AU2009202346B2 - A Padlock Suitable for Use in Hazardous Environments - Google Patents

Abstract

Abstract A padlock is disclosed which has a body and a shackle. The shackle is made from a plastic or polymer material and has a first leg member and a second leg member. The body has a first aperture for receiving the first leg member and a second aperture for receiving the second leg member. Moving the shackle towards the body into a locking position in which the leg members are inserted into the respective apertures locks the padlock, but when the padlock is open the shackle is at least partially withdrawn relative to the body so that at least the second leg member is retracted out of the second aperture and the shackle is able to pivot relative to the body. The padlock also has shackle alignment means which helps to ensure that the shackle can only move towards the body into the locking position when the first leg member is aligned with the first aperture and the second leg member is aligned with the second aperture. By providing shackle alignment means, the invention reduces the ability of the shackle to be inserted or forced into the padlock body in a twisted orientation. c-Il -- ----------- ----- ------ ----- cc ~ e4..L

Description

- 1 AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION Invention Title: A Padlock Suitable for Use in Hazardous Environments Applicant: Assa Abloy Australia Pty Limited The invention is described in the following statement.

2 FIELD OF THE INVENTION The present invention relates to padlocks that are suitable for use in hazardous environments, and in particular to padlocks that are suitable for use in environments where electrical conduction and sparking poses a significant safety risk. These 5 environments include, for example, electrical power supply and generation environments where there is a significant risk of electrocution, and also mining, mineral processing, oil and gas extraction and processing environments where there is a significant danger of sparks igniting combustible materials and causing fires or explosions. Those skilled in the art will appreciate that there are also a wide range of 10 other hazardous environments in which the padlock of the present invention would be suitable for use. BACKGROUND In mining, mineral processing, petrochemical and other like industries there is a general requirement for tools and other devices to be "non-sparking" to minimise the 15 risk of ignition which can lead to fire or explosion. Also, in the environments commonly experienced in some of these industries there is a problem that safety/deterrent devices such as conventional metal padlocks can rapidly corrode due to the extreme conditions (e.g. the extreme corrosive salt water conditions of offshore oil/gas platforms). 20 "Plastic padlocks" and similar devices have previously been proposed. However, in the majority of these, the U-shaped shackle (or equivalent component) is still made of metal. Devices such as these are unsuitable, particularly in the kinds of environments described above where there is a risk of sparks leading to explosions or fires, because the metal surface of the shackle has an inherent propensity to spark. For example, 25 sparking from the metal shackle may occur if a sufficiently large electrical potential difference (voltage) exists between the shackle and an unconnected nearby conductive object, or if the metal shackle impacts against or grazes past another hard object giving off sparks. One reason why existing devices such as the "plastic padlocks" discussed above 30 continue to use shackles and other components made from metal is because it has not generally been possible to simply replace existing metal components with identically 3 shaped and configured non-metal components without significantly impacting on the strength and performance of the padlock/device. Our earlier Australian Patent Application No. 2008200362 describes a padlock which addresses many of these problems. 5 Even in padlocks where the problems with strength and performance are overcome making it possible to use non-metal components, another problem can arise where shackles are used which are shaped like conventional metal padlock shackles, but which are made from plastic or polymer rather than metal. The problem arises because even high-strength plastics and polymers, which can be sufficiently strong to 10 enable the shackle to provide suitable security, are nevertheless typically softer than the hard metal (usually steel) normally used in making the shackles for conventional padlocks. As a result, with shackles shaped like conventional metal padlock shackles but made from plastic or polymer rather than metal, it can be possible to insert the shackle into the padlock body in a slightly rotated or "twisted" orientation and the 15 shackle can then become locked to the body in a faulty locking condition. The faulty locking condition is shown in Figures 1-6. Figures 1-6 are explained in this "Background" section, but they may be more fully understood and appreciated when considered together with the detailed explanations given in the section entitled "Detailed Description of the Padlock in Figures 7-8" below. 20 Those skilled in the art will appreciate that conventional padlocks have a U-shaped metal shackle. One leg of the shackle (the long leg) often remains pivotably and slidably retained in a long leg bore in the padlock body. The other leg (the short leg) inserts into and retracts out of a short leg bore in the padlock body as the padlock is locked and unlocked respectively. Hence, in order to lock a conventional padlock, the 25 shackle is typically pivoted relative to the body so as to bring the short leg into axial alignment with the short leg bore, and the shackle is then moved towards the padlock body such that the short leg inserts into that bore. Internal locking balls inside the padlock then typically engage with both legs of the shackle to secure the shackle with both legs inserted, thus locking the padlock. Generally, where the padlock has a 30 conventional metal shackle, it is not possible to insert the shackle into the body in a twisted orientation because the metal from which the shackle is made is inherently hard enough to prevent this.

