RELATED APPLICATIONS 
       [0001]    This application claims priority to and is a continuation-in-part application of U.S. patent application Ser. No. 12/439,957, entitled Blade Assembly for Excavating Apparatus, Filed on Sep. 2, 2009, which is a national stage application of and claims priority to International Application No. PCT/AU2007/001297, filed Sep. 4, 2007, which designates the U.S., which application claims priority to Australian Application No. 2006904874, filed on Sep. 4, 2006. Each of the above-identified applications are expressly incorporated herein by this reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a blade to be mounted to an excavating machine. Excavating machines comprise but not limited to bulldozers, tractor shovels, graders, drag line apparatuses and compacting machines. 
         [0003]    In the context of the invention a blade is intended to cover any type of working tool with an edge which is intended to contact material so that it can be moved. Thus a blade includes but not limited to a bucket, collector and spreader. 
         [0004]    By way of example the present invention will be described in relation to a bulldozer blade. 
       BACKGROUND OF THE INVENTION 
       [0005]    A bulldozer can be used on a variety of working sites. The blade can be used for a variety of different operations including digging, carrying of soil or other material, banking, compacting and levelling. The design of the blade and how it is used determines the efficiency of the bulldozer in a working situation. It is advantageous to maximise working efficiency by designing a blade which is easier to use and can perform at least one function better than an existing blade. 
         [0006]    The ability of a blade to dig into the ground depends on the shape of the front edge, force for pressing the blade into the ground as well as the angle of the blade when it contacts the earth. U.S. Pat. No. 6,938,701 discloses one type of bulldozer blade in which the front edge of the blade has a width which is larger than the width between the tracks of the bulldozer which carries it. This front edge is straight and perpendicular to the direction of movement of the vehicle in a forward direction. On either side of the central section the blade is angled rearwardly and then forwardly to provide three separate sections of cutting edges. The side and end sections are connected in a V-type configuration which is completely behind the front edge of the central section. 
         [0007]    In operation the blade must be tilted downwardly with respect to its non-operative position in order to engage a ground surface. 
         [0008]    The blade described in this patent suffers a number of drawbacks which reduces overall operating efficiency. One of the disadvantages with the blade design is that the blade must be tilted upwardly in order retain material effectively on its surface. Furthermore, the blade must be tilted downwardly to engage a ground surface. Furthermore, the ability of the blade to cut through a ground surface is inferior to blades which have a point. As well material which is contacted by the front edge moves up the front face of the blade but interferes with excavation of further material in front of the blade. Any material which moves to the side of the front edge of the blade generally escapes beyond each edge of the blade if the blade moves too far forward without being tilted upwardly. 
         [0009]    Other disadvantages arise from the shape of the front face and difficulties associated with effectively cutting into a ground surface. 
         [0010]    For existing bulldozers, present practices when loading material onto a blade that is tight is to use the corner tips to achieve penetration and roll the blade back when loaded. This has a tendency to turn the dozer towards the corner tip as the load is now off centre. If the operator is not very experienced he will use the steering clutches in an attempt to keep the dozer moving straight. As well the existing blades do not fill to full capacity when in operation. 
       OBJECT OF THE INVENTION 
       [0011]    It is an object of the present invention to provide an alternate blade that overcomes at least in part one or more of the above mentioned disadvantages. 
       SUMMARY OF THE INVENTION 
       [0012]    In one aspect the invention broadly resides in a blade for an excavating apparatus comprising 
         [0013]    a substantially concave front face with a side wall on each side of the front face, said front face has a raised substantially concave centre section at a substantially central and lower position on the front face, said front face has a side gusset portion on each side of the centre section, side gusset portions slope from the centre section, said front face has a centre forward edge portion, a side forward edge portion on each side of the centre forward edge portion and an end forward edge portion on each distal side of the side forward edge portion; 
         [0014]    wherein the angular position of the centre forward edge portion is discontinuous with the concave arc of the centre section and the concave arc of the centre section is discontinuous with the concave arc of a front face section above the centre section to form three adjacent discontinuous sections which cooperate with the side gusset portions to direct excavated material outwardly from the centre section towards the side walls. 
         [0015]    Preferably the present invention provides a blade that can use its centre for penetration assisting the bulldozer&#39;s ability to use both tracks to push the blade and reduce the loading time then roll back after loaded. 
         [0016]    Preferably a blade in accordance with the present invention has a centre for penetration which results in power being applied to the centre of the blade when loading and not the corners. 
         [0017]    In one embodiment the end forward edge bottom edges are lower than the bottom edges of the side forward edges. The bottom corners of distal edges of the end forward edge are preferably the lowest point of the blade. 
         [0018]    It is preferred that the angle β is less than θ where β is the angle between the end forward edge and a line perpendicular to the centre forward edge and θ is the angle between the side forward edge and a line perpendicular to the centre forward edge. 
         [0019]    The centre forward edge preferably extends perpendicular to the forward direction of the blade. 
         [0020]    Preferably the side forward edges are each angled rearwardly with respect to the centre forward edge. 
         [0021]    At least one of the forward edge portions is attachable to the front face. 
         [0022]    At least one of the forward edge portions is removably attachable to the front face or other part of the blade. 
         [0023]    At least one forward edge is made separately from the rest of the blade. 
         [0024]    The side edges may extend forward from either side of the front face. 
         [0025]    According to one embodiment the side edges extend outwardly from either side of the front face. 
