TECHNICAL FIELD 
     The present invention relates to a tool shank mounting assembly for the mounting of shanks of earth working tools. 
     BACKGROUND ART 
     It is a common procedure to mount shanks of earth working tools to tool bars of agricultural equipment. It is desirable that the vertical height of the shank and thus the tool carried by the shank be conveniently adjustable. It is also desirable that the mounting arrangement for the shank firmly holds the shank in place when operating the shank and coupled tool in the ground. Tools which are attached to shanks in many cases can have considerable span to either side of the shank. Tools of this type, tend to apply twisting loads to shank and thus the shank mounting arrangement. 
     A common system for mounting shanks is to provide a series of holes in the shank, with cheek plates provided on opposite sides of the shank and mounted to the tool bar and bolts which are passed through the cheek plates and a selected hole or holes in the shank to set the height of the shank and clamp the shank in position. Vertical adjustment of the shank in such an arrangement is time consuming as the bolts have to be removed to allow the shank to be adjusted in height and then reinserted in a further hole or holes and through the shank. Further, the formation of such holes generally reduces the strength of the shank. In another system, serrated tracks are provided in the rear of the shank which is again clamped between two cheek plates. Bolts which clamp the plates together also cooperate with the track for positive height location of the shank. This arrangement is also time consuming to adjust and height of the shank in this system is limited by the spacing of the serrations. In yet a further arrangement, the tool shank is frictionally gripped between a pair of cheek plates which are clamped by bolts onto opposite sides of the shank. Cheek plates where used are difficult to keep tight when subject to inevitable asymmetric side loads. 
     SUMMARY OF THE INVENTION 
     The present invention aims to overcome or alleviate one or more of the above described disadvantages or at least provide an alternative to the current shank mounting systems. It is a preferred object of the present invention to provide a mounting assembly which will allow for the quick and easy adjustment of the height of shanks and tools carried thereby. It is another preferred object of the present invention to provide an assembly which will provide a secure mounting for the shank and which will withstand large side loads which are incurred by the shank. Other objects, aspects, and advantages of the present invention will be apparent from the following description. 
     The present invention thus provides in one aspect, a mounting assembly for mounting the shank of an earth working tool, said assembly comprising: 
     a shank holder having a passage therethrough adapted to receive said shank, said passage having at least one side wall, 
     a wedge member adapted for wedging between said shank and a said side wall of said passage to secure said holder to said shank at a selected position along said shank, and 
     means for selectively urging said wedge member longitudinally of said passage. 
     Preferably, the passage tapers in cross section inwardly from at least one end. Suitably the wedge member is adapted to cooperate with the tapered passage such that when urged longitudinally of the passage, the wedge member moves in parallelism inwardly towards the adjacent edge portion of the shank to wedge the shank in position. The urging means may include a bolt between the wedge member and holder. 
     The present invention in a further aspect provides a mounting assembly for mounting the shank of an earth working tool, said assembly comprising: 
     a shank holder having a passage therethrough adapted to receive said shank, said passage having at least one side wall, 
     a pair of wedge member adapted to be located at opposite ends of said passage for wedging between said shank and a said wall of said passage to secure said holder to said shank at a selected position along said shank, and 
     means for selectively urging said wedge members longitudinally of said passage and towards each other. 
     Preferably in this aspect, the passage tapers in cross section inwardly from one end of the passage towards a point substantially halfway along the passage and then tapers outwardly to the other end of the passage. The tapers in the passage are suitably defined by an end wall of the passage which is inclined or angled inwardly relative to the longitudinal axis of the passage from one end towards the point substantially halfway along the passage and then is inclined or angled outwardly to the opposite end of the passage. 
     The pair of wedging members are adapted to be received between the leading edge portion of the shank and the tapering walls of the passage which define therebetween tapering spaces so that the shank is wedgingly held at spaced positions. Separate means may be provided to urge the wedging members in opposite directions relative to the longitudinal axis of the passage. The separate urging means may comprise bolts between the wedging members and holder. For this purpose, the wedging members may include apertured end plates and the holder is provided with aligned apertures, preferably provided in flanges, to receive the bolts. 
