Patent Publication Number: US-2022220710-A1

Title: A securing device and removal tool for use with the securing device

Description:
FIELD OF THE INVENTION 
     The present invention relates to a securing device for releasably securing a first object to a second object. The invention also relates to an assembly of the first and second objects secured together by a securing device of the invention, as well as a removal tool for removing a securing device of the invention from its securing position. Methods for use of a securing device and removal tool embodied by the invention are also provided. 
     BACKGROUND OF THE INVENTION 
     Various securing devices have been described in the art for releasably securing a tooth to an adaptor of a mining or excavation bucket (e.g., a dragline bucket). Securing devices for securing a wear plate to such buckets or other equipment have also been described. However, conventionally known such securing devices involve the use of mechanical fastener for retention of the securing device in position or holding pins that involve the use of clips or brackets to retain the holding pin in position. 
     A securing device that involves the use of a mechanical fastener is for instance described in International patent publication No. WO 2015/054741. The use of a mechanical fastener can be problematic as dirt and detritus can become caked around the fastener head in use which can make access for removal of the device difficult. The fastener can also become cemented in position and/or incorrect use of tools can result in the head of the fastener being rounded or otherwise damaged which can also make loosening or removal of the fastener problematic. The need to fit and tighten the fastener is also time consuming. Likewise, the use of clips or brackets to retain a holding pin in position can also be cumbersome. 
     SUMMARY OF THE INVENTION 
     In a first aspect of the invention there is provided a securing device for releasably securing a first object to a second object, the device comprising:
         a casing having a top and a bottom; and   at least one magnet housed in the casing, the casing being configured for being inserted in a passageway formed by aligned openings of the first and second objects when assembled together whereby the casing blocks separation of the first object and the second object from one another, and the magnet is moveable from an initial position to a working position to form a magnetic coupling for holding the casing in position in the passageway.       

     Typically, the securing device is a unitary assembly in which the magnet is retained captive within the casing and is restricted to movement between the initial and working positions of the magnet. 
     Typically, the magnet is arranged for return to its initial position upon being withdrawn from the magnetic coupling to allow for removal of the casing from the passageway and thereby separation of the first and second objects. 
     In another aspect of the invention there is provided an assembly of a first object and a second object releasably secured together by a securing device comprising a casing and at least one magnet housed in the casing, the magnet being moveable between an initial position and a working position, wherein openings of the first object and the second object are aligned forming a passageway in which the casing of the securing device is positioned such that the casing extends from one of the first and second objects into the other of the first and second objects blocking separation of the first object and the second object from one another, the magnet being in its working position forming a magnetic coupling holding the casing of the securing device in position in the passageway. 
     In another aspect of the invention there is provided a method for releasably securing a first object to a second object, comprising: 
     providing a securing device for securing the first object and the second object together, the securing device comprising a casing housing at least one magnet moveable from an initial position to a working position; 
     assembling the first and second objects together whereby openings of the first and the second objects are aligned forming a passageway; and 
     positioning the casing of the securing device in the passageway such that the casing extends from one of the first and second objects into the other of the first and second objects blocking separation of the first object and the second object from one another, and the magnet is moved from its initial position to its working position to form a magnetic coupling holding the casing of the securing device in position in the passageway. 
     Typically, the securing device further comprises at least one further magnet, wherein the further magnet is arranged for being in a magnetically repelling relationship with the moveable magnet when the moveable magnet is in its working position. By magnetically repelling the moveable magnet the further magnet in at least some embodiments acts to dampen the movement of the moveable magnet into its working position when forming the magnetic coupling and assists release of the moveable magnet from the magnetic coupling for return of the moveable magnet to its initial position and thereby, the removal of the securing device from the passageway to allow for separation of the first object and the second object from one another. 
     Typically, in particularly preferred embodiments, one of the moveable and the further magnet is received by the other of those magnets. 
     Typically, the moveable magnet and the further magnet are oppositely poled to one another in the initial position of the moveable magnet, and wherein the moveable magnet is slidable relative to the further magnet. 
     In preferred embodiments described herein. the further magnet may be retained in a fixed position within the casing of the securing device. 
     Typically, the moveable magnet is moved into the magnetically repelling, relationship with the further magnet with travel of the moveable magnet from its initial position to its working position. 
     Typically, the securing device further comprises a plunger element to which the movable magnet is secured, the plunger element being moved from a resting position to a securing position with the movement of the moveable magnet from its initial position to its working position. 
     Typically, the securing device further comprises a cap on an outer end of the plunger, the cap being formed from a magnetically attracted material and arranged to move with the plunger to close the casing with the movement of the plunger to its securing position. 
     In another aspect of the invention there is provided a securing device for releasably securing a first object to a second object, the device, comprising: 
     a casing having a top and a bottom and an interior cavity; 
     a first magnet disposed in the cavity; and 
     a moveable magnet, one of the moveable and the first magnets being received by the other of the magnets, the first magnet and the moveable magnet being oppositely magnetically poled to one another in an initial position of the movable magnet and the movable magnet being slidable relative to the first magnet, and wherein the moveable magnet is arranged for being moved from its initial position into a working position in the casing for releasably securing the first object to the second object. 
     In at least some embodiments, the moveable magnet is arranged to be drawn into its working position to secure the first and second objects together by magnetic attraction of the moveable magnet when the casing of the securing device is located in position relative to the first object and the second object. 
     In other embodiments, the moveable magnet is arranged to be driven into its working position by application to the moveable magnet of a manual driving force. 
     Typically, the securing device further comprises a retaining element retaining the plunger element within the cavity of the casing. 
     Typically, the first/further magnet is retained in the cavity of the casing between the retaining element and the bottom of the casing. Most typically, the first magnet is retained in a fixed position by the retaining element and generally, the first magnet is seated on an internal ledge defined in the cavity of the casing. 
     Typically, the cap has an outer perimeter and further comprises a sealing element located about the outer perimeter for sealing the opening of the cavity when the plunger is in the securing position. 
     In other embodiments, the outer perimeter of the cap can be tapered for being seated on a correspondingly tapered wall of the casing, and a sealing element is located under the cap for sealing the cavity of the casing when the plunger is in its securing position. 
     Typically, the moveable magnet is secured to the plunger by a fastener. 
     Typically, the plunger and the casing are formed from a non-magnetic material and so are essentially non-magnetic. 
     Typically, the casing is profiled for being located within a corresponding through passageway of the first object for releasably securing the first object and the second object together. 
     In at least some embodiments, the casing has an end for abutment with one of the first and second objects and a protrusion extending from an opposite end for abutment of the protrusion with the other of the first and second objects to inhibit sliding withdrawal of the first and second objects apart from one another in use. The protrusion in at least some forms is a foot for being located in a recess formed by the first and second components when the first and the second components are in an assembled configuration for being secured together. 
     Typically, opposite ends of the casing are angled away from one another in a top to bottom direction of the casing. 
     Typically, in at least some embodiments, the casing has opposite side faces between the opposite ends of the casing, that are angled toward one another in the top to bottom direction of the casing. 
     In other embodiments, the casing can be cylindrical. In such embodiments, the casing can taper in the top to bottom direction of the casing whereby the width of the top of the casing is greater than that of the bottom of the casing, and so be essentially frustoconical in shape. 
     In at least some embodiments, a retaining element can be used for retaining the first object and the second object in an assembled configuration wherein the moveable magnet is held in a working position by magnetic attraction to the retaining element against sliding return of the moveable magnet to its initial position. 
