms can be used or aiternatively a locking mechanism that has become damaged or worn can be readily replaced, once the cartridge has been removed and the spring clip 71 detached from the assembled cartridge. It is therefore readily possible to vary the locking mechanism 59 in the padlock (for example locking mechanisms with different levels of security can be used) whilst retaining standard components for the remainder of the padlock.

Claims (13)

1. A high security padlock comprising a removable lock mechanism within a lock body and a lockable shackle which can form a closed loop with the lock body, said lock mechanism being releasably retained within the lock body by screw threaded means which comprise a retaining screw and a coacting threaded bore, the screw threaded means embodying a retaining screw provided with a hardened pin fixed within a bore extending in the direction of the longitudinal axis of the retaining screw.

2. A high security padlock as claimed in Claim 1 wherein said retaining screw is only accessible from the exterior of the padlock when said shackle is in its open position.

3. A high security padlock as claimed in Claim 1 or Claim 2 wherein said lock mechanism is mounted in a cartridge which is secured within the lock body by the aforesaid retaining screw.

4. A high security padlock as claimed in Claim 3 wherein hardened plates are disposed between the interior of the lock body and the exterior of the cartridge.

5. A high security padlock as claimed in Claim 3 or Claim 4 wherein said retaining screw engages a screw threaded bore formed in the cartridge.

6. A high security padlock as claimed in any one of Claims 3 or 4 or 5 wherein said locking mechanism comprises a key-operable angularly movable cylinder disposed within a bore or recess formed in said cartridge.

7. A high security padlock as claimed in Claim 6 wherein said cylinder is mounted within a sleeve adaptor which engages said cartridge bore or recess.

8. A high security padlock as claimed in Claim 6 or Claim 7 wherein said cartridge also contains a key-engageable rotor plate and means for determining the limits of angular movement of said cylinder.

9. A high security padlock as claimed in any one of Claims 6, 7 and 8 wherein the assembly which comprises the cartridge and all components mounted therein is held together by a removable resilient clip.

10. A high security padlock as claimed in any one of the preceding claims wherein the padlock includes a pair of separately formed bolts which are slidable towards and away from each other, the lock mechanism being connected to a bolt operating member which, on actuation of said lock mechanism, moves to force said bolts away from each other and into grooves or recesses formed in the padlock shackle.

11. A high security padlock as claimed in Claim 10 wherein said bolts are retained in position within the lock body by means of a removable resilient plate.

12. A high security padlock as claimed in any one of the preceding claims wherein the shackle is arranged to be removable from the body after the lock mechanism has itself been removed from the body.

13. A high security padlock substantially as hereinbefore described with reference to and as shown in Figures 1-7 or Figures 8 and 9 of the accompanying drawings.