AUSTRALIA Patents Act 1990 ORIGINAL COMPLETE SPECIFICATION INVENTION TITLE: LOCKING SYSTEM The following statement is a full description of this invention, including the best method of perfonning it known to us: 11/09/A8va 16810 coypag q I4 -2 The present invention relates to a locking system and relates particularly, although not exclusively, to a locking system to control operation of electrical devices. It is an object of the invention to provide a locking system which allows the lock 5 cylinder to be removed without disturbing a switch mechanism coupled thereto. With this object in view the present invention provides a locking system including a lock cylinder, a body member having an oversize recess to receive said lock cylinder, said oversize recess allowing said lock cylinder to pivot within said recess, a 10 releasable pivotal tab in a first position preventing pivotal movement of said lock cylinder in said oversize recess and in a second position allowing pivotal movement of said lock cylinder in said oversize recess, a cover plate which can rotate said lock cylinder when said pivotal tab is in said second position and a projection on said lock cylinder which engages a slot in said body member when said pivotal tab is in said 15 first position and which is free of said slot when said pivotal tab is in said second position to allow withdrawal of said lock cylinder from said body member after said lock cylinder has been pivotally rotated in said oversized recess. Preferably said lock cylinder further includes a second projection which engages a 20 further slot in said body member, said second projection being withdrawn from said further slot when a turnable element of said lock cylinder is rotated by key operation. In a practical embodiment said further slot opens into a groove in said body member to allow said second projection to be moved along said groove on withdrawal of said lock cylinder from said body member. 25 Also disclosed is a locking system including a lock cylinder, a body member having a recess to receive said lock cylinder, a first projection which engages a first slot in said body member, said projection being withdrawn from said slot when a turnable element of said lock cylinder is rotated by key operation. 30 In a practical embodiment said first slot opens into a groove in said body member to allow said first projection to be moved along said groove on withdrawal of said lock 27/10/15,ag16810 amended speci(2),2 -3 cylinder from said body member. Preferably said recess is an oversize recess to allow said lock cylinder to pivot within said recess, a releasable pivotal tab in a first position preventing pivotal movement of said lock cylinder in said oversize recess and in a second position allowing pivotal movement of said lock cylinder in said 5 oversize recess, and a cover plate which can rotate said lock cylinder when said pivotal tab is in said second position. A second projection on said lock cylinder may engage a second slot in said body member when said pivotal tab is in said first position and which is free of said second slot when said pivotal tab is in said second position to allow withdrawal of said lock cylinder from said body. 10 The structure and functional features of preferred embodiments of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which:-. Fig. 1 is an exploded perspective view of a prior art locking system; 15 Fig. 2 is shows front and rear perspective views of a locking system made in accordance with a preferred embodiment of the invention; Fig. 3 shows similar views to that of Fig. 2 with the front plate of the locking system being rotated; Fig. 4 is a front view of the locking system shown in Fig. 2; 20 Fig. 5 is a front view of the locking system shown in Fig. 3; Fig. 6 shows front and rear perspective views of the locking system of Fig. 2 with the lock cylinder being removed; Fig. 7 shows front and rear perspective views of the locking system of Fig. 2 with the lock cylinder almost completely removed; 25 Fig. 8 is an exploded rear perspective view of the locking system shown in Fig. 2 with the lock cylinder completely removed; Fig. 9 is an exploded cross-sectional view of the locking system shown in Fig. 2 with the lock cylinder removed; and Fig. 10 shows the circled view indicated by arrow 10 in Fig. 9; 30 In order to avoid duplication of description, identical reference numerals will be shown, where applicable, throughout the illustrated embodiments to indicate similar 11/INjV9/e 16810 siCCL -4 integers. In Fig. 1 of the drawings there is shown a prior art locking system 20 which includes a control box 24 typically switching cables (not shown) for an electrically driven 5 device (not shown). The cables would enter the control box 24 through