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BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention relates to earth working machines and, more particularly, to a cutting system for excavating different types of substances, such as, rock or dirt, and which includes a support block configured to receive a rotatable cutting tool, such as a conical bit cutting tool, or a non-rotatable, indexable cutting tool, such as a spade bit cutting tool, depending on the type of material that is being trenched or excavated. 
         [0003]    2. Description of Related Art 
         [0004]    Many coal mining and/or construction tools generally include a plurality of bits for cutting into either hard material, such as concrete, asphalt, or rock, or into soft material, such as dirt. The bits are held by support blocks which are generally welded to a cutting chain, drum or wheel, and the blocks may be arranged so that alternating bits project from opposite sides of or staggered positions on the wheel, drum or chain. 
         [0005]    Additionally, depending upon the material composition, it may be desirable to use a hybrid bit having properties of both the rotating conical bit and the non-rotating spade bit. Conical bits generally have a cylindrical surface and are rotatable within the support block. 
         [0006]    The prior art is directed to different designs for the bits and/or support blocks for holding the bits. U.S. Pat. No. 4,915,454 is directed to a cutting apparatus having a fixed holder and an orientable holder. The fixed holder is mounted to a cutting drum and the orientable holder receives a cutting bit, which may be a conical bit or a forward-attack bit. 
         [0007]    U.S. Pat. Nos. 3,318,401 and 4,316,636 are directed to construction tools having a block with a non-cylindrical bore adapted to accept a bit or a tool having a shaft with both a mating non-cylindrical portion and a cylindrical shaft portion. 
         [0008]    U.S. Pat. No. 5,106,166 is directed to a mining bit holding system, which includes a bit holder that attaches to a rotatable drum of a mining machine. The bit holder includes a base portion and a body portion. The body portion has an aperture for receiving a co-axial sleeve. The sleeve has a bore for rotatably receiving a cutting bit. The sleeve and the bit holder are constructed such that the angular position of the sleeve may be fixed relative to the common axis of the aperture in the sleeve in a plurality of positions, and the sleeve may be rotated with respect to the axis of the aperture of the body portion to another position and then fixed in that position. 
         [0009]    U.S. Pat. No. 4,727,664 is directed to an excavating machine having several support blocks, each having a cylindrical bore for receiving the cylindrical shank of a rotatable type bit. The support block is combined with a non-rotatable dirt type excavating tool. The tool has a cylindrical shank at one end made complementary respective to the block bore so that the shank can be telescopingly received in a captured manner within the bore of the support block. A stop means is formed on the block for engaging an abutment means of the tool and prevents axial rotation of the tool when the shank is received within the bore. The tool can be removed from the block, axially rotated into one of a plurality of axial positions respective to the block, and mounted within the bore of the support block. 
         [0010]    U.S. Pat. No. 5,007,685 relates to a trenching tool assembly with dual indexing capabilities that includes a block formed with a tool shank bore and a cutter bit having a shank, which is insertable into the tool shank bore. The shank includes a hex portion. An indexing washer has a central opening that is shaped to engage the polygonal section of the cutter bit shank and to prevent relative rotation therebetween. The washer engages the tool block in a number of fixed positions. To change the angle of attachment of the cutter bit, the indexing washer is disengaged from the tool block and cutter bit shank. The indexing washer and cutter bit shank can be indexed as a unit or independently of one another. 
         [0011]    U.S. Pat. No. 4,462,638 relates to a mining machine, which has cutting bits with conically-shaped heads and located in sockets of the support holders that have respective wear sleeves located on the shanks of the bits with the bit free to rotate with the sleeve interposed in the socket, thereby preventing wear mount. A retainer is engageable with a receptacle on the sleeve to ensure against undesired ejection of the bit. 
         [0012]    U.S. Pat. No. 4,346,934 is directed to a non-rotatable excavating bit that has a forward working portion and a rearward shank portion, which is circular in cross-section and is adapted to fit into a circular bore of a support block. A tang extends from a shoulder and is adapted to fit down over and mate with a surface of the support block so as to hold the bit non-rotatable bit in the support block. 
         [0013]    There is a need to provide a support block that can receive either a rotatable cutting bit, such as a conical bit, for cutting into hard surface materials or a non-rotatable cutting tool, such as a spade bit cutting tool, for cutting into soft surface materials. 