     In another aspect of the invention there is provided a securing assembly for releasably securing a first object to a second object, the assembly comprising: 
     a casing having a top and a bottom and an interior cavity; 
     a first magnet disposed in the cavity; 
     a moveable magnet, one of the moveable and the first magnets being received by the other of the magnets, the first magnet and the moveable magnet being oppositely magnetically poled to one another in an initial position of the movable magnet and the movable magnet being slidable relative to the first magnet; and 
     a retaining element for retaining the first object and the second object in an assembled configuration, the moveable magnet being held in a working position by magnetic attraction to the retaining element against sliding return of the moveable magnet relative to the first magnet to its initial position. 
     Typically, in such embodiments, the bottom of the casing is arranged for being seated on the retaining element when the securing device is located in position for securing the first object to the second object. 
     The retaining element in at least some forms comprises a further magnet for being fitted to the second object to align with the plunger element in an oppositely poled magnetic orientation to the moveable magnet for magnetic attraction of the moveable magnet into its working position. In such embodiments the retaining element can be in the form or a retaining plate comprising the further magnet. 
     In other embodiments the retaining element can be a holding pin received by the first object and the second object. 
     In another aspect of the invention there is provided a securing assembly releasably securing a first object to a second object, the securing assembly comprising: 
     a casing having a top and a bottom and an interior cavity; 
     a first magnet disposed in the cavity; and 
     a moveable magnet, one of the moveable and the first magnets being received by the other of the magnets, the first magnet and the moveable magnet being oppositely magnetically poled relative to one another in an initial position of the movable magnet, wherein the moveable magnet is in a working position in the cavity of the casing for magnetically retaining the securing device in position whereby the first and the second objects are releasably secured together, the movable magnet being held in the working position by magnetic coupling of the movable magnet with a magnetically attracted material and/or further magnet against sliding return relative to the first magnet to its initial position. 
     In another aspect of the invention there is provided a method for releasably securing a first object to a second object, the method comprising: 
     providing the securing device, the securing device comprising a casing, the casing having a top and a bottom and an interior cavity; a first magnet disposed in the cavity; and a moveable magnet, one of the moveable and the first magnets being received by the other of the magnets, the first magnet and the moveable magnet being oppositely magnetically poled relative to one another in an initial position of the movable magnet, and the movable magnet being slidable relative to first magnet; 
     arranging the first object and the second object together; 
     locating the casing of the securing device in position; and 
     securing the first and second objects together by movement of the movable magnet from the initial position into a working position in the cavity, the movable magnet being held in the working position by magnetic coupling of the movable magnet with a magnetically attracted material and/or further magnet against sliding return to its initial position, and the magnetic coupling of the movable magnet retaining the securing device in position. 
     Typically, in embodiments of a securing device as described herein the first magnet and the moveable magnet are each respectively provided as a single magnet. 
     In other embodiments, the first magnet and/or the moveable magnet may be provided in a number of respective magnet sections that may be spaced apart from one another but which are nevertheless arranged to function together as described herein. 
     In still another aspect of the present invention there is provide a removal tool for removing a securing device magnetically retained in a position securing first and second objects together by a magnet of the securing device to permit separation of the first and second objects, the removal tool comprising: 
     a casing; 
     a coupling magnet for magnetically coupling with the securing device by magnetic attraction of the coupling magnet for the securing device to facilitate withdrawal of the magnet of the securing device and thereby the removal of the securing device from its securing position, the coupling magnet of the removal tool being movable within the casing from a retracted position to a coupling position for magnetically coupling with the securing device; 
     a further magnet; and 
     a movable magnet slidable relative to the further magnet, the further magnet and the movable magnet being housed in the casing with the coupling magnet, and the coupling magnet and the movable magnet being connected together for drawing of the movable magnet into a magnetically repelling relationship with the further magnet to dampen the movement of the coupling magnet from its retracted position to its coupling position, and wherein the magnetic coupling of the coupling magnet with the securing device provides for withdrawal of the securing device from its securing position with withdrawal of the removal tool. 
     The coupling magnet of the removal tool can be for magnetically coupling with a cap of the securing device connected to the magnet of the securing device by a plunger. 
     In other embodiments the coupling magnet of the removal tool can be for magnetically coupling with the magnet of the securing device. 
     In yet further embodiments the coupling magnet of the removal tool can be for magnetically coupling with a further magnet of the securing device, the further magnet being connected to magnet of the securing device magnetically retaining the securing device in its position securing the first and second objects together. 
     Typically, in embodiments of the removal tool one of the further magnet and the coupling magnet of the removal tool is slidably received by the other of those magnets, and wherein the further magnet and the coupling magnet are oppositely poled to one another. Typically, the further magnet of the removal tool is retained in a fixed position within the casing of the removal tool. 
     In at least some embodiments of the removal tool the coupling magnet can be enclosed in a magnetically attracted material for enhancing magnetic field strength generated by the coupling magnet, and wherein an outwardly directed face of the coupling magnet remaining exposed for the magnetic coupling with the removal tool. 
     Typically, the removal tool further comprises a pulling handle for pulling the removal tool away from the securing device to withdraw the securing device from its securing position. 
     A removal tool in accordance with the invention can also additionally comprising a release handle movable from an initial position with the movement of the coupling magnet from its retracted position to its coupling position and for being returned to its initial position to withdraw the coupling magnet into the casing to effect separation of the coupling magnet from the securing device and thereby release of the securing device from the removal tool. The release handle may be formed by at least one handle member, the handle member passing from within the casing of the removal tool through a respective slot formed in the casing, the slot being orientated in the lengthwise direction of the casing and the movement of the release handle along the casing from its initial position being limited by the length of the slot. 
     The casing of the removal tool may be formed from any suitable essentially non-magnetic material, such as a suitable austenitic metal. 
     In yet another aspect of the invention there is provided a method for removing a securing device magnetically retained in position securing first and second objects together by a magnet of the securing device to permit separation of the first and second objects, the method comprising: 
     providing a removal tool for removing the securing device from its securing position, the removal tool comprising a casing and a coupling magnet for magnetically coupling with the securing device by magnetic attraction of the coupling magnet for the securing device to facilitate withdrawal of the magnet of the securing device and thereby the removal of the securing device from its securing position, the coupling magnet of the removal tool being movable within the casing from a retracted position to a coupling position for magnetically coupling with the securing device; 
     placing the removal tool on the securing device; 
     magnetically coupling the coupling magnet and the securing device with movement of the coupling magnet from its retracted position to its coupling position; and 
     withdrawing the removal tool with the securing device magnetically coupled with the coupling magnet of the removal tool. 
     Typically, the first and the second objects are first and second components for being held together in an assembly of those components. 
     The first and second components can, instance, be a tooth and an adaptor of a mining or excavation bucket for the tooth. 
     In other embodiments, the first and second components can be a wear plate and an adaptor for the wear plate. 
     In still other embodiments, the first and second components are machinery components. 
     In at least some embodiments, one of the first and second components can be pivotable relative to the other of the components when the components are secured together by a securing device as described herein. 
     As will be understood, the term “magnetic coupling” is used herein in the context of a magnetic bond with a magnetically attracted material arising from magnetic attraction for the magnetically attracted material. Similarly, “magnetically coupling” is used herein in the context of forming a magnetic bond with the magnetically attracted material. 