4 Figures 1-6 illustrate a prior art padlock which has a shackle 14 shaped like a conventional metal padlock shackle, but the shackle 14 is made from plastic or polymer rather than metal. Furthermore, Figures 1-6 show the prior art shackle 14 in the faulty locking condition. In this condition, the shackle 14 has been twisted 5 relative to the padlock body 12 before being moved towards the padlock body 12 in the direction of arrow "D" (see Figure 2). Consequently, the short leg 18 of the shackle passes down the outside of the padlock body 12 rather than inserting into the short leg bore 22 to lock the padlock as normal. It is possible to insert the shackle 14 in this incorrect "twisted" orientation largely 10 because the plastic or polymer from which shackle 14 is made is softer than the metal used on conventional padlock shackles. As a result, with the plastic or polymer shackle 14, it is possible for the flat retaining aperture 32 on the shackle (see Figures 7-8), or other surrounding ridges etc on the shackle's long leg, to deform slightly and thereby allow the shackle's long leg to force its way down past the metal locking ball 15 46. The ball 46 can then engage (at least partially) with the shackle's long leg 16. More specifically, in the faulty locking condition, the ball 46 may engage (at least partially) with the notch 26 (which is visible in Figure 3 because of the way the shackle 14 is twisted) thereby holding the shackle 14 in the faulty locking condition, even though the short leg 18 of the shackle is located outside the padlock body 12. 20 This deformation of the shackle and engagement of the ball 46 with the notch 26 may cause permanent indentation or other damage to the shackle 14, especially if the lock is placed into the faulty locking condition numerous times or repeatedly. Those skilled in this area will appreciate that, whilst damage to the shackle 14 caused by faulty locking is a potentially significant problem, another significant problem 25 associated with faulty locking is that the padlock is not properly locked. Hence, when the padlock is in the faulty locking condition it provides little or no security, and things which are intended to be locked between the shackle 14 and the body 12 may nevertheless be removed from between the shackle and the body. Faulty locking might also give rise to a situation where a user thinks they have locked the padlock, 30 but if the padlock shackle has somehow been twisted relative to the body before or as the padlock is locked, the padlock may actually be in the faulty locking condition and the user may not be aware of this unless they inspect the lock to ensure proper locking.

5a It will be clearly appreciated that any reference herein to background material, prior publications or technical problems does not constitute an acknowledgement or admission that any background material, prior publication(s), technical problem(s) or combination(s) thereof formed part of the common general knowledge in the field or 5 is otherwise admissible prior art, whether in Australia or any other country. DESCRIPTION OF THE INVENTION It is an object of the present invention to provide a padlock suitable for use in hazardous environments such as those described above, which at least partially ameliorates problems associated with faulty locking, or which at least provides a 10 useful or commercial alternative to existing products in the marketplace. In one form, the present invention resides broadly in a padlock having a shackle, a body, a lock cylinder and a shackle alignment arrangement; wherein the shackle is manufactured from a non-metalliferous material and has a first leg member and a second leg member; 15 the body has a first aperture for receiving the first leg member and a second aperture for receiving the second leg member; the shackle is movable towards the body to a locking position at which the first and second leg members are respectively inserted into the first and second apertures; and the shackle alignment arrangement prevents the from moving into the locking position 20 unless the first leg member is aligned with the first aperture and the second leg member is aligned with the second aperture. In another form, the invention resides broadly in a padlock having a shackle, a body and a lock cylinder, the shackle being made from a plastic or polymer material and having a first leg 25 member and a second leg member, the body having a first aperture for receiving the first leg member and a second aperture for receiving the second leg member, wherein the padlock is locked by moving the shackle towards the body into a locking position in which the leg members are inserted into the respective apertures, but when 5b the padlock is open the shackle is at least partially withdrawn relative to the body so that at least the second leg member is retracted out of the second aperture and the shackle is able to pivot relative to the body, the padlock also having shackle alignment means whereby the shackle can only move 5 towards the body into the locking position when the first leg member is aligned with the first aperture and the second leg member is aligned with the second aperture. By providing shackle alignment means which prevents the shackle from moving towards body into the locking position except when the leg members are aligned with their respective apertures in the body, the present invention may significantly reduce 10 the ability of the shackle to be inserted or forced into the padlock body in a twisted orientation. This may therefore significantly reduce instances of faulty locking and alleviate the associated problems.