         [0014]    It is therefore an object of the invention to provide an indexable cutting tool system for use in trenching and/or excavating different types of materials that includes a support block configured to selectively receive and retain either a non-rotatable, indexable cutting tool or a rotatable cutting tool. 
       SUMMARY OF THE INVENTION 
       [0015]    The invention relates to a system for mounting a non-rotating and rotating mining and/or construction tool, comprising a support block, a cutting tool selected from the group consisting of a non-rotatable cutting tool having a shank and a rotatable cutting tool having a shank. The support block has a bore with a central axis extending therethrough and a cylindrical portion configured to selectively receive the rotatable cutting tool shank. The block also has a first non-cylindrical portion configured to selectively receive and index the non-rotatable cutting tool shank. 
         [0016]    Another embodiment of the invention is directed to a system for mounting non-rotating and rotating mining and/or construction tools comprising a support block and a cutting tool selected from the group, consisting of a non-rotatable cutting tool and a rotatable cutting tool. The support block has a bore with a non-cylindrical portion extending along the entire length of the bore and is configured to selectively rotatably receive the rotatable cutting tool and to non-rotatably receive the non-rotatable cutting tool. 
         [0017]    Yet another embodiment of the invention is directed to a non-rotatable cutting tool for cutting ground material adapted to be mounted in a bore of a support block, which has a cylindrical portion and an adjacent first non-cylindrical portion. The non-rotatable cutting tool includes a cutting end and a shank with a central axis extending therethrough and has a cylindrical portion that is adapted to be received in the cylindrical portion of the bore of the support block and an adjacent first non-cylindrical portion that is adapted to engage the first non-cylindrical portion of the bore of the support block when the non-rotatable cutting tool is mounted in the support block. 
         [0018]    In yet another embodiment of the invention, a support block for supporting non-rotating and rotating mining and/or construction tools and has a bore with a first non-cylindrical portion configured to selectively receive and index a non-rotatable cutting tool and a cylindrical portion configured to selectively receive a rotatable cutting tool. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1  is a perspective side view of a support block and a spade cutting tool insertable in a support block of the invention; 
           [0020]      FIG. 2  is a perspective side view of a support block and a conical bit tool insertable in the support block of the invention; 
           [0021]      FIG. 3  is an front perspective view of the support block of  FIG. 1 ; 
           [0022]      FIG. 4  is a cross-sectional view taken along lines  4 - 4  of  FIG. 3 ; 
           [0023]      FIG. 4A  is a cross-sectional view taken along lines  4 A- 4 A of  FIG. 4 ; 
           [0024]      FIG. 5  is a view looking from the back directly into the bore of the support block along arrow  5  in  FIG. 1 ; 
           [0025]      FIG. 6  is a perspective front view of the support block and a perspective side view of the spade bit cutting tool of  FIG. 1  in an exploded relationship; 
           [0026]      FIG. 7  is a perspective rear view of the spade cutting tool of  FIG. 6A  inserted into the support block of  FIG. 6 ; 
           [0027]      FIG. 8  is an exploded side view illustrating a spade cutting tool being inserted into a support block of the invention; 
           [0028]      FIG. 9  is an exploded side view illustrating a conical bit tool being inserted into a support block of the invention; 
           [0029]      FIG. 10  is an enlarged side view of a spade cutting tool inserted into the bore of a support block of the invention; 
           [0030]      FIG. 11  is an enlarged side view of a conical bit tool inserted into the bore of a support block of the invention; 
           [0031]      FIG. 12  is an enlarged side view of a spade cutting tool inserted in a support block of a further embodiment of the invention; 
           [0032]      FIG. 12A  is a view looking into the bore of the support block taken along lines  12 A- 12 A in  FIG. 12 ; 
           [0033]      FIG. 13  is a side view of a conical bit tool inserted in a support block of a further embodiment of the invention; 
           [0034]      FIG. 13A  is a view looking into the bore of the support block taken along lines  13 A- 13 A of  FIG. 13 ; 
           [0035]      FIG. 14  is a view similar to that of  FIG. 12A , but illustrates a bore modified with flats to accommodate the shank of a spade cutting tool; 
           [0036]      FIG. 15  is an exploded side view similar to that illustrated in  FIG. 8 , but with the tool shank having a constant width; and 
           [0037]      FIG. 16  is a view similar to that illustrated in  FIG. 8 , but with the shank and the block bore each having a cylindrical portion and two non-cylindrical portions. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0038]    The present invention will be described with reference to the accompanying drawings, where like reference numbers correspond to like elements. The drawings are for purposes of illustrating the preferred embodiments of the invention only and not for purposes of limiting the same. 