     By employing magnetic coupling of the moveable magnet as described herein, one or more embodiments of the securing device described herein provide for rapid installation and removal of the securing device in use. The use of a mechanical fastener for retaining the device in position in use and associated disadvantages as described above may also be avoided. Advantageously also, as the cap in securing devices as described herein may inhibit dirt and external detritus from caking about the device when located in position in the assembly of the first and second components in embodiments as described herein, accessing and removal of the device may also be enhanced. Also, as magnets as described herein are employed, wear and maintenance of the device may also be minimised. 
     Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers, integers or steps. 
     Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the invention as it existed in Australia or elsewhere before the priority date of this application. 
     The features and advantages of the present invention will become further apparent from the following detailed description of exemplary embodiments of the invention together with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS 
         FIG. 1  is a cross-sectional end view of a securing device embodied by the invention; 
         FIG. 2  is an exploded view of the securing device of  FIG. 1 ; 
         FIG. 3  is cross-section end view of a securing assembly embodied by the invention in a separated form and comprising the securing device of  FIG. 1 ; 
         FIG. 4  is a cross-sectional end view of the securing assembly of  FIG. 3  in an assembled form; 
         FIG. 5  is a diagrammatic view from above of a first component and a second component secured together by a pair of securing assemblies of  FIG. 4 ; 
         FIG. 6  is a diagrammatic side view of the assembled configuration of the first component and the second component of  FIG. 5 ; 
         FIGS. 7 and 8  are diagrammatic side views illustrating the removal of one of the securing devices embodied by the invention from the assembled configuration of the first component and the second component of  FIG. 6 ; 
         FIG. 9  is diagrammatic view from above of a first component and a second component secured together by a pair of further securing devices embodied by the invention; 
         FIG. 10  is a diagrammatic side view of the first and second components of  FIG. 9  secured to one another; 
         FIG. 11  is a diagrammatic view from above of another securing device and securing assembly embodied by the invention; 
         FIG. 12  is a diagrammatic side view of the first and second components of  FIG. 11  secured together; 
         FIG. 13  is a diagrammatic view from above of another securing device and securing assembly embodied by the invention; 
         FIG. 14  is a side view of the first and second components of  FIG. 13  secured together; 
         FIG. 15  is a diagrammatic side view of the holding pin of the securing assembly of  FIG. 13 ; 
         FIG. 16  is a diagrammatic view from above of first and second components secured together by another securing device embodied by the invention; 
         FIG. 17  is a diagrammatic view from above of first and second components secured together by another securing device embodied by the invention, the securing device allowing for one of the components to pivot relative to the other of the components; 
         FIG. 18  is a diagrammatic side view of another securing device embodied by the invention having a moveable ring magnet and a cylindrical magnet retained in a fixed position, the moveable ring magnet being shown in its initial position; 
         FIG. 19  is a diagrammatic side view of the securing device of  FIG. 18  showing the moveable ring magnet in its working position; 
         FIG. 20A  is a diagrammatic side view of yet another securing device embodied by the invention showing the plunger of the device in its initial resting position.  FIG. 20B  shows the plunger of this embodiment in its working position.  FIG. 20C  is a diagrammatic side view illustrating the casing of this device; 
         FIGS. 21A and 21B  show a cutting edge secured to a support plate by securing devices of the type shown in  FIG. 20A ; 
         FIG. 22  is a diagrammatic side view illustrating a securing device (shown in phantom outline) of  FIG. 20A  securing the cutting edge to the plate of  FIG. 21 ; 
         FIGS. 23 to 31  are diagrammatic views illustrating alterative magnet arrangements of embodiments of securing devices as described herein; 
         FIG. 32  is a diagrammatic side view of a further securing device embodied by the invention having a fixed ring magnet and in which a movable cylindrical magnet is in its working position; 
         FIG. 33  is a diagrammatic side view showing the cyclindrical magnet in its initial position; 
         FIG. 34  is a diagrammatic view of a yet further securing device embodied by the invention having a fixed ring magnet and in which a movable cylindrical magnet in its initial position; 
         FIG. 35  is a diagrammatic side view showing the cyclindrical magnet in its working position; 
         FIG. 36  is an exploded diagrammatic view of the casing of the securing device of  FIGS. 34 and 35 ; 
         FIG. 37  is a diagrammatic side view of another tool for removing a securing device of the invention from its in use position showing the removal tool in an at rest configuration; 
         FIG. 38  is a diagrammatic side view of the removal tool of  FIG. 37  in an active configuration; and 
         FIG. 39  is a diagrammatic side view of the removal tool of  FIG. 36 . 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION 
     A securing device  10  embodied by the invention is illustrated in  FIG. 1 . The device  10  comprises a casing  12  formed from a non-magnetic material having a top  14  and a bottom  16 , and an internal cavity  18  which opens to the top of the casing. A plunger  20  which is also formed from an essentially non-magnetic material (i.e., a material that is not, or is essentially not, attracted by a magnet) is disposed in the cavity and to one end of which is secured a permanent cylindrical magnet  22  by a fastener  24 , the fastener being threadably engaged with an internal mating thread defined in plunger shaft  26  thereby fixedly securing the cylindrical magnet to the plunger shaft. A permanent ring magnet  28  is seated on the internal circumferential ledge  30  of the casing and is held stationary against the ledge by a retaining element in the form or a locking ring  32  threadably engaged with a corresponding female thread  34  defined in the casing wall. The cylindrical magnet  22  is partially received in an underside hollow of the locking ring  32  and the plunger shaft  26  slidably protrudes from a through opening  27  of the locking ring. 
     The cylindrical magnet  22  is received by the ring magnet  28 , and the cylindrical magnet and the ring magnet are in an oppositely poled magnetic (i.e., attracted) relationship to one another (i.e., N-S, S-N or S-N, N-S) wherein the cylindrical magnet  22  is slidable back and forth within the ring magnet  28  with movement of the plunger  20  back and forth within the casing between resting and securing positions of the plunger as further described below. As can also be seen, an air space  36  is provided between the bottom of the casing and the cylindrical magnet  22 . 
     A cap  38  fabricated from a magnetically attracted material (i.e., a ferromagnetic material) is fitted to the top end of the plunger shaft  26  and is secured in position by a retaining roll pin (not shown) inserted into the hole  40  in the plunger shaft. A sealing member in the form of an O-ring  42  is received about the cap in a groove  44  defined in the circumferential periphery of the cap and covers the retaining pin. In other embodiments, the sealing member can be a lip seal rather than an O-ring. In still yet further embodiments, a sealing member in the form of an O-ring can instead be provided in a circumferential groove defined in the inside face of the surrounding wall of the casing rather than on the cap itself. 
     An exploded view of the securing device  10  is shown in  FIG. 2  and the operation of the securing device is illustrated in  FIGS. 3 and 4 . 
     As shown in  FIGS. 3 and 4 , the securing device  10  in at least some embodiments of the invention is employed in combination with a retaining element in the form of a mild-steel retaining plate  46  in which is mounted a further permanent magnet  48 , the securing device and the plate forming a securing assembly embodied by the invention which in at least forms, can be employed to prevent separation of first and second components as described herein from one another, thereby securing the first and second components together. 