apertures which in this embodiment are sealed by plugs 26. The front face 28 of control box 24 has a predefined aperture 30 to allow the main body section 32 of a lock cylinder retaining member 34 to be inserted into control box 24. A rotary switch 36 is fitted to the end of main body section 32. Rotary switch 36 may or may not be a multi 10 position switch. Various control wires 38 are inserted into the rotary switch 36 which are connected inside the control box 24. The rotary switch 36 is adapted to be coupled to a cam 40 of a key turnable element 41 of a lock cylinder 42. Lock cylinder 42 slides into the main body section 32 and is held fast by a pin 44 which passes through apertures 45 of main body section 32 through a bore 46 of lock 15 cylinder 42. The interior of the main body section 32 has a complementary shape to that of the lock cylinder 42 to provide a smooth entry. A mounting flange 48 is located at one end of main body section 32 and is secured to the front face 28 of control box 24 using screws 50. A cover plate 52 has an aperture 54 which is complementarily shaped to the periphery of lock cylinder 42. The cover plate 52 is 20 typically a snap fit over the mounting flange 48 to provide an aesthetic finish. The prior art locking system 20 works very well except when the key (not shown) needs to be changed, for example, for breach of security, change of ownership or other reason. The lock cylinder 42 must be removed so the locksmith can change the 25 lock cylinder to be useable with the replacement key. This involves removal of the cover plate 52. Screws 50 must be removed to allow the lock cylinder retaining member to be withdrawn from the control box 24. The pin 44 is then withdrawn from the main body section 32 to release the lock cylinder 42. The locksmith can then make the adjustments to the lock cylinder to allow its use with the replacement 30 key. This process must then be reversed to re-assemble the locking system. The replacements can take a lot of time, especially if there are a number of replacements involved. H1/09/08,Va 16810 speci,4 A first preferred embodiment of the invention is shown in Figs. 2 to 10. The preferred embodiment operates in the same environment as locking system 20 described in Fig. 1. A wall plate 58 acts as a mounting surface and has a main body 5 section 60 affixed at the rear thereof or integrated therewith when manufactured. A pair of guide slots 62 are provided which include an enlarged aperture 64 at one end and a stop member 66 at the other end. A cover plate 68 in the form of a flat surface of any shape has an aperture 70 (Fig. 8) with a complementary shape to the periphery of lock cylinder 42. The end 72 of lock cylinder 42, will, in use, be flush with the 10 outer face of cover plate in the assembled position shown in Figs. 2 and 3. A pair of pins 74 are located on the inner face of cover plate 68 and are terminated with protuberances 76. The protuberances 76 are of the same size or smaller than enlarged apertures 64. The positioning of the protuberances 76 allows the pins 74 to locate within respective stop members 66 with the protuberances overlapping the 15 stop members 66 as best seen in Figs. 2 in the assembled position. In this position cover plate 68 cannot be moved. As cover plate 68 is not affixed to wall plate 58 it can be pivoted as shown in Fig. 3, to be described later. Attached to main body section 60 is a pivotal tab 78 which can move between its locked position as shown in Fig. 4 and its unlocked position as shown in Fig. 5. Main body 60 has an oversize 20 interior shape 82 which allows lock cylinder to move between the positions shown in Figs. 4 and 5. With pivotal tab 78 extended as shown in Fig. 4, lock cylinder 42 cannot be moved because pivotal tab 78 prevents such movement. Fig. 5 illustrates the use of removable pin or shim 80 which pushes pivotal tab 78 out of the way and allows lock cylinder 42 to be rotated to the position shown in Fig. 5. The removable 25 pin or shim 80 is very thin and can fit between the lock cylinder 42 and cover plate 68 / oversize interior shape 82. A pin member 84 extends from lock cylinder 42 and is adapted to, in its locked position, to locate within slot 86. Once pin member 84 is in slot 86 and pivotal tab 30 78 is in the position shown in Fig. 4, then lock cylinder 42 cannot be rotated or withdrawn from main body section 60. Attached at the edge of cam 40 (best seen in Fig. 9) is a tongue 88 which, in the locked position is located in slot 90. Slot 90 I 1/09va 16810 sped,5 -6 opens into a groove 92 which runs towards the front of main body section 60. In the locked position tongue 88 will also prevent the lock cylinder 42 from being withdrawn from main body section 60. When the key 94 is twisted it