         [0039]      FIGS. 1-11  pertain to a support block  10  of an embodiment of the invention, and  FIGS. 12-13  pertain to a support block  50  of a further embodiment of the invention. 
         [0040]    As shown in  FIG. 1 , a support block generally indicated at  10  is configured to receive and retain either a non-rotatable indexable cutting tool, referred to as a spade bit cutting tool, generally indicated at  12 , or as shown in  FIG. 2 . The support block  10  is configured to receive and retain a rotatable cutting tool, that is, a conical bit cutting tool, generally indicated at  14 , depending on the type of material that is being trenched or excavated. Support block  10  is one of a plurality of such support blocks mounted around the outside of the generally circular drum (not shown) or on a movable chain or track (not shown) in a manner known to those skilled in the art. 
         [0041]    Referring particularly to  FIG. 1 , the spade bit cutting tool  12  includes a forward cutting end  16  and a shank  18  or rear end thereof. The forward cutting end  16  includes an angled nose portion having angled surfaces  16   a  and  16   b . Forward cutting end  16  is preferably made of a hard wear-resistant material, such as one of a number of refractory coated cemented carbide materials, which are well known in the art. The cemented carbide may include tungsten carbide, titanium carbide or TiC—TiN. Shank  18  or the rear end of spade bit cutting tool  12  has an upper cylindrical portion  20  and a lower non-cylindrical or indexable portion  22  adjacent to the upper cylindrical portion  20 . Lower non-cylindrical portion  22 , as shown in  FIG. 1 , has several flat indexing surfaces  22   a  circling around the lower indexable portion  22 . A flange portion  24  has a diameter greater than that of the shank  18 , and separates the forward cutting end  16  from the shank  18 . The flange portion  24  is shaped so that when the shank  18  is inserted into the support block  10 , a bottom surface  24   a  of flange portion  24  rests against a top surface  10   a  ( FIG. 1 ) of support block  10 . The lower indexable portion  22  of shank  18  includes a reduced diameter area portion  26  having an end  26   a . The reduced diameter area  26  is configured to receive a retaining pin or clip (not shown in  FIG. 1 ) for securing and mounting the spade cutting tool  12  to support block  10  when shank  18  is inserted in the support block  10 . 
         [0042]    Referring particularly to  FIG. 2 , the rotatable cutting tool or conical bit cutting tool  14  is rotatable within the support block  10  in a manner well known to those skilled in the art. Conical bit cutting tool  14  includes a forward cutting end  28  and a shank  30  or rear end thereof. The forward cutting end  28  includes a hardened nose  32 , preferably made of a hard wear-resistant material such as one of a number of refractory coated cemented carbide materials, which are well known in the art. The cemented carbide may include tungsten carbide, titanium carbide or TiC—TiN. The forward cutting edge  28  also includes a tapered portion  34 , an enlarged portion  36  and a flange portion  38 , which separates the enlarged portion  36  and the shank  30 . The flange portion  38  is shaped so that when the shank  30  is inserted into the support block  10 , a bottom surface  38   a  of the flange portion  38  rests against the top surface  10   a  ( FIG. 2 ) of the support block  10 . The shank  30  or the rear end of conical bit cutting tool  14  has an upper cylindrical portion  40  and a lower cylindrical portion  42 , which is adjacent to the upper cylindrical portion  40 . The lower cylindrical portion  42  generally is configured with a reduced diameter portion  45  adjacent an end  45   a  to accept a retaining pin or clip (not shown), which secures the conical bit cutting tool  14  in the support block  10  in a manner well-known to those skilled in the art. Such a retaining pin or clip may be similar to that disclosed in the aforesaid United States Patent Application Publication No. U.S. 2003/0015907 A1, published Jan. 23, 2003, to Phillip A. Sollami, and may be a spring steel retaining clip which is positioned over the shank  30  of the conical bit cutting tool  14  and shaped so that when the cutting tool  14  is inserted into the support block  10 , the retaining clip will secure the conical cutting tool  14  therein, while allowing it to rotate from external forces. Alternatively, the shank may be secured within a bore of a support block using an expansible clip which fits within a groove around the shank and engages the walls of the bore, in a manner similar to that illustrated and described in U.S. Pat. No. 4,316,636, assigned to the Assignee of the present application and for which the contents are hereby incorporated by reference. 