     In use, the retaining plate  46  is located in position on the first component as described in greater detail below, such that the further magnet  48  is in an oppositely poled (i.e., attracted) magnetic orientation relative to the cylindrical magnet  22  (i.e., N-S or S-N). The bottom of the securing device  10  is then seated on the top of the retaining plate  46  so that the cylindrical magnet  22  of the device aligns with the further magnet  48 . 
     Initially, the plunger  20  is in its resting position as shown in  FIG. 3  whereby the cylindrical magnet  22  is located above the space  36  provided within the casing between that magnet and the bottom  16  of the casing  12 . 
     With the positioning of the casing on the retaining plate  46 , the cylindrical magnet  22  is partially, slidably drawn though the ring magnet  28  by magnetic attraction of the cylindrical magnet for the further magnet  48  whereby the cylindrical magnet is moved from its initial position into its working position in the space  36  and magnetically couples with the further magnet  48 , thereby holding the securing device against the retaining plate  46 . As with other embodiments of the securing device  10  as described herein, the bottom  16  of the casing has a thickness of typically about 0.5 to about 1.5 mm that is reduced compared to the surrounding side wall of the casing to facilitate the attraction and magnetic coupling of the cylindrical magnet  22  with the further magnet  48 /retaining plate  46  or other magnetically attracted component as described herein. 
     As the cylindrical magnet  22  is drawn into its working position, the plunger  20  is likewise automatically drawn from its resting position to its securing position in which the top of the cap  38  is generally flush with the top of the casing  12  as shown in  FIG. 4 . In this position, the opening of the cavity  18  is closed by the cap and the interior of the cavity is substantially sealed by the O-ring of the cap, essentially preventing dust and detritus from entering the casing  12  through the cavity opening. Further, in this position, the top region of the cylindrical magnet  22  is in a repelling magnetic relationship (i.e., N-N or S-S) with the bottom region of the ring magnet  28 , the magnetic attraction between the cylindrical magnet  22  and the further magnet  48  overcoming the magnetic repulsion between the cylindrical magnet and the ring magnet  28 . The magnetic repulsion between the cylindrical magnet and the ring magnet that develops as the cylindrical magnet is drawn into its working position acts to dampen that movement. Likewise, the magnetic repulsion between the cylindrical and ring magnets assists the release and return of the cylindrical magnet from its working position to its initial position during removal of the securing device. 
     The use of the securing assembly shown in  FIGS. 3 and 4  to secure a tooth component  50  of a mining or excavation (e.g., drag-line) bucket to another component i.e., an adaptor  52  of the bucket, is illustrated in  FIGS. 5 and 6 . The adaptor  52  in use is welded or otherwise fixed to the bucket in the conventionally known manner. 
     An opening in the form of a recess  54  is provided in the outer face of each side of the nose  56  of the adaptor for reception of a respective retaining plate  46 . To secure the tooth  50  to the adaptor, a retaining plate is first located in each slot whereby each plate  46  is retained in position by the magnetic attraction of its further magnet  48  to the adaptor. The tooth  50  is then slid onto the nose  56  of the adaptor such that the nose is snugly received in the corresponding cavity  58  of the tooth as best shown in  FIG. 6  whereby each recess  54  aligns with a respective through opening  60  defined in the adjacent side wall of the tooth, forming a passageway into which the a securing device is positioned in use as further described below. As shown in  FIG. 5 , once the tooth and the adaptor components are in their assembled configuration, one end of each retaining plate  46  is received under a respective ledge  62  of the tooth. 
     A securing device  10  is then inserted into one of the openings  60  at an angle such that the foot  64  of a forwardly directed protrusion  66  of the casing  12  is fitted into the recess  54  and slid under the overhanging ledge  62  provided by the tooth. With continued lowering of the casing the foot  64  slides into abutment with the front end  68  of the recess  54  and the cylindrical magnet  22  is magnetically attracted to the further magnet  48  in the retaining plate  46  as described above as the bottom  16  of the casing is seated on the retaining plate. The plunger  20  is thereby automatically moved into its securing position whereby the opening to the internal cavity  18  of the casing  12  of the device is closed by the cap  38  as the cylindrical magnet  22  is drawn into its working position by magnetic attraction to the further magnet  48  of the retaining plate. When the casing is located in position its rear end face  70  is disposed immediately adjacent to the wall  72  defining the opening  60  of the tooth. Another securing device is then inserted through the other of the through openings  60  so as to be seated on the other retaining plate  46  in the same manner as described above. 
     As can be seen in  FIG. 5 , the front end face  74  and opposite rear face  70  of the casing  12  of each securing device  10  are inclined relative to one another so that the length of the casing increases in the top to bottom direction of the casing to facilitate the insertion of the casing  12  into position and subsequent removal of the device from the opening  60 . Whilst not shown, the opposite sides  74  and  76  of the casing between the front and rear ends of the casing are inclined relative to one another so that the width of the casing decreases in the top to bottom direction of the casing to also facilitate locating the casing in position. 
     When in position the securing assembly comprising the securing device  10  and the retaining plate  46  prevents the withdrawal of the tooth  50  from the nose  56  of the adaptor, and so acts as a “chock” effectively locking the tooth and adaptor together. That is, withdrawal of the adaptor from the tooth is stopped by abutment of the rear end of the casing  12  with the corresponding wall  72  of the tooth whilst withdrawal of the tooth from the adaptor is stopped by abutment of the front of the foot  64  of the casing with the front end of the corresponding recess  54 . 
     Thus, the casing of a securing device  10  as described herein is sufficiently strong, rigid and robust to prevent the withdrawal/separation of the two objects secured together by the location of the device between the two objects (in the present example, the tooth  50  and adaptor  52 ). 
     Extraction of a securing device  10  from the assembled configuration of the tooth and the adaptor is simply the reversal of the insertion of the device which can be assisted with the use of a removal tool  78  as illustrated in  FIGS. 7 and 8 . 
     In the embodiment illustrated in  FIG. 7 , the removal tool comprises a non-magnetic housing  80  open at a bottom end  82  thereof and in which there is a permanent magnet  84  located on the end of a spindle  86  that is threadably received in a collar  88 . The spindle protrudes from the housing and a handle  90  is mounted on the outer end of the spindle. Whilst not shown, the cylindrical magnet  84  is enclosed in a cup formed from a magnetically attracted material (e.g., mild steel) except for the outwardly directed bottom face  85  of the magnet. The circumferential periphery of the magnet  182  is spaced from the cup as in conventionally known pot magnets. In the present embodiment, a thin layer of an epoxy is utilised to fill the spacing about the circumferential periphery of the magnet from the cup. Any suitable epoxy (e.g. an epoxy resin or adhesive) may be utilised for this purpose. As is known with conventional pot magnets, the encasing of the permanent magnet with a magnetically attracted material can substantially enhance the magnetic field generated for enhanced magnetic coupling as described herein. 
     Depending on which way the handle  90  is rotated, the magnet  84  is raised or lowered with the housing. To remove the securing device  10  from position on the retaining plate  46  and thereby the device from the tooth, the bottom end  82  of the removal tool is placed on the cap  38  of the device and the magnet  84  is wound down to the cap by rotation of the handle  90  for magnetic coupling of the magnet  84  with the cap. By rotating the handle  90  of the removal tool in the opposite direction the cylindrical magnet  22  is drawn into the casing  12 , and the cap and thereby the plunger  20  are also drawn toward the housing of the removal tool resulting in the cylindrical magnet being drawn away from the bottom of the casing  12  of the securing device, releasing the securing device  10  from the retaining plate  46 . The lifting of the cylindrical magnet away from the retaining plate is assisted by magnetic repulsion that is generated between the cylindrical magnet and the ring magnet when the cylindrical magnet is in its working position. 
