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CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims domestic priority on U.S. Provisional Patent Application Ser. No. 61/184,350, filed on Jun. 5, 2010, the content of which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention generally relates to an apparatus for preparing a stone base for subsequent construction and, more particularly, to a screed machine that will level a stone base for the installation of a pre-cast concrete wall. 
       BACKGROUND OF THE INVENTION 
       [0003]    Construction of a large number of structures, including buildings, sewer lines, prefabricated structures, etc., begins with the placement of a stone base. In some instances, the stone base must be accurately placed and graded for the proper construction of the structure. For example, a gravity sewer line is constructed at a sloped grade under which the stone base is graded at that same slope to provide proper support for the sewer line. Another example of a stone base that requires precise grading is the stone base under a pre-cast concrete wall. 
         [0004]    A pre-cast concrete wall is manufactured at a remote site and shipped to the job site to be erected. A pre-cast concrete wall, constructed as disclosed, for example, in U.S. Pat. No. 7,530,203, granted on May 12, 2009, to Robert W. Hare, et al., is formed with a footer beam that is placed on a graded stone base. A plurality of the pre-cast concrete wall panels are placed around the pre-graded stone base to form an enclosed foundation for a building to be subsequently built on the foundation. The proper support of the footer beams requires that the stone base beneath the pre-cast concrete walls is graded level in both longitudinal and transverse directions so that the stone will contact the underside of the footer beam all along the erected foundation. 
         [0005]    Conventionally, the grading of the stone base is first rough graded to within about an inch of being level around the location for the erection of the pre-cast concrete walls. Final grading is accomplished by first setting grading monuments, such as a piece of a wooden two by four placed into the stone base, around the perimeter of the foundation to be erected and then leveled at the desired elevation by a laser level. The stone base can then be hand graded by sliding a screed between consecutive monuments so that the stone base between the monuments is at the same elevation as the adjacent monuments. This process is repeated around the perimeter of the foundation until the entire area on which the pre-cast concrete walls are to be erected is leveled at the desired grade elevation. This process is extremely time consuming and labor intensive. 
         [0006]    Accordingly, it would be desirable to provide an apparatus that would be operable to grade a stone base accurately and uniformly without requiring the setting of elevation monuments and hand screeding to accomplish the graded stone base. 
       SUMMARY OF THE INVENTION 
       [0007]    It is an object of this invention to overcome the aforementioned disadvantages of the known prior art by providing a manually operated screed machine for leveling a stone base for the installation of pre-cast concrete walls. 
         [0008]    It is another object to provide a screed assembly that is vertically movable relative to ground support members to maintain a selected grade elevation for the stone base as the screed machine is moved along the stone base where the pre-cast concrete walls are to be positioned. 
         [0009]    It is a feature of this invention that the screed assembly is mounted on a telescopic mast that is operably connected to an actuator to affect vertical movement of the screed assembly. 
         [0010]    It is an advantage of this invention that the actuator can be electronically coupled to a laser receiver to affect movement of the screed assembly in conjunction with a laser level defining the final grade for the stone base. 
         [0011]    It is another feature of this invention that the screed machine is supported on the ground by a pair of longitudinally spaced rollers. 
         [0012]    It is another advantage of this invention that the rollers allow the screed machine to be moved over the stone base. 
         [0013]    It is still another advantage of this invention that the screed assembly is positioned in front of the forwardmost roller so that the rollers are supporting the screed machine on the final grade of the stone base. 
         [0014]    It is still another feature of this invention that the screed assembly is formed with a forwardly projecting wedge portion that sweeps excess stone base laterally as the screed machine is moved forwardly over the stone base. 
         [0015]    It is yet another feature of this invention that the screed assembly is formed with a pair of laterally extending wings that project in opposing directions from the wedge portion to deflect stone base material laterally away from the rollers. 
         [0016]    It is yet another advantage of this invention that each of the wings is mounted on a pivot to permit a positioning of the wings in selective angular orientations relative to the wedge portion. 
         [0017]    It is still another advantage of this invention that the rollers compact the leveled stone base after the stone base is leveled by the screed assembly. 
         [0018]    It is still another object of this invention to provide a method of fine grading a stone base to prepare for the installation of pre-cast concrete walls on the stone base. 
         [0019]    It is a further feature of this invention that the stone base is rough graded before the screed machine is placed on the stone base. 