will rotate cam 40 and withdraw tongue 88 from slot 90 to allow tongue 88 to be able to be moved 5 along groove 92 to remove lock cylinder 42 from main body section 60. A rotatable engagement member 96 (Fig. 9) co-operates with cam 40 to enable coupling with rotary switch 36. The operation of the locking system shown in Figs. 2 to 10 will now be described. In 10 its normal day to day operation the turning of key 94 will rotate the key turnable element 41 which will rotate cam 40. As cam 40 is coupled to rotatable engagement member 96 the rotary switch 36 will be actuated in its predetermined configuration. Lock cylinder 42 cannot be rotated as pivotal tab 78 prevents such rotation together with the protrusion of lock cylinder 42 through aperture 70 of cover plate 68. Lock 15 cylinder 42 also cannot be forced through cover plate 68 because of the engagement of pin member 84 in slot 86 and tongue 88 in slot 90. This arrangement provides substantial security to prevent unauthorized removal of lock cylinder 42 from main body section 60. When it is desired to have a locksmith change key 94, then lock cylinder 42 must be removed. The normal position is shown in Fig. 2. The removal 20 of lock cylinder 42 is a multi stage process. Firstly, key 94 must be in lock cylinder 42 as shown in Fig. 2. The removable pin or shim 80 is inserted between lock cylinder 42 and cover plate 68 and oversize interior shape 82 of main body section 60. Pin or shim 60 will push pivotal tab 78 out of the way into the position shown in Fig. 5. Lock cylinder 42 can then be rotated to the position shown in Figs. 2 and 5 25 by rotating cover plate 68 as indicated by the arrows 98. Pin member 84 will be free of slot 86. Pins 74 will be moved from stop members 66 as best seen in Figs. 4, 5 and 7. Lock cylinder 42 cannot be withdrawn from the main body section 60 unless the key 94 is moved from the locked position shown in Fig. 4 to the unlocked position shown in Fig. 5. The rotation of the key turnable element 41 will cause cam 30 40 to be rotated which will withdraw tongue 88 from slot 90. Tongue 88 will then be aligned with groove 92. With pin member 84 free of slot 86, pivotal tab 78 out of the way and tongue 88 aligned with groove 92, lock cylinder 42 can be withdrawn from 11 10 9/O8.va 16810 spec46 -7 main body section 60 as shown in Figs. 6 and 7. Lock cylinder 42 can be rekeyed and the lock cylinder replaced in the reverse order back to the position shown in Fig. 2. The invention provides a simple method where the rotary switch 36 does not need to be disturbed to change the key combination. Cover plate 68 can also be removed, 5 in the unlocked position for maintenance of the rotary switch 36. No special tools are required to withdraw the lock cylinder 42 and the locking system is secure. The embodiment shown in Figs. 11 to 13 is a variation of the prior art shown in Fig. 1 and the embodiment shown in Figs. 2 to 10. In view of the raised nature of 10 mounting flange 48 it is not possible to use a flat cover plate 68 in the embodiment of Figs. 2 to 12. Cover plate 52 has aperture 54 which is complementarily shaped to the periphery of lock cylinder 42 which protrudes through aperture 54 in a flush mount. Rotation of cover plate 52 will rotate lock cylinder 42. Mounting flange 48 has angled sides 100, 102 which allows cover plate 52 to rotate with respect to mounting 15 flange 48 as indicated by arrows 104 in Fig. 13. Main body section 32 has an oversize interior shape 82 which allows lock cylinder 42 to move between the positions shown in Figs. 12 and 13. The operation of the locking system shown in Figs. 11 to 13 is identical to that of the embodiment previously described with reference to Figs. 2 to 10 to avoid repetition of description. The difference is the 20 shape and operation of the cover plate 52 of Figs. 11 to 13 as opposed to cover plate 68 of Figs. 2 to 10. Although the preferred embodiment provides a useful solution the invention is not limited to the embodiment disclosed. The preferred embodiment describes use of the 25 locking system for operation of electrical or electronic equipment. The locking system can also be used for mechanical operations where the key operated turnable element is coupled to a latching element which can release a lock bolt. The shape and rotation of the cover plates 52, 68 can be altered to suit requirements. 30 The invention will be understood to embrace many further modifications as will be readily apparent to persons skilled in the art and which will be deemed to reside within the broad scope and ambit of the invention, there having been set forth herein I ]/0903,va 16810 speci,7 only the broad nature of the invention and certain specific embodiments by way of example. II/09/0,va 16810 speci,8