     The return of the cylindrical magnet to its initial position from its working position and thereby the return of the plunger of the device from its securing position to its resting position is facilitated by the common (repelling) polarity of the cylindrical magnet relative to the ring magnet  28  in the working position of the cylindrical magnet. The generation of magnetic repulsion between the cylindrical magnet  22  and the ring magnet as the cylindrical magnet is drawn into its working position likewise dampens the movement of the cylindrical magnet to that position. 
     In embodiments described herein, the lifting force applied to the cap  38  by the removal tool in order to release the securing device from the retaining plate is typically substantially less than the force required to dislodge the casing of an embodiment of the securing device from the surface of the magnetically attracted material to which it is magnetically coupled in use. 
     In the embodiment presently shown, once the securing device  10  has been released from the retaining plate, the device  10  can be lifted from the corresponding through opening  60  of the tooth by the removal tool as illustrated in  FIG. 8 . 
     The above removal process using the removal tool is repeated for the other securing device  10  on the opposite side of tooth and adaptor assembly and once both securing devices  10  have been removed, the tooth can then be slipped from the adaptor. 
     In other embodiments, the retaining element or plate  46  may be located or received on the adaptor in any suitable way so as to be retained in position thereon other than being located in a cavity or recess of the adaptor. 
     A further embodiment of a securing device  10  in accordance with the invention coupling a tooth  50  to the nose  56  of an adaptor  52  of a mining or excavation bucket is illustrated in  FIGS. 9 and 10 . As with the embodiment described above, this securing device also includes a cylindrical magnet  22  secured to the bottom end of a plunger  20  and received by a stationary ring magnet  28  wherein in use, the cylindrical magnet is slidable relative to the ring magnet from an initial position into a working position in a space provided in the bottom region of the casing  12  to releasably secure the tooth to the adaptor. In this embodiment, the casing  12  of the device is cylindrical and desirably tapers in its top to bottom direction for being inserted in correspondingly tapered aligned through openings  92  and  94  of the tooth and the adaptor so as to be placed in an end to end relationship with a like securing device  10   a  as shown in  FIG. 9 . The moveable cylindrical magnet  22  of the securing device  10  is oppositely poled (i.e., N-S or S-N) with respect to the cylindrical magnet  22  of the other securing device  10   a  whereby the cylindrical magnets are attracted and magnetically couple with one another thereby holding the securing devices  10  and  10   a  in position and releasably securing the tooth  50  on the adaptor. To assist location and for maintaining the securing devices  10  and  10   a  in position, the casing  12  of each device is provided with a flange  96  which rests on the corresponding side face of the adaptor. 
     Another embodiment of a securing device  10  in accordance with the invention is illustrated in  FIGS. 11 and 12 . In this embodiment, a single securing device  10  is used to secure the tooth  50  in position on the nose of the adaptor  52  in combination with ferromagnetic holding pin  98 . In this embodiment the casing  12  is again generally frustoconical in shape and is inserted into aligned correspondingly tapered openings  100  and  102  of the tooth  50  and adaptor  52  whereby the bottom of the casing is received in a round recess  104  provided in the side of the holding pin  98  which itself has been inserted into openings  106  of the tooth and though opening  108  of the adaptor whereby the casing and the holding pin  98  are disposed substantially perpendicularly to each other. As will be understood, in this embodiment, the cylindrical magnet  22  is magnetically attracted to the holding pin  98  and magnetically couples with the holding pin, maintaining the pin in position and releasably securing the tooth to the adaptor. Other embodiments of this type can also be provided wherein the holding pin  98  is inserted into the tooth and adaptor assembly in the side to side (i.e., transverse) direction of the assembly whilst the securing device is inserted in a top to bottom direction of the assembly. 
     Likewise, the holding pin  98  can be provided in a shape other than as a flattened bar as illustrated in  FIGS. 11 and 12 . 
     Such an embodiment illustrated in  FIGS. 13 to 15 . In this embodiment, the movable cylindrical magnet  22  of the securing device is again received by the stationary ring magnet  28  and is slidable relative thereto as described above. However, in this instance, the bottom  110  of the casing  12  is concaved for mating with the ferromagnetic round holding pin  98  in a circumferentially directed groove  112  of the pin as best shown in  FIG. 15 . In this embodiment, the cylindrical magnet can likewise be concaved at its bottom end for enhancement of the magnetic coupling of that magnet with the holding pin  98 . A side view of the holding pin  98  is illustrated in  FIG. 15 . Whilst the holding pin  98  in this embodiment can therefore rotate about its longitudinal axis relative to the securing device  10 , the pin is nevertheless held in position within the tooth and adaptor assembly by the securing device  10  by virtue of the reception of the casing  12  within the circumferentially directed groove of the pin. 
     Yet another embodiment of the invention is illustrated in  FIG. 16  with respect to the securing of a tooth  50  to an adaptor  52  of a mining excavation bucket. In this embodiment, the casing  12  of the securing device  10  is elongated and is inserted into aligned openings  114   a  and  114   b  of the tooth  50  the second of which is blind, via through opening  11  of the nose  56  of the adaptor  52 . The securing device  10  in this embodiment thereby acts as a magnetic holding pin and the tooth is secured to the adaptor by the securing device without the need for a separate holding pin  98 . As also illustrated in  FIG. 16 , the cylindrical magnet  22  when in its working position magnetically couples with the ferromagnetic material (e.g., steel) from which the adaptor is made. Further, in this embodiment, the cap  38  of the securing device  10  is located in a recess  116  defined in the side face of the tooth  50  when the cylindrical magnet  22  is in its working position as shown in  FIG. 16  whereby the top of the cap is substantially flush with the side face of the tooth. 
     Whilst the above embodiments are described in the context of securing a tooth to an adaptor of a mining or excavation bucket, the invention is not limited thereto and securing devices  10  have a range of applications such as securing wear plates (e.g., comprising a tough and highly wear resistant ceramic or alloy material overlaid on a less dense material such as a mild steel or chromium steel plate) to equipment or a chute, bin, hopper, bucket or other material handling component to protect that component from abrasive material (e.g., rock, ore, minerals or the like) with which it would otherwise come into contact with in use. Typically, in such embodiments, the securing device is fitted into an aligned through opening and recess or slot of the wear plate and component assembly to secure the wear plate and the component to one another in the manner as described above. 
     In further embodiments, a securing device in accordance with the invention can be used for securing a first component to a second component wherein the first and the second components can pivot relative to one another. Such embodiments have application, for example, as a linkage pin for securing a pivoting component of machinery such as an excavator, backhoe or the like to a fixed component of the machinery. An example of such an embodiment is shown in  FIG. 17 . 
     As shown in  FIG. 16 , the stationary part  118  has a cavity  120  which opens to one side  122  of that part, and a recess  124  in a front end  126  in which the pivoting part  128  is located. The securing device  10  is inserted into the cavity  120  and extends entirely through the through passageway  130  of the pivoting part  128  whereby the bottom of the casing  12  of the device is in abutment with the side wall  130  defining the bottom of the cavity  120 . As will be understood, the pivoting part  128  is pivotable relative to both the securing device  10  and the stationary part  118 . 