6 The body of the padlock may be of any size and shape, although it is envisaged that the body may generally be sized such that the padlock is easily operable by hand and so that it will not interfere with the device to which it is secured or create an undue obstruction. Therefore, the size of the body may be similar to that of conventional 5 padlocks. The body of the padlock may be constructed from a plastic or polymer material, or from a composite material. High-strength and non-conductive engineering polymers and fibre reinforced polymer/fibre composites are examples of materials that may be suitable. Simpler plastics might also be used, particularly in embodiments where the padlock is not required to provide an especially high level of 10 security. As noted above, the shackle has a first leg member and a second leg member. It is envisaged that, in most embodiments, the shackle will comprise a rigid U-shaped component. The invention will therefore be described primarily with reference to shackles of this general shape. One of the leg portions of the "U" may form the first 15 leg member, and the other leg portion of the "U" may form the second leg member. Suitably, the first leg member may be longer than the second leg member. Hence, the first leg member may be referred to as the long leg of the shackle, and the second leg member may be referred to as the short leg of the shackle. The shackle is made from a plastic or polymer material. This should also be 20 understood to include materials such as fibre reinforced composites and the like. Therefore, as for the body above, high-strength and non-conductive engineering polymers and fibre reinforced polymer/fibre composites are examples of materials that may be suitable for making the shackle. Other similar polymer-type or plastic type materials known to those skilled in the art may also be used. And again, simpler 25 plastics might also be used, particularly in embodiments where the padlock is not required to provide an especially high level of security. The shackle may be pivotably attached, or pivotably attachable, to the body. For shackles having a "U-shape", this pivotable attachment of the shackle to the body is quite common and allows the shackle to pivot with respect to the body when the 30 padlock is open. If the body is generally block shaped as in conventional padlocks, even if made from polymer-type or plastic-type materials rather than metal, the body may have an upper 7 surface or surfaces forming the top of the body, and the upper surface or surfaces may contain the apertures which receive the leg members of the shackle. The apertures may be in the form of bores extending downwardly into the body of the padlock, and it is envisaged that each bore may have a cross-sectional shape corresponding to the 5 cross-sectional shape of the portion of the shackle which it is adapted to receive. The body may be provided with shackle support means for providing additional support to the shackle. This may be particularly beneficial if, as is possible, the material from which the shackle is made results in the shackle having somewhat reduced strength and robustness, at least compared with conventional metal padlock 10 shackles. The shackle support means may comprise a "built up" portion of the body at the location where a portion of the shackle inserts into the body (typically near the top of the body). This "built-up" portion may therefore surround and provide support for a greater proportion of the insertable part of the shackle. Put another way, the "built up" shackle support means may reduce the length of the portion of the shackle 15 that extends unsupported out of the body. This may reduce the effective "lever arm" length of the unsupported portion of the shackle, thereby reducing the possible bending stresses and the like which can be applied to the unsupported portion of the shackle. Hence, the chance of shackle failure may be reduced. The shackle support means may comprise a built up portion of the body around the 20 location where one or both of the legs of the shackle insert into the padlock body. Preferably, the body may be built up around where the long leg of the shackle inserts into the body, but the region where the short leg inserts into the body may remain un built up. This may help to prevent the built-up portion of the body from impeding the rotation of the shackle about the long leg when the padlock is open. Those skilled in 25 the art will recognise that it is common for the shackles of padlocks to be rotatable when the padlock is open (i.e. when the short leg is retracted out of the padlock body). In general, the long leg is pivotably mounted within the body so that the short leg and the arcuate portion of the U-shaped shackle can rotate about the long leg when the shackle is open. By providing shackle support means in the form of a built-up portion 30 of the body around the region where the long leg inserts into the body, but not around the region where the short leg inserts, it may be possible to provide additional support the padlock shackle without impeding the rotation of the shackle when the padlock is open.

8 In order to provide security, the shackle is preferably lockably securable to the body when the padlock is closed. The shackle may be releasable (allowing the padlock to be unlocked) by way of a key operated mechanism. The key operated mechanism will generally comprise a conventional key cylinder. Conventional key cylinders are 5 typically made from metal due to the intricacies of their design and their high wear resistance requirements etc. However, no particular limitation is meant thereby and any other material may be used in the construction of the key cylinder if desired. Furthermore, non-conventional key operated mechanisms may also be used. Combination lock-type mechanisms may also be used. Nevertheless, it is envisaged 10 that conventional metal key cylinders will be used most often. The body of the padlock may have a main opening to accommodate the key cylinder and the one or more key cylinder receiving components. It is envisaged that the main opening will often comprise an opening in or through the base of the padlock body. The padlock may be provided with one or more key cylinder receiving components 15 which engage with the key cylinder and the body to mount the key cylinder within the body when the padlock is assembled. Preferably, the key cylinder receiving components may be shaped so as to "marry" with or snugly mate against the key cylinder, and preferably also with the inside of the padlock body. One or more or all of the key cylinder receiving components may be made from a 20 rigid non-conductive and non-sparking material similar to that described with reference to the shackle and the body above. Therefore, even though there may be direct contact between the key cylinder (which may be made of metal) and one or more of the key cylinder receiving components, conduction of dangerous electrical currents therebetween may be prevented by the non-conductive properties of the one 25 or more receiving components. Also, there should preferably be no openings left between the key cylinder and the cylinder receiving components, and the body. Hence, there should preferably be no gaps or openings that may expose the inner workings of the padlock to unauthorised tampering etc through the main opening or otherwise when the padlock is locked. 30 Suitably, the key cylinder receiving components may comprise a key cylinder receiving insert and a key cylinder cover. During assembly, the key cylinder receiving insert may first be inserted into the padlock body through the main opening.

9 Some or all of the peripheral surfaces of the key cylinder receiving insert may be shaped in a manner that conforms to the internal shape of the padlock body, or at least to a portion of the inside of the body. The key cylinder receiving insert may also have a part or surface that is shaped in a manner that conforms to the shape of at least a 5 portion of the key cylinder. Like the key cylinder receiving insert, some or all of the peripheral surfaces of the key cylinder cover may be shaped in a manner that conforms to the internal shape of the padlock body, or at least to a portion of the inside of the body. A part or surface of the key cylinder cover may also be shaped in a manner that conforms to the shape of at 10 least a portion of the key cylinder. Therefore, before they are inserted into the padlock body, the key cylinder and the key cylinder cover may be assembled together so that the said part or surface of the key cylinder cover marries against a portion of the key cylinder. When assembled in this way, the key cylinder and the key cylinder cover form, in effect, a single component that may be inserted into the body of the 15 padlock. When they are so inserted (as one), a side of the key cylinder may marry closely against the abovementioned part or surface of the key cylinder receiving insert and the peripheral surface of the key cylinder cover may conform to the internal shape of the padlock body, or at least to a portion of the inside of the body. Hence, the insert, the key cylinder and the cover can be inserted to be snugly received 20 and mounted within the padlock body without leaving any gaps in or around the main opening. One or more of the key cylinder receiving components may be provided with body mounting means for mounting the key cylinder and the key cylinder receiving components within the padlock body. The mounting means may comprise any form 25 or combination of physically engaging mechanisms, snap fit arrangements, inter engaging teeth, clips, mutually engaging protrusions and recesses and the like that those skilled in the art would recognise as being suitable for physically retaining the key cylinder and the cylinder receiving components in the body. The inside of the body may also comprise whatever other forms of internal shaping, 30 sculpting or other features as may be necessary to house, interrelate and interoperate with the various components of the padlock in use or assembly of the padlock.

