1. TECHNICAL FIELD OF THE INVENTION

The present invention relates generally to a high security lock that is capable of resisting opening by application of rotary force with elements other than matching key thereby ensuring the said lock to be force-proof and hence capable of preventing thefts or unauthorized access.

2. BACKGROUND OF THE INVENTION

As is known various types of locks for example padlocks, tubular locks, cylinder locks, (pin tumbler locks, wafer tumbler locks and disc tumbler locks) have been extensively utilized to lock cupboards, drawers, cabinets, windows and doors to deter theft of money, goods or documents.

A disc tumbler lock is a lock composed of slotted rotating retainer discs wherein a specially cut orbit key rotates the discs like tumblers of a safe to align the slots, allowing the sidebar to drop into the slots, thus opening the lock. Contrary to the wafer tumbler lock or a pin tumbler lock, this mechanism does not use springs. Hence from a security standpoint, the disc tumbler lock cannot be bumped and it is difficult to pick such a lock. Picking such a lock is time consuming, requires expertise and professionally made tools, however it is not impossible as disc tumbler locks can be forcibly opened. This has prompted lock manufacturers to use hardening material for locks to give it mechanical strength which entails high cost.

To overcome the above shortcomings of conventional locks being violated in many different ways and to ensure that the lock is force-proof, a high security lock is provided wherein the lock will be able to resist opening by application of rotary force with tools or otherwise inserted in the key-slot except for a matching key inserted into the key hole of the lock mechanism.

The present invention is directed to new and useful alternatives to known arrangements.

3. SUMMARY OF THE INVENTION

Accordingly, it is the primary aim of the present invention to provide a high security lock that is force-proof.

It is yet another object of the present invention to provide a high security lock that is capable of resisting opening by application of rotary force with tools or otherwise inserted in the key-hole of the lock mechanism save for a matching key. It is yet another object of the present invention to provide a high security lock that is capable of resisting unauthorized opening of the lock.

Yet another object of the present invention is that the side bar of the lock is sparred from being distorted, bent or damaged when there is a non-authorized opening by force.

It is a further object of the present invention to provide a high security lock which is simple in construction.

Other further objects of the invention will become apparent with an understanding of the following detailed description of the invention or upon employment of the invention in practice.

These and other objects of the present invention are achieved by,

A high security lock that is capable of resisting opening by application of rotary force with elements other than matching key comprising, a lock housing (4) at least a locking cylinder (6) a lock ring (12) having a key hole (14) characterized in that said locking cylinder (6) is maintained in a stationary position when rotary force is applied by an element other than a matching key .

4. BRIEF DESCRIPTION OF THE DRAWINGS

Other aspect of the present invention and their advantages will be discerned after studying the Detailed Description in conjunction with the accompanying drawings in which:

FIG. 1 is a cross-sectional view of a typical disc lock.

FIG. 2 is a first embodiment of the present invention wherein a propel disc is provided with at least a retractable protrusion.

FIG. 2-A shows a plan view of the propel disc in FIG. 2 housed in a locking cylinder.

FIG. 3 is a second embodiment of the present invention wherein at least a retractable arm integrally provided to the propel disc as a single unit is provided.

FIG. 3-A shows a plan view of the propel disc in FIG. 3 housed in a locking cylinder. FIG. 4 shows a plan view of a third embodiment of the present invention wherein the propel disc provided with at least a leaf spring is housed in a locking cylinder.

FIG. 4-A is a view of the propel disc at the portion provided with a leaf spring showing the leaf spring in its retracted position.

FIG. 5 shows a plan view of the fourth embodiment of the present invention wherein a propel disc provided with a substantially round aperture having at least a retractable inwardly directed protrusion and a flange extending outwardly from the outer circumference of the propel disc is housed in a locking cylinder.

FIG. 6 is a view of a fifth embodiment of the present invention wherein a propel disc is provided with at least an upwardly protruding hill-like element.

FIG. 6-A shows a plan view of the propel disc in FIG. 6 housed in a locking cylinder. FIG. 7 shows a view of the propel disc of the sixth embodiment wherein the propel disc having a bigger diameter than the rest of the normal locking disc is provided with at least a hump-like protrusion to contact the base of the locking cylinder. FIGS. 7-A and 7-B show two views of the sixth embodiment showing the arrangement of the hump-like protrusion of the propel disc and the base of the locking cylinder.

FIG. 8 is a view of the propel disc comprised in the seventh embodiment wherein the propel disc is provided with at least a stub-like protrusion extending from the circumference of the propel disc.

