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BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to an excavating tooth assembly and a method for assembling and using an excavating tooth assembly. 
         [0002]    Various devices and methods have been used to attach excavating teeth to excavating equipment. In most existing devices, a tooth holder is attached to an excavating instrument such as an auger, and an excavating tooth is detachably combined with to the tooth holder. The detachability of the excavating tooth from the excavating equipment allows the tooth to be replaced or repaired when it is worn out or broken. In one type of tooth assembly, the tooth holder includes an elongated web member. The tooth includes two spaced apart prongs which embrace the opposite sides of the web. A resilient member is inserted between the prongs and the web and is frictionally compressed therebetween to aid in holding the tooth to the tooth holder. 
         [0003]    Various types of resilient members have been used to secure excavating teeth to their tooth holders. In most prior art devices, the resilient member is a U-shape that surrounds both sides of the web and the end nose of the web. Examples of these types of devices are shown in U.S. Pat. Nos. 5,184,412; 3,323,236; and 2,968,880. 
         [0004]    Examples of U-shaped members used in the prior art are shown in  FIGS. 5 and 6 . With reference to the device shown in  FIG. 5 , the numeral  66  designates a tooth and the numeral  72  designates a tooth holder. The tooth  66  includes a pair of spaced apart prongs  68 ,  70 . The tooth holder  72  includes a web  74  which is elongated and which includes a nose  80  at its end. A U-shaped resilient member  76  is shown between the prongs  68 ,  70  and the web  74 . This U-shaped member  76  is not attached to the tooth  66 , but is instead placed between the prongs  68 ,  70  and the web  74  during insertion of the web  74  between the prongs  68 ,  70 . One disadvantage of the resilient member  76  in this prior art device is that it is not long enough to extend the entire length of the web  74  or the prongs  68 ,  70 . Consequently, the tooth  66  becomes misaligned with the tooth holder  72  as can be seen at the contact point  82  and at the spaced apart point  84 . This misalignment causes uneven wear on the tooth  66 , and reduces the useful life of the tooth  66  during the cutting process. 
         [0005]      FIG. 6  shows another example of a prior art U-shaped resilient member similar to the device shown in  FIG. 5 . However, the device shown in  FIG. 6  comprises resilient member  78  that is longer than the prongs  68 ,  70  so that resilient member  78  has ends  86 ,  88  protruding outwardly from the slot between the two prongs  68 ,  70 . One problem with the device shown in  FIG. 6  is that it prevents the nose  80  from fitting tightly into the interior end of the slot between prongs  68 ,  70 . This reduces the area of contact between the resilient member  78  and the side walls of the web  74  thereby reducing the resilient member&#39;s  78  ability to secure the excavating tooth  66  to the tooth holder  72 . Another problem with this device is that the tooth  66  and tooth holder  72  are allowed to compress and recoil against the resilient member  78  due to the resilient member  78  being between the tooth  66  and tooth holder  72  which reduces the life of the tooth  66 . 
         [0006]    Therefore, an object of the present invention is the provision of an excavating tooth assembly which permits the nose of the web to engage the inner end of the slot between the two prongs of the tooth. 
         [0007]    A further object of the present invention is the provision of an excavating tooth assembly which maximizes the area of contact between the resilient members and the walls of the web. 
         [0008]    A further object of the present invention is the provision of an excavating tooth assembly which maximizes the area of contact between the tooth and the resilient members. 
         [0009]    A further object of the present invention is the provision of an excavating tooth assembly which minimizes the wear to the tooth during the cutting operation. 
         [0010]    A further object of the present invention is the provision of an improved excavating tooth assembly and method which is simple to use, economic to manufacturer, and efficient to operate. 
       SUMMARY OF THE INVENTION 
       [0011]    The foregoing objects may be achieved with an excavating tooth assembly comprising a tooth holder having upper and lower members and a web extending between the upper and lower members. The web is elongated and includes a nose end and an inner end. It also has elongated first and second opposite side walls extending along the length thereof between the nose end and the inner end. A tooth includes a cutting end and an attachment end. The attachment end has first and second spaced apart prongs adapted to embrace the first and second opposite side walls of the web, respectively. In one embodiment, a first resilient member is attached to the first prong and a second resilient member is attached to the second prong. In use, the first resilient member is compressed between the first prong and the first side wall of the web and the second resilient member is compressed between the second prong and the second side wall of the web for frictionally securing the tooth to the tooth holder. 