         [0043]      FIGS. 3-6  more clearly illustrate the configuration of support block  10 . Support block  10  has a bore  44  with an upper cylindrical portion  46  with a cylindrical surface  46   a  and a lower non-cylindrical portion  48 , which is adjacent to the upper cylindrical portion  46 . The lower portion  48  of bore  44  has several flat surfaces  48   a  that encircle this lower portion  48  of bore  44  and correspond to the number of flat indexing surfaces  22   a  of the lower indexable portion  22  of spade bit cutting tool  12  ( FIG. 1 ).  FIG. 6  more clearly illustrates, by the double-headed arrow A, that the spade bit cutting tool  12  is to be inserted into the support block  10  and that the indexing surfaces  22   a  of the lower non-cylindrical or indexable portion  22  of spade bit cutting tool  12  are to be received within the bore  44  to engage flat surfaces  48   a  of the lower portion  48 . Together, the indexing surfaces  22   a  of the lower non-cylindrical or indexable portion  22  of spade bit cutting tool  12  and the flat indexing surfaces  48   a  of non-cylindrical portion  48  of bore  44  of support block  10  prevent the spade bit cutting tool  12  from rotating within the support block  10 . 
         [0044]    As shown best in  FIG. 4 , the upper cylindrical portion  46  of bore  44  has a diameter D 1  that is greater than the width of the opening formed by the flat indexing surfaces  48   a  of the lower non-cylindrical portion  48 , and that the upper cylindrical portion  46  and the lower non-cylindrical portion  48  are adjacent to each other. As best shown in  FIG. 4A , the opening formed by the flat indexing surfaces  48   a  has a maximum width indicated by the double arrow  48   b  and a minimum width indicated by the double-headed arrow  48   c . As best shown in  FIGS. 4A and 5 , the lower non-cylindrical portion  48  of bore  44  has six flat surfaces  48   a  that will correspond to and engage the flat surfaces  22   a  ( FIG. 1 ) of the lower non-cylindrical or indexable portion  22  of the shank  18  of the spade bit cutting tool  12  when the spade bit cutting tool  12  is inserted into the bore  44 . With respect to the conical bit cutting tool  14 , the cylindrical surface  46   a  of the upper cylindrical portion  46  of bore  44  will rotatably support the upper cylindrical portion  40  ( FIG. 2 ) of the shank  30  of the conical bit cutting tool  14  when the conical bit cutting tool  14  is inserted into bore  44 . 
         [0045]    Referring particularly to  FIGS. 8 and 10 , when the spade bit cutting tool  12  is inserted into bore  44 , the indexing flat surfaces  22   a  of the lower non-cylindrical or indexable portion  22  of the spade bit cutting tool  12  engages the corresponding flat surfaces  48   a  of the lower non-cylindrical portion  48  of bore  44  and the upper cylindrical portion  20  of shank  18  of spade bit cutting tool  12  is supported within the cylindrical surface  46   a  of the upper cylindrical portion  46  of bore  44 . The shank  18 , therefore, does not rotate within the bore  44 . The shank  18  of the cutting tool  12  may be indexed within the bore  44  to position the cutting tool  12  at different angles within the support block  10 . 
         [0046]    Referring particularly to  FIGS. 9 and 11 , when the conical bit cutting tool  14  is inserted into bore  44 , the upper cylindrical portion  40  of the cutting tool  14  is rotatably supported by the cylindrical surface  46   a  of the first upper portion  46  of bore  44 , the lower cylindrical portion  42  of the conical bit cutting tool  14  is received in the lower non-cylindrical portion  48  of bore  44  and the retaining clip (not shown) will engage against the back surface  49  of the support block  10 . However, the diameter D 2  of the lower cylindrical portion  42  of the shank  18  is less than the minimum width  48   c  ( FIG. 4A ) of the non-cylindrical portion  48  of the bore  44 . As a result, the conical bit cutting tool  14  may rotate within the bore  44  while the spade bit cutting tool  12  ( FIG. 10 ) within the bore  44  may not rotate. 
