the present invention is an assembly and method for locking and unlocking a ground engaging tool to a support structure . the assembly allows a person to easily lock and remove the tool with little chance of injury as compared with prior art methods and assemblies . a preferred embodiment of the assembly suitable for attaching digging teeth to adapters comprises a pin and pin retainer / carrier , and preferably uses magnets to help hold the pin in the retainer during use . in preferred embodiments of the present invention , the first workpiece comprises a ground engaging tool such as an excavating tooth or lip shroud and the second workpiece comprises a support structure such as an adapter or bucket lip respectively . the first workpiece is slidably mounted onto the second workpiece . while the present invention is described in this art area , it can be seen that the invention is capable of broader application and such applications are applicable herein . in the present assembly , the purpose of the pin is to resist digging forces that could remove the first workpiece from the second workpiece . it does this by conveying these forces from the first workpiece into the second workpiece either directly or via the pin carrier . the pin can be any desired or suitable shape . pins in the form of a “ t ”, or inverted “ l ” or headless ( sometimes called “ i ” pins ) are suitable . the pin may additionally comprise removal means , typically a lip or rib for engaging a prying device . the pin retainer cooperates with the first workpiece to retain the pin in the locked position . the pin carrier further cooperates with the pin and the second workpiece to convey workpiece - removing forces from the pin to the second workpiece . the first workpiece may comprise a first arm or surface and a second arm or surface adapted to slidably envelop and engage at least part of the second workpiece . in this situation , the pin - receiving means may comprise a second opening running through the second workpiece or , more preferably , may extend further to also comprise a recess or a third opening in the second arm or surface alignable with the opening in the first arm or surface and the second opening in the second workpiece . with reference to the figures , a ground engaging tool such as an excavating tooth or lip shroud generally has a triangular shaped cross - section and is formed so as to be received over the working end of a support structure such as an adapter or bucket lip . for example , the bucket lip shown in the side view in fig2 and 7 illustrates a preferred embodiment of the present invention in the case where the ground engaging tool is a lip shroud and the support structure is a bucket lip . the tool has a thick section near its tip which comes to a general point p for engaging the ground when placed on the working end of the support structure q . extending back from the point p on the ground engaging tool are two arms . the first arm 3 extends along the upper portion of the tool . the second arm 5 extends along the lower portion of the tool and is shorter and thinner in cross - section than the first arm . between these arms , there is defined an area for receiving the working end of the support structure q . when the ground engaging tool is placed on the support structure , the inner surface 21 of the tool engages the outer surface 19 of the support structure . the point p of the tool has hard facing 9 on its surface , as shown in fig1 to extend its life and reduce its rate of wear . the inner surface 21 of the tool may be equipped with fit pads 17 as shown in fig5 and 6 . the working end of the support structure may also have fit pads 17 on its outer surface 19 ( shown in fig1 and 20 ) positioned under the first arm 3 of the tool for receiving the pin carrier which will be described in more detail below . the fit pads 17 are raised ridges on the tool and its support structure . the pin carrier is positioned between the fit pads when the present invention is assembled . the outer surface of the lip shroud support structure is fitted with a boss 34 ( shown in fig7 and 20 ) or may already have a boss extending therefrom . the boss 34 is preferably dovetailed in shape however other embodiments may be used . particularly where a dovetail configuration is not used , a dovetail boss adapter may be used to ensure a tight fit with the ground engaging tool . the first arm 3 of the ground engaging tool shown in fig1 and 2 has an outer surface 11 , inner surface 21 and an end surface 23 . the tool has a standard lifting lug 15 on its outer surface 11 . the upper surface 11 of the tool 13 has an elongated opening 37 perpendicular to its longitudinal axis and corresponding to the shape of the pin 43 . this opening is adapted to receive the pin 43 when the present invention is fully assembled as will be described in more detail below . this pin opening 37 is shown in more detail in fig6 and 19 . it has end walls 39 that slope inwardly and may end with a ledge 41 extending inwardly