         [0012]    According to one feature of the invention the first and second spaced apart prongs define an elongated slot having a closed inner end and an open outer end. The first and second resilient members each have an outer end adjacent the outer end of the slot and an inner end adjacent the inner end of the slot. The nose end of the web engages the inner end of the slot and the first and second resilient members engage the first and second opposite side walls of the web along substantially the entire length thereof between the nose and the inner end of the web. 
         [0013]    The method of assembling and using the present invention comprises attaching the first and second resilient members to either the first and second prongs or to the first and second side walls of the web. The prongs are then moved into an attached position engaging the first and second opposite side walls of the web so that the first resilient member is compressed between the first prong and the first side wall of the web and the second resilient member is compressed between the second prong and the second side wall of the web. 
         [0014]    It should be understood that although the present invention has particular application to earth augers, trenching machines, and the like, its may be used to secure teeth to other machinery including graters, dippers, backhoes, harrows, scarifiers, cable plows. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is a perspective view of the excavating tooth assembly of the present invention showing the tooth separated from the tooth holder; 
           [0016]      FIG. 2  is a sectional view taken along line  2 - 2  of  FIG. 1 ; 
           [0017]      FIG. 3  is a sectional view similar to  FIG. 2  showing the tooth attached to the tooth holder; 
           [0018]      FIG. 4  is a sectional view taken along line  4 - 4  of  FIG. 3 ; 
           [0019]      FIG. 5  is a sectional view of a prior art excavating tooth assembly having a U-shaped resilient member that is shorter than the prongs; and 
           [0020]      FIG. 6  is a sectional view of a prior art excavating tooth assembly having a U-shaped resilient member that is longer than the prongs. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0021]    Referring to the drawings, the numeral  10  generally designates the excavating tooth assembly of the present invention. Assembly  10  includes a tooth  12  and a tooth holder  14 . The tooth holder  14  is combined with a machine such as an auger or backhoe. Tooth  12  includes a cutting end  16  and an attachment end  18 . Cutting end  16  has a tooth edge  20  and a pair of side reinforcing ribs  22 . Tooth  12  also includes at the opposite end a first prong  24  and a second prong  26  which are spaced apart and which form a U-shaped slot  28 . Slot  28  includes an open end  30  and a closed end  32 . In one embodiment the tooth  16  is comprised of steel, however any other suitable material may be used. 
         [0022]    As seen best in  FIGS. 1-4 , attached to the prongs  24 ,  26  are a first resilient member  34  and a second resilient member  36 , respectively. Resilient members  34 ,  36  may be comprised of rubber or any other suitable material which is capable of compressing and which is capable of exerting a friction against an elongated member on the tooth holder  14 . The elongated member is sometimes referred to in the industry as a web  50 . In one embodiment, the resilient members  34 ,  36  comprise a tapered outer end  38  and a tapered inner end  40 . The tapered outer end  38  is tapered to help the tooth  12  combine with the tooth holder  14  without damage to the resilient member  34 ,  36 . Tapered inner end  40  is tapered to help the resilient members  34 ,  36  fit properly against the curved portion of the tooth&#39;s  12  closed inner end  32 . It should be noted that the two resilient members  34 ,  36  leave the closed end  32  of the slot  28  exposed so as to not cover the closed inner end  32  ( FIG. 2 ). 
         [0023]    The resilient member  34 ,  36  may be combined with the inner edges of the prongs  24 ,  26  by any suitable means, including adhesively, mechanically (such as screws or rivets), or by a process of vulcanization. The preferred method of combining the resilient members  34 ,  36  with the prongs  24 ,  26  is by a vulcanization process in which an adhesive is vulcanized to the metal prongs  24 ,  26 . In this vulcanization process, adhesives are applied between the resilient material  34 ,  36  and the prongs  24 ,  26 . The rubber of the resilient material  34 ,  36  is held to its respective prong  24 ,  26  by an adhesive that is exposed to a temperature of about 160° C. for about eight minutes. Then, a compressed set of the adhesive is applied at about 70° C. for about twenty-two hours. The resulting resilient material has a hardness of about 67(a), which is measured on the Durometer scale. It has a tinsel strength of about 17.32 Mega Pascals (Mpa). 