10 The padlock may further be provided with release means which may be used to disengage at least one of the key cylinder receiving components (and hence the key cylinder as well) from the padlock body. The release means should be accessible from the outside the padlock body so that the at least one cylinder receiving 5 component and the key cylinder can be removed if necessary. One reason why this might be necessary is to "re-key" the padlock by replacing the key cylinder with an alternative cylinder that operates with a different key. Suitably, released means similar to those explained in our earlier Australian Patent Application No. 2008200362 may be used. 10 As explained above, the padlock has shackle alignment means whereby the shackle can only move towards the body into the locking position when the first leg member (the long leg) of the shackle is aligned with the first aperture (the long leg bore) and the second leg member (the short leg) of the shackle is aligned with the second aperture (the short leg bore). Any means or mechanism capable of providing this 15 functionality may be used, and the term "shackle alignment means" should be understood to include all such means and mechanisms. Suitably, the shackle alignment means may comprise a shackle portion and a body portion. The shackle portion may be a part or portion of the shackle, or component (or part thereof) which is separate from the shackle but associated with the shackle. 20 The body portion may be a part or a portion of the body, or a component (or part thereof) which is separate from but associated with or housed within the padlock body. The shackle portion and the body portion may be configured such that the two portions become engaged with each other when the shackle is moved in to the locking position to lock the padlock, but wherein it is only possible to move the shackle in this 25 way to engage said portions if the shackle is correctly aligned as described above. In some preferred embodiments of the invention, the shackle portion may comprise a part of (or attached to) the long leg of the shackle which has a noncircular cross section. Depending on the particular configuration of the padlock, the long leg bore which receives the shackle's long leg may be formed directly in the body of the 30 padlock, or it may be formed by a component housed within the body of the padlock, or a combination of both. In any event, the body portion may be part of the long leg bore. The body portion may be located in the long leg bore such that, when the I1 padlock is locked, the noncircular part of the shackle's long leg slots at least partially into the body portion. However, the body portion may be shaped (or otherwise configured) such that the noncircular portion on the shackle is prevented from slotting even partially into the body portion except when the shackle is correctly aligned. This 5 may be how the padlock is prevented from being locked except when the shackle is correctly aligned relative to the body. Suitably, the shackle portion may comprise a portion extending from an end of the shackle's long leg which has a noncircular cross-section, for example a cross-section which is square, rectangular, triangular etc. Where the shackle portion takes this 10 form, the body portion may comprise a portion in the end of the long leg bore in which that portion takes a corresponding internal shape to the shackle portion, for example square, rectangular, triangular etc. The corresponding internal shape of the bore portion will generally be slightly larger than the shape of the shackle portion so that the shackle portion can slot into the bore portion when the shackle is correctly 15 aligned and pushed into the padlock body. It will be appreciated that when the shackle is withdrawn relative to the body to open the padlock, the shackle portion may become disengaged from the body portion such that the shackle is able to pivot as normal. Also, the shackle portion and the body portion may be configured so as not to interfere with the operation of other 20 components of the padlock. In another aspect of the invention, there is provided a padlock having a shackle, a body and a shackle alignment arrangement; the shackle is manufactured from a non-metalliferous material and having a first leg member and a second leg member; 25 the body having a first aperture for receiving the first leg member and a second aperture for receiving the second leg member; the shackle is movable towards the body to a locking position at which the first and second leg members are respectively inserted into the first and second apertures; and wherein 12 the shackle alignment arrangement prevents the shackle to be moved to the locking position unless if the first leg member is aligned with the first aperture and the second leg member is aligned with the second aperture. The lock may include a locking mechanism the operation of which secures the 5 shackle in the locking position to the body. BRIEF DESCRIPTION OF THE DRAWINGS Figures 1-8 all relate to a prior art padlock and are provided to assist in understanding the invention and to enable the invention to be put into effect. Figures 7-8 specifically relate to the padlock described in our earlier Australian Patent Application No. 10 2008200362. One particular embodiment of the invention is shown in Figures 9-14. It will be clearly appreciated that the various Figures and associated descriptions are provided to assist in understanding the invention only, and the invention is not necessarily limited to or by the particular features described. Figure 1 is a perspective illustration of a prior art padlock which has a shackle shaped 15 like a conventional metal padlock shackle, but the shackle is made from plastic or polymer not metal. The shackle is shown in a faulty locking configuration. Figure 2 is a front view of the prior art padlock in Figure 1. Figure 3 is a partial cross-sectional view taken along section A-A in Figure 2. Figure 4 is a top view of the padlock in Figure 1. 20 Figure 5 is a partial cross-sectional view taken along section B-B in Figure 2. Figure 6 is a partial cross-sectional view taken along section C-C in Figure 2. Figure 7 is an exploded perspective view of the components of the padlock from our earlier Australian Patent Application No 2008200362. Figure 8 shows a partially sectional view of the padlock in Figure 7 when assembled. 25 Figure 9 is a perspective illustration of a padlock in accordance with one particular embodiment of the invention. Figure 10 is a front view of the padlock in Figure 9.