     Alternatively, single urging means such as a bolt may be provided between the wedging members to urge the wedging members longitudinally and relatively towards each other. The single urging means may comprise a bolt which passes through the apertured end plates of the wedge members and the apertures in the holder. Tightening the bolt will thus urge the wedge members towards each other to firmly wedge the shank in position. 
     Preferably, the passage in cross section is generally complementary to the cross sectional form of the shank and suitably includes opposite side walls which are spaced apart a distance slightly greater than the spacing between the front and rear, or leading and trailing edges of the shank. 
     Suitably the opposite ends of the passage are of V-shaped cross section and the leading edge portion of the shank is also of V-shaped cross section. Preferably, the V-shaped ends and edge portion have an included angle of approximately 90 degrees. Each wedging member preferably includes a leg which is of V-shaped cross section and complementary to the V-shaped cross section of the passage and shank leading edge portion. The leg of the wedging member is preferably of tapering form in cross section to match the inclination of the inclined surfaces of the passage such that when the wedging member is moved slidably into the passage in contact with the inclined end of the passage, the leg of the wedging member moves inwardly in parallelism. This is achieved by having the operative forward V-sectioned surface of the wedge member at an inclination matching the inclination of the complementary inclined surface of the passage. The rear V-shaped surface of the wedging member preferably extends substantially parallel to the longitudinal axis of the passage and thus to the longitudinal axis of the shank so that the leg of the wedging member engages the leading edge of the shank along its full length. Where two wedging members are employed, this is achieved at spaced apart positions in the passage. 
     The opposite end wall of the passage may also be of V-shaped cross section for cooperation with a similarly shaped V-shaped trailing edge of the shank. Again the V-shaped cross sections have an included angle of approximately ninety degrees. 
     The V-shaped cross section of the leading edge of the passage and complementary form of the wedge and shank provides a substantial surface (defined by the faces of the V&#39;s) to resist twisting loads applied to the shanks. A similar effect can be achieved by substituting for the V-shaped cross sections of the shank, holder passage and wedge members, a part-circular cross section or a multi-surface cross section or any other sectional form which will resist twisting loads on the shank. 
     The present invention in yet a further aspect provides in combination a tool shank and tool holder, said tool shank having a leading end of substantially V-shape in cross section, and said tool holder having a passage therethrough receiving said tool shank, the leading end of said passage being of V-shape in cross section, and a pair of pair of wedge members at opposite end of said passage, each said wedge having a leg portion of V-shaped cross section extending between said leading end of said passage said tool shank, and means for selectively urging said wedge members into said passage. 
     Preferably the leading end of the passage is inclined inwardly towards the leading end of the shank from the opposite end of the passage to define openings of tapering cross section for receipt of the leg portions of the wedge members. Preferably, the leg portions of the wedge members have a corresponding taper in cross section. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In order that the invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings which illustrate a preferred embodiment of the invention and wherein: 
     FIG. 1 illustrates a tool shank engaged with a tool holder according to a preferred embodiment of the invention; 
     FIG. 2 is a sectional view of the shank along line A—A of FIG. 1; 
     FIGS. 3 and 4 illustrates the main holder part in plan and side elevational view; 
     FIG. 5 is an enlarged sectional view of the main holder part along line B—B of FIG. 3; 
     FIGS. 6 and 7 illustrate a wedge member in side and elevational view. 
     FIG. 8 is a sectional view along line C—C of FIG. 1 showing the main holder part and engagement between a wedge member and shank; and 
     FIG. 9 illustrates the shank engaged with the holder in further embodiment. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the drawings and firstly to FIG. 1, there is illustrated a shank holder  10  which is formed in two parts  11  and  12  which cooperate in this embodiment for attachment to a square sectioned tool bar  13 . The main part  11  of the holder  10  includes a right angled facing plate  14  and the other part  12  includes a clamping plate  15 . In use, the facing plate  14  is juxtaposed with a pair of faces of the tool bar  13  and the clamping part  15  is juxtaposed with the other two faces of the tool bar  13  and the facing plate  14  and clamping plate  15  cooperate to clamp onto the tool bar  13  by means of bolts  16  on one side and a shear pin connection  17  on their other side. Such a clamping arrangement is disclosed in my Australian patent No. 655449. It will of course be appreciated that the holder  10  may be attached to any form of tool bar, frame or machinery and may be attached thereto by any suitable arrangement. Further the holder  10  as shown in FIG. 1 is shown forwardly of the tool bar  13 . It may have be provided on the rear side of the tool bar  13  and also inverted if desired. 
