Abstract:
The present invention is a road grader attachment that attaches to a bulldozer. The attachment has an elongated blade with mutually parallel side members attached to the lateral ends of the blade where each of the side members comprise a pair of spaced apart walls that house a plate movable in an up and down direction within the side member. Each of the movable plates is attached at its lower edge to a ground contacting skid. A hydraulic piston interconnects each side member with its respective interior plate for moving the plate up and down within the side housing member in order to raise or lower the skid that is attached to the movable plate

Description:
RELATED APPLICATIONS 
       [0001]    The present invention claims priority on patent application Ser. No. 11/397,399, filed on Apr. 5, 2006, entitled “Road Grader/Spreader” and is hereby incorporated by reference. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
       [0002]    Not Applicable 
       THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT 
       [0003]    Not Applicable 
       REFERENCE TO A SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING 
       [0004]    Not Applicable 
       BACKGROUND OF THE INVENTION 
       [0005]    The prior art reveals a considerable number of devices designed to spread materials over the ground or over existing layers of material where it is desirable to obtain a finished grade. All of the known apparatus of this kind are towable behind a tractor or similar vehicle. Such a device is disclosed in U.S. Pat. No. 6,308,785 to Rhoden, issued Oct. 30, 2001. 
         [0006]    Machines similar to the Rhoden grader/spreader are satisfactory for their intended agricultural purposes but have limitations when applying and spreading materials for road and highway construction. The depth or thickness of layers of gravel and other materials that comprise a road or highway are carefully specified by the design engineers. In many cases the depth requirement is a minimum figure and unintended deposition of a greater amount of material is wasteful and overly expensive. For example, many excess cubic yards of material would be consumed if one inch of material in excess of the specification is applied to a multi-mile roadway thirty feet wide. Failure to maintain a minimum depth of gravel can result in expensive rework. Commonly, the minimum depth for a gravel road is maintained by having a surveying crew place blue tops into the base grade every 60 feet or so. A blue top is a survey or grade stake usually made of plastic with a solid cylinder at one end and a plurality of flexible tails on the second end. Then gravel is placed on the base grade so that the blue tops are covered by the gravel. A road grader then grades the gravel so that the top of the gravel is at the beginning point of the blue tops. Often this takes multiple passes by the road grader. In addition, error can occur in the areas of the road between the blue tops. As a result, considerable time and effort is used to obtain a consistent depth of gravel for a road. 
         [0007]    When a grader/spreader is pulled by a vehicle it can be assumed that the towing vehicle is going to traverse surface variations that are going to cause the grader/spreader to undulate in response to the pitching motions of the towing vehicle. Where the work is being done to construct or resurface a road or highway the rising and falling movement of the grader results in an uneven surface on the material being spread, together with significant departures from the design specification. Agricultural endeavors do not require the grader precision that must be present in road and highway work. Previous devices require a survey team to place blue tops along the base grade of a gravel road. The blue tops define the height of the gravel road and have to be accurately placed at spaced intervals requiring an expensive survey crew. The gravel is then placed over the blue tops and a road grader moves the gravel until all of the tail of the blue tops is exposed but not the body. This process takes multiple passes by the grader to be accurate. Also this does not ensure that the depth between the blue tops is accurate. If the level of the gravel between the blue tops is too low, this requires expensive rework. The previous methods of laying a gravel road often place additional gravel on the road to avoid this rework. However, this is wasteful and expensive. 
         [0008]    Thus there exists a need for a road grader/spreader that accurately lays down a layer of gravel in a single pass. 
       BRIEF SUMMARY OF INVENTION 
       [0009]    The present invention is a road grader attachment that attaches to a bulldozer. The attachment has an elongated blade with mutually parallel side members attached to the lateral ends of the blade where each of the side members comprise a pair of spaced apart walls that house a plate movable in an up and down direction within the side member. Each of the movable plates is attached at its lower edge to a ground contacting skid. A hydraulic piston or similar in reciprocating device interconnects each side member with its respective interior plate for moving the plate up and down within the side housing member in order to raise or lower the skid that is attached to the movable plate. Up and down movement of the skids with respect to the side members that are attached to the blade results in selective positioning of each end of the blade so their respective elevations above the grade on which the skid rests will result in a precise depth and slope of the material that is being spread. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0010]      FIG. 1  is a perspective view of a bulldozer pushing the grader/spreader of the present invention. 
           [0011]      FIG. 2A  is a rear perspective view of the grader blade of the present invention showing in cross section a fragmentary view of the bulldozer blade that mounts the grader blade. The illustrated left side skid is shown in the retracted position that allows the left end of the grader blade to be at essentially the same level as the skid. 