     The cylindrical magnet  22  is shown in its working position in  FIG. 17  in which it is magnetically coupled to the ferromagnetic material of the end wall  130  of the stationary part  118 , whereby the cap  38  is in its closed position by virtue of its connection to the cylindrical magnet  22  via the plunger  20 . As also shown, the surrounding side wall  132  of the casing  12  in this embodiment is relatively thick and includes radially directed channels  134  which open to the exterior  136  of the side wall of the casing. The channels  134  are in communication with a one-way inlet valve in the form of a lubrication nipple  138  securing the cap  38  to the plunger  20  via central longitudinal channel  140  of the plunger shaft  26 , and open to circumferential grooves defined in the exterior of the side wall  132  forming grease/lubrication lines  137 . The longitudinal channel  140  and the radially directed channels  134  form conduits for the passage of grease or other lubricant to the exterior of the side wall of the casing  12  to allow for periodic lubrication of the exterior of the side wall, including between the casing and the pivoting/pivotable part  128 . A one-way valve  131  protrudes from a through passageway of the stationary part for passage of excess grease from the assembly. The sealing means in the form of O-ring  42  about the circumferential periphery of the cap  38  closes the cavity though again, it will be understood that a lip seal or other suitable seal may be used instead. Sealing means in the form of further O-ring seals  142  also protect the securing device  10  from external dust and other detritus. 
     In each of the embodiments of the securing device  10  and  10   a  described above, the movable cylindrical magnet  22  is drawn into its working position by magnetic attraction of that magnet to e.g., a retaining plate  46 , a ferromagnetic material such as a holding pin  98 , or an oppositely poled cylindrical magnet such as that of another securing device  10  (e.g., magnet  22 ), as described above. However, in other embodiments, the cylindrical magnet can be moved to its working position by manually depressing the cap  38  to drive the plunger  20  downwardly whereby the cylindrical magnet is then retained in its working position and the securing device is held in position, by the cylindrical magnet magnetically coupling with the retaining plate  46 , ferromagnetic holding pin  98  or oppositely poled magnet. Whether the cylindrical magnet  22  is automatically drawn into its working position by magnetic attraction of that magnet or the cap  38 /plunger  20  needs to be depressed in order to at least initiate the movement of the cylindrical magnet into its working position depends on the size and magnetic field strength of the cylindrical magnet  22  and the ring magnet  28  relative to one another, as well as the nature of the material to which the cylindrical magnet  22  is attracted. Generally, if the magnetic field of the ring magnet  28  is weaker than that of the cylindrical magnet  22 , the cylindrical magnet will typically be automatically drawn by magnetic attraction to its working position in use. Likewise, if the magnetically attracted material to which the cylindrical magnet  22  is magnetically coupled in its working position is only relatively thin or the cylindrical magnet is only attracted to that material relatively weakly, the movement of the cylindrical magnet to its working position in that instance may not be automatic. Persons in the field to which this invention relates will be able to determine the size and magnetic field strength of the cylindrical magnet  22  and the ring magnet  28  for either automatic or manually driven movement of the cylindrical magnet into its working position to suit the particular application of the securing device  10  in use. 
     Also, whilst the cylindrical magnet  22  is moveable and the ring magnet  28  is held in a stationary position in the above described embodiments, in other embodiments of the invention the cylindrical magnet  22  may be held in a stationary position and the ring magnet  28  is moveable from an initial position to a working position in use. An example of such an embodiment is illustrated in  FIGS. 18 and 19 . 
     As shown in  FIG. 18 , the casing  12  of the device  10  is again elongate in shape. In this embodiment though the ring magnet  28  is secured to the base  144  of the plunger  20  by mechanical fasteners indicated by the numeral  146  and so is moveable between initial and working positions relative to the cylindrical magnet  22  with travel of the plunger within the casing as described further below. The ring magnet is shown in its resting position in  FIG. 18  with a circumferential air space  36  provided between the end of the cavity of the casing and the bottom of the ring magnet. The cylindrical magnet is securely mounted in a fixed position on a raised rest  148  of the casing and is received by the ring magnet  28 . A recess  150  is formed in the base of the plunger  20  for reception of a top portion of the cylindrical magnet  22  when the plunger is moved to its securing position as shown in  FIG. 19 . 
     When not in use, the ring magnet  28  is in its initial position and receives the cylindrical magnet  22 , and the cap  38  is spaced from the top of the casing. The ring magnet and the cylindrical magnet are oppositely poled (e.g., N-S, S-N or S-N, N-S) and in the initial resting position of the ring magnet, the ring magnet and the cylindrical magnet are attracted to one another. 
     In use, the casing of the device is placed on a magnetically attracted material as in embodiments described above such as a sheet or plate  164  of ferromagnetic material (e.g., a mild-steel retaining plate). To secure the device  10  to the sheet, the cap  38  is depressed moving the ring magnet  28  to its working position with the travel of the plunger  20  to its securing position (or the ring magnet is otherwise automatically drawn into its securing position), wherein the ring magnet is magnetically coupled to the plate  164 . In this position, the ring magnet is repelled by the cylindrical magnet (i.e., the magnets are N-N or S-S to each other) but the magnetic coupling of the ring magnet secures the device to the ferromagnetic plate. 
     Yet another embodiment of a securing device  10  in accordance with the invention is illustrated in  FIG. 20A . In this embodiment, the cap  38  is again formed from a magnetically attracted material but in this instance, the circumferential periphery of the cap is tapered to seat on a correspondingly tapered wall  116  defined in the top  14  of the casing  12  of the device as shown in  FIG. 20B . A sealing member in the form of an O-ring  118  is located in position under the cap in a recess  120  adjacent the bottom end of the tapered wall and the receives the plunger shaft  26  to seal the cavity of the casing against entry of dirt and detritus. Locating the O-ring in this position also protects it against mechanical damage. A diagrammatic longitudinal cross-sectional view of the casing  12  of this embodiment is illustrated in  FIG. 20C . In this embodiment the ring magnet  28  is retained in a fixed position. However, it will be understood that as with other embodiments as described herein, forms of the device may be provided in which the cylindrical magnet  22  is movable between initial and working positions whilst the ring magnet is retained in a fixed position within the casing. 
     A cutting edge  120  secured to a support plate  122  by a pair of spaced apart securing devices  10  of the type shown in  FIG. 20A  is illustrated in  FIG. 21A . As best illustrated in  FIG. 21B , each securing device is received in a respective passageway  124  which extends through the support plate from the outer surface of the cutting edge. In practice, the support plate can for instance be the lip of an excavation bucket. Likewise, rather than a cutting edge as shown, one or more securing devices of the type shown in  FIG. 20A  may be used to secure a replaceable excavation tooth to the lip of an excavation bucket or more generally, to an adaptor of an excavation bucket for the tooth. 
     Whilst in embodiments described above the first magnet and the moveable magnet (e.g., the ring magnet  28  and the cylindrical magnet  22 ) are each respectively provided as a single magnet, in other embodiments the first magnet and/or the moveable magnet may be provided in a number of respective magnet sections that may be spaced apart from one another but which are arranged to function together. It is also not essential that the first magnet and the moveable magnet are each circular in transverse cross-section, and magnets having other transverse cross-sectional shapes may be used in embodiments of the invention. Examples of embodiments of such magnet arrangements are illustrated in  FIG. 22A  in which the respective magnets have a triangular transverse cross-sectional profile and  FIG. 23A  in which the magnets each have a square transverse cross-sectional profile. A diagrammatic side view of these magnet arrangements is illustrated in  FIG. 22B  and  FIG. 23B , respectively. 