         [0026]    Each forward edge may comprise a metal plate or plate of other impact resistant material. 
         [0027]    Preferably the blade is described on the basis it is resting on a ground surface or in a neutral position. 
         [0028]    According to one embodiment the end forward edge has a forward most end edge which is behind the centre front edge. 
         [0029]    According to another aspect of the present invention there is provided a blade for an excavating apparatus comprising a front face, side walls on each side of the front face, a centre forward edge portion, a side forward edge portion at each side of the centre forward edge portion and an end forward edge portion at each distal side of the side forward edge portion; wherein each side wall has a front edge which is behind the forward most edge of the end forward edges and in front of the rearmost portion of the side forward edge portions. 
         [0030]    Each side wall may have a lower edge portion which is slanted rearwardly. 
         [0031]    The lower front edge of the side walls may be in front of the rearmost portion of the end forward edges. 
         [0032]    Each upper portion of each side wall preferably extends over the end forward edges. 
         [0033]    Each end forward edge may be disposed inwardly of an outer portion of each end forward edge. 
         [0034]    It is preferred that each side wall has a front edge which is located behind the centre forward edge portion. 
         [0035]    Preferably the rearmost point of the side forward edge portions is located behind the front edge of the side walls. 
         [0036]    According to one embodiment the corner portion located between the end forward edges and the side forward edges is located behind the front edge of the side walls. 
         [0037]    According to one embodiment the centre forward edge portion comprises a lower edge which extends rearwardly below the front face in a generally horizontal orientation. 
         [0038]    According to another aspect of the present invention there is provided a blade for an excavating apparatus comprising a front face, side walls on each side of the front face, a centre forward edge portion on each side of the centre forward edge portion and an end forward edge portion on each distal side of the side forward edge portion; 
         [0039]    wherein the front face comprises a substantially concave centre section and side gusset portion on each side thereof for directing material outwardly toward the side walls. 
         [0040]    Preferably each gusset portion comprises a curved plate section curved towards respective side walls. 
         [0041]    Each gusset portion may comprise a generally triangular surface portion. 
         [0042]    Each centre section preferably has substantially the same width as the centre forward edge portion. 
         [0043]    The centre section may be aligned behind the centre forward edge portion. 
         [0044]    Each gusset portion may extend at a slant forwardly to an outer mid section of the side forward edge. 
         [0045]    Preferably the front face is contoured so that material slides off it when the blade is oriented in a neutral position (tilted neither up or down). 
         [0046]    Alternatively or in conjunction the front face is contoured so that the material slides off it when the side walls top edge is parallel to the ground. 
         [0047]    According to one embodiment the width of the centre forward edge portion is less than the width between tracks of a vehicle or wheels of a vehicle to which the blade is connected/attached. 
         [0048]    The blade may be adapted to be tilted forward and back/down and up. 
         [0049]    Preferably the width W of the centre forward section is less than the width of the side forward edge portions M. 
         [0050]    The width of the end forward edge portions is preferably less than the width of the side forward edge portions. 
         [0051]    Preferably the width of the end forward edge portions is less than the width of the centre forward edge portion. 
         [0052]    According to one embodiment of the invention the side walls are straight/vertical in a neutral position of the blade. 
         [0053]    Preferably each optional feature of the invention can be used in any aspect of the invention. 
         [0054]    Each edge may be inclined forward between 70° and 30° when the blade is in a neutral position. 
         [0055]    Preferably the side forward edge is at an obtuse angle with respect to the centre forward edge. 
         [0056]    According to one embodiment the blade is attached to a controlling machine through a lower pivot and an upper pivot connected to an actuable piston, which is adapted to tilt the blade upwardly or downwardly with respect to the lower pivot. 
         [0057]    According to another aspect of the present invention each of the forward edge portions may be made separately as removably attachable plates. 
         [0058]    It is preferred that the end forward edges have pointed lower end edges, which are configured to engage a ground surface before any part of the centre forward edge portion. 
         [0059]    It is preferred that the front face comprises a concave surface from a lower end portion to an upper end portion. 
         [0060]    Preferably the whole of the front face is concave. 
         [0061]    According to one embodiment the front face comprises two concave portions, the lower concave portion being configured to allow retention of material thereon if the blade is tilted upwardly from its neutral position. 
         [0062]    According to one aspect of the present invention anyone of the blades hereinbefore described is part of a blade assembly including attachment portions to enable the blade to be attached to an excavation apparatus such as a bulldozer, backhoe, or any other vehicle which utilises an excavation bucket. 
         [0063]    It is to be understood that reference to “blade” is to be interpreted broadly to cover an excavation bucket, a digging implement which collects material and any other device which engages a ground surface or material deposited on a ground surface or equivalent and is able to cut or dig through the material and collect it on its upper surface. 
         [0064]    According to another embodiment of the present invention there is provided a blade assembly comprising a blade according to any one of the above defined embodiments. 
         [0065]    It is preferred that a blade assembly in accordance with one of the above defined embodiments includes one or more attachment portions for attachment to controlling rams for tilting the blade. 
         [0066]    According to another embodiment of the present invention a blade according to any one of the previously described embodiments includes an attachment portion for attachment to a lifting ram. 
         [0067]    According to a further embodiment of the present invention there is provided a blade assembly including a blade according to any one of the previously defined embodiments and an attachment portion which is configured to be attached to a lifting arm of a vehicle such as a bulldozer or grader. 