         [0020]    It is still a further feature of this invention that the screed machine is pulled along a path on the stone base corresponding to the location along which the pre-cast concrete wall panels are to be installed. 
         [0021]    It is a further advantage of this invention that the final grade is set on a laser level with the signal therefrom being received on the screed machine to cause vertical adjustment of the position of the screed assembly. 
         [0022]    It is yet another object of this invention to provide a pivot mechanism to allow the screed machine to turn corners on the stone base without disturbing the final grade thereof. 
         [0023]    It is still another feature of this invention that the frame of the screed machine supports a jack stand that is selectively positionable into engagement with the stone base to allow the screed machine to be lifted above the stone base and rotated to change directions for the movement thereof. 
         [0024]    It is still another advantage of this invention that the jack stand is positioned at approximately the center of gravity of the screed machine so that the entire screed machine can be balanced on the jack stand for rotation about the axis corresponding to the jack stand. 
         [0025]    It is yet another advantage of this invention that the extension of the jack stand is powered by an actuator. 
         [0026]    It is still another object of this invention to provide a monitor to indicate the lateral inclination of the screed machine. 
         [0027]    It is another feature of this invention that the lateral level monitor includes a sight level mounted the mast of the screed machine. 
         [0028]    It is yet another feature of this invention that the frame of the screed machine is provided with a handle assembly that allows an operator to manually pull the screed machine along the desired path on the stone base. 
         [0029]    It is a further feature of this invention that all of the actuators on the screed machine are electrically powered from a battery supported on the screed machine. 
         [0030]    It is yet another object of this invention to provide a screed machine for leveling a stone base that is durable in construction, inexpensive of manufacture, carefree of maintenance, facile in assemblage, and simple and effective in use. 
         [0031]    These and other objects, features and advantages are accomplished according to the instant invention by providing a screed machine having a forwardly positioned screed assembly including a wedge portion and pivoted wing members. The frame is supported on two rollers longitudinally spaced behind the screed assembly. The screed assembly is mounted on a mast for vertical movement in conjunction with a laser receiver that provides a signal indicating the final desired grade of the stone base. The machine can be turned at a corner by extension of a jack stand to elevate the entire machine for rotation about the axis defined by the centrally located jack stand so that the screed machine can be redirected into a different direction without disturbing the final grade of the stone base. The screed machine is manually moved along the stone base by an operator pulling on the handle pivotally connected to the frame. A sight level provides a monitor for the lateral orientation of the screed assembly. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0032]    The advantages of this invention will be apparent upon consideration of the following detailed disclosure of the invention, especially when taken in conjunction with the accompanying drawings wherein: 
           [0033]      FIG. 1  is an upper, left front perspective view of the screed machine incorporating the instant invention, the wings being pivoted outwardly to widen the screed width of the apparatus; 
           [0034]      FIG. 2  is an upper, right rear perspective view of the screed machine shown in  FIG. 1 ; 
           [0035]      FIG. 3  is a left rear perspective view of the screed machine shown in  FIG. 1 ; 
           [0036]      FIG. 4  is a front elevational view of the screed machine having the wings pivoted inwardly to a non-operational position; 
           [0037]      FIG. 5  is a front elevational view of the screed machine similar to that of  FIG. 4 , but having the screed broken away to view the structure at the front of the apparatus, the wings being pivoted outwardly; 
           [0038]      FIG. 6  is a left side elevational view of the screed machine having the wings pivoted outwardly; 
           [0039]      FIG. 7  is a rear elevational view of the screed machine, the wings being pivoted inwardly to a non-operative position; 
           [0040]      FIG. 8  is a rear elevational view of the screed machine similar to that of  FIG. 7 , but having the wings pivoted outwardly; 
           [0041]      FIG. 9  is a top plan view of the screed machine having the wings pivoted inwardly; 
           [0042]      FIG. 10  is a top plan view of the screed machine similar to that of  FIG. 9 , but having the wings pivoted outwardly; 
           [0043]      FIG. 11  is a right rear perspective view of the screed machine with the handle being broken away to better view the frame components of the apparatus, the wings being pivoted outwardly; 
           [0044]      FIG. 12  is a right side elevational view of the screed machine having the wings pivoted outwardly and the central support jack extended to allow the screed machine to make a turn; 