           [0012]      FIG. 2B  is a fragmentary perspective view of the grader blade with the illustrated left end of the blade raised above the level of the left side skid. 
           [0013]      FIG. 3  is a cross sectional view taken along lines  3 - 3  in  FIG. 2A . 
           [0014]      FIG. 4  is a top right perspective view of the front of an expandable grader attachment in accordance with one embodiment of the invention. 
           [0015]      FIG. 5  is a top right perspective view of the back of the expandable grader attachment in accordance with one embodiment of the invention. 
           [0016]      FIG. 6  is a flow chart of the steps of creating a gravel road in accordance with one embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]    The grader/spreader  2  of the present invention is shown in  FIG. 1  as mounted on and carried by the front blade  4  of a bulldozer  6  is spreading gravel  8  to a specified layer depth. Prior to spreading the gravel is piled in front of the blade  10  of the grader/spreader  2 . The bulldozer operates on top of the finished grade  12  of the gravel, or other material that is being spread, thereby assuring a level and constantly accurate depth of the layer  14 . 
         [0018]    The depth of the layer  14  above the base grade  16  is controlled by the elevation of the bottom edge of the blade  10  above the base grade. The elevation of each lateral end of the blade  10  may be independently set by hydraulic controls in the cockpit of the bulldozer. This selective adjustment of the height of the blade allows the grade to be sloped from right to left or left to right, or with equal height of each blade end resulting in a level grade. 
         [0019]    The novel apparatus for selective adjustment of the height of the blade ends is illustrated in  FIGS. 2A and 2B . To the lateral ends of the grader blade  10  there are attached side members  20  and  22 . Each of the side members includes a pair of spaced apart steel panels  24  and  26  between which is disposed a plate  28  that is slidable in an up and down direction. The bottom edge of the plate  28  is secured to a flat skid  30  that is adapted to run along the base grade  18  of the roadway being worked on. To provide the force necessary to slide the plate  28  between the panels comprising each of the end members and thus raise or lower the skid  30 , a hydraulic piston  32  is provided. One end of the piston is attached to the skid  30  while the other end of the piston is housed within the hydraulic cylinder  34  that is attached to the side of the outside side member panel  24 . The hydraulic piston and cylinder are conventional in their construction and are operated by the pressure of hydraulic fluid controlled by valves. The controls for the hydraulic system are located in the cockpit of the bulldozer (not shown). Appropriate application of the hydraulic controls will cause the piston  32  to extend out of the cylinder  34  and force the movable plate  28  downwardly and partially out of the side member housing  20 . This movement of the plate  28  causes the end member  20  and the left end of the blade  10  to be raised with respect to the skid  30  ( FIG. 2B ). With opposite adjustment of the hydraulic controls the piston  32  is made to retract into the cylinder  34 , thus lowering the elevation of the blade  10  with respect to the skid  30  ( FIG. 2A ). While hydraulic apparatus is the preferred form of motive force, other well known means may be employed that provide sufficient downward pressure on the skids  30  and keep the bottom of the blade at the right height above the base grade  16 . 
         [0020]    While a single hydraulic piston may be sufficient to supply the power to raise and lower the blade end, a single piston may be structurally unstable. To overcome the instability a tubular sleeve  40  is attached to the outside side member panel  24  and the distal end of a slidable insert  42  is attached to the skid  30 . Thus, while the hydraulic piston and cylinder are supplying the necessary force to move the plate  28  within the end member, the sleeve and slidable insert supply the required structural stability between the movable members. 
         [0021]    To ensure that the skid  30  remains in solid contact with the base grade  16  an auxiliary plow  46  is angularly attached to the front of each skid  30 . The plow is angled inwardly toward the blade  10  so that the material being spread will not collect in front of the skid  30  so as to pass beneath the skid and upset the precision of the height adjustment of the blade  10 . 
         [0022]    As seen in  FIGS. 2A and 3  the bottom of the bulldozer blade  4  rests on the top surface of a plurality of rearwardly protruding brackets  50 . In one embodiment, a stop  52  carried by the bracket is screwed against the back of the bulldozer blade  4  to hold the bulldozer blade in place against the grader blade  10 . Between the top portion of the bulldozer blade and the top of the back side of the grader blade a jack screw  55  provides a compression connection between the two blades. Adjustment of the jack screw operates to establish the tilt of the grader blade. 
