Abstract:
A connector for earth-moving equipment subjected to contact with earth, abrasive materials and the like has a nut with a body and a hole extending through the body. A bolt with a shank adapted to extend into the hole has an enlarged head at one end of the shank. Cooperating thread formations are defined on the shank and in the hole. The thread formations have cooperating matching cross-sections that decrease from a vicinity of the head of the screw towards the other end of the screw and that extend over a circumference of less than 360° and typically of no more than 270°. The connector is adapted to connect various components, including teeth and adapters, to each other and to lips at the front end of earth moving buckets and the like.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application claims priority from pending provisional patent application No. 61/139,503 filed Dec. 19, 2008, the disclosure of which is incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention is directed to a screw connector for earth-moving equipment and the like adapted to secure components of the equipment to each other with a screw-nut connection that remains operable in environments involving earth, dirt, abrasives and the like. 
         [0003]    Earth-moving equipment, such as power-driven shovels, loaders, scoops, dippers and the like, typically has a bucket, the earth-digging front end of which is normally defined by a generally U-shaped heavy-duty lip that is suitably fastened to the bucket. The lip includes a plurality of digging teeth which project from a front edge of the lip as well as wear plates which line interior surfaces of the lip to protect it from being worn down by earth, coal and the like into which the lip is pushed during earth-moving maneuvers. The teeth mounted to the lip are subject to much wear and require frequent replacement. To accommodate such replacements without requiring undue labor, the teeth are typically removably attached to an adaptor which in turn is secured to the lip. 
         [0004]    In the past, wear plates lining the inside of the lip were welded onto the lip so as to not obstruct the rearward movement of earth and the like over the lip into the bucket while preventing the lip per se from being worn down by earth moving across it. Replacing welded-on wear plates from the lip is labor-intensive. First, the welds securing the plates to the lip must be removed and ground down so that a new wear plate can be installed. Next, the plates must be positioned on the lip and then welded onto the lip to securely mount them thereon. This task has to be repeated each time a wear plate must be replaced. 
       SUMMARY OF THE INVENTION 
       [0005]    To overcome disadvantages of prior art power-driven earth-moving equipment connectors for components attached to lips, buckets and the like of the equipment, the present invention provides a unique screw connection defined by a screw cooperating with an appropriately shaped nut. The screw of the connection typically has a tapered shank and a head for rotating the shank about its axis and for engaging a component of an earth moving equipment that is to be attached to another component of the equipment. The screw further has a thread that extends over less than one full rotation or circumference of the screw, that is, that extends over less than 360° and that preferably extends over no more than about a three-quarter turn (270°) of the screw. The thread cross-section tapers over its circumferential length and has a maximum cross-section at a point in the vicinity of the head of the screw. The smallest cross-section of the thread is at the other end of the thread. The nut cooperating with the threaded shaft has a complementary, tapered thread that is configured to receive the tapered thread on the shaft of the screw. 
         [0006]    To connect the screw and the nut to each other, typically with one or more components between them, the screw is aligned with the corresponding bore in the nut and rotated three-quarters of a turn. At the beginning of the turn, the relatively small end of the thread at the end of the screw shank remote from the head is loosely received in the much wider thread of the nut. As a result, there is ample space between the threads on the screw shank and in the nut hole through which sand, abrasives and other materials that might become lodged between the opposing threads and interfere with properly securing the screw to the nut can readily drop downwardly and away from the threads so that the screw can be fully rotated through the designated, e.g. three-quarter, turn, thereby firmly securing the parts between the nut and the screw head to each other. 
         [0007]    To signal to the operator when the screw has been fully inserted into the nut, e.g. by rotating it through the required three-quarters of a turn, the screw and the nut are preferably provided with visual indicators that signal to the operator whether the required turn of the screw has been completed. For example, the screw may be provided with a laterally extending pin that engages a stop or the like on the nut. Other arrangements for determining the completion of the required turn can of course be used. 