           [0045]      FIG. 13  is a front elevational view of the screed machine shown in  FIG. 12 ; 
           [0046]      FIG. 14  is a cross-sectional perspective view of the left side of the screed machine taken along lines  14 - 14  of  FIG. 9 ; 
           [0047]      FIG. 15  is a cross-section perspective view near the center of the screed machine taken along lines  15 - 15  of  FIG. 10 ; and 
           [0048]      FIG. 16  is a perspective view of the screed machine collapsed into a compact transport orientation. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0049]    Referring to  FIGS. 1-16 , a screed machine incorporating the principles of the instant invention can best be seen. Left, right, front and rear references are use as a matter of convenience and are determined by standing at the rear of the machine  10  and facing the handle assembly  16  mounted at the forward end to pull the machine  10  along a direction of operative travel. The screed machine  10  has a generally rectangular main frame  11  having a central transverse cross member  11   a . The main frame  11  rotatably supports a pair of longitudinally spaced, transversely extending rollers  15  that engage the surface of the stone base to compact and smooth the surface being leveled, as will be discussed in greater detail below. The main frame  11  has a pair of grips  13  located on each transverse side of the frame to provide an apparatus on which people can grasp to push the screed machine  10  when necessary. The main frame  11  also includes a crane hoist  14  centrally located on the main frame  11  so that a crane can be attached to the main frame  11  to lift the machine  10  into and out of a foundation excavation. Preferably, a removable or hinged cover plate  12  is mounted on top of the frame  11  to shield the operative devices described in greater detail below. 
         [0050]    The handle assembly  16  is mounted at the front end of the main frame  11  and projects forwardly to be grasped to pull the machine  10  over the surface of the stone base. The handle assembly  16  is preferably pivotally attached to the main frame  11  by pivots  17 . The handle assembly  16  can be formed with a U-shaped handle  16   a  that terminates in a mounting leg  16   b  that is oriented orthogonally to the handle  16   a . The mounting legs  16   b  are connected to the pivots  17  so that the height of the handle  16   a  can be varied to the preference of the operator. As best seen in  FIGS. 3 and 11 , the handle assembly  16  also includes a pivot control device  18 , including an apertured plate  18   a  affixed to the main frame  11  and a pivot lock  19  that is engagable with a selected one of the apertures in the plate  18   a  to lock the handle  16   a  in a selected height. 
         [0051]    A screed assembly  20  is pivotally mounted on the main frame  11  and is positioned in front of the main frame  11  to engage the top surface of the stone base to level the stone base. The screed assembly  20  includes a U-shaped support frame  21  pivotally connected to the main frame  11  at pivots  23  located approximately centrally on the main frame  11  to give the pivotal movement of the screed assembly  20  an arc that is substantially linear forwardly of the main frame  11 . The support frame  21  has mounted thereon a screed member  25  that includes a rearward linear portion  26  extending transversely across the entire front of the machine  10  and projecting outboard of the main frame  11  to either side thereof. The screed member  25  also includes a V-shaped wedge portion  28  mounted to the front of the linear portion  26  to provide a screed member  25  that has longitudinal depth and operates to move excess stone outboard of the surface being leveled by the machine  10 . 
         [0052]    The screed assembly  30  also includes a pair of laterally spaced side extension wings  30  positioned at each respective outboard end of the linear portion  26  of the screed member  25 . Each side extension wing  30  is pivotally connected to the respective end of the linear portion  26  by a vertical hinge  32  to permit the side extension wing  30  to move between a retracted, inoperative position seen in  FIGS. 4 ,  7  and  9 , and an extended operative position seen in  FIGS. 1 ,  2 ,  5 ,  6 ,  8 ,  10  and  11 . The movement of the side extension wings  30  is best seen in comparison of  FIGS. 4 and 5 , and in comparison of  FIGS. 7 and 8 , and also  FIGS. 9 and 10 . A position control apparatus  35  is operable to lock each of the side extension wings in a selected pivoted position. 
         [0053]    An apertured plate  36  mounted on top of the vertical hinge  32  is engaged by a spring-loaded pivot lock  38  having a perpendicularly extending actuation lever  39 . With the spring-loaded pivot lock  38  retracted, the side extension wing  30  can be pivoted to the desired position and the actuation lever released to engage the pivot lock  38  with one of the holes in the plate  36  to lock the side extension wing  30  in position. The movement of the side extension wings  30  into an operative position expands the transverse width of the surface of the stone base being leveled by the screed assembly  20 , which will provide room for the machine  10  to make a turn, as will be described in greater detail below. 