13 Figure 11 is a partial cross-sectional view taken along section A-A in Figure 10. Figure 12 is a top view of the padlock in Figure 9. Figure 13 is a partial cross-sectional view taken along section B-B in Figure 10. Figure 14 is a partial cross-sectional view taken along section C-C in Figure 10. 5 DETAILED DESCRIPTION OF THE PADLOCK IN FIGURES 7-8 Figure 7 shows a padlock assembly 10 which has a padlock body 12 and a shackle 14. Shackle 14 comprises a long leg 16 and a short leg 18. Also, from Figure 8 it can be seen that long leg 16 is adapted to be inserted in a long leg bore 20 in body 12, and short leg 18 is adapted to be inserted into a short leg bore 22. 10 The general shape of shackle 14 in the prior art padlock is similar to that of an inverted "U". Therefore, the two parallel portions of the U form the long leg 16 and the short leg 18, and the upper end of the respective legs are integrally connected by an arcuate member 24 corresponding to the curved portion of the U. More specifically, the long leg 16 and the short leg 18 are both substantially cylindrical (i.e. 15 having a substantially circular cross-section) of equal diameter, and the long leg 16 is substantially longer than short for leg 18 so that a lower end of the long leg 16 extends substantially below the lower end of the short leg 18. Because the respective legs are substantially cylindrical, therefore the arcuate member 24 (which is integrally formed with the legs) has a substantially semi-toroidal shape connecting the top of the two 20 legs and having approximately the same cross-section as the legs. Both the body 12 and the shackle 14 are made of a high-strength, non-conductive engineering polymer plastic. Because of this plastic construction, the strength of the shackle 12 is somewhat reduced compared with traditional metal padlock shackles. To compensate for this, the body 12 is provided with a built-up portion 17 which 25 provides additional support to the long leg 16 by reducing the length of leg 16 which is exposed and thus reducing the possible bending stresses that could be applied to leg 16. However, it will be noted that the built-up portion 17 does not extend to the region where the short leg 18 inserts into the body and so the shackle can pivot as described below.