         [0008]    Should replacement of one of the parts of the components secured by the screw connection be required, the operator engages the screw head, rotates it in the opening direction, and then withdraws the screw from the threaded nut hole to enable replacement of the part or parts in question. As soon as the screw and the nut have been slightly moved in the opening direction, the threads on them become separated and contaminants that may be present between the opposing threads cannot interfere with fully opening the connection. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a perspective view of a screw and a cooperating nut constructed in accordance with the present invention and provided with respective threads that extend over less than the entire circumference of the screw and the hole and which have cooperating cross-sections that taper from the vicinity of the screw head towards the other end; 
           [0010]      FIG. 2  is a perspective view of a screw constructed in accordance with the present invention and to better illustrate the extent and configuration of the thread; 
           [0011]      FIG. 3  is a schematic representation of the cross-section of the thread on the screw shown in  FIGS. 1 and 2  and shows that the cross-section of the thread is largest in the vicinity of the screw head and is smallest at the thread; 
           [0012]      FIG. 4  is a perspective, schematic view of a lip for attachment to a bucket, a shovel and loader or the like and illustrates how wear plates are secured to the lip between tooth supporting adaptors with the improved screw connection of the present invention; 
           [0013]      FIG. 5  is a perspective, exploded, side elevational view of portions of a lip, the shroud, the wear plate and the bolts and nuts used to secure them to each other; 
           [0014]      FIG. 6  is a cross-sectional view showing the parts illustrated in  FIG. 5  in their assembled condition; 
           [0015]      FIG. 7  is a perspective view of a screw retainer collar used in connection with the nut and screw illustrated in  FIGS. 6 and 7 ; 
           [0016]      FIG. 8  is an underneath view of an adapter and an earth digging tooth attached thereto in accordance with the present invention; 
           [0017]      FIG. 9  is a side elevational view taken on line  9  of  FIG. 8 ; 
           [0018]      FIG. 10  is an exploded, perspective view of a connector constructed in accordance with the present invention that is particularly adapted for securing digging teeth to adapters; 
           [0019]      FIGS. 11-13  are fragmentary, cross-sectional views which are taken on lines  10 - 10 ,  11 - 11  and  12 - 12 , respectively, of  FIG. 9 ; 
           [0020]      FIG. 14  is a plan view of another embodiment of the present invention and illustrates a tooth secured to an adapter with a horizontally oriented bolt; and 
           [0021]      FIGS. 15 and 16  are fragmentary, cross-sectional views which are taken on lines  15 - 15  and  16 - 16  of  FIG. 14 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0022]    Referring to  FIGS. 1-3 , a screw connection  2  constructed in accordance with the present invention has a screw or threaded bolt  4  and a cooperating nut  6 . Screw  4  has a screw head  8  at its “upper end” and a shaft  10  that extends coaxially away from the head in a “downward” direction, as illustrated in  FIG. 1 . The shaft is preferably slightly tapered in a downward direction (away from the screw head) and includes a smooth lower portion  12  and an upper portion  14  over which a three-quarter turn (270°) thread  16  extends from the vicinity of the screw head  8 , e.g. beginning at about and preferably slightly below the lower end of the screw head  8  and extending downwardly at the selected helix angle. 
         [0023]    The cross-section of thread  16  and in particular its height is largest at its uppermost end  19  (in the vicinity of the screw head). It gradually and linearly decreases in a downward direction to a thread end point  17  that is typically slightly rounded.  FIG. 3  schematically illustrates along a straight line the decreasing cross-section (and therewith also the decreasing axial extent) of the thread from its uppermost point  19  to its lowermost end point  17 . In the preferred embodiment, the periphery of thread  16  also includes a slight downward taper in the axial direction of the shaft  10 , typically at the same angle as the taper of the shaft, although this taper can be dispensed with if desired. 
