the present invention is susceptible of embodiment in many different forms . while the drawings illustrate , and the specification describes , certain preferred embodiments of the invention , it is to be understood that such disclosure is by way of example only . there is no intent to limit the principles of the present invention to the particular disclosed embodiments . with initial reference to fig1 , a towable agricultural implement 10 selected for purposes of illustration includes a floating hitch section 12 and a framework 14 . the floating hitch section 12 includes a hitch connector 16 at a terminal end thereof . it will be appreciated by one of ordinary skill in the art that the hitch connector 16 is configured for coupling the implement 10 to a corresponding towing hitch on a driving power source ( not shown ) for pulling the implement 10 across a field . it is also noted that such a driving power source could take the form of a tractor , or any other suitable power source known in the art , without departing from the teachings of the present invention . the framework 14 is supported above the ground 18 by wheels 20 , rotatably connected to the framework 14 by bolts 22 , in a manner known in the art and not shown in detail here . with reference to fig3 , the implement 10 is pulled through a field in the direction indicated by the large arrow . thus , the wheels 20 support the rear portion of the framework 14 . the front portion of the framework 14 is supported by the connection of the floating hitch section 12 to a driving power source and an additional section 15 of the framework 14 is supported in the front by a supplemental swiveling support wheel 24 . as shown in fig1 , the swiveling support wheel 24 is journaled to a wheel arm 44 for rotation therebetween . the wheel arm 44 is pivotally coupled to a forward extension 46 in a manner known in the art and not shown in detail here . the forward extension 46 brackets to the toolbar 28 to space the swiveling support wheel 24 ahead of the toolbar 28 as the implement 10 moves across a field . it is noted that the swiveling support wheel 24 is disposed on the section 15 of the framework 14 that is not otherwise supported in the front by the connection of the floating hitch section 12 to a driving power source . additionally , this section 15 of the framework 14 may pivot upwards relative to the central section of the framework 15 to facilitate transport of the implement 10 across the ground other than in a field , as will be readily appreciated by one of ordinary skill in the art . it is noted , however , that such arrangement of the framework 14 is not critical to the principals of the present invention . returning now to fig1 , the framework 14 also includes a vertically extending support member 26 , extending downwardly from the framework 14 . the support member 26 connects the framework 14 to a toolbar 28 , through a spacing element 30 , in a manner known in the art . as shown particularly in fig3 , the toolbar 28 extends transverse to the direction of travel of the implement 10 . a plurality of soil opener assemblies 32 are coupled to the toolbar 28 , as described in more detail below . it is noted that fig3 depicts a plurality of soil opener assemblies 32 linearly coupled to the toolbar 28 in a single gang . however , it will be appreciated that the layout of the plurality of soil opener assemblies 32 could take other forms , such as a two gang configuration , or be variously configured in any manner known in the art , including any alternative suitable number or spacing of soil opener assemblies 32 . it is further noted that each soil opener assembly 32 is virtually identically configured to each other soil opener assembly 32 . thus , in each of the drawing figures other than fig3 , only a single soil opener assembly 32 is depicted , with the understanding that other soil opener assemblies 32 are similarly constructed . with continued reference to fig1 , the exemplary soil opener assembly 32 depicted broadly includes a drawbar assembly 36 , a sectored disc assembly 38 , an injector boot assembly 40 , and a closing wheel 42 . the drawbar assembly 36 is bracketed to the toolbar 28 to thereby pull the other components of the soil opener assembly 32 behind the toolbar 28 while yieldably biasing the components downwardly into engagement with the ground 18 as the implement 10 moves through a field . with particular reference to fig2 and 5 , a swiveling assembly 48 is attached to the toolbar 28 with a plurality of bolts 50 . the swiveling assembly includes an inner member 52 and a coaxial outer member 54 that are configured for relative rotation therebetween . a mounting bracket 56 extends outwardly from the outer member 54 . the bolts 50 pass through a plate 58 , around the toolbar 28 , and are secured to the mounting bracket 56 to thereby clamp the swiveling assembly 48 to the toolbar 28 . a drawbar bracket 60 connects the drawbar assembly 36 to the inner member 52 so that the drawbar assembly 36 can swivel relative to the toolbar 28 . a locking pin 62 selectively locks the inner member 52 and the outer member 54 together to prevent relative rotation therebetween , thereby permitting an operator to “ lock out ” the swiveling movement of the drawbar assembly 36 . such locking out of the swiveling assembly 48 is often used , for example , to prevent drift of the soil opener assemblies 32 as the implement 10 is towed along