14 The long leg 16 and the short leg 18 of the prior art shackle both have a locking notch therein. The notches in the long leg 16 and the short leg 18 are indicated by reference numerals 26 and 28 respectively. Notches 26, 28 comprise substantially semi-tubular cutouts in the inner side of the respective legs, the cutouts being oriented such that the 5 longitudinal axis of each semi-tubular cutout is substantially perpendicular to the longitudinal axis of the respective legs and offset inwardly thereof. The notch 28 is located towards the lower end of the short leg 18, and the notch 26 is located roughly two thirds of the way down the length of the long leg 16. Consequently, both notches are located at substantially the same level, thus effectively making each notch a mirror 10 image of the other. The long leg 16 further comprises a groove 30 (shown in Figure 7), a retaining aperture in the form of an inner flat 32 (shown in Figure 8) and a bottom portion 34. The groove 30, located towards the lower end of the long leg 16, has a roughly semicircular cross-section and extends all the way around the long leg 16. Thus, the 15 groove 30 forms a substantially circumferential cutout around the lower end of the long leg 16. Importantly, the maximum depth to which the groove 30 is recessed into long leg 16 is substantially less than the maximum depth to which notches 26, 28 are indented into the respective legs. The reason for this will be explained below. The inner flat 32 comprises a substantially flat surface extending down the inner side 20 of the long leg 16 from the lower edge of the notch 26 to the groove 30. The inner flat 32 is also slightly indented into the long leg 16 and it therefore forms a slightly recessed flat surface. The depth to which the inner flat 32 is recessed into the long leg 16 is approximately the same as the depth of the groove 30. Therefore, the inner flat 32 effectively blends smoothly into the groove 30 at the point where the two meet, 25 and there is no distinct ridge, edge or other delineation between the two. The bottom portion 34 is the portion of the long leg 16 extending downwardly below the groove 30. The bottom portion 34 has the full diameter of the long leg 16. The edge where the groove 30 meets the bottom portion 34 forms a lip 37. From Figure 7, it can be seen that the padlock assembly 10 has a number of 30 components that form an internal locking mechanism for locking and unlocking the padlock. The locking mechanism comprises a conventional metal key cylinder 40, a plastic cylinder cover 41, a metal entraining member 42, a plastic camming member 15 44, metal locking balls 46 and 48, a metal spacer 43, a metal retainer plate 45 and a metal cam spring 47. The key cylinder 40 has a conventional metal construction that will be well known to those skilled in the art. Hence, it will be understood that a key may be inserted into 5 the barrel of the key cylinder 40 and that, if the key is the correct key for the key barrel, the key can then be rotated thereby rotating the key barrel. It will also be understood that rotation of the key and key cylinder mechanism causes the end of the key cylinder, or a portion thereof, or a pin or other abutment, to rotate accordingly. This causes rotation to be imparted into the other components of the locking 10 mechanism to operate the padlock as explained in greater detail below. It can be seen that the plastic camming member 44 comprises a pair of convex camming surfaces 56 located on opposite sides thereof, and a pair of concave cavities 58 also located on opposed sides thereof and interposed between the camming services 56. The metal locking balls 46 and 48 are positioned one on either side of the 15 camming member 44. The camming member 44 is pivotable between a locked position and an unlocked position. Figures 7-8 show the camming member 44 in the locked position wherein the camming surfaces 56 contact with the balls 46 and 48, thereby pushing the ball 46 into engagement with notch 26 in the long leg 16 and the pushing ball 48 into engagement with the notch 28 in the short leg 18. It will be 20 clearly understood that the diameter of each of the balls 46 and 48 is such that the balls 46 and 48 fit snugly and sufficiently deeply into the notches 26 and 28 so as to prevent vertical movement of the respective legs within the body. Thus, when the camming member 44 is in the locked position and the legs of the shackle are inserted into their respective bores in the body 12, the legs are retained within the body 12 by 25 engagement of the balls 46 and 48, and the padlock is locked. The camming member 44 can be pivoted from the locked position into the unlocked position by rotating the camming member 44. This is done by operating the key cylinder 40, as explained in greater detail below. When they calming member 44 is pivoted into the unlocked position, the locking 30 balls 46 and 48 are no longer in engagement with the camming surfaces 56 and therefore they are not being pushed into engagement with the notches 26 and 28 in the legs. Instead, the locking balls 46 and 48 are allowed to retreat into the cavities 58 in 16 the camming member 44. It will be understood that the cavities 58 are sufficiently deep, and that the locking balls 46 and 48 can retreat sufficiently far into the cavities 58, such that the bottom edges of the respective notches 26 and 28 can move upwardly within the padlock for body 12 past the balls 46 and 48. Hence, rotation of 5 the camming member 44 into the unlocked position (which is achieved by operating the key cylinder) allows the legs 16 and 18 of the shackle to move upwardly within the body 12. In particular, it allows the short leg 18 to be retracted entirely out of the short leg bore 22, thus opening the padlock. The shackle 14 moves upwards within the body under the bias of a helical metal spring 19 which is mounted below the long 10 leg 16 as shown in Figure 8. However, it will also be understood that, even when the balls 46 and 48 are retracted into the recesses 58, they are not retracted entirely within the cavities. Therefore, the balls 46 and 48 extend outwardly to some extent even when they are retracted into the cavities 58, albeit to a lesser extent than they do when they are pushed into 15 engagement with the notches 26 and 28 by the camming surfaces 56. This is particularly important in relation to the ball 46. It will be recalled that inner the flat 32 (which is recessed slightly into the long leg 16 but less deeply than the notch 26) extends down the inside of the long leg 16 between the lower edge of the notch 26 and the groove 30. Therefore, even though the ball 46 retracts out of the notch 26 when 20 the balls are retracted into the cavity 58, nevertheless the ball 26 still extends outwardly sufficiently to engage with the inner flat 32. It will also be recalled that the lower edge of the groove 30 forms the lip 37. Therefore, even when the ball 46 is retracted into the cavity 58 and the short leg 18 is retracted out of the short leg bore 22 so that the padlock is open, nevertheless the engagement of the ball 46 with the inner 25 flat 32 and the lip 37 prevents the long leg 16 from being retracted out of the long leg bore 20. The circumferential shape of the groove 30 allows the long leg 16 to rotate within the long leg bore 20 (i.e. the shackle 14 can be rotated about the long leg 16) when the padlock is open. The groove 30 effectively creates a track within which the ball 46 30 can roll as the shackle 14 rotates. Figures 7-8 show that metal entraining the member 42 comprises a substantially disk shaped member having approximately the same diameter as the key cylinder 40. It 17 can also be seen from Figure 7 that the entraining member 42 is secured to the top of the key cylinder 40, coaxially therewith. Hence, rotation of the key cylinder 40 by a key in the manner described above causes corresponding rotation of the entraining member 42. The entraining member 42 also has a pair of entraining posts 54. The 5 respective entraining posts 54 are positioned directly opposite each other on the upper surface of the entraining member 42, towards the outer edge thereof, and they extend vertically upwards. Figure 7 also shows that the plastic camming member 44 has a pair of cam blocks 60 protruding downwardly from its base. Together the cam blocks 60 extend across 10 substantially the entire width of the camming member 44. When the padlock assembly 10 is assembled, the cam blocks 60 reside between the respective entraining posts 54 of the entraining member 42. Hence, rotation of the entraining member 44 (caused by rotation of the key in the key cylinder 40) causes the entraining posts 54 to come into contact with the cam blocks 60. Therefore, rotation of the key cylinder 40 15 causes the camming member 44 to rotate between the locked and unlocked position in which it respectively locks and unlocks the padlock by interacting with the balls 46 and 48 as described above. However, it will be appreciated from the above description, and from Figures 7-8, that the camming member 44 can rotate from the unlocked position back into the locked position only when the legs 16 and 18 are 20 reinserted into the bores 20 and 22 to lock the padlock. When the legs are reinserted, the camming member rotates back into the locked position under the bias of metal cam spring 47, thus moving the balls to lock the padlock as described above. Referring again to Figure 7, it will be seen that the padlock assembly comprises a key cylinder receiving insert 39. The insert 39 is a plastic component. Together, the 25 insert 39 and the plastic cylinder cover 41 comprise the key cylinder receiving components. The insert 39 has an elongate concave receiving cavity 62 of corresponding shape to the convex cylindrical surface of the key cylinder 40. Hence, the convex cylindrical surface of the key cylinder 40 is able to be received snugly in concave receiving the cavity 62 when the padlock is assembled. Similarly, the 30 cylinder cover 41 is shaped to snugly fit over the blocklike portion of the key cylinder 40 which houses the split pins. The outer surfaces of the insert 39 and the cover 41 both have a shape that corresponds with the internal surface shape of the padlock body 12.