         [0024]    Nut  6  may have a variety of exterior dimensions and configurations to suit particular applications. The nut illustrated in  FIG. 1  has a straight portion  18  joined by a semicircular portion  20  and defines a through hole  22  including a thread  24  that is complementarily shaped to thread  16  on screw  8  so that the screw can be threadably received by the thread in nut  6 . 
         [0025]    To connect screw  8  to nut  6 , shaft  12  of the screw is axially aligned with hole  22  in base  6  and is then axially advanced through the hole until thread  16  on the screw engages thread  24  on the nut. Rotation of the screw relative to the nut is continued through the entire arc over which the threads extend, in the presently preferred embodiment over an arc of about 270°. To facilitate turning of the screw, screw head  8  includes a non-circular socket, for example a square socket  26  that extends in the axial direction. Other socket configurations or other means for rotating the screw, such as a conventional hexagonal head, for example, can be used. 
         [0026]    To signal the operator that he has or has not completed the required three-quarter turn of the screw to firmly engage it with the nut, the screw may be provided with a pin or the like (not shown) which engages an appropriately placed stop in the nut (not shown), or vice versa. So long as the pin does not engage the stop, the operator knows that the screw has not been completely turned, and when the pin is engaged with the stop, the operator is signaled that the required three-quarter turn has been completed and no further turning of the screw is possible. 
         [0027]    Due to the decreasing cross-section of thread  16  on screw  8 , there will be play between it and the corresponding thread  24  in nut hole  22  through which loose sand, dirt and the like, if any, can escape to prevent contaminants that may otherwise lodge between the cooperating threads from preventing a complete closure of the screw relative to the nut. Similarly, if, after a period of use, the screw connection  2  must be loosened, a very slight rotational movement of screw  8  relative to nut  6  disengages and separates the thread flanks of the screw and from the thread flanks in the nut. As a result, any contaminants that might have become lodged underneath screw head  8  and/or between the threads during normal use of the thread connection of the present invention are immediately freed and can drop out of the way. Any contaminants that might remain on the threads do not interfere with the opening of the screw because a slight turn of the screw relative to the base immediately separates the thread flanks. As a result, the contaminants no longer are an obstacle to the complete separation of the screw from the nut. 
         [0028]    Referring to  FIGS. 4-6 , details of connecting various components such as wear plates and shrouds are illustrated in greater detail. 
         [0029]    A lip  30  of a power-driven shovel, loader and the like that has a horizontal portion  32  and a front edge  35 . A shroud  40  positioned between adjacent teeth is placed over the front edge of the lip. It has an aperture  58  through which the elongated shaft  10  of a screw  4  constructed as previously described (and shown in  FIGS. 1 and 2 ) extends. Aperture  58  is aligned with a corresponding, preferably slightly tapered aperture  60  located proximate front edge  35  of the lip, as is shown in  FIG. 6 . The top of aperture  60  has an enlarged recess  62  which receives a nut  6  as shown in  FIG. 1 . By virtue of its configuration, nut  6  is non-rotatable inside recess  62 . The shroud has upper and lower legs  64 ,  66  and a blind hole  68  in the lower leg that is aligned with hole  58  in the upper leg of the shroud. 
         [0030]    After nut  6  has been placed inside recess  62  and the shroud has been placed over the front edge  35  of the lip, screw  4  is lowered through aperture  58  until its thread  16  engages the corresponding thread in nut  6 . Following turning of the screw through three-quarters of a turn, the screw is firmly anchored to the upper leg  66  of the shroud, its elongated shaft  10  is in firm engagement with the aperture  60  in the lip, and a lowermost end  70  of the screw extends into the blind hole in the lower leg  64  of the shroud. With screw  4  firmly tightened against nut  6  as shown in  FIG. 10 , the shroud is fully secured to the lip and prevented from becoming loose (unless the screw is turned open) because the screw, including screw head  8 , are completely disposed inside bores  58 ,  60  and  68  and are locked in place by the shroud until the screw is loosened. 