         [0047]      FIGS. 8 and 10  more clearly illustrate a spade bit cutting tool  12  being inserted into the bore  44  of the support  10 , and  FIGS. 9 and 11  more clearly illustrate a conical bit cutting tool  14  being inserted into the bore  44  of support  10 , wherein the upper cylindrical portion  20  of shank  18  is positioned within the cylindrical surface  46   a  of the upper cylindrical portion  46  of bore  44 . 
         [0048]    Referring to  FIGS. 8 and 10 , when spade bit cutting tool  12  is inserted into bore  44 , the bottom surface  24 A of the flange portion  24  of the spade bit cutting tool  12  locates the spade bit cutting tool  12  within the bore  44 . Additionally, a shoulder  20   a  of upper cylindrical portion  20  of shank  18  may abut a ledge  44   a  of bore  44 . Similarly, referring again to  FIGS. 9 and 11 , when the conical bit cutting tool  14  is inserted into bore  44 , the bottom surface  38   a  of the bottom flange portion  38  of the conical bit cutting tool  14  locates the cutting tool  14  within the bore  44 . A shoulder  40   a  may abut the ledge  44   a  of bore  44 . The length of the first upper portion  46  of bore  44  may be approximately the same length as the upper cylindrical portion  20  of shank  18  of the spade bit cutting tool  12  and approximately the same length as the upper cylindrical portion  40  of shank  30  of the conical bit cutting tool  14 . The length of the lower portion  48  of bore  44  may be approximately the same length as the lower indexable portion  22  of shank  18  of the spade bit cutting tool  12  and approximately the same length as the lower cylindrical portion  42  of the conical bit cutting tool  14 . 
         [0049]      FIG. 10  more clearly illustrates the spade bit cutting tool  12  in bore  44  of support block  10 , and  FIG. 11  more clearly illustrates the conical bit cutting tool  14  in bore  44  of support block  10 . As discussed, directing attention to  FIGS. 4 and 4A , the upper cylindrical portion  46  of bore  44  has a diameter D 1  that is greater than the opening formed by the flat indexing surfaces  48   a  of the lower non-cylindrical portion  48 , and the opening formed by the flat indexing surfaces  48   a  has a maximum width indicated by the double-headed arrow  48   b  and a minimum width indicated by the double-headed arrow  48   c . The block  10  is capable of accommodating the lower non-cylindrical portion  22  of the non-rotatable indexable cutting tool  12  ( FIG. 1 ) and the lower cylindrical portion  42  of the shank  30  of the rotatable cutting tool  14  ( FIG. 2 ). Of particular relevance, is that the width between indexing surfaces  22   a  of the lower non-cylindrical portion  22  of the non-rotatable indexable cutting tool  12  is slightly less than the minimum width  48   c  such that the lower non-cylindrical portion  48  non-rotatably supports the shank  18  of the cutting tool  12 . However, the diameter D 2  of the lower cylindrical portion  42  of the rotatable cutting tool  14  is less than the minimum width  48   c , such that the lower cylindrical portion  42  and the entire shaft  18  may rotate within the bore  44  of the support block  10 . 
         [0050]    As stated above,  FIGS. 12 and 13  illustrate a second embodiment of a support block  50  for selectively receiving either the spade bit cutting tool  12  of  FIG. 12  or the conical bit cutting tool  14  of  FIG. 13 , respectively. In this embodiment, the support block  50  ( FIG. 12 ) includes a flat outer surface  50   a  and a bore  152 . Bore  152  has at least one non-cylindrical portion  154  extending along the entire length of the bore  152 . A longitudinal view of bore  152 , as shown in  FIGS. 12A and 13A , shows six flat indexing surfaces  154   a  forming a hexagon where the opening of bore  152  has a maximum width  48   b  and a minimum width  48   c .  FIG. 12  shows that the indexable surfaces  122   a  extend along the length of the shank  118 , such that the shank  118  is held iion-rotatably within the block  50  by matching flat indexing surfaces  154   a  of the non-cylindrical portion  154  extending along the length of the bore  152 . As illustrated in  FIG. 12A , the extended indexable portion  122  of shank  118  of the spade bit cutting tool  12  is received within the opening or bore  152  formed by the flat indexing surfaces  154   a . Also, a retaining pin or clip (not shown) is attached to the reduced diameter  26  of shank  118  of the spade bit cutting tool  12  and engages against the back surface  55  of the support block  50  for retaining the spade bit cutting tool  12  in bore  152  of support block  50 . 