into the pin opening 37 at the lower end of the opening . the end surface 23 of the tool 13 has an opening 25 extending into a pin carrier slot 27 . the slot 27 extends through the lower portion of the tool arm 3 along the longitudinal axis of the ground engaging tool . the pin carrier slot 27 is a recess cut into the lower surface of the tool 13 and comprises an inner end wall 29 , upper wall 31 , and side walls 32 , 33 . the sidewalls 32 , 33 of the slot 27 are shown in more detail in fig5 , 19 and 20 . they are preferably angled inwardly in a dovetail shape to engage the dovetail boss . fig5 and 6 show an angle of approximately 20 degrees , however , any angle and shape may be used which allows the slot to engage the boss . the tool is slid over the support structure so that the slot 27 of the tool slideably engages the boss 34 . when the tool is slid over the support structure , the boss engages the inner end wall 29 of the tool 13 . while the boss 34 is preferably a dovetail shaped boss , other configurations may be used . dovetail adapters may be fitted around the boss in order to achieve a dovetail configuration or other configurations known in the art may be used with which the ground - engaging tool may engage the boss . one example is shown in fig1 - 18 . these figures depict a dovetail adapter 45 that has an inner ridge 47 for engaging a non - dovetail boss . the outer walls 49 of the dovetail adapter 45 are shaped so as to correspond to the inner sidewalls 32 , 33 of the pin carrier slot 27 for engagement and retention with the slot . the assembly of the present invention includes a pin carrier 35 shown in more detail in fig8 - 11 , 24 , 25 , 28 and 29 . the pin carrier 35 is elongated having an end wall 51 extending upwardly and a generally flat elongated lower section 53 extending from the lower end of the end wall 51 . the outer portion of the lower section 53 may extend at a downward angle providing a tapered end 59 to the pin carrier 35 . the upper surface of the lower section 53 contains receptacles 55 for magnets 57 . these receptacles are shown as three round areas in fig8 and 10 ; however , other arrangements of magnets may be used . an example is shown in fig2 and 29 . the pin carrier 35 may be slideably inserted into the pin carrier slot 27 through the opening 25 in the end surface 23 of the tool 13 . it is fully inserted when the pin carrier is in alignment with the pin opening 37 in the tool . the boss 34 extends from the rear wall of the tool to the pin opening . the rear surface of the boss is positioned forward of the pin opening towards the point of the tool so that the pin carrier may be inserted into the slot and positioned under the pin opening and against the boss . the pin opening 37 in the upper surface of the tool 13 and the inserted pin carrier define a pin - receiving chamber . the pin 43 is shown in fig1 - 14 , 22 , 23 , 26 and 27 . it is an elongated piece having one end with a lip portion 61 and the opposing end with openings 63 , 65 therein . the pin 43 may be inserted through the pin opening 37 in the tool 13 into the pin - receiving chamber . a portion of the pin 43 remains in the pin opening 37 in the tool 13 and may extend therefrom . the lip 61 at one end of the pin 43 engages the lower surface of the tool 13 as shown in fig1 . the lip 61 helps to maintain the pin 43 in the pin opening 37 . the pin 43 is made of a material that will be drawn to the magnets and preferably is steel . the magnets 57 are arranged and aligned so as to attract the pin 43 to the pin carrier 35 , thereby retaining it in the pin - receiving chamber . the magnetic attraction of the pin 43 to the pin carrier 35 is sufficient to maintain the pin 43 in the pin opening 37 in the tool 13 and thereby maintain the ground engaging tool on the working end of its support structure during use . to remove the pin 43 from the pin carrier 35 , a pry bar or other similar tool may be used . one end of the pry bar is inserted into the upper opening 63 in the end of the pin 43 by insertion down the angled wall of the pin opening 37 in the tool as is shown in fig1 . the protrusion at the lower end of the opening and the angled wall provide leverage and support for the pry bar . the pry bar is forced into the opening 63 and is used to leverage the pin 43 out of the pin carrier 35 . if necessary , the pin may be partially removed and the pry bar inserted into the second lower opening 65 in the pin to further leverage it out of the pin opening in the tool . as the pin is lifted and moved away from the pin carrier and the magnets , the magnetic force on the pin will decrease thereby releasing the pin . once the pin is removed , the pin carrier and the ground engaging tool may be removed from the end of the support structure and the tool replaced . an alternative embodiment of the pin is shown in fig2 and 27 . these figures shown a pin cylinder 67 near one end of the pin . it may be manually rotated 90 degrees about its center axis . it contains a plurality of magnets 