     In  FIG. 24  the ring magnet is shown provided in four sections  28   a - d  spaced apart from one another around the cylindrical magnet  22 . In  FIG. 25 , the ring magnet is provided in two sections  28   a - b . A diagrammatic side view of the magnet arrangement of  FIG. 24  or  FIG. 25  is illustrated in  FIG. 26 . Further, such magnet arrangements are shown in  FIGS. 27-28 . 
     More particularly,  FIG. 27A  illustrates an arrangement in which spaced apart L-shaped magnets  122  functioning as a ring magnet  28  are positioned about the corners of a square shaped magnet  124  functioning as a cylindrical magnet  22 . A diagrammatic side view of this magnet arrangement is shown in  FIG. 27B . In  FIG. 28A , the magnet arrangement comprises a triangular shaped magnet  126  about which are positioned flat magnets  127   a - c  functioning as a ring magnet and which are respectively disposed adjacent a corresponding face of the triangular magnet  126 . A diagrammatic side view of this magnet arrangement is illustrated in  FIG. 28B . 
     Examples of embodiments in which the cylindrical magnet  22  is provided in a number of sections are illustrated in  FIG. 29A  and  FIG. 30A . As can be seen, in  FIG. 29A  the cylindrical magnet is provided in two sections  22   a - b  whilst in  FIG. 30A  the cylindrical magnet is in four sections. In at least some embodiments, the magnet sections can be secured to the plunger shaft  26  as shown. A diagrammatic side view for the magnet arrangement of  FIG. 29  or  FIG. 30  is illustrated in  FIG. 31 . 
     A yet further embodiment of a securing device  10  as described herein is illustrated in  FIG. 32 . This embodiment has a short casing  12  which includes a removable base in the form of a closure plug  166  that is threadably received by a mating female thread of the casing and so is readily removable from the main body  168  of the casing  12  by unscrewing the base from the main body. In this embodiment, the plug  166  is again formed from the same essentially non-magnetic material from which the main body  168  of the casing  12  is formed. As shown, the floor  167  of the plug again has a reduced thickness (i.e., a thickness of typically from about 0.5 mm to about 1.5 mm) compared to the surrounding side wall of the plug to facilitate the magnetic coupling of the cylindrical magnet  22  for retention of the casing/securing device in its in use position as described above in relation to other embodiments of the invention. In other embodiments, the plug may be formed from a magnetically attracted (e.g., ferric) material. In this instance, a stronger permanent cylindrical magnet  22  may be utilised to account for possible loss of magnetic coupling strength as a result of flux of that magnet being at least partially redirected by the magnetic attracted material from which the plug is formed. As also further illustrated in  FIG. 32 , the embodiment shown does not include a plunger  22  or plunger cap  38 . Rather, the top end of the casing  12  is integrally formed with the surrounding side wall of the casing. 
     As with other embodiments as described above, in the embodiment illustrated in  FIG. 32  the ring magnet  28  again slidably receives the cylindrical magnet  22  and is retained in a fixed position within the casing. In its initial position the cylindrical magnet is located in the upper end of the internal cavity  18  of the casing  12  as illustrated in  FIG. 33 , and there is an air space  36  between the plug and the bottom of the cylindrical magnet. In use, the cylindrical magnet is automatically slidably drawn through the fixed ring magnet  28  into the air space  36  from its initial position to its working position as shown in  FIG. 32  by attraction to the magnetically attracted material to which it magnetically couples which may e.g., be an adaptor  52  or a retaining plate  46  as in embodiments described above, for holding the securing device  10  in its in use position. 
     Another embodiment of a securing device  10  which operates similarly to that shown in  FIGS. 32-33  is illustrated in  FIGS. 34-36 . In this embodiment though the casing  12  is longer than that of the embodiment illustrated in  FIGS. 32-33  and has a removable bottom closure member in the form of plug  166  as well as top closure member in the form of plug  170 , both of which are threadably mated with corresponding female threads provided in the opposite ends of the main body  168  of the casing. Being longer, this embodiment may be used as a securing pin as generally illustrated in e.g.,  FIGS. 16-17 . In the present embodiment, the width of the casing tapers in the top to bottom direction of the casing whereby the bottom of the casing is slightly wider than the top. However, in embodiments of may also be provided in which the width of the casing remains essentially constant along its length. 
     More particularly, as can be seen in  FIG. 34 , this embodiment includes a connecting member in the form of a shaft  172  with cylindrical magnet  22  mounted on one end of the shaft. A further permanent (e.g. rare earth) magnet in the form of cylindrical magnet  174  is mounted on the opposite end of the shaft  172  for facilitating removal of the securing device as further described below. The cylindrical magnet  22  is again received by a permanent ring magnet  28  which is located within recess  176  of the main body  168  of the casing and retained against ledge  177  in a fixed position therein by a spacer in the form of a spacer ring  175  which in turn is seated on the bottom plug  166 , whereby an air space  36  is formed between the floor of the bottom closure plug  166  and the bottom of the cylindrical magnet  22  when the cylindrical magnet  22  is in its initial position as shown in  FIG. 34 . As with the embodiment shown in  FIGS. 32-33 , the cylindrical magnet  22  in this embodiment is automatically slidably drawn through the fixed ring magnet  28  into the air space  36  from its initial position to its working position by attraction to the magnetically attracted material to which it magnetically couples to hold the securing device in its in use position when securing the first and second objects together such as e.g., an excavating tooth and an adapter of an excavation bucket, as described above. As will be understood, the shaft  172  and thereby the further cylindrical magnet  174  is also drawn along the casing with the movement of the cylindrical magnet  22  into its working position within the casing  12  as shown in  FIG. 35 . 
     An exploded view of the casing  12  of the embodiment illustrated in  FIGS. 34-35  is illustrated in  FIG. 36 . 
     A further removal tool  178  for removing embodiments of securing devices  10  of for instance the type shown in  FIGS. 32-36 , is illustrated in  FIGS. 37-39 . The removal tool  178  comprises an essentially non-magnetic housing  80  open at a bottom end thereof. Rather than a single permanent magnet  84  as in the embodiment of the removal tool illustrated in  FIG. 7 , the embodiment shown in  FIG. 36  and  FIG. 37  comprises a permanent cylindrical coupling magnet  18  as well as a further permanent cylindrical magnet  182  received by an oppositely poled permanent ring magnet  184  that is held in a fixed position within the interior of the housing  80  as further discussed below. As with the cylindrical magnet  84  of the removal tool  78  illustrated in  FIG. 7 , the cylindrical magnet  180  is enclosed in a cup  186  formed from a magnetically attracted material (e.g., mild steel) except for the outwardly directed bottom face  188  of the magnet. Again, the circumferential perimeter of the magnet  180  is spaced from the cup as in conventionally known pot magnets, whilst the top face of the magnet  180  is in direct contact with the cup (as is the top face of the magnet  84  of the embodiment illustrated in  FIG. 7 ) as is also known in conventional pot magnets. In the present embodiment, a thin layer of an epoxy is again utilised to fill a spacing of about 1 mm (indicated by the numeral  183 ) from the surrounding cup  186 . 