         [0031]    Still referring to  FIGS. 4-6 , a wear plate  42  is secured to the horizontal portion  32  of the lip by initially forming an enlarged diameter, blind circular depression  72 . A retainer  74 , shown in  FIG. 7 , is welded in place inside the circular depression so that an upper surface  73  of the retainer is substantially flush with the horizontal surface  32  of the lip. The retainer extends over less than 360° to define an access  77  to a central opening  76  into which a screw  78  (shown in  FIG. 6 ) can be inserted. The screw has an enlarged diameter head  80  and a shaft  82 , including a thread  84  constructed as described above and illustrated in  FIGS. 1-3 . The diameter of shaft  82  and thread  84  is slightly less than the diameter of opening  76  in retainer  74  so that the screw can be slidably inserted by slipping its head  80  beneath the retainer until its shaft engages the walls of the opening defined by the retainer. The length of shaft  82  is selected so that an end surface  86  of the shaft is substantially flush with the upper surface of wear plate  42 . 
         [0032]    A nut  88  that cooperates with screw  78  is welded into a hole  90  in the wear plate that is to be attached to the plate. Nut  88  has a tapered thread as described above in connection with  FIGS. 1-3 . 
         [0033]    To attach the wear plate to the lip, screws  78  are slipped beneath retainers  74  in the circular openings  72  in the lip so that their heads  8  are rotatably and removably retained beneath retainer  74  as seen in  FIG. 6 . The wear plate is placed onto the lip so that its nuts  88  are in substantial alignment with screws  78  in the lip, and a turning tool (not shown) is inserted into sockets  90  in the nuts to turn the nuts through the preferred angle of about 270° until a stop mechanism, constructed as described above, engages which signals the operator that the screw-nut connection has been completed and the wear plate has been firmly secured to the screw and therewith the lip. 
         [0034]      FIG. 4  illustrates an entire lip  30  that is to be attached to a bucket or the like for moving earth and other materials (not shown). The lip has a generally U-shaped configuration and includes a horizontal portion  32  joined by upstanding lateral arms  34  at respective ends of the horizontal portion. A front edge  35  of the lip mounts a number of spaced-apart adaptors  36  to which digging teeth  38  are movably attached. 
         [0035]    As previously described, shrouds  40  are located between adjacent teeth and arranged along the front edge of the lip. Shrouds are frequently also installed on the two forwardly facing surfaces of lateral arms  34 . 
         [0036]    Wear plates  42  are arranged on the top surface of horizontal portion  32  of the lip. For this purpose, the lip has embedded openings  44  defined by depressions  72  and opening  77  on retainer  74  through which screws  78  including their heads  80  and shafts  82  can be slidably inserted so that, thereafter, the screw cannot be pulled upwardly. 
         [0037]    The hole pattern  52  in the wear plates corresponds to that of embedded openings  44  in the horizontal portion of the lip. Nuts  88  welded to the wear plates have tapered threads extending preferably over about three-quarters of their respective circumferences, as described above in connection with  FIGS. 1-3 . The nuts in the wear plates are aligned with screws  78  projecting through retainers in the lip, and the screws are tightened three-quarters of a turn until the pin on one of the nuts (not shown) and the screws and the cooperating stop (not shown) on the other one engage each other. This signals that the screw connection has been satisfactorily completed. When desired or otherwise needed, the wear plates applied to the lip can have other configurations; for example, a single wear plate can extend over the entire length and/or width of the lip. 
         [0038]    When it is time to replace the wear plates, or only those wear plates which exhibit excessive wear, the respective screws thereof are loosened and withdrawn to disengage the wear plates from the screws, the worn wear plates are replaced with fresh ones, and the fresh wear plates are again secured to the horizontal portions  32  of the lip as described above. The loosening of the screws typically lifts the wear plates off the underlying lip surface, which facilitates the removal of the plates. 
