Abstract:
An excavating adapter/tooth point assembly has an interfit configuration in which the front end surface of the adapter base has a curved front surface portion that slidingly and complementarily engages a facing curved rear end surface portion of the tooth point. The adapter nose received in the tooth point pocket is somewhat smaller in cross-section that the pocket to permit a limited vertical rocking movement of the point relative to the adapter nose, about a connector structure captively retaining the point on the adapter nose, while transferring rearwardly directed excavating loads on the point to the curved sliding adapter/point interface area. Top and bottom sides Of a rear end portion of the point have curved ear projections which extend rearwardly and outwardly along the adapter base and function as built-in wear guards that protect underlying surface portions of the adapter base.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention generally relates to excavating apparatus and, in a preferred embodiment thereof, more particularly provides an excavating adapter/tooth point assembly in which the tooth point is retained on a nose portion of the adapter for limited rocking motion relative thereto while a curved rear end surface area of the tooth point slidingly bears against a complementarily curved front surface area of a base portion of the adapter.  
           [0002]    Large excavating buckets, dippers and the like are typically provided with a series of earth-cutting teeth which are each formed from two primary parts—a relatively large adapter, and a relatively small replaceable tooth point. The adapter has a base portion which is connectable to the forward lower lip of the bucket, and a tapered nose portion onto which the tooth point is removably secured, with the tapered adapter nose being received in an interior pocket portion of the point, by a suitable connecting pin or other connecting structure. Compared to that of the adapter, the useful life of the point is rather short—the adapter typically lasting through five or more point replacements until the tremendous earth forces and abrasion to which the adapter is subjected necessitates its replacement.  
           [0003]    AS conventionally designed, adapter/tooth point assemblies of this type are configured in a manner such that the adapter nose has a tapered configuration and is snugly and complementarily received in a tapered interior pocket portion of the tooth point in a manner limiting vertical rocking movement of the point relative to the adapter during excavating operations. While this snug tapered interfit between the adapter nose and a replacement tooth point captively retained thereon has been a long-accepted design feature in conventional adapter/tooth point assemblies, it has at least one well known disadvantage arising from this purposely snug fit between the tooth point and the adapter nose.  
           [0004]    Specifically, after the assembly has been used in excavation tasks, the tremendous front-to-rear loads imposed on the tooth point tends to rearwardly drive it along the tapered adapter nose to an extent elastically deforming the tooth point side walls in lateral directions which, in turn, tends to firmly clamp the tooth point onto the adapter nose to an extent which often renders the subsequent task of removing the worn point from the adapter nose an inordinately difficult one.  
           [0005]    In view of this it can be seen that a need exists for an adapter/tooth point assembly in which this problem is eliminated or at least substantially reduced. It is to this need that the present invention is primarily directed.  
         SUMMARY OF THE INVENTION  
         [0006]    In carrying out principles of the present invention, in accordance with a preferred embodiment thereof, specially designed excavating apparatus is provided that comprises an adapter illustratively securable to a front edge portion of an excavating lip structure, a wear member representatively in the form of a replaceable tooth point, and a connection structure which is representatively in the form of a connector pin.  
           [0007]    The adapter has a base with a curved front surface, and a nose projecting forwardly from the curved front surface. The wear member has a curved rear surface through which a pocket area forwardly extends, the pocket area being configured to removably receive and laterally envelop the adapter nose, and the curvature of the rear wear member surface being complementary to that of the front surface of the adapter base. Preferably, the curved front surface of the adapter base has a forwardly convex curvature, the curved rear surface of the wear member has a forwardly concave curvature, and the curved front adapter base surface slidingly engages substantially all of the complementarily curved rear wear member surface. When the adapter nose is placed in the wear member pocket area, the connector structure is inserted through aligned openings in the adapter nose and wear member to releasably retain the wear member on the adapter.  