FIG. 9 is an eighth embodiment of the present invention wherein a retractable element is provided to the lock cylinder at the top of the housing.

FIG. 10 is a ninth embodiment of the present invention wherein a retractable element is provided to the lock cylinder at the bottom of the housing.

5. DETAILED DESCRIPTION OF THE DRAWINGS

In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those with ordinary skill in the art that the invention may be practised without these specific details. In other instances, well known methods, procedures and/ or components have not been described in detail so as not to obscure the invention. The invention will be more clearly understood from the following description of the embodiments thereof, given by way of example only with reference to the accompanying drawings that are not drawn to scale.

Referring to the drawings in which like numerals indicate like parts throughout the views shown, FIG. 1 shows a cross-sectional view of a typical disc lock. The typical lock comprises a lock housing (4) which houses a locking cylinder (6), a lock ring (12) having a key-hole (14). In the said illustrations, a plurality of locking discs (10) are located therein a locking cylinder (6). Each locking disc (10) is separated by a disc separator (8) and the function of the disc separator (8) is to prevent adjacent locking disc (10) from being rotated when it is not supposed to rotate. The lock housing (4) preferably comprises a short length cut from a continuous solid bar, the section being penetrated in a longitudinal direction at each end (4A) (4B) [that is from one end or the top of the lock housing (4)] to accommodate the long and short ends of the shackle (5) and penetrated upwardly preferably centrally of the lock housing (4) [that is at the bottom of the lock housing (4)] to accommodate or house the locking cylinder (6). The upper part of the lock housing (4) where the shackle (5) is situated is also provided with a recessed part (4C) to accommodate a pair of ball device (7) and the said ball device (7) is controlled by the locking cylinder (6) to either abut the recessed part (4C) [when the lock is locked] or be distanced from the recessed part (4C) [when the lock is opened]. In most conventional locks such as illustrated in FIG. 1, when the locking discs in the conventional locking cylinder are made to come into alignment using an element other than a matching key such as a lock-forcing tool for example an alien key, a crime perpetrator or a trained person or an unauthorized person can forcibly rotate the locking cylinder (6) to eventually unlock the lock.

The high security lock of the present invention is also provided with the components of the typical lock illustrated in FIG. 1 and is a disc tumbler type save for the introduction of a propel disc (11). In the present invention the locking cylinder (6) is maintained in a stationary position when rotary force is applied by an element other than a matching key. This is made possible by having a propel disc (11) provided with at least a protrusion that is capable of being retracted so as not to have any firm contact with the locking cylinder (6) in order to afford factional force between the protrusion of the propel disc (11) and the locking cylinder (6) to move the locking cylinder (6) when an element other than a matching key is inserted into the key-hole and forced to rotate or by having a protrusion that is capable of displacing the locking cylinder (6) upwardly or downwardly when the propel disc (11) rotates so as not to cause the locking cylinder (6) to rotate but only to move up or down. Several embodiments of the propel disc (11) with various types of protrusions that are capable of providing the abovesaid security are described below but it is to be understood that the embodiments are not exhaustive as long as the propel discs (11) is able to facilitate either a retractable effect by for example having an element or protrusion on the propel disc (11) that is capable of being retracted so as not to form any concrete contact with the locking cylinder (6) to the extent that the said contact is able to rotate the locking cylinder (6) or capable of displacing the locking cylinder (6) so as not to cause the locking cylinder (6) to rotate but only to move up or down when an element other than a matching key is inserted into the key hole and forced to rotate.

Referring now to FIGS. 2 and 2- A, there are shown two views of a first embodiment of the present invention that is a first propel disc (11A) provided with at least a retractable protrusion (26) and a lateral cross sectional view of the first propel disc (HA) housed in a locking cylinder (6) employed together with other typical locking discs (10) respectively. In this preferred embodiment, at least a first propel disc (11A) is stacked amongst other typical locking discs (10). The first propel disc (11A) in this first embodiment can be positioned anywhere amongst a stack of locking discs (10) including being the first or the last to be stacked or in between locking discs (10). The first propel disc (11A) of this first embodiment is similar in all respects to a typical locking disc (10) save for being provided with at least a retractable protrusion (26) preferably comprising at least a ball device (26A) attached to at least a resilient element (26B) to facilitate its retraction or extension. Here the ball device (26A) acts as a solid object for contact with another surface whilst the resilient element (26B) acts as a retractable element to retract the solid object when circumstances permit as described below.