steep inclines , as will be readily appreciated by one of ordinary skill in the art upon review of this disclosure . turning now to fig4 and 5 , the drawbar assembly 36 includes a disc opener arm 64 pivotally coupled to the drawbar bracket 60 with a pin 66 . the pivotal movement of the drawbar assembly 36 allows the components thereof to be vertically adjusted relative to the ground 18 . the vertical position of the drawbar assembly 36 is controlled by an adjustable - length strut 68 . the strut 68 includes an outer cylinder 70 and a telescopingly interfitted inner rod 72 , wherein the inner rod 72 is coaxial with and configured for relative sliding within the outer cylinder 70 . a strut pin 74 passes through the outer cylinder 70 and into at least a portion of the inner rod 72 in a manner known in the art to lock the strut 68 at a particular length . a strut support 76 is fixed to and extends vertically upwardly from the drawbar bracket 60 . the ends of the adjustable - length strut 68 extends between a fixed position on the strut support 76 and a fixed position on the disc opener arm 64 . in the illustrated embodiment , an end of the outer cylinder 70 is coupled to the top of the strut support 76 with a bolt - and - nut assembly 78 in a manner known in the art . similarly , an end of the inner rod 72 is coupled to the disc opener arm 64 with a bolt - and - nut assembly 80 in a manner known in the art . it is noted that the depicted orientation of the strut 68 could be reversed , or an alternative device for adjusting the vertical height of the drawbar assembly 36 relative to the ground 18 could be used , without departing from the teachings of the present invention . the sectored disc assembly 38 is rotatably coupled with and vertically fixed to the disc opener arm 64 , as is discussed in greater detail below , for relative rotation therewith . thus , it is noted that as the drawbar assembly 36 , including the disc opener arm 64 , is vertically adjusted relative to the ground 18 as described above , the sectored disc assembly 38 is correspondingly vertically adjusted relative to the ground 18 . it is further noted that the principles of the present invention are not limited to the production of any particular crop and can readily be adapted to virtually all crops generated by placement of seed and / or fertilizer in the ground , as will be understood by one of ordinary skill in the art . a closing wheel arm 82 is adjustably mounted to the disc opener arm 64 , wherein the closing wheel arm 82 rotatably supports the closing wheel 42 at the end thereof . the closing wheel arm 82 is fixed to a closing wheel arm mounting bracket 84 that attaches to the disc opener arm 64 with a pair of bolt - and - nut assemblies 86 . the bolt - and - nut assemblies 86 attach the mounting bracket 84 to the disc opener arm 64 by extending through a selected pair of a plurality of holes 88 in the disc opener arm 64 . extending the bolt - and - nut assemblies 86 through distinct pairs of holes 88 allows the closing wheel arm 82 to be adjustably mounted to the disc opener arm 64 . by extension , this relative adjustability affects the relative position of the components mounted to the end of each of these arms , namely the sectored disc assembly 38 and the closing wheel 42 , respectively . as shown in the difference between fig4 and 5 , it is noted that the closing wheel 42 , and its associated closing wheel arm 82 , are depicted in fig4 by way of example only and that the principals of the present invention do not depend on the selective inclusion of these elements , as will be readily appreciated by one of ordinary skill in the art upon review of this disclosure . with continued reference to fig5 , an injector boot support element 90 is fixed to the end of the disc opener arm 64 with a pair of bolt - and - nut assemblies 92 . the bolt - and - nut assemblies 92 attach the boot support element 90 to the disc opener arm 64 by extending through a selected pair of a plurality of holes 94 in the disc opener arm 64 . extending the bolt - and - nut assemblies 92 through distinct pairs of holes 94 allows the boot support element 90 to be adjustably mounted to the disc opener arm 64 . the injector boot assembly 40 is fixed to the distal end of the boot support element 90 relative to the disc opener arm 64 by a bolt - and - nut assembly 96 . thus , adjustment of the boot support element 90 relative to the disc opener arm 64 as described above changes the disposition of the injector boot assembly 40 relative to the sectored disc assembly 38 . the injector boot assembly 40 broadly includes a pair of conduits 98 and 100 for carrying and controllably inserting seed , fertilizer , or both , into the ground in a manner generally known in the art and not described in detail here . additionally , as shown in fig6 , a threaded extension 102 controls the lateral disposition of a distribution end 104 of the injector boot assembly 40 relative to the sectored disc assembly 38 . the threaded extension 102 is coupled to the boot support element 90 and secured thereto with a nut 106 . in the depicted embodiment , the distribution end 104 of the injector boot assembly 40 is adjacent an end of the sectored disc assembly 38 , although this placement could be changed without departing from the teachings of the present invention . as discussed briefly above , the sectored disc assembly 38 is rotatably coupled to the disc opener