         [0039]    The entire process of replacing the wear plates only takes minutes as compared to the time-consuming removal of welded-on wear plates and their replacement with fresh wear plates, which must also be welded on as required in the prior art. Significant cost savings are thereby attained. 
         [0040]    Wear pads  56  applied to the exterior and/or interior surfaces of upright lip arms  34  can be applied to the side arms in the same manner as wear plates  42  described in the preceding paragraphs. 
         [0041]    In a preferred embodiment of the invention, the teeth  38  shown in  FIG. 4  are attached to adapters  36  in an analogous manner with a screw and a nut (not separately numbered in  FIG. 4 ) constructed and arranged analogously to the manner in which the shrouds are attached to the lip. 
         [0042]    Preferably, the releasable connection between a tooth  38  and an adapter  36  employs a version of the bolt of the present invention which, in addition to the above-discussed thread of a decreasing axial height, includes a resilient member between the head  8  of the bolt and its shank  10  which biases the shank into a mating bore, as is further described below. 
         [0043]    Referring to  FIG. 10 , the “axially resilient” bolt  90 , like bolt  4  described above, has a bolt head  8  and a preferably tapered shank  10 , although the shank could be of a cylindrical cross-section for a given application. 
         [0044]    Head  8  of bolt  90  is defined by an enlarged diameter, upper section  92  from which a cylindrical shaft  94  depends downwardly. Shaft  94  is dimensioned so that it slidably fits into a hole  96  in shank  10  to allow shaft  94 , and therewith head  8 , to move axially and rotationally relative to the shank. Shaft  94  includes a recess  98  along a portion of its lower periphery which is spaced from the lower end of the shaft and which has a circumferential extent that equals the circumferential extent of helical screw thread  100 . The axial length of recess  98  is selected so that head  8  can axially move relative to shank  10  over a desired distance that is selected to generate a desired force in the axial direction before and while the thread formation is tightened. 
         [0045]    The helical thread  100  on the enlarged portion of head  8  extends over no more than 360° and, preferably, extends over an arc substantially less, for example an arc in the range between about 120° and 180°. A hole  101  extends across the diameter of enlarged head portion  92  so that one end of the hole is in substantial alignment with a lowermost end  102  of the thread and preferably immediately adjacent to the end of the thread. Although not clearly shown in  FIG. 10 , thread  100  has a decreasing axial height as shown in  FIG. 3 . A metal cap  104  with a rounded end is slipped into the hole so that its rounded end protrudes past the opening of the hole at the lower end  102  of the thread. The hole (not shown) includes an internal recess that engages an end flange  106  of the cap to retain the cap inside the hole and prevent it from being pushed out of the other end. When installed, as further described below, a resilient member, such as a plug  108  made of an elastomeric material, such as plastic or rubber, or a compression spring (not shown), has a shaft portion  110  that extends into the interior of cap  104 . Rubber plug  108  includes an enlarged head which engages the surface of the bore into which shank  10  extends to keep it compressed, thereby urging the rounded end of the metal cap past the lower end  102  of the thread into a stop hole (not shown in  FIG. 10 ) for releasably locking the bolt in place. For turning the bolt, head  108  is preferably provided with a connection, such as a square protrusion  112  (or hole, shown in  FIG. 1 ), for turning the bolt with a wrench or the like. 
         [0046]    Disposed between the upper end of shank  10  and the lower end of enlarged head portion  92  is a resilient member, for example a ring  114  constructed of a resilient material, such as rubber or plastic. In a preferred embodiment, relatively thin metal washers  116  are disposed between the respective ends of the ring and the opposing surfaces of shank  10  and enlarged head portion  92 . 