           [0008]    According to a key feature of the present invention, when the wear member is operatively mounted on the adapter, and the curved rear wear member surface is slidingly and complementarily engaged with the curved front surface of the adapter base, the wear member is permitted to pivot relative to the adapter through a limited arc (generally centered about an axis rearwardly offset from the connector structure) in a manner causing the curved wear member rear surface to slide along the curved adapter base front surface. In this manner, reactive loads created by rearwardly directed operating forces on the wear member are desirably shifted to the curved adapter base surface as opposed to being positioned more forwardly on the adapter nose.  
           [0009]    Representatively, the adapter nose has a stabilizing tip portion with a front end surface that engages an inner end surface of the wear member pocket area, and a lateral clearance area is defined within the pocket area around the adapter nose therein. This clearance area causes a portion of the stabilizing tip portion to act as an abutment surface that limits the pivotal movement of the wear member relative to the adapter. The clearance area also prevents the wear member from being tightly wedged on the adapter nose, thereby facilitating removal of the wear member from the adapter nose.  
           [0010]    According to another feature of the invention, the wear member has a pair of opposite outer side walls which extend rearwardly past the curved rear surface of the wear member and define abrasion shield structures that protectively overlie opposite side surface portions of the adapter base.  
           [0011]    Illustratively, the wear member has a pair of opposite first and second outer side walls through which an aligned pair of first and second connection openings extend into the pocket area, the adapter nose has a third connection opening extending therethrough in alignment with the first and second connection openings, and the connection structure extends through the first, second and third connection openings. Representatively, the connection structure extends along an axis parallel to and spaced forwardly apart from the axis about which the wear member is pivotable relative to the adapter, the first and second connection openings have non-circular shapes and have curvatures generally parallel to the curvature of curved front adapter base surface, and the third connection opening has a circular cross-section.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 is a partially cut away, somewhat simplified perspective view of a specially designed excavating adapter/tooth point assembly incorporating therein principles of the present invention; and  
         [0013]    [0013]FIG. 2 is an enlarged scale, partially cut away, simplified cross-sectional view through the assembly taken generally along line  2 - 2  Of FIG. 1 and illustrating the assembly connected to a representative excavating bucket lip. 
     
    
     DETAILED DESCRIPTION  
       [0014]    As illustrated in FIGS. 1 and 2, the present invention provides a specially designed adapter/tooth point assembly  10  which may be suitably secured to a front edge section  12   a  of a lip portion  12  of a bucket structure used in excavation operations. Assembly  10  is elongated in a left-to-right or front-to-rear direction and longitudinally extends along a horizontal axis A 1 . The assembly  10  includes an adapter member  14 , a wear member representatively in the form of a removable tooth point  16 , and a suitable elongated connector structure  18  which is representatively a connector pin having a circular cross-section along its length, but which may be of an alternate construction if desired. Connector pin  18  longitudinally extends along a horizontal axis A 2  which is transverse to axis A 1 .  
         [0015]    The adapter  14  includes a generally U-shaped base portion  20  having a closed left or front end section  22  from which vertically spaced apart top and bottom side legs  24 , 26  rearwardly extend, legs  24 , 26  defining a cavity  28  therebetween. Front end section  22  has a forwardly facing, convexly curved outer end surface  30  from which a reduced cross-section tapered nose portion  32  forwardly projects, the rear end of the nose  32  being circumscribed by the convexly curved end surface  30  of the adapter base  20 . Outer or front end surface  30  curves rearwardly about a horizontal axis A 3  which is parallel to and spaced rearwardly apart from the axis A 2 . Adapter nose  32  has, at its front end, a stabilizing tip portion  34  with generally horizontal top and bottom sides  36 , 38  and a front end surface  40 . Diverging top and bottom side surfaces  42 , 44  of the adapter nose  32  respectively slope upwardly and downwardly from the tip portion  34  to the convexly curved outer end surface  30 . A circular connection opening  46 , positioned rightwardly or rearwardly from the tip portion  34 , extends horizontally through the adapter nose  32  between its opposite left and right sides as viewed from the front end of the adapter nose  32 .  