         [0068]    According to another aspect of the present invention there is provided a method of controlling a blade according to any one aspect of the invention previously defined, the method comprising moving the blade downwardly, forcing the lowermost edge of the blade below a ground surface and tilting the blade upwardly while the lowermost edge is below the ground surface. 
         [0069]    It is preferred that the lowermost edge comprises the centre forward edge portion. 
         [0070]    Preferably the blade is tilted to a generally horizontal disposition. 
         [0071]    It is preferred that the blade is tilted upwardly so front edges of the side walls are substantially in a vertical orientation. 
         [0072]    According to another aspect of the present invention there is provided a controller for controlling operation of a blade assembly comprising a blade according to any one of the aspects of the invention previously defined, lifting pistons, tilting pistons and support arms, wherein the blade is able to be controlled by the pistons and support arms to engage a ground surface and roll back/tilt upwardly once the blade cuts into the ground surface. 
         [0073]    According to a further aspect of the present invention there is provided a controller for controlling operation of a blade as defined in any one of the previous aspects of the present invention, the controller comprising a first module for controlling operation of tilting pistons, a second module for controlling lifting pistons and a third module for controlling blade support arms, wherein based on data relating to the material which is to be engaged by the blade, the first module is operated to control the lifting piston to drop the blade, the second module is operated to control the tilting piston to tilt the blade downwardly and wherein when the centre forward edge portion has cut into the ground surface/material module is operated to control the tilting piston to tilt the blade upwardly while maintaining the lowermost edge of the centre forward edge portion below the ground surface/material surface. 
         [0074]    It is preferred that the third module maintains the blade in a substantially constant position relative to the ground surface. In this respect it is to be understood that the supporting arms are preferred to be in a horizontal disposition when the blade is tilted downwardly and the centre forward edge portion engages the ground surface/material. 
         [0075]    According to the preferred embodiment of the present invention the support arms are pivotally connected to a rearward back portion of the blade through an attachment portion. 
         [0076]    It is to be understood that the blade in accordance with one or more embodiments of the invention is connected to a machine such as a bulldozer through mountings including rams/pistons and supporting arms in a configuration consistent with conventional bulldozers. 
         [0077]    According to one embodiment each module comprises a sub program of a computer program. 
         [0078]    According to one embodiment of the present invention the controller includes one or more sensors for sensing the orientation of the blade. 
         [0079]    According to another embodiment of the present invention each mounting (piston, arm, etc. includes a sensor for sensing the position/length of extension or contraction of a mounting. 
         [0080]    According to one embodiment of the invention the tilting piston comprises a cylinder and rod and a position sensor for sensing the relative position of the rod and the cylinder. 
         [0081]    According to another embodiment the lifting piston comprises a cylinder, rod and sensor for sensing the relative position of the rod and cylinder. 
         [0082]    According to another embodiment of the present invention the support arms comprise a sensor for sensing the orientation of the arms with respect to a horizontal and/or vertical axis. 
         [0083]    According to a further aspect of the present invention there is provided a method of controlling a blade in accordance with the present invention as defined in any one of the previous aspects, comprising collecting material on a front face of the blade, lifting the blade upwardly by operating the lifting pistons, tilting the blade upwardly by operating the tilting pistons whereby lowermost edges of the blade disengage from a ground surface. 
         [0084]    It is preferred that the method includes moving the blade forward once it has disengaged from a ground surface. 
         [0085]    In another aspect the invention broadly resides in a blade for an excavating apparatus comprising 
         [0086]    a substantially concave front wall with a side wall on each side of the front wall, said front wall has a front face that has a raised substantially concave centre section at a substantially central and lower position on the front face, said front face has a side gusset portion on each side of the centre section, side gusset portions slope from the centre section, said front face has a centre forward edge portion, a side forward edge portion on each side of the centre forward edge portion and an end forward edge portion on each distal side of the side forward edge portion; 
         [0087]    wherein the angular position of the centre forward edge portion is discontinuous with the concave arc of the centre section and the concave arc of the centre section is discontinuous with the concave arc of a front face section above the centre section to form three adjacent discontinuous sections which cooperate with the side gusset portions to direct excavated material outwardly from the centre section towards the side walls. 
         [0088]    Preferably the side gusset portions extend from the centre section to the side forward edge portion adjacent the end forward position. Each side gusset portion preferably forms a substantially triangular shaped sloping section. 
         [0089]    Preferably each of the side gusset portions extend from the centre section to a position where the side forward edge portion is adjacent to the end forward edge portion and forms a substantially triangular shaped sloping section either side of the centre section. 
         [0090]    Preferably the centre forward edge portion and the side forward edge portions are substantially in line providing a substantially continuous edge portion. 
         [0091]    Preferably the end forward edge portion is substantially in line with the side forward edge portion. Preferably the end forward edge portions provide a substantially continuous edge portion section with the side forward edge portions and the centre forward edge portion. Preferably the end forward edge portions are substantially aligned along a horizontal axis with the side forward edge portions and the centre forward edge portion. 
         [0092]    In a preferred embodiment the centre forward edge portion is lower than the other edge portions so that it contacts the ground first and excavated material consequently moves up the centre forward edge portion and centre section. 
         [0093]    In an alternate embodiment the end forward edge portion forms a v-shape with the adjacent side forward edge portion. 