         [0051]    As illustrated in  FIGS. 13 and 13A , the block  50  has a bore  152  with the same configuration as the bore  152  in  FIG. 12 . However, now the non-rotatable spade bit cutting tool  12  is replaced by the rotatable conical bit cutting tool  14 . The shank  218  of the cutting tool  14  is cylindrical and fits within the flat indexing surface  154   a  of the non-cylindrical portion  154  of the bore  152 , such that the shank  218  may rotate within the bore  152 . In particular, the diameter D 2  of the shank  218  must be less than the minimum width  48 C of the bore  152 . 
         [0052]    As a result, even though the bore  152  of the block  50  has flat indexing surfaces  154   a  suitable to non-rotatably secure the shank  118  of the spade bit cutting tool  12 , the same bore  152  of the block  50  may also accommodate the rotatable conical bit cutting tool  12  having the cylindrical shank  218 . 
         [0053]    As shown in  FIG. 4 , the non-cylindrical portion  48  of the bore  44  has flat indexing surfaces  48   a . Directing attention to  FIGS. 4 and 14 , the bore  44  of block  50  may be formed by first machining to form the upper cylindrical portion  46  and a circular bore for the lower non-cylindrical portion  48 . The lower non-cylindrical portion  48  may then be broached and machined to form corners  47  having flat surfaces  48   a  in the lower portion  48 . As a result, the non-cylindrical portion  22  of the bore  44  will have curved segments  156  with curved surfaces  156   a  adjacent to the flat indexing surfaces  48   a . Therefore, when the non-rotating shank  18  of the spade bit cutting tool  14  is placed within the bore  44 , the flat indexing surfaces  22   a  (three surfaces shown in phantom in  FIG. 14 ) are engaged only by the flat indexing surfaces  48   a  created by the broach. There will be a gap  158  between the flat indexing surface  22   a  and the curved surface  156   a  of the bore  44 . This gap  158  will minimize buildup of residual material between the shank  18  and the bore  44  in the region of the non-cylindrical portion  44 . This same broaching arrangement may be applied to the entire bore  152  described with respect to  FIGS. 12 and 13  herein. 
         [0054]    In the illustrations, there are six flat indexing surfaces  22   a  on the shank  18  and six corresponding flat indexing surfaces  48   a  within the bore  44  of the block  50 . However, in order to non-rotatably secure the shank  18 , it is necessary to have only one indexing surface  48   a . This number preferably will be at least one, and may be as many as needed to properly secure and index the spade bit cutting tool  12 . In some instances, the number of flat indexing surfaces  22  of lower portion  22  of spade bit cutting tool  12  may be as many as four, six or eight to form a square, hexagon or octagon in cross-section. The spade bit cutting tool  12  can be set within the support block  10  at different rotational positions to provide various angles depending on the number of indexing surfaces of spade bit cutting tool  12  and bore  44  of support block  10  ( FIG. 10 ) or bore  152  of support block  50  ( FIG. 12 ). As is well known in the art, these angles for positioning the spade bit cutting tool  12  relative to a drum, wheel or chain are necessary depending on whether the material is to be removed, mixed, shaved or conveyed. 
         [0055]    As can be appreciated, according to the embodiments of the invention, either the spade bit cutting tool  12  or the conical bit cutting tool  14  can be easily inserted into bore  44  of support block  10  or bore  152  of support block  50  depending on whether the material to be worked is soft or hard. The above features of the bore  44  of support block  10  create areas in the smaller diameter portion  48  that are now larger than the diameter of shank  30  of conical bit cutting tool  14  such that these openings allow for fine cut material to pass easier from the bore openings to assist in better rotation of the conical bit cutting tool  14 . 
         [0056]    Even though the bore  44  of the support block has been described and illustrated as having an upper cylindrical portion  46  and a lower non-cylindrical or indexable portion  48 , it is to be appreciated that these portions  46 ,  48  can be switched around without departing from the invention. Also, in this instance, it is obvious that the upper cylindrical portion  20  and the lower non-cylindrical portion  22  of the shank  18  of the spade bit cutting tool  12  can be switched around to fit this new configuration for bore  44  and, furthermore, the upper cylindrical portion  40  and the lower cylindrical portion  42  of the conical cutting tool  14  can be switched around to fit this new configuration for bore  44 . 