     As can be further seen, the cylindrical magnets  180  and  182  of the removal tool  178  are secured to either side of the cup  186  by respective mechanical fasteners in the form of internal screws  192  and  194 , and the ring magnet  184  is seated on an internal ledge  196  of the housing  80 . A closure member in the form of plug  198  of the housing  80  retains the ring magnet  184  in position on the ledge  196  and in the embodiment shown, the plug  198  threadably mating with the main body of the housing. 
     Handle members  200   a  and  200   b  extend from the cup  186  and together form a release handle. As best shown in  FIG. 39 , the handle members  200   a  and  200   b  each extend through a corresponding slot  202   a  and  202   b  formed in the surrounding side wall of the main body of the housing  80 . As each slot is orientated in the longitudinal direction of the housing, the cylindrical magnets  180  and  182  are able to move back and forth in the lengthwise direction of housing with travel of the release handle as also described further below. Further handle members  204   a  and  204   b  extend from the plug  198  of the housing and together form a pulling handle. In at least some embodiments, these handle members may be integrally formed with the threaded closure plug  198 . When the cylindrical coupling magnet  180  is in its initial position as shown in  FIG. 37 , an air space  36  is provided in the housing  80  immediately below that magnet. 
     To remove a securing device  10  as for instance exemplified in  FIGS. 32-36  from its in use position using the removal tool  178  such as from the passageway formed by aligned openings of a tooth and adaptor therefor of a mining or excavation bucket as described above, tool  178  is positioned bottom down on the top of casing  12  of the device. 
     The removal of the securing pin  10  comprises travel of the cylindrical magnet  180  of the removal tool  178  along the housing  80  to magnetically couple with the corresponding cylindrical magnet  22  or  174  against the magnetic repulsion provided by the ring magnet  184  to the travel of the further cylindrical magnet  182 . The travel of the cylindrical coupling magnet  180  along the housing from its initial position is limited to the bottom end of the housing by the length of the slots  202   a  and  202   b , and can be driven by the manual application of force to the pin release handle formed by handle members  200   a  and  200   b  or automatically by magnetic attraction of the cylindrical magnet  180  of the removal tool for the corresponding cylindrical magnet  22  or  174  of the securing device  10 . In either case, the resistance to the travel of the cylindrical coupling magnet  180  provided by the ring magnet  184  acts to dampen the movement of the cylindrical magnet into a magnetic coupling relationship with the cylindrical magnet  22  or  174 . Once this magnetic coupling is formed, the removal of the securing device  10  is then achieved by pulling rearwardly on the pulling handle of the removal tool formed by handle members  204   a  and  204   b  to dislodge the securing device from position. As will also be understood, the removal of the securing device  10  from its in use position is further facilitated by the attraction of the cylindrical magnet  22  or  174  of the securing device for the cylindrical magnet  180  of the removal tool. 
     When removed from its in use position the securing device  10  remains magnetically attached to the base of the removal tool  174 . To physically remove the securing device from the removal tool, the release handle formed by handle members  200   a  and  200   b  is squeezed toward the pulling handle causing the cylindrical magnet  180  of the removal to be retracted into the housing  80 . This movement is further facilitated by the magnetic repulsion between the ring magnet  184  and the further cylindrical magnet  182  acting to return that cylindrical magnet to its initial position with respect to the ring magnet  184 . This ring magnet and cylindrical magnet arrangement thus functions in a corresponding manner to the ring magnet  28  and cylindrical magnet  22  arrangements of securing devices  10  as described herein. As described above, the casing  12  and plunger  20  of embodiments of a securing device  10  as described above are fabricated from a material that is essentially non-magnetic. Any suitable such material having the requisite strength, rigidity and robustness for the intended use of the device can be utilised. Most desirably, the casing and plunger are fabricated from an austenitic metal e.g., an austenitic steel or stainless steel. Similarly, the casing  80  of a removal tool e.g.,  178  embodied by the invention may be formed from any suitable essentially non-magnetic or austenitic metal as described above. As will also be understood, a non-magnetic or essentially non-magnetic material is one which has no or magnetic properties or is an essentially non-magnetically attracted material for the intended purpose and use of the material. 
     Preferred austenitic steels are those including some or all of the additives selected from the group consisting of manganese (Mn), molybdenum (Mo), chromium (Cr), nickel (Ni), carbon (C) and nitrogen (N). In particularly preferred austenitic steels, the magnetic relative permeability of the steel is less than about 1.001. Most desirably, the nickel content of the steel is less than about 2% w/w. Suitable austenitic steel castings are, for example, available from Keech Castings Australia Pty Ltd, Bendigo, Victoria, Australia. In other embodiments where the strength and robustness of the casing need not be as great, a non-magnetic material such as a suitable plastics material or an aluminium or aluminium alloy may be used. 
     In some embodiments of the invention employing a retaining plate  46  or  164  as described above, the retaining plate may also be fabricated from a suitable austenitic or essentially non-magnetically attracted material although in such embodiments, the retaining plate can incorporate a further magnet as described above to which the cylindrical magnet or the ring magnet magnetically couples in use of the securing device. 
     Any suitable permanent magnets may be utilised for the purposes of the moveable and other magnet(s) of a securing device embodied by the invention, including rare-earth magnets and rare-earth-free magnets. Rare earth magnets can be selected from samarium-cobalt magnets and neodymium (e.g., neodymium, iron and boron) magnets. 
     As will also be understood, securing devices as described herein find broad application and can be used for instance to secure digger, ripper and excavation teeth, cutting edges, wear plates and the like to excavation buckets, drag-line buckets, and rotating excavator buckets of diggers, excavators, mining and ground engaging machinery. However, applications of securing devices and methods as described herein are not limited thereto, and the present disclosure extends to the use of securing devices as describe herein in articulation hinges and hitches to earth moving and mining machinery, booms gates and boom points, sprockets and idlers, and rack and pinion systems, amongst a broad range of other uses. 
     From the above it will be apparent that embodiments of the invention may variously provide one or more of the following advantages.
         A relatively quick an easy way of securing components together as described herein;   Securing together of the components without the need for tightening of a mechanical fastener (e.g., a bolt or screw) and thereby, avoiding risk of damage to the fastener and/or the fastener rusting or otherwise becoming stuck or cemented in position;   Ready removal of the securing device allowing for ease of separation of the secured components from one other;   Protection against external dust and debris accumulating about the securing device  10  by virtue of the cap moving to a closed position in use, blocking the entry of dust and debris into the assembly of the components secured by the device;   Minimisation of wear and thereby maintenance of the device by virtue of the use of a fixed and a moveable permanent magnet as described above;   Damping of the movement of the plunger  20  of a device  10  as the plunger is moved to its securing position by virtue of the magnetic polarities of the fixed and movable magnets, allowing for the use of damping means such as compression and/or tension springs which are prone to wear and loss of elasticity;   Use of the securing device  10  in a range of different applications; and   Reusability of the device.       

     As will also be understood, feature(s) and/or integer(s) of an embodiment as described above may be implemented in conjunction with feature(s) and/or integer(s) of other embodiments, e.g., aspects of one embodiment may be combined with aspects of another embodiment to realize yet further embodiments within the scope of the present disclosure, and all such arrangements and embodiments are expressly provided for herein. 
     Although a number of embodiments of the invention have been described above it will be understood that various modifications and changes may be made thereto without departing from the invention. The above described embodiments are therefore only illustrative and are not to be taken as being restrictive.