         [0094]    Preferably the end forward edge portions are substantially in line with the side forward edge portions and the centre forward edge portion and the centre forward edge portion is orientated lower than the other edge portions so that it contacts the ground first and excavated material consequently moves up the centre forward edge portion and centre section. Preferably the end forward edge portions provide a substantially continuous edge portion section with the side forward edge portions and the centre forward edge portion and the centre forward edge portion is orientated lower than the other edge portions so that it contacts the ground first and excavated material consequently moves up the centre forward edge portion and centre section. Preferably the end forward edge portions are substantially aligned along a horizontal axis with the side forward edge portions and the centre forward portion and the centre forward edge portion is disposed vertically lower than the end forward edge portions and the side forward edge portions. 
         [0095]    Preferably a top section of the front wall adjacent the side walls curves over towards the front of the blade. Preferably the top section of the blade adjacent the side walls curves over by several degrees. Preferably the top section of the front wall adjacent the side walls bends towards the front of the blade by several degrees. 
         [0096]    The side walls preferably extend higher than the front wall. More preferably the side walls extend higher and rearward of the front wall. 
         [0097]    A corner formed by the front wall and the side wall is preferably supported by a bracket and without a boxed gusset. 
         [0098]    A blade with an upper corner formed by the front wall and the side walls with the curved top section of the front wall and with the side walls that extend above the front wall preferably enables an increased volume of excavated material to be retained on the blade. 
         [0099]    Preferably the top section of the blade has a plurality apertures for an operator to view in front of the blade. Preferably the plurality of apertures are spaced along a central and side sections of the top section of the blade. 
         [0100]    Preferably there is an upper attachment point located on each of the side walls above and preferably behind the front face of the blade. Preferably the upper attachment point is used by cranes to lift the blade. The position of the upper attachment point is preferably a balanced position for a crane to lift the blade without swinging crooked. 
         [0101]    Preferably there are a plurality of mountings on the back wall of the blade. The plurality of mountings preferably provides connection to one or more lifting arms and one or more rams. More preferably the plurality of mountings are positioned adjacent the back wall of the blade to have the centre of gravity of the blade closer to the associated vehicle thereby providing more control over the blade and helping balance the vehicle with the blade. 
         [0102]    The attachment of the lifting arms and rams to the blade preferably orientates the blade in a manner so that substantially all of the carried excavated material can be discharged when the blade is in a forward tilt position. 
         [0103]    The one or more rams attached to the mountings can preferably tilt the blade forward at an angle between 89 and 70 degrees relative to the ground level. Preferably the blade can tilt forward to a maximum of approximately 75.8 degrees relative to the ground level. Preferably the blade can tilt forward to an extent that allows the blade to unload substantially all of the carried excavated material. 
         [0104]    The one or more rams attached to the mountings can preferably tilt the blade backwards at an angle between 91 and 100 degrees relative to the ground level. Preferably the blade can tilt backwards to a maximum of approximately 92.3 degrees relative to the ground level. 
         [0105]    The degree of forward and rearward tilt is preferably achieved with rams that have longer piston strokes. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0106]    Preferred embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings in which: 
           [0107]      FIG. 1  shows a diagrammatic plan view of a blade according to a first preferred embodiment of the present invention; 
           [0108]      FIG. 2  shows a diagrammatic front view of the blade shown in  FIG. 1 ; 
           [0109]      FIG. 3  shows a diagrammatic cross-sectional side view of the blade shown in  FIG. 1 ; 
           [0110]      FIG. 4  shows another diagrammatic cross-sectional view of the blade shown in  FIG. 1 ; 
           [0111]      FIG. 5  shows a diagrammatic side view of the blade shown in  FIG. 1  at cross section A; 
           [0112]      FIG. 6  shows a diagrammatic side view of a bulldozer with a blade in accordance with the first preferred embodiment of the present invention in a neutral position; 
           [0113]      FIG. 7  shows the bulldozer shown in  FIG. 6  with the blade raised; 
           [0114]      FIG. 8  shows the blade and bulldozer shown in  FIG. 7  with the blade pitched forward; 
           [0115]      FIG. 9  shows a bulldozer and blade in accordance with a first preferred embodiment of the invention on a horizontal ground surface; 
           [0116]      FIG. 10  shows the bulldozer and blade shown in  FIG. 9  with the blade tilted downwardly; 
           [0117]      FIG. 11  shows the bulldozer and blade shown in  FIG. 10  with the blade lowered below the horizontal ground surface; 
           [0118]      FIG. 12  shows the bulldozer and blade shown in  FIG. 9  moving down an inclined surface; 
           [0119]      FIG. 13  shows the bulldozer and blade of  FIG. 9  with the blade tilting upwardly prior to entering a second horizontal ground surface; 
           [0120]      FIG. 14  shows the bulldozer and blade shown in  FIG. 9  with the bulldozer about to enter the lower horizontal ground surface; 
           [0121]      FIG. 15  shows the bulldozer and blade of  FIG. 9  moving along a lower horizontal ground surface; 
           [0122]      FIG. 16  shows a blade according to a first preferred embodiment of the invention attached to a bulldozer with the blade oriented downwardly to engage a horizontal ground surface; 