The said ball device (26A) is advantageously a steel ball and the resilient element (26B) is advantageously a spring but other materials and forms are possible as long as the retractable protrusion (26) is resilient in nature. The first propel disc (11A) of this first embodiment is also provided with a locking disc slot (10A) as in typical locking discs (10) to accommodate the side bar (10B) when it drops into the locking disc slots (10A) upon all the locking disc slots (10A) of each locking disc (10) being aligned by a matching key to facilitate simultaneous rotation of all the locking discs (10) in the said locking cylinder (6). It is also provided with a substantially central aperture (IOC) to accommodate the key for rotation purposes. When a matching key is inserted and turned the initial predetermined degree preferably 90 degrees from insertion point all the locking discs (10) will turn enabling their respective locking disc slots (10A) to come into alignment. Prior to reaching the end of the initial predetermined degree turning the retractable protrusion (26) does not yet come into contact with the locking cylinder (6) of the first embodiment and the side bar (10B) also remains fixed to the lock housing (4). Turning further after the initial predetermined degree will cause the side bar (10B) to drop to be accommodated by the aligned locking disc slots (10A) thereby freeing it from the lock housing (4). When this happens further turning of the matching key will cause turning of the lock cylinder (6) of the first embodiment, this is made possible by means of the frictional force generated between the ball device (26A) of the retractable protrusion (26) of the first propel disc (HA) and the locking cylinder (6). Hence the locking cylinder (6) will rotate simultaneously with all the locking discs (10) including the first propel disc (11 A) thereby opening the lock.