         [0047]    Axially resilient bolt  90  is assembled by initially placing an elastomeric ring  114  and washer  116  combination onto shaft  94  of head  12 , and thereafter shaft  94  is inserted into hole  96  in the shank until recess  98  in the shaft of the head is axially positioned so that it overlies an aperture in shank  10  through which a locking pin  118  can be inserted. Upon insertion of the locking pin, its inner end projects into recess  98 , thereby limiting axial movements between head  8  and shank  10  to the vertical height of the recess and circumferential or pivotal movements to the circumferential arc of the recess. 
         [0048]    Referring to  FIGS. 8-13 , in one preferred embodiment of the invention, axially resilient bolt  90  is installed between an adapter  36  and a tooth  38  in an upright position. The adapter has a nose  120  that extends into and is snugly received in a rearwardly open cavity  122  inside tooth  38 . The adapter-tooth assembly has upwardly and downwardly facing surfaces generally indicated by reference numeral  124 ,  126  which slopingly converge in a forward direction as shown in  FIG. 9 , and the assembly has generally upright sides  128  as seen in  FIG. 8 . 
         [0049]    Although the bolt  90  can be installed at any place across the width of upper and lower surfaces  126 , in the presently preferred embodiment of the invention a bore  130  that receives the axially resilient bolt  90  is arranged in the vicinity of one of the two upright sides  128  of the adapter-tooth assembly  36 ,  38 , as seen in  FIG. 8 . Bore  130  is tapered, that is, it converges in an upward direction as seen in  FIG. 9 , and the larger, lower end of the bore is an open end  132  to provide access to the bore from the exterior. The other end of the bore may be blind, as shown in  FIG. 9 , or open (not shown in  FIGS. 8-13 ). 
         [0050]    The lower end  132  of bore  130  opens into a downwardly open, enlarged recess  134 , the approximate forward half of which is a continuation of bore  130 , and the aft portion of which extends rearwardly past the bore, as can be seen in  FIG. 9 . A helical groove  136 , which is complementary to helical thread  100  on bolt  92 , is arranged in the adapter wall defining bore  130  so that at least an upper end  138  of the groove is located within recess  134 . At the lower end, helical groove  136  terminates in a stop hole  140 , dimensioned to receive metal cap  104  when bolt  90  is installed. The lower end of the helical groove may be located partially or wholly inside bore  130  or within recess  134 . 
         [0051]    To secure tooth  38  to adapter  36 , the cavity  122  of the tooth is slipped over nose  120  of the adapter and pushed rearwardly to the maximum extent possible, at which point both define bore  130 , as is further described below. Thereafter the axially resilient bolt  90  is inserted into bore  130  until the tapered shank  10  of the bolt engages the correspondingly tapered surfaces of bore  130 . Next the operator pushes downwardly on head  8  of the bolt to compress elastomeric ring  114  until the lower end  102  of helical thread  100  becomes aligned with the upper end of helical groove  138  in recess  134  of the adapter. Upon alignment, the operator turns head  8 , for example with a wrench engaging the square drive projection  112  at the top of bolt head  8 . Due to the compression of the resilient ring, an additional axial force, generated as head  8  is turned, reaches a maximum when the head has been turned over the full arc of the thread thereon, at which point resilient plug  108  pushes metal cap  104  into stop hole  140  in the adapter to thereby lock the bolt in place. Any possible force that might be encountered between the tooth and the adapter with bolt  90  secured in place cannot dislodge the bolt, and the firm and secure connection between the tooth and the adapter established by the bolt is maintained. In this context, it is noted that since the respective ends of bolt  90  are within the surrounding bore and are not directly accessible from the exterior, no encountered exterior force can cause the bolt to rotate and end cap  104  remains in place in stop hole  140 . 
         [0052]    When it is time to replace tooth  38  on adapter  36 , the operator engages the actuator  112  at the top of head  92  with a wrench and turns it in the opposite, opening direction. To permit this, the stop hole engaging end of cap  104  is rounded, as shown, or otherwise tapered (not shown), so that, upon the application of a sufficient torque onto the bolt head, cap  104  is pushed out of and becomes disengaged from the stop hole, thereby enabling further rotational movement of the bolt until its thread  100  becomes disengaged from helical groove  136  in the adapter and can be removed. 