           [0123]      FIG. 17  shows the blade and bulldozer of  FIG. 16  with the blade tilted upwardly after engaging the ground surface; 
           [0124]      FIG. 18  shows the bulldozer and blade of  FIGS. 16 and 17  with the blade tilted upwardly and rolled back after collecting material in the blade; 
           [0125]      FIG. 19  shows a diagrammatic view of a second preferred embodiment of the blade attached to a bulldozer wherein the blade is in a level position at ground level; 
           [0126]      FIG. 20  shows diagrammatic view of a second preferred embodiment of the blade attached to a bulldozer wherein the blade is at full tilt back at ground level; 
           [0127]      FIG. 21  shows a diagrammatic view of a second preferred embodiment of the blade attached to a bulldozer wherein the blade is at full tilt forward at ground level; 
           [0128]      FIG. 22  shows a diagrammatic view of a second preferred embodiment of the blade attached to a bulldozer wherein the blade is at a full tilt forward at ground level on an incline; 
           [0129]      FIG. 23  is a diagrammatic front view of a second preferred embodiment of the blade; 
           [0130]      FIG. 24  is a diagrammatic front view of a second preferred embodiment of a section of the side of the blade marked C in  FIG. 23 ; 
           [0131]      FIG. 25  is a diagrammatic side view of a second preferred embodiment of the blade; 
           [0132]      FIG. 26  is a diagrammatic view of a mounting portion of the blade marked K in  FIG. 25 ; 
           [0133]      FIG. 27  is a diagrammatic view of another mounting portion of the blade marked L in  FIG. 25 ; 
           [0134]      FIG. 28  is a diagrammatic front view of the blade similar to  FIG. 23 ; and 
           [0135]      FIG. 29  is a diagrammatic view of a side top section of the blade marked A in  FIG. 28 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0136]    In accordance with the preferred embodiments of the present invention, a blade will be described that can use its centre forward edge for penetration. The blade attached to a bulldozer will be described and the ability to use the centre forward edge of the blade for penetration will assist the dozer&#39;s to use both tracks to push the blade and reduce the loading time and then roll back after being loaded. 
         [0137]      FIGS. 1 to 18  show a first preferred embodiment of the blade whereas  FIGS. 19 to 29  show a second preferred embodiment of the blade. 
         [0138]    With reference to the first preferred embodiment of the blade,  FIGS. 1 and 2  shows a blade  10  having a front face  11 , a centre edge  12 , middle edges  13  and  14  on either side of the centre edge  12  and end edges  15  and  16  on each end of the side edges  13 ,  14 . 
         [0139]    Each of the front edges  12 ,  13 ,  14 ,  15  and  16  are preferably separately made from the rest of the blade and are removably attachable thereto. Thus in  FIGS. 1 ,  2  and  5 , there is a series of holes  17  which serve as attachment points. 
         [0140]    Rearward of each edge  12 ,  13 ,  14 ,  15 , and  16 , the front face  11  is specially shaped to enhance cutting by the blade as well as distribution of cut material away from the centre of the blade and furthermore retaining of excavated material on the blade when it is tilted upwardly from its cutting position. 
         [0141]    The centre edge  12  of the blade extends rearwardly in a generally concave arc which preferably constitutes a rolled section of constant width and of the same width as the centre edge  12 . This rearward centre section  18  extends approximately half way along the front face  11  as shown in  FIG. 4 . In  FIG. 2  the central front section  18  appears rectangular. 
         [0142]    It is preferred that the central front section  18  is a separately formed metal plate which is formed on the front face  11 . 
         [0143]    Left and right side gussets  19 ,  20  curve to each side from the left and right side  21 ,  22  of the central front section  18 . In  FIG. 2  these gussets  19 ,  20  look triangular and extend forwardly from the rearmost end of the central front section  18  to middle blades  13  and  14  respectively to a point closer to their outer ends than their inner ends. 
         [0144]    In effect both the central front section  18  and side gussets  19  and  20  appear as a raised section in the centre of the front face  11 . 
         [0145]    The centre edge  12  is essentially straight and perpendicular to the direction of movement of the blade in the forward direction. Each of the middle edges  13 ,  14  slant rearwardly at a angle of approximately 25° with respect to the centre edge  12 . Each of the middle edges  13  and  14  are approximately twice as long as the centre edge  12  and at their outer ends  22 ,  23  form a V-shaped angle with the end edges  15  and  16  respectively. 
         [0146]    The thickness of each of the front edges  12  to  16  is generally the same and each of them may be in the form of a metal plate. 
         [0147]    The end edges  15  and  16  are angled forwardly and laterally from the middle edges  13  and  14 . They form an angle of approximately 110° with respect to each of the middle edges  13 ,  14 . 
         [0148]    As shown in  FIG. 1 , each end edge  15 ,  16  has a lower front corner  25 ,  26  which is located behind the centre edge  12 . It is also noted that the front edge  27 ,  28  of the end edges  15 ,  16  are slanted slightly forwardly to form a slightly pointed corner  25  and  26  respectively. 
         [0149]    As shown in  FIG. 2  the horizontal level of the centre edge  12  and middle edges  13  and  14  is approximately the same. However the end edges  15  and  16  are angled slightly downwardly and forwardly from the ends  23  and  24 . 
         [0150]    The front face  11  which is generally a concave shaped shovel has a general curvature on either side of the central front section  18  to each side  29 ,  30 . These sides  29 ,  30  are represented as vertical crease lines which form corner sections with outer wall sections  31 ,  32  which extend laterally and forwardly at a similar angle to the end edges  15  and  16  with respect to the middle edges  13  and  14 . Side plates  33  and  34  extend from these walls  31  and  32  generally in a forward direction and thus perpendicular to the centre edge  12 . 