When an element or device other than a matching key (hereinafter referred to as "a non-matching key") is inserted into the key hole (14), all the locking disc slots (10A) of the locking discs (10) including that of the first propel disc (HA) fail to come into alignment to enable accommodation of the side bar (10B) with the initial predetermined degree turn. Further turning of the non- matching key although able to bring the retractable protrusion (26) to come into contact with the locking cylinder (6) would still not be able to turn the locking cylinder (6) as the side bar (10B) is not able to drop to be accommodated by the locking disc slots (10A) which are not aligned so the side bar (10B) remains fixed to the lock housing (4). The locking cylinder (6) of the first embodiment will not move because the side bar (10B) is not freed from the lock housing (4). In attempting to force open the lock by rotary force, a force in excess of that required in normal opening of the lock is most often employed. When this happens the retractable protrusion (26) because of its resilient nature will function to slip from the locking cylinder (6) thereby not forming any firm contact with the locking cylinder (6) and hence freeing the first propel disc (11 A) from the locking cylinder (6) and the first propel disc (11A) will rotate freely without turning the locking cylinder (6). Thus the lock of this first embodiment cannot be opened even if force in excess of that required in normal opening of the lock is employed. The locking discs (10) including the first propel disc (11 A) will only rotate with the non-matching key but the locking cylinder (6) of this first embodiment will remain stationary and the side bar (10B) fixed to the lock housing (4). Hence it is not possible to open such locks by force using non- matching keys including anti-allen key or other tools inserted into the keyhole (14). The side bar (10B) remaining intact in its original position [that is fixed to the lock housing (4)] will not obstruct the rotation of the locking discs (10) and the first propel disc (HA) and in this manner the side bar (10B) is spared from being distorted, bent or damaged when there is non-authorized opening by force. This would not be possible in forceful openings of conventional locks as the locking cylinder will rotate simultaneously with the non-aligned locking discs (10) thereby distorting, bending or damaging the side bar which is obstructing its forced rotary movement. The advantage with having the retractable protrusion (26) is to ensure it is flexible and resilient and does not break in instances of forced opening and thus no replacement of parts are required save for wear and tear. Referring now to FIG. 3 and 3-A, FIG. 3 shows a second embodiment of the present invention wherein at least a retractable arm (27) integral to the second propel disc (11B) as a single unit is provided and FIG. 3-A shows a lateral cross sectional view of the said second propel disc (11B) in FIG. 3 housed in a locking cylinder (6) employed together with other typical locking discs (10). This second embodiment functions in the same manner as the retractable protrusion (26) of the first embodiment except that the retractable effect is provided by the retractable arm (27) of this second embodiment. The retractable arm (27) is actually an extension from the second propel disc (11B) in contrast to the ball device (26A) and resilient element (26B) of the retractable protrusion (26) of the first embodiment which are separate components provided to the body of the second propel disc (11B). The retractable arm (27) of this second embodiment comprises a curved arm (27 A) which is linked to the rest of the body of the retractable propel disc (11B) by means of a small connecting area (27B) and terminates preferably as a substantially round device (27C). The curved arm (27 A) follows the profile of the second propel disc (11B) such that as a whole it substantially takes the shape of typical locking discs (10). The small area of connection between the curved arm (27 A) and the body of the second propel disc (11B) serves to give the retractable effect to the said retractable arm (27) of this second embodiment. Here the round device (27C) acts as a solid object for contact with another surface whilst the small connecting area (27B) between the curved arm (27 A) and rest of the body of the second propel disc (11B) acts as a retractable element to retract the solid object such as a round device (27C) when circumstances permit. Referring now to FIGS. 4, 4-A, FIG. 4 shows a plan view of a third embodiment of the present invention wherein the third propel disc (11C) provided with at least a leaf spring (29) is housed in a locking cylinder (6) and FIG. 4-A is a view of the third propel disc (11C) of this third embodiment at the portion provided with the said leaf spring (29) showing the leaf spring (29) in its retracted position. The said leaf-spring (29) is configured to take the shape of a central protrusion (29 A) with side flaps (29B). The third propel disc (11C) of this embodiment is configured to have at least a inward recessed portion (28) preferably in the shape of a substantial plus symbol to accommodate at least a leaf-spring (29). The side flaps (29B) rests on the horizontal step (28 A) of the inward recessed portion (28) [hereinafter referred to as the supports). This third embodiment functions in the same manner as the first propel disc (HA) of the first embodiment except that retractable effect is provided by the said central protrusion (29A) of the configured leaf-spring (29) moving into the inward recessed portion (28) distorting the side flaps (29B) upon pressure being exerted to the tip of the said central protrusion (29 A) when the locking discs (10) together with the third propel disc (11C) are forced to rotate by a non-matching key. This is illustrated in FIG. 4-A. Here the said central protrusion (29A) acts as the solid object for contact with another surface whilst the side flaps (29B) resting on the supports (28A) acts as a retractable element to retract the solid object when circumstances permit. Referring to FIG. 5 shows a plan view of the fourth embodiment of the present invention wherein a fourth propel disc (11D) provided with a substantially round aperture (IOC) having at least a inwardly directed retractable protrusion (30A) and at least a flange (30B) extending outwardly from the outer circumference of the fourth propel disc (11D) is housed in a locking cylinder (6). The inwardly directed retractable protrusion (30A) comprises a retractable element and a solid object and may take the form of the retractable protrusion (26) of the first embodiment or the retractable arm with protrusion (27) of the second embodiment or the leaf-spring (29) configured to take the shape of a central protrusion (29 A) with side flaps (29B) resting on supports (28) of the third embodiment. The solid object of the inwardly directed retractable protrusion (30A) is made to protrude into the aperture (IOC) to the extent that in its original un-retracted form, it allows only limited initial predetermined turn (preferably 90 degrees) of the fourth propel disc (11D) when the matching key is turned. Turning more than the initial predetermined turn (preferably 90 degrees) or by force will cause the fourth propel disc (11D) to be retracted and when that happens the key (13) will turn freely within the aperture (IOC). The said inwardly directed retractable protrusion (30A) extending into the said aperture (IOC) is positioned in such a manner that it is able to allow the key (13), which is usually rectangular or four-sided in configuration to be inserted. Similarly as in the first, second and third embodiments, the fourth propel disc (11D) can be positioned anywhere amongst a stack of locking discs (10) including being the first or the last to be stacked or in between locking discs (10). The said outwardly protruding flange (30B) will be in contact with a sufficient surface area of the locking cylinder (6) to move the said locking cylinder (6) when the matching key is inserted. When a matching key is inserted and initially turned within the predetermined degree allowable by the inwardly directed retractable protrusion (30A), preferably 90 degrees, all the locking discs (10) are initially aligned enabling the side bar (10B) to drop into the locking disc slots (10A) to be accommodated. Further turning after the initial predetermined degree turn will cause the locking cylinder (6) to be rotated by means of the said outwardly protruding flange (30B) that is in contact with a sufficient surface area of the locking cylinder (6). The said outwardly protruding flange (30B) is stationarily fixed and will only turn together with the locking cylinder when a matching key is inserted. Without a matching key the said outwardly protruding flange (30B) which always contacts the said locking cylinder (6) will not budge and the said fourth propel disc (11D) will not move at all.