18 In order to assemble the padlock, the insert 39 is first inserted into the body as can be seen in Figure 8. Then, while the key cylinder 40 and the cover 41 are separate from the padlock, the cover 41 is slotted onto the blocklike portion of the key cylinder 40. Together the key cylinder 40 and the cover 41 are then inserted into the body. It will 5 be appreciated that the entraining member 42, the camming member 44, the locking balls 46 and 48, the spacer 43, the retainer plate 45 and the cam spring 47 will all have been assembled on top of the key barrel 40, or alternatively in the padlock body, in the manner shown in Figure 8, before the key barrel 40 and the cover 41 are inserted. From Figure 7, it can be seen that the outer surfaces of the insert 39 and the cover 41 10 each also have an arcuate ridge 63 near their respective bases. The insert 39 and the cover 41 further have an arcuate indent 64 on their respective outer surfaces near the top. Each arcuate ridge 63 has a corresponding indent 65 in the padlock body and each indent 64 has a corresponding ridge 66 in the body. Therefore, when the insert 39 is inserted into the padlock body, and similarly when the key cylinder 40 and the 15 cover 41 are inserted, the ridges 63 engage with the indents 65, and the indents 64 engage with the ridges 66. This maintains the insert 39, and the key cylinder 40 and the cover 41, within the body as shown in Figure 8. Referring now to Figure 8, it should be emphasised that the following components are made from plastic and metal respectively. Plastic components Metal components Body 12 Key cylinder 40 Shackle 14 Helical spring 19 Camming member 44 Spacer 43 Insert 39 Cam spring 47 Cylinder cover 41 Metal retainer plate 45 Locking balls 46, 48 20 As a consequence of the way these components are configured as shown in Figure 8, all of the metal components (they are all associated with the operation of the key cylinder 40 and they may therefore be collectively considered as a key cylinder mechanism) are electrically insulated by the plastic components, meaning that there is 25 no path through which electricity can flow through the padlock.

19 Also, the only metal component which is exposed when the padlock is assembled is the base of the key cylinder 40. However, because of the shape of the padlock, it is highly unlikely that this metal portion which protrudes very little (if at all) from the base could come into contact with another hard object when the padlock is applied to 5 secure a device in use. This is particularly so because the metal portion is in the base and not the more exposed sides of the padlock. Therefore, the padlock is configured so that the risk of sparking due to impact of any exposed metal portion of the padlock with another hard object is minimised (it being appreciated that all of the other exposed surfaces of the padlock a formed from a non-conducted and non-sparking 10 material). DETAILED DESCRIPTION OF THE PADLOCK IN FIGURES 9-14 The padlock in accordance with the present invention shown in Figures 9-14 is mostly the same as the prior art padlock shown in Figures 1-6. Also, the internal locking mechanism used in the padlock in Figures 9-14 may be mostly the same as that 15 described with reference to Figures 7-8. Consequently, components and features shown in Figures 9-14 which are the same as those shown in Figures 1-8 will be given the same reference numerals. Features shown in Figures 9-14 which differ from the earlier Figures will be given a three digit reference numerals with a leading 1. For example, the shackle in Figures 9-14 is modified compared with the shackle in the 20 earlier Figures, and so the shackle in Figures 9-14 is designated by reference numeral 114 (rather than reference numeral 14 as in the earlier Figures). Because the padlock in accordance with the present invention shown in Figures 9-14 is mostly the same as described in the earlier Figures, Figures 9-14 will be described mainly with reference to the differences which embody invention in this particular embodiment. 25 As noted above, the shackle 114 in Figures 9-14 has been modified compared with the shackle 14 in the earlier Figures. In particular, the long leg 116 has an additional shackle portion 70 extending from the end of the bottom portion 134. This shackle portion is visible in Figures 11 and 14. As these Figures show, the shackle portion 70 is integrally formed on the end of bottom portion 134 of the shackle 114, and it has a 30 substantially square cross-section. Another component which has been modified in Figures 9-14 compared with the earlier Figures is the cylinder receiving insert. The modified key cylinder receiving 20 insert 139 differs from the earlier key cylinder receiving insert 39 in that the portion of the insert 139 which receives the long leg 116 of the shackle (i.e. the portion of the insert 139 which forms part of the padlock's long leg bore) has an additional "body portion" 72. The body portion 72 is an extension on the inner end of the bore in the 5 insert 139 which receives the long leg 116. Together, the shackle portion 70 and the body portion 72 form the shackle alignment means in this embodiment. As seen in Figure 14, the body portion 72 has an internal shape which is square like the outer shape of shackle portion 70. The square shape of the body portion 72 is slightly larger than that of shackle portion 70 so the shackle portion 70 can insert into 10 the body portion 72 when the shackle is correctly aligned and pushed into the body. Importantly, if the padlock is open so the shackle 116 is withdrawn relative to the body, the shackle portion 70 moves up into the middle/upper portion of the long leg bore in the insert 139. This portion of the bore has a larger substantially circular internal shape. Consequently, the square shape of the shackle portion 70 does not 15 contact with the sides of the circular bore portion, and hence the square shackle portion 70 does not prevent the shackle from pivoting within the long leg bore as normal when the padlock is open. However, it is only possible to insert the shackle into the padlock to lock the padlock if the shackle is oriented relative to the body such that the square shackle portion 70 is aligned to insert into the square body portion 121, 20 and this only occurs when the shackle is correctly aligned with the short leg of the shackle aligned with the short leg bore. If an attempt is made to insert the shackle into the body when the shackle is not correctly aligned (i.e. when the shackle is "twisted"), at least the corner edges of the shackle portion 70 will collide with the ridges 74 at the top of the body portion 72 thereby preventing the shackle from 25 moving into the body. Hence, it is not possible to insert the shackle into the padlock body in a twisted configuration, and this significantly reduces the possibility of faulty locking. It should be noted that Figures 9, 12 and 13 show the shackle in an impossible "skewed" orientation. For instance, in Figure 9, the short leg 118 of the shackle 30 appears to be extending through the top face of the padlock body 12, rather than inserting correctly into the short leg bore 22. A similar "skew" of the shackle is visible in cross-sectional view in Figure 13. However, this has been done to demonstrate a particular point, namely the way that inserting the shackle portion 70 21 into the body portion 72 also helps to hold the shackle against twisting. Consider the hypothetical situation where a torque is applied about the axis of the long leg 116 as shown by arrow "T" in Figure 9. Imagine also that the short leg 118 could move through the side of the body 12 (of course it cannot, but imagine that it could). The 5 point is that, even in this imaginary situation, the torque T would only cause the short leg 118 to move the small amount illustrated because of the way the shackle is rigidly held by the insertion of the shackle portion 70 into the body portion 72. This small amount of movement is much less than the amount shown in Figures 1-6 associated with faulty locking. Of course, in reality, the short leg 118 of the shackle would be 10 held securely within the short leg bore 22, which would prevent twisting of the shackle like that shown in Figure 9. It should be appreciated that various other changes and modifications can be made to the embodiment described without departing from the spirit and scope of the invention. 15 The invention provides a shackle alignment arrangement which promotes the correct alignment of the shackle relatively to the body to which the shackle is to be secured. The shackle alignment arrangement prevents the shackle to be moved to a locking position without a long leg member and a short leg member of the shackle being registered with corresponding first and second apertures which have been formed into 20 the body. However, the shackle alignment arrangement is such that once the shackle has been moved away from the locking position, the shackle alignment arrangement no longer prevents pivotal movement of the shackle relatively to the body about the long leg member of the shackle. The foregoing embodiments are illustrative only of the principles of the 25 invention, and various modifications and changes will readily occur to those skilled in the art. The invention is capable of being practiced and carried out in various ways and in other embodiments. It is also to be understood that the terminology employed herein is for the purpose of description and should not be regarded as limiting. The term "comprise" and variants of the term such as "comprises" or 30 "comprising" are used herein to denote the inclusion of a stated integer or stated integers but not to exclude any other integer or any other integers, unless in the context or usage an exclusive interpretation of the term is required.