         [0151]    The side walls  33 ,  34  are typically in the form of large metal plates extending from the top of the front face  11  forwardly in a straight line then vertically downwardly to a slanted section  35  approximately three quarters of the length from the top corner edge  36  and inwardly to a point on the front face behind the end edges  15 ,  16 . 
         [0152]    As shown in  FIG. 1 , front end  37  of the side walls  33 ,  34  extend over part of the end edges  15  and  16  to a forward position approximately half way across them. The front edges  27  and  28  of the end edges  15  and  16  are the lateral most parts of the front face  11  and extend beyond the side walls  33 ,  34  in a lateral direction. It is also noted that the corners  25  and  26  are both in front of and further to the side of the side walls  33 ,  34  than their front edges  37 . 
         [0153]    It is preferred that the overall concave curvature of the front face  11  with the raised central sections  18 ,  19  and  20  is such that when the blade is connected to the bulldozer and is in a neutral position, that is it is not tilted forward or backward, any material on the front face of the blade is able to slide off it. Furthermore, only a slight tilting upwardly of the blade results in retention of a significant amount of material on the front face of the blade. 
         [0154]    As shown in  FIGS. 3 and 4 , the centre edge  12  and middle edges  13  and  14  are generally flat and straight. In  FIG. 5  the rear face of the middle edge  14  is shown and this is also generally flat and straight and each of the edges appears as a thick metal plate. 
         [0155]    Behind the blade  10  connection points  50  and  51  are provided at the lower end and close to the top end. The lower end is connected through a pivotal support part through connecting arms to a bulldozer and the point  51  is connected to a pivotal piston arm of the bulldozer. As a result tilting of the blade  10  occurs by movement of the piston and hence pivoting of the blade with respect to the connection point  50 . 
         [0156]    A blade having the features described above when connected to a bulldozer is able to be tilted slightly downwardly so that the centre edge  12  is able to engage a ground surface or material on a ground surface. Initially the corners  25  and  26  of the end edges  15  and  16  contact the ground because they are lower. This also has the result that they wear more quickly than the centre edge and provide a barrier to help capture material within the confines of the blade. 
         [0157]    As the blade moves forward, material moves up the centre edge  12  onto the central front section  18  and is distributed by side gussets  19  and  20  outwardly in a lateral direction. This directs material towards the side walls  33 ,  34 . These walls act as a barrier which helps retain material within the confines of the blade. This retention is enhanced by the front edge  37  being located in front of the rearward edge of the end edges  15  and  16 . 
         [0158]    Because the material is directed outwardly to the sides of the blade, cutting/grading by the centre edge  12  is enhanced because material is moved away from the central region. This movement to the sides may be enhanced by increasing the size of each of the gussets  19  and  20  and reducing the width of the section  11 . For example the section  11  may be made triangular with an apex at a rearward most point, thus having a triangular appearance with the apex of the triangle at a rearward point and the sides of the triangle leading into each of the gussets  19 ,  20 . 
         [0159]    Some of the noteworthy features of the first preferred embodiment include the following: 
         [0160]    the centre cutting edges forward of the corner tips; 
         [0161]    the centre cutting edge is at the same level as the corner tips when the blade is in the central or carry position; 
         [0162]    the corner tips are lower than the centre cutting edge when the blade is in the central or carry position; 
         [0163]    the centre cutting edge is lower than the corner tips when the blade is rotated forward or down into the digging position; 
         [0164]    the centre cutting edge is higher than the corner tips when the blade is rotated back; 
         [0165]    the blade has larger side plates to carry more material; and 
         [0166]    the side plates are forward of the back edge of the corner tip. 
         [0167]    When the blade is used on a dozer it provides the dozer with a number of operational features which are not available to dozers with existing blades. 
         [0168]    Thus according to one embodiment, larger dozers with the blade according to the present invention have a function that allows the on board processor of the dozer to pitch the blade forward to dump material from the blade when the blade is raised past a preselected position. This function can be expanded to control the pitch of the blade when a digging operation is undertaken. 
         [0169]    In accordance with the first preferred embodiment of the invention when the dozer is in the neutral position the cutting edges of the blades are all level with the ground except for the corner tips or outside cutting edges which may be lower. As shown in  FIG. 6  the supporting arms  61  of dozer  60  are generally horizontal with tilting pistons  62  at approximately 45° with the control arms  61  and lifting pistons  63  also approximately at 45° with respect to the arms  61 . In this position the blade  64  is able to push material to a dump site. As shown the side plates  65  generally have their front edges  65  vertical and their top edges  66  horizontal. 
         [0170]    After the blade  64  is raised by pivoting the arm  61  upwardly using the lifting piston  63 , as shown in  FIG. 7 , the onboard processor may be operated to pitch the blade  64  forward as shown in  FIG. 8 . This is achieved by operation of the tilting pistons  62 . 
         [0171]    As shown in  FIGS. 7 and 8  when the blade  64  is raised, edges  65  and  66  effectively pivot clockwise whereas in  FIG. 8  they pivot anticlockwise. The result is the edges  65  and  66  are no longer in the vertical and horizontal disposition shown in  FIG. 6 . 