     The holder  10  includes as shown also in FIGS. 3 to  5 , a passage  18  which extends through the holder  10  which is oblong form in cross section. The passage  18  in use extends substantially normal to the tool bar  13  to which the holder  10  is secured in use and is oriented generally vertically. 
     The opening  18  at its forward and rearward ends is V-shaped in cross section and tapers in cross section longitudinally from each end towards a point  19  substantially halfway along the passage  18  where it is of minimum width. This is achieved by forming the forward V-shaped surface  20  of the passage  18  as a first portion  21  which slopes or is angled slightly inwardly relative to the longitudinal axis of the passage  18  from the top to the point  19  of the passage  18  and then slopes or is angled outwardly towards the bottom of the opening  18  as at  22 . A four degree angle from vertical or from the longitudinal axis of the passage  18  has been found to be a suitable angle for the surfaces  21  and  22 . The opposite end wall  23  of the passage  18  which is also V-shaped in plan view extends substantially parallel to the longitudinal axis of the passage  18 . 
     The opposite side walls  24  of the passage  18  are substantially parallel to one another and spaced apart a distance slightly greater than the distance between the opposite sides of a shank  26  to be received in the passage  18  whereby the shank may be moved freely longitudinally in the passage  18  until secured in position. The holder  10  may also be provided in opposite sides with aligned openings  25  to receive a pin or bolt for cooperating with a shank to be mounted to the holder  10  as described further below. 
     A typical shank  26  which may be suitably secured at its upper end to the tool bar  13 , for example the tool bar  13  of an earthworking or agricultural device, via the holder  10 , is shown in FIGS. 1 and 2. The shank  26  has an integrally formed foot  27  at its lower end. The shank  26  at its rearward or trailing edge  28  is of substantially V-shaped form in cross section which is complementary to the V-shaped surface  23  of the passage  18 , the V-shaped edge  28  having an included angle of approximately ninety degrees. The edge  28  may also includes a plurality of equally spaced indentations  29  with which a bolt or pin  30  passed through the opening/s  25  may cooperate to provide additional security if required to set the height of the shank  26 . The opposite or leading edge  31  of the shank  26  is also of V-shaped cross section with an included angle of approximately 90 degrees to be complementary to the surface  21  or  22 . 
     The width of the shank  26  is slightly narrower than the distance between the side walls  24  of the holder opening  18  and the distance between the V-shaped edges  29  and  31  is less than the minimum width of the passage  18  at the point  19  to permit the tool shank  26  to be passed into the passage  18  and allow vertical movement of the tool shank  26  relative to the holder  10 . The distance between leading and trailing edges  31  and  28  of the shank  26  is such that when received in the passage  18 , the forward V-shaped edge  31  of the shank  26  has substantial clearance to the rear surfaces  21  and  22  of the opening  18  so that, when the holder opening  18  receives the shank  26 , tapering gaps  32  are defined at opposite ends of the passage  18  to permit the insertion of the wedging members  33  between the passage walls  21  and  22  and shank  26 . 
     The wedging members  33  as shown more clearly in FIGS. 6 and 7 include an end plate  34  and a depending leg  35  which has front and rear V-shaped surfaces  36  and  37  which have included angles which are substantially ninety degrees to cooperate with the rear surfaces  21  and  22  of the holder passage  18  and edge  31  of the shank  26  as will become apparent. The surfaces  37  extend substantially at right angles to the plate  34  whilst the surfaces  36  are inclined slightly to the plate  34  at a similar inclination to the surfaces  21  and  22  so that the leg  35  is of tapered form. The end plate  34  is also provided with a central aperture  38 . The holder  10  includes upper and lower flanges  39  and  40  which extend forwardly of the opening  18  and which are provided with apertures  41  which are aligned with each other and in use with the apertures  38  in the end plates  34  of the wedging members  33 . 