         [0024]    In an alternate embodiment, the resilient members  34 ,  36  are attached to the side walls  56 ,  58  of web  50  instead of attaching the resilient members  34 ,  36  to the inner surfaces of prongs  24 ,  26 . This attachment may be by any of the same attachment means described in the previous paragraph including adhesively, mechanically (such as screws or rivets), or by a process of vulcanization. 
         [0025]    As best seen in  FIGS. 1 and 2 , the tooth holder  14  includes a closed portion  42  at one end to which are joined an upper jaw member  44  and a lower jaw member  46  which are spaced apart from one another. A notch  48  is formed in the lower jaw member  46 . The notch  48  is adapted to receive a drift punch, screw driver head, or any other suitable tool that can be used to pry the tooth  12  from the tooth holder  12 . As best seen in  FIG. 2 , an elongated web  50  extends from the closed portion  42  into the space between the upper jaw member  44  and the lower jaw member  46 . A closed side wall  51  extends along one side of the tooth holder  14  between the upper jaw member  44  and the lower jaw member  46 . Web  50  includes an inner end  52  adjacent the closed portion  42  and a nose end  54 . Nose end  54  conforms to the closed inner end  32  of the slot  28  of tooth  16 . Web  50  includes first and second elongated concave side walls  56 ,  58 . The concave side walls  56 ,  58  are adapted to receive a locking means such as a ribbed rubber lock to help secure the tooth  12  to the tooth holder  14 . Spaces on the opposite side of web  50  form prong receiving slots  60 ,  62  for receiving the prongs  24 ,  26  of the tooth  16 . 
         [0026]    As best seen in  FIG. 1 , the upper surfaces of prongs  24 ,  26  include V-shaped notches  64  therein. These V-shaped notches  64  are configured to receive inserts or pegs (not shown) as disclosed in U.S. Pat. No. 2,968,880, the disclosure of which is incorporated herein by reference. 
         [0027]    In order to attach the tooth  16  to the tooth holder  14 , the prongs  24 ,  26  are inserted into the receptacles  60 ,  62  respectively so that the prongs  24 ,  26  engage the opposite side walls of the web  50 . The dimensions of the slot  28  and the thickness of the web  50  are chosen so that the resilient members  34 ,  36  are tightly compressed against the opposite side walls  56 ,  58  of the web  50 . This compression causes frictional engagement of the tooth  16  to the tooth holder  42 . 
         [0028]    Referring to  FIG. 3 , several features of the excavating tooth assembly  10  are shown. First, the nose end  54  of the web  50  engages the inner end  32  of slot  28 . This metal to metal contact is not achieved in known prior devices. The metal to metal contact increases the life of the tooth  12  because the tooth&#39;s  12  movement relative to the tooth holder  14  is reduced relative to prior art devices ( FIGS. 5 and 6 ) in which the tooth  66  and tooth holder  72  would compress and recoil due to the resilient member  76 ,  78  being between the tooth  66  and tooth holder  72 . Second, the resilient members  34 ,  36 , engage the side walls  56 ,  58  along substantially the entire length thereof. This increases the surface area of frictional engagement, and provides a tighter attachment. Third, the resilient members  34 ,  36  are evenly compressed on the opposite sides of the web  50  so as to insure that the tooth  20  is not misaligned, and that it is securely held in place. 
         [0029]    In the drawings and specification there has been set forth a preferred embodiment of the invention, and although specific terms are employed, these are used in an illustrative and descriptive sense only and not for purposes of limitation. Changes in the form and the proportion of parts as well as in the substitution of equivalents are contemplated as circumstances may suggest or render expedient without departing from the spirit or scope of the invention as further defined in the following claims.

Summary:
An excavating tooth assembly comprising a tooth holder and a tooth which are attachable together. The tooth includes a pair of prongs which are inserted into a pair of receptacles in the tooth holder and which embrace a web within the tooth holder. A pair of resilient members are attached either to the prongs or to the web and are compressed between the prongs and the web to aid in frictionally securing the tooth to the tooth holder.