         [0172]    With the blade pitched forward, material collected on the blade is able to flow down from the blade and hence reduce any material from sticking to the blade and being carried back to the dig position. 
         [0173]    It is preferred that the onboard processor is programmed for an autopitch step involving the raising and lowering of the blade as shown in  FIGS. 7 and 8 . Alternatively an operator can perform these steps manually. 
         [0174]    It is preferred that this function is part of a normal digging cycle involving loading, dumping and clearing/dislodging material on the blade. 
         [0175]    According to one embodiment it may be an advantage to set the dig or pitch forward auto operation in an aggressive setting for hard material. This would start the pitching of the blade when the blade is lowered a short distance from the neutral position. It may also be an advantage to set the auto pitch in a less aggressive setting when digging softer material. This less aggressive setting would allow the blade to be lowered a larger distance from the neutral position before the blade is pitched forward. 
         [0176]    The dump auto settings may be set in the same manner outlined above. 
         [0177]    In the operation described above a bulldozer is able to be used to push material to a dump site. According to another operational task a bulldozer may be required to operate on a downwardly or upwardly inclined slope.  FIGS. 9 ,  10 ,  11 ,  12 ,  13 ,  14  and  15  show how a bulldozer with a bucket according to the first preferred embodiment may be operated so as to control the orientation of the bucket as the bulldozer moves forward. Thus as shown in  FIG. 9 , the bulldozer  70  with a bucket  71  is operated so that the onboard processor uses the auto pitch feature to follow the contour of the ground surface. Thus in  FIG. 10  the blade  71  is pitched/tilted forwardly using tilting pistons  72  after a slight lifting of the blade  71  by operation of arms  73  and lifting pistons  74 . 
         [0178]    In  FIG. 11  the bulldozer  70  moves forward and the blade moves downwardly first under operation of pistons  74  and  72  and arms  73 . As a result the blade  71  has an initial forward pitch as the dozer starts to dig and after the dozer follows the blade into the inclined area as shown in  FIG. 12 , the blade is returned to its neutral position again by operation of pistons  72  to  74  and arms  73 . 
         [0179]    After the dozer is following the incline downwardly, the blade  71  is loaded with material and the blade is then required to pitch backwardly so that the dozer can start pushing the material to the dump site. 
         [0180]    Thus in  FIGS. 13 and 14  it is shown how operation of pistons  72  and  74  results in an upward tilt of blade  71  as the dozer moves from the incline to the flat surface and then once on the flat surface or as the dozer completes movement to the flat surface, the blade is again tilted back to the neutral position as shown in  FIG. 15 . 
         [0181]    Although the example given above relates to movement of the dozer from a level to a downwardly inclined slope and back to a level surface, the operations involved with regard to movement of piston arms and blade  71  are simply reversed if the dozer moves in the opposite direction. As a result it is clear that there are movements of the blade which are effectively repeated and can be stored in the data processor for automated operation depending upon the type of terrain on which the dozer is to work. Thus the onboard data processor or even a remote data processor which has information relayed to it from the bulldozer can be programmed to tilt the blade in accordance with the operation shown in  FIGS. 9 to 11  to the neutral position shown in  FIG. 12  and then again tilt the blade in the manner shown and described in relation to  FIGS. 13 and 14  with the result that it again ends in the neutral position as shown in  FIG. 15 . For an upwardly inclining movement of the bulldozer the tilting movement of the blade is simply reversed. 
         [0182]    It is to be understood that tilting of the blade is controlled by the tilting and lift pistons and the control arms of the bulldozer. Accordingly a data processor effectively through sensors located on each of these components can determine the orientation of the blade and can automatically control these components to tilt the blade as the bulldozer moves. Likewise sensors can be located on the blade. 
         [0183]    In accordance with another mode of operation of a dozer utilising the blade of the preferred embodiment of the invention, it is noted that if the blade  81  as shown in  FIG. 16  is tilted forwardly to cut into a ground surface there is a tendency because of the design of the blade to cut deeper into the ground surface. This causes the blades cutting edges and/or corner tips to dip lower than the ground level and adjustments need to be made with the lift mechanism to keep the blade at the same height. Accordingly it is preferable that after the forwardmost cutting edges of the blade cut into the ground, there is a rollback operation involving tilting the blade upwardly as shown in  FIG. 17  back to a neutral position. As shown in  FIG. 18  a final slight tilting upwardly can be initiated to collect material on to the blade and enable it to be carried to a dumping location. 
         [0184]    The data processor can be programmed to operate the lifting and tilting pistons in conjunction with the supporting arms to initially tilt the blade  81  forward so that the forward most edge cuts into a ground surface and then to operate these components to tilt the blade  81  to a neutral position so the bottom edge of the front edge of the blade is able to travel in a horizontal orientation. Finally material collected within the confines of the blade  81  is able to be transferred to another location by a slight further tilting of the blade upwardly so that the forward most edge of the blade is not engaging with the ground surface. 
         [0185]    Alternatively a data processor on board the bulldozer or remote from the bulldozer is programmed to adjust the blade to keep the nominated cutting edges or corner tips at a constant height. The actual height selected will be dependent upon a number of factors such as the hardness of the ground surface, the size of the bucket, the size of the dozer, the angle of the ground surface etc. 
         [0186]    The use of the blade reduces the dependency of the steering clutches and brakes to keep a bulldozer moving straight when loading the blade. As the majority of the load will be centrally located on the blade, the operator has comparatively improved steering and a greater control of the blade. 