         [0053]    In a preferred embodiment of the invention, bore  130  is divided into three axially extending sections. A lowermost bore section  142  and an uppermost bore section  144  are defined by full, 360° through bores  142 ,  144 , respectively, as is illustrated in  FIGS. 11 and 13 . 
         [0054]    A center section  150  of the bore is jointly defined by a rounded, approximately semicircular recess  152  formed into adapter  36  and a similar, at least partially circular cutout  154  formed in a rearwardly extending flange  156  of the tooth, a rearward end  158  of which is received in a recess  160  in the adapter as seen in  FIG. 12 . 
         [0055]    For stability, the opposite side of tooth  38  has a similar, rearwardly extending flange  156  that is snugly received in a recess (not shown) in the adapter. 
         [0056]    Tooth  38  and adapter  36  are assembled by pushing them together as far as permitted to substantially align sections  142 ,  144 ,  150  of bore  130 , and the axially resilient bolt  90  is inserted into aperture  130  as far as possible. Thereafter, an axial force is applied to bolt head  8  until thread  100  becomes aligned with the thread receiving groove in the adapter. Bolt head  92  is then turned over the arc of its thread  100 , which further presses the shank into tapered bore  130 . The thus inserted bolt maintains the nose and the adapter locked to each other because the bolt and the opposing surfaces of the adapter and the tooth overlap and become immovably secured to each other until bolt  90  is loosened again as above described. 
         [0057]    Referring to  FIGS. 14-16 , in another preferred embodiment of the present invention, the axially resilient bolt  90  is placed between adapter  36  and tooth  38  in a horizontal orientation and is located at the upper portion of the resulting assembly, that is, above adapter nose  120  that extends into the rearwardly open cavity  122  in the tooth. 
         [0058]    In this embodiment, tapered bore  130  is defined by overlapping sections of the adapter and the tooth. The adapter defines a downwardly extending, generally horizontal, semicircular groove  162 , an aft end of which terminates in an enlarged, rearwardly extending recess  164  in the adapter. The depression extends substantially over the full length of the bore. 
         [0059]    Tooth  38  includes a relatively wide, rearwardly extending flange  166  which, on its underside, includes a boss  168 , the inside of which defines an at least partially circular, downwardly open groove  170  that is aligned with groove  162  in the adapter to thereby define bore  130  between them in which bolt  92  is received. 
         [0060]    To fully assemble adapter  36  and tooth  38  in the embodiment shown in  FIGS. 14-16 , the tooth is slipped over nose  120  of the adapter as far rearwardly as possible, at which point the semicircular grooves  162  and  170  in the adapter and the tooth, respectively, are in substantial alignment with each other. Bolt  90  is then inserted into bore  130 , the elastomeric ring  114  between the head and the shank of the bolt is compressed until the helical thread  100  on the bolt becomes aligned with helical groove  136 , and the bolt is rotated over the arc of its helical thread until metal cap  104  becomes aligned and is pushed into stop hole  140  by rubber plug  108 , the head of which is engaged by the surface of bore  130  against which it rests. When cap  104  becomes aligned with the stop opening, the cap is driven into the opening, thereby fixing the bolt relative to the nut and the adapter and preventing the two from becoming separated from each other until the bolt is forcibly withdrawn as was described above. 
         [0061]    As is true for the earlier discussed embodiment, tooth  36  includes another rearwardly extending flange  166  located on the underside (not shown in  FIGS. 14-16 ) of the adapter. 
         [0062]    A particular benefit of this embodiment of the invention is that by placing bolt  90  in a horizontal position at the upper side of the adapter-tooth assembly, the bolt becomes a force transmitting member which transmits forces applied to the tooth to the adapter, thereby reducing the stresses to which other parts of the adapter are exposed.