When a non-matching key is inserted into the key hole (14) and initially rotated within the limited allowable turn or predetermined degree, advantageously 90 degrees, all the locking discs (10) including the retractable propel disc (11) fail to come into alignment to allow the side bar (10B) to drop to be accommodated by the locking disc slots (10 A). Further forced rotation will cause said solid object of the inwardly directed retractable protrusion (30A) to be retracted away from the centre of the aperture (IOC) thereby providing a smooth passage for easy turning. When this happens only the key (13) will rotate by itself without the said fourth propel disc (11D) or the other typical locking discs (10). As a result the said outwardly protruding flange (30B) which functions to rotate the locking cylinder (6) and is always in contact with the said locking cylinder (6) will not be propelled and it will not budge as the rotary action is within the aperture (IOC) itself which by reason of the inwardly directed retractable protrusion (30A) is able to provide a smooth passage for easy turning. Although it has been illustrated in FIG. 5 that the inwardly directed retractable protrusion (30 A) is similar to the retractable protrusion (26) of the first embodiment it is to be understood that it may take other forms as described above as what is advantageous is that the inwardly directed retractable protrusion (30A) comprises an element which is resilient enabling the solid device attached to the resilient element to be retracted when circumstances permit. Referring to FIG. 6 and 6-A, FIG. 6 is a fifth embodiment of the present invention, a fifth propel disc (HE) provided with at least a protruding hill-like configuration (31A) and FIG. 6-A shows a vertical cross sectional view of the fifth propel disc (HE) in FIG. 6 housed in a locking cylinder (6) employed together with other typical locking discs (10). The fifth embodiment is similarly provided with a locking disc slot (10A) to accommodate the side bar (10B) and a substantially central aperture to accommodate the key for rotation purposes as in typical locking discs (10). A retractable supporting element (34) that is capable of retracting and extending is employed in this embodiment to support the stack of locking discs (10) including the fifth propel disc (HE) that is preferably positioned at the top. Preferably a backing disc (36) is positioned at the bottom of the whole stack of locking discs (10). The said retractable supporting element (34) is positioned to contact and attach to the said backing disc (36) to support the whole stack of locking discs (10) from the bottom. When a matching key is inserted, initial predetermined degree turning (preferably 90 degree turning) will align all the locking discs (10) including the fifth propel disc (HE) to allow the side bar (10B) to be accommodated into the locking disc slots (10A) hence enabling all the locking discs (10) to rotate together with the locking cylinder (6) of the fifth embodiment. Prior to reaching the end of the initial predetermined degree turning the protruding hill-like element (31A) does not come into contact with the locking cylinder (6). Turning further after the initial predetermined degree turning will cause the protruding hill-like element (31 A) to come into contact with the said locking cylinder (6) which will be turned by the protruding hill-like element (31 A) which is in abutment with the complementarily indented receiving portion (31B) preferably located at the top of the said locking cylinder (6). When a non-matching key is inserted and turned, all the locking discs (10) including the fifth propel disc (HE) fail to come into alignment to allow the side bar (10B) to drop to be accommodated by the locking disc slots (10A) and hence further turning by a force in excess of that normally employed to open a lock will cause the protruding hill-like element (31A) to slip out of its abutment with the complementarily indented receiving portion (31B) and be out of proper arrangement. The said disengaging of the protruding hill-like element (31 A) from the complementarily indented receiving portion (31B) is caused by the protruding hill like element (31A) slipping out and displaced from its complementarily indented receiving portion (31B) when the said retractable supporting element (34) retracts downwardly when rotation with excess force is applied. When this happens the said cylinder (6) will not be able to rotate together with the locking discs (10). Alternatively the fifth propel disc (HE) of this fifth embodiment can be positioned at the bottom or anywhere amongst the stack of locking discs (10) provided another complementary disc configured to accommodate the protruding hill-like protrusion (31 A) is employed together with it to allow the engaging or disengaging of the protruding hill-like element (31A) with its accommodating portion on the complementary disc.