         [0016]    Tooth point  16  has a pointed leading or front edge portion  48 , opposite left and right vertical side walls  50  and  52 , and rearwardly and vertically diverging top and bottom side walls  54  and  56  disposed at the rear of the tooth point  16 . The right or rear end surface  58  of the tooth point  16  has a forwardly concave curvature substantially identical to the forwardly convex curvature of the outer end surface  30  of the adapter base portion  20 . A forwardly and inwardly tapered pocket  60  extends forwardly into the tooth point  16  through its concavely curved rear end surface  58  and is laterally enveloped by the outer side wall section of the tooth point  16 . Pocket  60  has a shape generally complementary to that of the adapter nose  32 , and forwardly terminates within the tooth point  16  at a vertical front end surface  61 . Aligned connection openings  62  (only one of which is visible in the drawings) are formed through the opposite vertical side walls  50 , 52  and are spaced apart along the axis A 2 . Openings  62  have non-circular configurations, are slightly elongated in the vertical direction, and are curved generally parallel to the curvature of rear tooth point surface  58 . For purposes later described herein, the sloping top and bottom side walls  54 , 56  have rear portions  54   a , 56   a  that rearwardly extend past the top and bottom edges of the concavely curved rear end surface  58  of the tooth point  16 .  
         [0017]    The adapter  14  is operatively mounted on the front edge section  12   a  of the bucket lip  12  by placing the lip section  12   a  in the adapter cavity  28  and then securing the top and bottom adapter legs  24 , 26  to the lip section  12   a  in a suitable known manner not pertinent to the present invention. Tooth point  16  is mounted on the adapter  14  by inserting the adapter nose  32  into the point pocket  60 , so that the entire lateral periphery of the inserted nose  32  is enveloped by the tooth point  16 , and then inserting the connector pin  18  through the aligned tooth point openings  62  and the adapter nose opening  46 . AS illustrated, the diameter of the connector pin  18  is somewhat less than the horizontal widths of the tooth point openings  62 . In this manner, the pin  18  is protected against the imposition of rearwardly directed tooth point loads as the point/adapter interface areas begin to wear away prior to tooth point replacement.  
         [0018]    With the tooth point  16  mounted on the adapter  14  in this manner, the front end surface  40  of the adapter nose tip portion  34  abuts the forward end surface  61  of the point pocket  60 , and the concavely curved rear end surface  58  of the tooth point  16  slidingly and complementarily abuts the identically curved convex front end surface  30  of the adapter base  20  along essentially the entire extent of the curved tooth point surface  58 . The rearwardly projecting portions  54   a , 56   a  of the top and bottom walls  54 , 56  of the tooth point  16  respectively overlap and shield from abrasion front top and bottom exterior surface portions of the adapter base  20 . For a purpose later described herein, the rearwardly projecting wall portions  54   a , 56   a  (which function as abrasion shield structures) are spaced outwardly apart from their underlying surface portions of the adapter base  20  and form gaps  64  therewith.  
         [0019]    Although the adapter nose  32  and the point pocket  60  have generally complementary configurations, the point pocket  60  is slightly laterally oversized relative to the adapter nose  32  in a manner such that a small interior pocket surface lateral clearance  66  extends around the inserted adapter nose tip portion  34 , and a somewhat larger interior pocket surface lateral clearance  68  extends around the balance of the inserted adapter nose  32 . Representatively, but not by way of any limitation, the width of the lateral clearance  66  is approximately 0.030″, and the width of the lateral clearance  68  is approximately 0.060″. AS will be readily appreciated by those of ordinary skill in this particular art, this designed-in lateral clearance between the adapter nose  32  and the interior surface of the tooth point pocket  60  is in sharp contrast to the snug lateral abutment conventionally provided between a tooth point pocket and an adapter nose operatively inserted therein.  