         [0057]    So far discussed and illustrated in the figures is a shank, for example, shank  18  in  FIG. 8 , having a cylindrical portion  20  with a diameter D 1  and a non-cylindrical portion  22  having a maximum width  48   c  (See also  FIG. 4A ). As illustrated in  FIG. 8 , the diameter D 1  of the cylindrical portion  20  is greater than the maximum width  48   c  of the non-cylindrical portion  22 . This same relationship holds true for the cylindrical portion  46  of the bore  44  and the non-cylindrical portion  48  of the bore  44 . However, the purpose for these different dimensions is to accommodate the configuration of many currently available tools. 
         [0058]    It is possible, as illustrated in  FIG. 15 , for the diameter D 1  of the cylindrical portion  20  of the shank  18  to be approximately equal to the maximum width  48   c  of the non-cylindrical portion  22  of the shank  18  with the configuration of the bore  44  shaped accordingly. By doing so, the bottom surface  24   a  of the flange  24  of cutting tool  12  will act as a locating surface in conjunction with the outer surface  50   a  of the support block  50  to locate the tool  12  within the support block  50 . 
         [0059]    Directing attention again to  FIG. 16 , what has been discussed so far are a shank  318  and a bore  344 , each having a single cylindrical portion  320 ,  346  and a single non-cylindrical portion  322 ,  348 . While this arrangement is entirely acceptable, any torsion transmitted to the cutting end  316  of the tool  312  will be transmitted along the shank to the non-cylindrical portion  322  of the shank  318 . As a result, the cylindrical portion  320  of the shank  318  is placed in torsion. 
         [0060]    Directing attention to  FIG. 16 , an alternate embodiment includes a shank  318  having a central axis  319  extending therethrough. The shank  318  includes a cylindrical portion  320  with a first non-cylindrical portion  322  located along the central axis  319  on one side of the cylindrical portion  320  and a second non-cylindrical portion  324  located along the central axis  319  on the other side of the cylindrical portion  320 . Furthermore, the support block  350  includes a bore  344  extending along the central axis  319  and a cylindrical portion  346 . A first non-cylindrical portion  348  is located along the central axis  319  on one side of the cylindrical portion  346  and a second non-cylindrical portion  349  of the bore  344  is located along the central axis  319  on the other side of the cylindrical portion  346  of the bore  344 . As a result, any rotation transmitted to the cutting tool  312  will be transmitted to both the first non-cylindrical portion  322  and the second non-cylindrical portion  324  of the shank  318 , which in turn will be transmitted to the associated non-cylindrical portions  348 ,  350  within the bore  344  of the support block  350 . While the shank  318  and the bore  346  in  FIG. 16  are illustrated with cylindrical portions having a diameter and the non-cylindrical portions having a width different than the diameter, it should be appreciated that the diameter of the cylindrical portion and the width of the non-cylindrical portion may be equal in a fashion similar to that illustrated in  FIG. 15 . 
         [0061]    The present invention has been described with reference to the preferred embodiments. Obvious modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the invention be construed as including all such modifications and alterations.

Summary:
A system for excavating and/or trenching hard and soft ground material includes a support block having a bore with a cylindrical portion and a non-cylindrical portion with flat surfaces and a cutting tool mounted in the bore, which may be a non-rotatable cutting tool having a shank with flat surfaces or a rotatable cutting tool having a shank with a cylindrical portion. The non-cylindrical portion of the bore rotatably engages the cylindrical portion of the rotatable cutting tool and the flat surfaces of the bore engage the flat surfaces of the non-rotatable cutting tool. A further embodiment includes a support block having a bore with flat surfaces along the entire length of the bore that engage the flat surfaces of the shank of the non-rotatable cutting tool and which bore receives the cylindrical portion of the shank of the rotatable cutting tool but does not restrain rotation thereof. In yet another embodiment, the support block may have two non-cylindrical portions and a single cylindrical portion, while the cutting tool may have a shank with two non-cylindrical portions and a single cylindrical portion corresponding to those within the bore of the support block.