     The shank holder  10 , wedging member  33  and shank  26  can be made of any suitable material such as by being cast metal and by any suitable method known to those skilled in art. 
     In use and as shown in FIGS. 1 and 8, the opening  18  of the holder  10  is slid over the shank  26  until the holder  10  is at the desired height for the shank  26  as shown in FIG. 1. A wedging member  33  is then inserted from the top between the shank forward edge  31  and passage surfaces  21  and whilst a further wedging member  33  is inserted from the underside between the shank forward edge  31  and passage  22 . The surface  36  of the wedging member  33  is thus juxtaposed with the surface  21  (or  22 ) and the opposite surface  37  juxtaposed with the edge  31  of the shank  26 . Bolts  42  may be inserted between aligned apertures  38  and  41  in the end plates  34  of the wedging members  14  and flanges  39  and  40  and engaged with nuts  43 . The nuts  43  may then be tightened to urge the wedging members  33  longitudinally of the passage  18  in the spaces  32  between the shank end  31  and surfaces  21  and  22  with the respective V-shaped surfaces of the wedging members  33  mating with the complementary surfaces in the passage  18  and at the edge  31  of the shank  26 . As the angle of the wedging member surface  36  is substantially the same as the angle of the surfaces  21  and  22 , the wedging surfaces  36  will move in parallelism towards the central axis of the passage  18  as the wedging members  33  are urged further into the passage  18  so that the trailing edge  28  of the shank  26  is forced into engagement with the passage surface  23 . The shank  26  thus becomes firmly gripped at spaced positions and is thus accurately located at a desired position relative to the holder  10 . Further, the cooperating V-shaped surfaces of the shank  26 , the holder passage  18 , and the wedging member  33  provide excellent load bearing for not only the rearward and forward stresses which are incurred, but also for the large side loads which are incurred by the shanks  26 . 
     In a further arrangement shown in FIG. 9, a single bolt  45  may be proved to extend between both wedging members  33  passing through the end plate apertures  38  and holder apertures  42  and tightened to draw the wedging members  33  relatively towards each other. Such an arrangement will ensure that equal force will be applied to each wedging member  33 . 
     Where a pair of wedging members  33  are used, the tool shank  26  is clamped to the holder at spaced position providing full support, minimizing movement or rattle of the shank  26  relative to the holder thereby minimizing wear. In addition, the spaced support of the tool shank  26  resists twisting of the shank  26  in the event say that the tool point  27  or tool carried thereby strikes an obstruction with load transferred to the V-surfaces of the passage  18 . 
     In a simplified form, only one wedging member  33  may be provided either at the top or bottom of the holder  10  and secured in position by a bolt  42  and nut  44  as described above. 
     The connection arrangement described above permits infinite adjustment of the position of the tool shank  26  relative to the holder  10  by simply locating the tool shank  26  at a required position and applying a wedging member or members  33 . Removal of the shank  26  may simply be easily accomplished by a hammer blow under the end plates  34  after the bolts have been removed, which will free the wedging members  33  which can then be removed. 
     Whilst the ends of the shank  26  are preferably of V-shaped form and the ends of the passage  18  and leg of the wedging members  33  correspondingly shaped, they may be of other configurations such as or part circular form or of multi surface form in cross section. 
     The above has been given by way of illustrative embodiment of the invention however it will be realized that many variations and modifications may be made thereto by persons skilled in the art without departing from the broad scope and ambit of the invention as herein set forth.
A mounting assembly for a shank including a shank holder having a passage for receiving the shank, the passage having at one end opposite tapering surfaces which define with the leading edge of the shank opposite tapering spaces for receiving wedge members. Bolts are provided between the wedging members and holder to urge the wedging members longitudinally of the passage to wedge the shank in a selected position relative to the holder.