         [0020]    This unique lateral clearance between the adapter nose  32  and the interior side surface of the point pocket  60 , coupled with the sliding engagement between the complementarily curved and slidingly abutting adapter base and tooth point surfaces  30  and  58 , permits the tooth point  16  to pivot upwardly and downwardly through a limited vertical arc, as indicated by the arrows  70 , relative to the adapter nose  32  about the horizontal axis A 3  during excavation operations. During this limited pivotal movement of the tooth point  16 , the tooth point surface  58  slides along the corresponding adapter base surface  30 , and the tooth point openings  62  are circumferentially shifted relative to opposite end portions of the pin  18 .  
         [0021]    The degree of clockwise and counterclockwise pivoting of the tooth point  16  relative to the adapter nose  32  is respectively limited by the abutment of a top point pocket interior surface area with the top side  36  of the adapter nose tip portion  34 , and by the abutment of a bottom point pocket interior surface area with the bottom side  38  of the adapter nose tip portion  34 . The gaps  64  between the rearward abrasion shielding extensions  54   a , 56   a  on the tooth point  16  and their underlying adapter base surfaces prevents the extensions  54   a ,  56   a  from undesirably being brought into forcible contact with the adapter base  20  during this designed-in limited pivotal movement of the tooth point  16  and the adapter nose  32 .  
         [0022]    During excavation operations, rearward digging forces imposed on the tooth point  16  are transmitted from the front pocket surface  61  to the front end surface  40  of the stabilizing tip  34 , with the reactive force being borne by convexly curved adapter base surface  30  which is pivotally and slidingly engaged by the correspondingly curved tooth point surface  58 . This positioning of the reactive force directly on the adapter base  20  gives the assembly  10  a desirable strength advantage compared to conventional tooth point/adapter assemblies in which such reactive force is borne by the less massive adapter nose portion of the assembly.  
         [0023]    The unique lateral clearance  66 , 68  extending around the adapter nose  32  advantageously prevents the adapter nose  32 , in response to rearwardly directed digging forces imposed on the tooth point  16 , from wedging into and elastically deforming the tooth point  16  in a manner causing the tooth point  16  to be frictionally locked onto the adapter nose  32  such that removal of the tooth point  16  from the adapter nose  32  becomes an inordinately difficult task.  
         [0024]    AS will readily be appreciated, the relatively small tooth point  16  functions as a replaceable wear member for the adapter nose portion  32  of the much larger adapter portion  14  of the overall assembly  10 . However, the principles of the present invention are not limited to a tooth point/adapter assembly, and may be advantageously employed in a variety of other types of excavation assemblies in which a wear member is mounted on another excavation structure for limited pivotal movement relative thereto.  
         [0025]    Also, while the tooth point  16  has been representatively illustrated and described herein as being pivotable relative to the adapter nose  32  about the horizontal axis A 3 , the tooth point  16  (or another wear structure such as an intermediate adapter connected to the adapter  32 ) could also be pivotable about a differently oriented axis. Furthermore, the illustrated stabilizing adapter nose tip  34  could be shortened or eliminated, if desired, the result being that the pivotal stop surface area on the adapter nose  32 , which functions to limit the pivotal movement of the tooth point  16  relative to the adapter  14  would be shifted rearwardly along the adapter nose  32 .  
         [0026]    Moreover, while the front surface  30  of the adapter base  20  has been representatively illustrated and described herein as having a forwardly convex curvature, and the rear surface  58  of the tooth point  16  has been representatively illustrated and described herein as having a forwardly concave curvature complementary to the curvature of the adapter base surface  30 , it will be appreciated that these curvatures could be reversed, if desired, such that the front surface  30  and the rear surface  58  were respectively provided with complementary concave and convex curvatures.  
         [0027]    The foregoing detailed description is to be clearly understood as being given by way of illustration and example only, the spirit and scope of the present invention being limited solely by the appended claims.