Referring now to FIG. 7, 7- A and 7-B, there are shown views of a sixth embodiment of the present invention. FIG. 7 shows a view of a sixth propel disc (11F) of the sixth embodiment wherein the sixth propel disc (11F) is provided with at least a hump-like protrusion (41) at the top adjacent to the edge of the sixth propel disc (11F) to contact with the base (8) of the locking cylinder (6). The hump-like protrusion (41) preferably has sloped sides. The base (8) of the locking cylinder (6) comprises at least two levels a first level indicated by the reference numeral (8A) and a second level indicated by the reference numeral (8B), the second level (8B) is lower than the first level (8A). FIGS. 7-A and 7-B show two views of the arrangement of the hump-like protrusion (41) of the sixth propel disc (11F) and the base (8) of the locking cylinder (6). Referring to FIG. 7-A, when a matching key is inserted the hump-like protrusion (41) will be rotated within the predetermined degree turning (preferably 90 degree turning) to unlock the lock. The predetermined degree turning is indicated by the letter "x" in FIG. 7-A. The contact of the hump-like protrusion (41) of the sixth propel disc (11F) to the base (8) of the locking cylinder (6) at its first level (8 A) provides frictional force to move the locking cylinder (6) when a matching key is inserted. If further force is applied to unlock the lock as in the case of forced opening using a non-matching key the hump-like protrusion (41) will be forced to turn more than predetermined degree turning to unlock the lock and it will in turn be displaced from the first level (8 A) to occupy the second level (8B) as illustrated in FIG. 7-B. Further turning of the retractable propel disc (11) will bring hump-like protrusion (41) from the second level (8B) to occupy the first level (8A) again and so on. When a non-matching key is used to unlock the lock by force the sixth propel disc (11F) will move up and down caused by the displacement of the hump-like protrusion (41) from the first level (8A) to the second level (8B) and the second level (8B) to the first level (8A) and this continues as long as the non- matching key is turned. Alternatively the hump-like protrusion can be provided on the base (8) of the locking cylinder (6) instead of on the propel disc (11) and the two uneven levels, the first and second levels (8A) (8B) are provided on the circumference of the propel disc (11F) instead of the base (8) of the locking cylinder (6), as what is advantageous is that the contact allows frictional force to be generated between the hump-like protrusion (41) and the locking cylinder (6) to move the locking cylinder (6) when a matching key is inserted.

In another embodiment a seventh propel disc (11G) as illustrated in FIG. 8, is employed. The seventh propel disc (11G) comprised in this seventh embodiment is provided with at least a stub-like protrusion (42) extending from the circumference of the said seventh propel disc (11G) instead of having a hump-like protrusion (41) as in FIG. 7. The stub-like protrusion (42) preferably has sloped sides to enable it to be displaced. The workings are similar to that in FIG. 7.

The first, second, third, fourth, fifth, sixth and seventh propel discs (HA), (11B), (11C), (11D), (HE), (11F) and (11G) are collectively and generally referred to as the propel disc (11).

Alternatively instead of using a propel disc (11) to provide friction between the protrusion of the propel disc (11) and the locking cylinder (6) to move the locking cylinder (6) when a matching key is inserted or to maintain the locking cylinder (6) in a stationary position when a non matching key is used to forcefully move the locking cylinder (6), friction between the locking cylinder (6) and the locking disc (10) may be used in replacement. This is disclosed in the eighth embodiment as shown in FIG. 9 wherein the use of the retractable propel disc (11) to provide friction between the protrusion of the retractable propel disc (11) and the locking cylinder (6) to move the locking cylinder (6) when a matching key is inserted is eliminated. Instead the friction that is required to move the locking cylinder (6) when a matching key is inserted is achieved by using a retractable element (38) preferably a spring at the top of the lock housing (4). By placing a retractable element (38) such as a spring at the top of the lock housing (4) the retractable element (38) will be able to push the locking cylinder (6) towards the locking disc (10) and such contact is sufficient to generate the required frictional force to move the cylinder (6) when a matching key is inserted into the key-hole (14). Alternatively the retractable element (38) preferably a spring may be provided between the locking disc (10) and the lock ring (12) as disclosed in the ninth embodiment as illustrated FIG. 10. The function is the same as the eighth embodiment that is when the retractable element is provided at the top of the lock housing (4). Hence the eighth and ninth embodiments are simpler to fabricate and therefore less costly, however, the disadvantage of both the eighth and ninth embodiments is that in the absence of the propel disc (11), there is no fixed position for key withdrawal. While the present invention has been described in some detail as being a padlock, it will be appreciated that the said invention is applicable to other types of lock such as those used for drawers, cupboards, display cabinets and the like as long as it utilizes the disc type of locking mechanism as what is advantageous in accordance with the present invention is the fact that the lock is force-proof.

While the preferred embodiment of the present invention and its advantages has been disclosed in the above Detailed Description, the invention is not limited thereto but only by the spirit and scope of the appended claim.