arm 64 for relative rotation therewith . the sectored disc assembly 38 broadly includes a rotatable hub 108 and a plurality of disc sectors 110 disposed around the hub 108 to cooperatively form a substantially continuous disc 111 . in the illustrated embodiment , the hub 108 has considerable mass , weighing slightly more than one hundred pounds , substantially contributing to the total weight of each soil opener assembly 32 of approximately five hundred pounds . the disc sectors 110 cooperate with the hub 108 to present a tongue - and - groove connection therebetween along the interface between the disc sectors 110 and the hub 108 . as will be readily appreciated by one of ordinary skill in the art , as the agricultural implement 10 moves across a field , the soil opener assemblies 32 are often disposed at a slight angular offset relative to the direction of travel of the implement 10 . it is particularly noted that while fig3 depicts the soil opener assemblies 32 generally aligned with the direction of travel , the soil opener assemblies 32 may move about the swiveling assembly 48 during operation and often do not precisely follow the direction of travel . it is additionally noted that sometimes the soil opener assemblies 32 are intentionally offset from the direction of travel to facilitate the opening of the soil . this angular offset can lead to the introduction of considerable lateral forces to the components of the soil opener assemblies 32 , including the substantially continuous disc 111 . the tongue - and - groove connection between the disc sectors 110 and the hub 108 of the unique sectored disc assembly 38 described herein directs these lateral forces inward to the central hub 108 such that axial movement of the disc sectors 110 is restricted . as shown particularly in fig6 , a spindle 112 is fixed to the disc opener arm 64 with a pair of bolts 114 , wherein the spindle 112 extends generally transverse to the direction of travel of the implement 10 across a field . the hub 108 includes a generally central hole 116 therethrough about which the hub 108 is disposed about the spindle 112 for relative rotation therewith in a manner generally known in the art . a cap 118 is attached to the hub 108 with a plurality of screws 120 to cover the hole 116 when the hub 108 is disposed on the spindle 112 . the cap 118 prevents dirt or other debris from entering the hole 116 in the hub 108 , as will be appreciated by one of ordinary skill in the art . with continued reference to fig6 and turning also to fig7 and 8 , the component parts of the sectored disc assembly 38 will be discussed in greater detail . the hub 108 is generally circular and presents a continuous outer periphery 122 , although it is noted that it is within the ambit of the present invention to incorporate alternative hubs of other general shapes ( e . g ., polygonal ), so long as such a hub is rotatable about the spindle 112 or the like . the hub 108 also includes a radially inwardly extending circumferential groove 124 that extends continuously about the outer periphery of the hub 108 . in the illustrated embodiment , the hub 108 includes an additional groove 126 , substantially identical to the groove 124 , but disposed axially away from the groove 124 . the second groove 126 can provide an alternative location for the disposition of the plurality of disc sectors 110 . the second groove 126 can also provide a location for the disposition of a depth band for controlling the depth to which the soil is opened , as will be appreciated by one of ordinary skill in the art . although it is not necessary to provide multiple grooves in the hub 108 , it is further noted that more than the two depicted grooves could be provided in the hub 108 , so long as there is at least one groove to cooperate with the plurality of disc sectors 110 to form the substantially continuous disc 111 of the sectored disc assembly 38 . it is further noted that an alternative hub ( not shown ) could present a noncontinuous groove without departing from the teachings of the present invention , as will be readily appreciated by one of ordinary skill in the art upon review of this disclosure . the plurality of disc sectors 110 , depicted individually in detail in fig7 , each includes a radially inner margin 128 and a radially outer margin 130 . each disc sector 110 further includes radially extending side surfaces 132 and 134 that extend generally flatly between the inner margin 128 and the outer margin 130 . the disc sectors 110 are each partially received within the groove 124 to restrict axial movement of each disc sector 110 relative to the hub 108 . the disc sectors 110 and the hub 108 interfit in a tongue - and - groove connection along the outer periphery 122 of the hub 108 to form the substantially continuous disc 111 about the hub 108 , as will be described in more detail below . the radially outer margins 130 of the plurality of disc sectors 110 are generally arcuate and cooperate to form a substantially continuous disc edge 136 . the disc edge 136 is generally circular and serves as the end of a blade to open the soil as the implement 10 moves across a field , as will be readily appreciated by one of ordinary skill in the art . it is noted that it is clearly within the ambit of the present invention to provide alternative disc sectors that cooperate to form a disc edge that is noncontinuous and presents , for example , an edge that is