         [0187]      FIGS. 19 to 29  describe a second embodiment of the blade. With reference to  FIGS. 19 to 22 , blade  100  is attached to dozer  101 . The lifting arms  102  of the dozer  101  are attached to arm mountings  103  on the back of the blade  100 . Horizontal rams  104  and vertical rams  109  of the dozer  101  are attached to ram mountings  105  on the back of the blade  100 . The arm mountings  103  and ram mountings  105  are described more fully with reference to  FIGS. 25 ,  26  and  27 . The arm mountings  103  and ram mountings  105  are located adjacent the back wall  107  of the blade  100  thereby positioning the blade  100  as close as possible to the dozer  101 . By reducing the space between the dozer  101  and blade  100 , the centre of gravity is brought back towards the dozer  101  and consequently provides the dozer  101  with a comparatively greater control and balance when using the blade  100 . As a consequence of the attachment of the blade  100  to the lifting arms  102 , horizontal rams  104  and vertical rams  109 , the orientation of the blade  100  is such that there is approximately 43 degrees between an axis formed between the forward edge portions  110  and the forward edge portions  110  and the mounting  105  that connects with the horizontal rams  104  when the forward edge portions  110  are in a level position at ground level. 
         [0188]    With reference to  FIG. 20 , the blade  100  can be tilted back approximately 92.3 degrees between the blade  100  and the ground level when in a level position at ground level. The degree of backward tilt enables the carried excavated material to be retained on the blade  100 . 
         [0189]    With reference to  FIG. 21 , the blade  100  can be tilted forward approximately 75.8 degrees between the blade  100  and the ground level when in a level position at ground level. The degree of forward tilt enables substantially all of the carried excavated material to be discharged from the blade  100 . 
         [0190]    With reference to  FIG. 22 , the blade  100  can be tilted forward at approximately 43 degrees when moving along and incline with a gradient of 14 degrees. 
         [0191]    With reference to  FIGS. 23 and 24 , the blade  100  has forward edge portions  110 , side walls  111  and front wall  112 . The forward edge portions  110  include centre forward edge portion  115 , side forward edge portions  116  and end forward edge portions  117 . The forward edge portions  110  are substantially aligned in a horizontal axis with the centre forward edge portion  115  inclined downwardly relative to the side forward edge portions  116  and end forward edge portions  117 . 
         [0192]    The front wall  112  generally has a concave shape. The front wall  112  has a raised substantially concave centre section  119 . The centre section  119  has a substantially central and low position on the front wall  112 . The angular position of the centre forward edge portion  115  is different to the concave arc of the centre section  119  which is different to the arc of the concave front wall  112  above the centre section  119 . There is a discontinuity in the shape of the front face from the centre forward edge portion  115  through the centre section  119  to the front wall  112  above the centre section  119 . 
         [0193]    On either side of the centre section  119  there is a side gusset portion  121  that slope downwardly from the centre section  119  to the outer sections of the front wall  112 . Each of the side gusset portions  121  extends from the raised centre section  119  to the side forward edge portions  116  adjacent the end forward end portions  117 . 
         [0194]    Material such as dirt is picked up by the centre forward edge portion  115 , moved towards the centre section  119  and directed outwardly from the centre section  119  via the side gusset portions  121  towards the side walls  111 . 
         [0195]    The top section  123  of the front wall  112  is curved or bent over towards the front wall  112  by a few degrees to maintain a concave shape and assist in retaining excavated material. The side walls  111  extend above the top of the front wall  112  and cooperate with the front wall  112  to retain excavated material. The bracket  124  is positioned between the top section  123  and the side walls  111  to strengthen the integrity of the blade  100 . There is an attachment point  125  on the side wall  111  positioned above and behind the front wall  112 . The position of the attachment point  125  above and behind the front wall  112  enables a crane to lift the blade  100  without being unbalanced and swinging crookedly. 
         [0196]    In the first preferred embodiment, there is shown a boxed gusset in the corner formed between the side wall and the front wall. In the second preferred embodiment, there is no need for the boxed gusset as the side wall  111  extends above the front wall  112  and the attachment point  125  for lifting the blade  100  is above and behind the front wall  112 . 
         [0197]    With reference to  FIGS. 25 ,  26  and  27 , mountings  103  and  105  located on the back face  132  of the blade  100  allow attachment of lifting arms  102  and rams  104 , 109  respectively. The mountings  103 ,  105  are located close to the back face  132  in order that the centre of gravity is moved back towards the dozer  101  thereby providing the dozer  101  with greater control and balance with respect to operation of the blade  100 . 
         [0198]    With reference to  FIGS. 28 and 29 , there is shown apertures  127  in the top section  123 . These apertures  127  are located in the centre and sides of the top section  123 . These apertures  127  provide the operator with a view of what is in front of the blade  100 . The second preferred embodiment has apertures  127  on both sides of the top section  123 . 
         [0199]    It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or in any other country. 
         [0200]    In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word “comprise” or variations such as “comprises” or “comprising” is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.
An improved blade assembly for an excavating apparatus having a front wall with a raised concave centre section with sloping side gussets on each side of the centre section for directing excavated material from the centre to the side of the blade is described. There are improvements to the side gussets to further assist in directing excavated material, improvements to the shape of the front wall of the blade to retain excavated material and improved mountings to the dozer to improve blade control and balance and discharging of excavated material.