22 Any reference to publications cited in this specification is not an admission that the disclosures constitute common general knowledge in Australia.

Claims (11)

1. A padlock having a shackle, a body, a lock cylinder and a shackle alignment arrangement; wherein the shackle is manufactured from a non-metalliferous material and has a first leg member and a second leg member; the body has a first aperture for receiving the first leg member and a second aperture for receiving the second leg member; the shackle is movable towards the body to a locking position at which the first and second leg members are respectively inserted into the first and second apertures; and the shackle alignment arrangement prevents the shackle from moving into the locking position unless the first leg member is aligned with the first aperture and the second leg member is aligned with the second aperture.

2. A padlock according to claim 1 wherein the shackle alignment arrangement includes a shackle portion which is associated with the shackle and a body portion which is associated with the body.

3. A padlock according to claim 2 wherein the shackle portion and the body portion are configured such that the shackle and body portions must be registered with each other before the shackle can be moved to the locking position.

4. A padlock according to claim 2 or 3 wherein movement of the shackle to the locking position causes the shackle portion to be inserted, at least partly, into the body portion.

5. A padlock according to claim 4 wherein the body portion includes a cavity into which the shackle portion can be inserted; and the cavity has a maximum cross sectional diameter which is slightly larger that a maximum cross-sectional diameter of the shackle portion so that the shackle portion, once inserted into the body portion, has little lateral play inside the cavity. 24

6. A padlock according to any one of claims 2 to 5 wherein the shackle portion is integrally formed with the shackle and the body portion is integrally formed with a component of the body.

7. A padlock according to any one of claims 2 to 6 wherein the first leg includes a bottom portion which carries the shackle portion and the body portion is associated with the first aperture.

8. A padlock according to any one of claims 2 to 7 wherein the shackle portion and the body portion each has a profile, when viewed in cross section, which is noncircular.

9. A padlock according to claim 8 wherein each of the shackle and body portions have the same cross-sectional profile which is selected from any one of the following: square, rectangular, triangular and oval.

10. A padlock according to any one of claims 2 to 9 wherein the shackle is moved away from the locking position causes shackle portion to disengage from the body portion so that the shackle can be pivoted about the first leg member relatively to the body.

11. A padlock having a shackle, a body and a lock cylinder; the shackle being made from a plastic or polymer material and having a first leg member and a second leg member; the body having a first aperture for receiving the first leg member and a second aperture for receiving the second leg member; wherein the padlock is locked by moving the shackle towards the body into a locking position in which the leg members are inserted into the respective apertures, but when the padlock is open the shackle is at least partially withdrawn relative to the body so that at least the second leg member is retracted out of the second aperture and the shackle is able to pivot relative to the body, the padlock also having shackle alignment means whereby the shackle can only move towards the body into the locking position when the first leg member is 25 aligned with the first aperture and the second leg member is aligned with the second aperture.