69 on its lower surface . the pin carrier contains a matching plurality of magnets on its upper surface . the poles of these magnets are arranged so that with the cylinder 67 rotated to the lock position , the pole alignments for the pin and carrier magnets are such that the pin and carrier are strongly attracted together thereby holding the pin firmly in place . when the cylinder is rotated 90 degrees to the unlocked position , the alignment of poles between the pin and carrier magnets reverses and the magnetic forces become repulsive . the pin is thus easily removed from the opening by hand . a further embodiment of the pin is shown in fig3 and a corresponding pin retainer is shown in fig3 . this type of pin is designed to be inserted through a transverse pin opening 37 in upper arm 3 . the shape of pin 43 matches the shape of transverse pin opening 37 . the pin carries pry grooves 63 , 65 at opposed side ends of the pin and comprises magnets 57 inserted in a machined under - surface of the pin . the pin also carries a leg 74 large enough to fit through a corresponding orifice through bucket lip q and through lower arm 5 so that the bottom 76 of leg 74 is flush with a bottom surface of lower arm 5 . the orifice through bucket lip q is optionally tapered at the bottom to provide a debris reservoir . this option is shown in broken lines as 75 . when pin 43 is in place , length 71 sits in upper arm 3 , length 72 sits in bucket lip q and length 73 sits in lower arm 5 . in alternative embodiments leg 74 may only extend ( a ) part of the way into lower arm 5 , ( b ) only through bucket lip q but not through lower arm 5 , or ( c ) only part way through bucket lip q . in further alternative embodiments the pin and / or leg may be wholly or partly cylindrical . [ 0061 ] fig3 illustrates a pin retainer 80 for use with the pin 43 of fig3 . the pin retainer may fit a matching recess in the upper surface of bucket lip q and is held in position by inner surface 21 of upper arm 3 . magnets 57 grip the flat upper surface 81 of the pin retainer . leg 74 passes through orifice 82 of the pin retainer . typically the pin retainer is cut from flat steel plate and the matching recess in the upper surface of bucket lip q is formed during casting . in alternative embodiments the matching recess is located in the inner surface 21 of upper arm 3 and the pin retainer is held in position within the recess by magnetic or resilient means along one or more sides or is simply supported from below by the upper surface of bucket lip q . to install the pin of fig3 the operator first places the pin retainer 80 into the matching bucket lip recess , the lip shroud is then slid over the bucket lip and transverse pin opening 37 aligned with the corresponding orifice through bucket lip q before the pin is dropped in so that the magnets 57 engage the upper surface of the pin retainer . to remove the pin of fig3 , the pin 43 is pried loose with a pry bar placed in at least one of openings 63 and 65 . the end of the pin above 63 or 65 may be recessed slightly or alternatively the transverse pin opening 37 may be correspondingly recessed slightly to allow access for the pry bar to openings 63 and 65 . the pin of fig3 permits a simpler design of lip shroud and bucket lip in that leg 74 functionally effectively replaces boss 34 and pin carrier slot 27 . the pin and related pin retainer design of fig3 and 31 is therefore also suitable for locking excavating teeth to adapters that are not equipped with bosses and boss - receiving slots . alternative embodiments to the “ t ” pin design illustrated in fig3 include an inverted “ l ” design ( one top arm of the “ t ” has been deleted ), or an “ i ” design comprising effectively only leg 74 with a magnet or magnets on a side face of the leg or inset into a matching part of upper arm 3 , bucket lip q or lower arm 5 . it can be seen that the utility of this type of reversible coupling extends beyond ground engaging tools and their support structures and is of utility anywhere that firm , dependable but readily reversible coupling is required . since the pin may be easily removed by a worker with a pry bar , it poses little danger to workers . there is less chance of injury to workers in removing and replacing ground - engaging tools . as well , standard assemblies to attach teeth to adapters often fail during use . with the present invention , the magnetic attraction of the pin to the pin carrier is unlikely to fail causing injury to nearby workers . the above - described embodiments of the present invention are meant to be illustrative of preferred embodiments and are not intended to limit the scope of the present invention . variations of the invention will be readily apparent to persons skilled in the art and may be made without departing from the spirit or scope of the invention . these variations are intended to be within the scope of the present invention . the only limitations to the scope of the present invention are set out in the following appended claims .