fluted , serrated , or spoked . the axial width of the disc sectors 110 taper inwardly from the radially inner margins 128 to the radial outer margins 130 such that the tongue - and - groove connection is sufficiently strong to take the lateral forces and the disc edge 136 is sufficiently narrow to penetrate into the soil to form the furrow . in the illustrated embodiment , the radially inner margins 128 of the disc sectors 110 are also generally arcuate and correspond with the shape of the groove 124 in the hub 108 to interfit therein . it is noted , however , that with an alternately shaped hub , such as described above , it is clearly within the ambit of the present invention for the corresponding radially inner margins of cooperating alternative disc sectors to have a shape that is nonarcuate to flushly engage a corresponding surface on the outer periphery of such an alternative hub . with continued reference to the embodiment depicted in fig7 and 8 , it is noted that the illustrated groove 124 of the hub 108 presents a generally u - shaped channel with opposed faces 138 and 140 . similarly , the groove 126 of the hub 108 presents a generally u - shaped channel with opposed faces 142 and 144 . also in the illustrated embodiment , the each disc sector 110 includes a tongue section 146 that presents opposed engagement surfaces 148 and 150 . in the tongue - and - groove connection between the disc sectors 110 and the hub 108 , the opposed faces 138 and 140 of the groove flushly contact the engagement surfaces 148 and 150 of the tongue section 146 . it is clearly within the ambit of the present invention to provide an alternative groove that is not u - shaped , so long as the tongue and groove sections correspond for a snug connection therebetween . it is additionally specifically noted that in an alternative embodiment ( not shown ) that the components of the tongue - and - groove connection could be switched , such that a central hub presents a tongue section and a plurality of disc sectors present a corresponding groove . in such an alternative embodiment , similar flush contact would result between opposed faces and engagement surfaces such that a substantially continuous disc would be formed about the hub , wherein axial movement of the disc sectors relative to the hub was restricted . regarding additional specifics of the depicted central hub 108 , it is noted that the hub 108 includes a pair of axially opposed , generally planar side portions 152 and 154 . the grooves 124 and 126 in the central hub 108 define radially extending flange sections 156 , 158 , and 160 along the outer periphery 122 of the hub 108 , wherein the grooves 124 and 126 extend between the flange sections 156 , 158 , and 160 . the flange section 156 extends axially between the hub side portion 152 and the opposed face 138 of the groove 124 . similarly , the flange section 158 extends axially between the opposed face 140 of the groove 124 and the opposed face 142 of the second groove 126 . also , the flange section 160 extends axially between the opposed face 144 of the second groove 126 and the hub side portion 154 . regarding additional specifics of the depicted individual disc sectors 110 , it is noted that each disc sector includes a pair of axially extending flared shoulder sections 162 that each extend axially outward beyond the dimension of the tongue section 146 . each of the shoulder sections 162 present a radially inner shoulder surface 164 . in the sectored disc assembly 38 , the shoulder surfaces 164 flushly contact the outer periphery 122 of the hub 110 . as described briefly above , the radially extending side surfaces 132 and 134 of each disc sector 110 extend generally flatly between the inner margin 128 and the outer margin 130 . a surface 132 of an individual disc sector 110 bears against the corresponding surface 134 of an adjacent disc sector 110 to restrict circumferential movement of any individual disc sector 110 of the substantially continuous disc 111 . in addition , as shown in fig8 , the generally flat shape of the side surfaces 132 and 134 allow a single disc sector 110 to be removed from or inserted into the hub 108 without disturbance to the other disc sectors 110 . with continued reference to the embodiment depicted in fig7 and 8 , a plurality of bolt connectors 166 are included to secure each of the disc sectors 110 to the central hub 108 . the hub 108 includes a plurality of holes 168 that extend axially therethrough , spanning all of the flange sections 156 , 158 , and 160 . each of the disc sectors 110 similarly includes a hole 170 that is axially aligned with the corresponding hole 168 in the hub 108 when the disc sector 110 is disposed therein . a bolt 166 extends through a washer 172 , through one of the holes 168 in the flange section 156 , through one of the holes 170 in the disc section 110 , and through the remainder of the hole 168 in the hub 108 . each of the disc sectors 110 are secured to the hub 108 in like manner , as will be readily appreciated by one of ordinary skill in the art . the front side 152 of the hub 108 also includes a recess 174 around each of the holes 168 . the recess 174 is axially larger than the diameter of the hole 168 and extends radially inwardly through the flange 156 toward the groove 124 . each of these recesses 174 allow the head of the bolt 166 to countersink below the surface of the front side 152 of the hub 108 as shown in fig8 . the countersinking of the bolts 166 into the hub 108 provides the sectored disc assembly 38 with a clean design without exposed hub nuts or bolts to disturb material as the blade cuts into the soil . finally , it is noted that in the illustrated embodiment , the sectored disc assembly 38 includes four substantially identical disc sectors 110 that each define a quadrant of the substantially continuous disc 111 . it is clearly within the ambit of the present invention to provide alternative disc sectors that are not substantially identical or require more or fewer than the depicted four sectors to make up a substantially continuous disc . such variations will be readily appreciated by one of ordinary skill in the art upon review of this disclosure . the disc sectors 110 are preferably , although not necessarily , formed by casting the sectors from a metal alloy . examples of preferred alloys for the material of the disc sectors 110 include steel 8630 , astm 897 heat treated , and yc chrome , as will be understood by one or ordinary skill in the art . the efficient and simple ability to change out individual disc sectors 110 allows an operator to replace damaged or worn disc sectors 110 without the cost of replacing an entire unitary disc . in addition , an operator can easily change the material of the disc sectors 110 , and thus the entire disc 111 , as desired to match the material of the disc to the particular characteristics of the soil to be worked by the implement 10 . the method of replacing a given disc sector 110 of the sectored disc assembly 38 should be apparent from the foregoing and , therefore , will be described here only briefly . with particular reference to fig7 and 8 , the connecting bolt 166 is accessed through the recess 174 and removed from the sectored disc assembly 38 in the axial direction . after the removal of this single connecting bolt 166 , the disc sector 110 to be removed is simply moved radially outwardly and away from the hub 108 . as the disc sector 110 is moved away from the hub 108 , the opposed faces 138 and 140 of the groove 124 and the corresponding engagement surfaces 148 and 150 of the tongue section 146 slide radially past each other so that the disc sector 110 moves smoothly out of the hub 108 . in substantially the reverse of the above - described removal procedure , a replacement disc sector 110 is placed into contact with the hub 108 so that the replacement disc sector 110 and the hub 108 cooperatively form a tongue - and - groove connection extending along the periphery of the hub 108 . in making such tongue - and - groove connection , the engagement surfaces 148 and 150 of the tongue section 146 of the replacement disc sector 110 contact and slide into a snug connection with the corresponding opposed faces 138 and 140 of the groove 124 . as the replacement disc sector 110 is inserted into the groove 124 of the hub 108 , the generally flat radially extending side surfaces 132 and 134 of the replacement disc sector 110 slidingly engage the corresponding side surfaces 132 and 134 of the adjacent disc sectors 110 already secured to the hub 108 . as is shown particularly in fig8 , this sliding engagement of the side surfaces 132 and 134 allows removal and insertion of a single disc sector 110 relative to the hub 108 without removing other disc sectors 110 . finally , the connecting bolt 166 is inserted into the hole 168 in the hub 108 and extended axially through the hole 170 in the replacement disc sector 110 to secure the disc sector 110 to the hub 108 . as will be readily appreciated by one of ordinary skill in the art , the ability to replace a disc sector 110 with manipulation of only a single connecting bolt 166 and without disturbance of the other disc sectors 110 in the sectored disc assembly 38 allows for replacement in an efficient and simple manner as described above . the preferred forms of the invention described above are to be used as illustration only , and should not be utilized in a limiting sense in interpreting the scope of the present invention . obvious modifications to the exemplary embodiments , as hereinabove set forth , could be readily made by those skilled in the art without departing from the spirit of the present invention . the inventor hereby states his intent to rely on the doctrine of equivalents to determine and access the reasonably fair scope of the present invention as pertains to any apparatus not materially departing from but outside the literal scope of the invention set forth in the following claims .
a sectored disc assembly , removable disc sector , and method of replacing a disc sector are disclosed for use with a soil opener that uses a disc assembly to open the soil prior to injection of a fertilizer or seed into the ground . the sectored disc assembly includes a rotatable hub and a plurality of disc sectors cooperatively forming a substantially continuous disc around the hub . connectors , such as bolts , secure each of the disc sectors to the hub . the disc sector includes a body with radially inner and outer margins and side margins that are configured for continuous abutment with adjacent side margins of other disc sectors . the method of replacing a disc sector includes removing the connector securing the disc sector to the hub , moving the disc sector radially outwardly away from the hub , placing a replacement disc sector into contact with the hub , and inserting the connector .