         [0023]      FIG. 4  is a top right perspective view of the front of an expandable grader attachment  100  in accordance with one embodiment of the invention. The expandable grader attachment  100  is similar to that shown in  FIGS. 1-3 , but is expandable. This embodiment of the expandable grader attachment  100 , has a blade made of three portions  10   a ,  10   b ,  10   c . The outer portions  10   a  &amp;  10   b  have a number of adjustment holes  102  that align with the adjustment holes  104  of the center portion. Bolts and nuts are used to lock the three portions of the expandable blade  10   a ,  10   b ,  10   c  together. Slides or other forms of holding the blade portions  10   a ,  10   b ,  10   c  together are not rigid enough to produce a high quality gravel road surface. This figure also shows that the hydraulic pump  106  is mounted to the backside of the expandable grader blade  100 . The hydraulic pump  106  connects electrically  116  to a bulldozer&#39;s electrical system and provides the hydraulic power to hydraulic cylinders and pistons  32 . Each blade portion  10   a ,  10   b ,  10   c  has an adjustable crown plate  106   a ,  106   b ,  106   c . The crown plates  106   a ,  106   b ,  106   c  have slots  108   a ,  108   b ,  108   c  that align with holes in the blade portion  10   a ,  10   b ,  10   c . Bolts are loosened to change the position crown plates  106   a ,  106   b ,  106   c  and then tightened to hold them in place. These adjustable crown plates  106   a ,  106   b ,  106   c  allow the expandable grader blade  100  to contour the gravel road to have a custom crown. 
         [0024]    The skids  30  are equipped with replaceable wear pads  110 . Since the skids  30  ride on the base grade they wear out over time. The wear pads  110  are designed to be replaced. The outer portions of the expandable blade  10   a  &amp;  10   b  have braces  112  that connect the blade portion to plate  24 . This add stability to the system  100 . 
         [0025]      FIG. 5  is a top back perspective view of the front of the expandable grader attachment  100  in accordance with one embodiment of the invention. This view shows that the expandable blade has a rack and pinion system  114  that is used to expand or contract the size of the expandable blade  10   a ,  10   b ,  10   c . Once the expandable blade  10   a ,  10   b ,  10   c  is in the desired position, then the blade portions are bolted together for stability. This view also shows the electrical cord  116  that connects to the bulldozer&#39;s electrical system. The plurality of rearward protruding brackets  50  are shown in this view. A pair of height gages  118 ,  120  allows the operator of the bulldozer to view the depth of the gravel  14 . Note the height of each side of the expandable grader blade can be set separately. A pair of stability arms  122  (only one is shown) has a pintle hitch  124  connecting to the grader blade  10 . An expandable arm  126  has a number of preset lengths and a screw for finer adjustments of the length. A second pintle hitch  128  attaches to a bulldozer. The stability arms provide bracing to the side blades when they are extended beyond a certain point, since the structure will have increase leverage loads toward the ends of the side blades when the side blades are extended. 
         [0026]      FIG. 6  is a flow chart of the steps of creating a gravel road in accordance with one embodiment of the invention. The process starts, step  140 , by preparing a base grade at step  142 . A width of the road is determined at step  144 . A grader/spreader system is attached to the front blade of a bulldozer at step  146 . A length of the expandable grader blade is set at step  148 . A height of the expandable grader blade is set hydraulically at step  150 . A plurality of crown plates are set on the expandable grader blade at step  152 . A pair of ground contacting skids of the grader/spreader system are placed on the base grade at step  154 . A mound of gravel is placed in front of the grader/spreader system at step  156 . At step  158 , the bulldozer is driven forward which ends the process at step  160 . 
         [0027]    Using the system described herein an accurate depth of gravel is laid on the base grade in a single pass without any rework being necessary. The system does not require blue tops, associated surveying costs, or multiple passes like previous techniques of laying down an accurate gravel road. Accurate depth of the gravel road is accomplished by the down pressure applied from the bulldozer through the hydraulic cylinders  32 . The front blade of the bulldozer rests on the brackets  50  and applies down pressure on the expandable grader blade. The pitch screws  55  set the pitch of the expandable grader blade. By setting these so that the grader blade is pitched forward, additional down pressure is created as the bulldozer moves forward. It is important that the bulldozer push the grader blade as this creates a down pressure that cannot be created by pulling the grader blade and allows the bulldozer tracks to ride on the finished grade. The finish grade is level, while the base grade may have some non-uniformity. If the bulldozer tracks rode on the base grade these non-uniformities would translate into non-uniformities in the finish grade. In one embodiment, the invention is attached to a tracked skid steer instead of a bulldozer. 
         [0028]    While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alterations, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alterations, modifications, and in variations in the appended claims.