         [0054]    The screed assembly  20  is pivotally movable to cause a vertical adjustment of the screed member  25  by a screed control mechanism  40 . A mast  41  is mounted on the transverse support frame member  22  to be vertically movable therewith. The mast  41  preferably includes a base member  42  and an extendable top mast member  43  supported by the base member  42  which is attached to the transverse support frame member  22 . A laser receiver  45  is connected to the top mast member  43  by an adjustable mounting apparatus  46  that permits the laser receiver  45  to be positioned vertically along the top mast member  43 . An electrically powered linear actuator  47  is mounted on the main frame  11  and operatively connected to the base member  42 . The linear actuator  47  is operatively coupled to the laser receiver  45  through a controller  48  that incorporates switches for automatic control of the screed member  25  and manual control thereof. 
         [0055]    When in the automatic control mode, the controller  48  receives a signal from the laser receiver  45  that the laser receiver  45  is moving up and/or down with respect to a laser level signal (not shown). The controller  48  activates the linear actuator  47  to cause the linear actuator  47  to expand or contract, as appropriate, to move the mast member  41  and, thus, the screed member  25 , thereby keeping the screed member  25  at a level orientation as the machine  10  is moved across the top surface of the stone base. The support panel  44 , on which the control mechanism  48  is mounted, is preferably mounted on the handle  16  for convenient access by the operator. The control mechanism  48  is also provided with a sight level  49  that indicates the level of the machine  10  in a transverse direction. One skilled in the art will recognize that electrical wires for the control mechanism and related electrically powered components are removed from the drawings for purposes of clarity, although some components, such as the operative connection between the laser receiver  45  and the control mechanism  48  may be wireless. 
         [0056]    An electrically powered jack  50  is mounted on the frame  11 , preferably the transverse cross member  11   a . The jack  50  has a pivotable linkage member  52 , configured as a four-bar linkage, to permit the bottom plate assembly  51  to remain in a vertical orientation. The bottom plate assembly  51  includes a bottom plate member  54  that is rotatable relative to the remainder of the assembly  51 . The pivotable member  52  is operatively connected to an electrical jack actuator  53  that upon extension and contraction effects vertical movement of the linkage member  52 . The bottom plate  52  at the terminus of the linkage member  52  can swivel relative to the linkage member  52  on which it is mounted. As is represented in  FIGS. 12-15 , the extension of the linkage member  52  presses the bottom plate  54  onto the stone base and raises of the screed machine  10  above the surface of the stone base. The swiveling bottom plate  54 , on which the weight of the machine  10  is supported on the stone base, allows the entire machine  10  to be rotated and, thus, affect a turn of the machine  10  to be movable in a different direction. Once the machine  10  is reoriented, the linkage member  52  is retracted and the screed machine  10  is free to operate in the new direction. 
         [0057]    Power for the electrically operated components, such as the linear actuator  47 , the control mechanism  48  and the jack actuator  53 , is provided by a 12-volt marine battery  55  supported on a battery support pan  57  mounted on the main frame  11  between the rollers  15 . The battery support pan  57  is positioned higher than the rollers  15  and, thus, will not contact the stone base. The support panel  44  has mounted thereon a battery life gauge  59  operably connected to the battery  55  to provide a visual indication of the amount of electrical power remaining in the battery  55 . The battery  55  is preferably rechargeable. 
         [0058]    The screed machine  10  operates in conjunction with a laser level (not shown) that is set up on site and emits a laser signal to indicate the proper grade of the stone base being prepared. In the case of a stone base to be prepared for a pre-cast concrete wall, the laser level emits a laser signal that indicates a level grade at a given elevation. In the case of a sewer line that is placed on a slope gradient, the laser level emits a laser signal that is indicative of that slope gradient. The laser signal is received by the laser receiver  45  that must be positioned on the top mast member  43  by manipulating the mounting apparatus  46 . The screed machine  10  is then placed on the stone base at a position corresponding to the desired elevation of the prepared stone base in an orientation that will coordinate the movement of the screed machine  10  with the alignment of the position of structure to be erected on the stone base, typically by a crane or a powered lift that is connected to the crane hoist member  14  to lower the screed machine  10  into the excavation where the stone base has been placed. 
         [0059]    The screed machine  10  has the jack  50  retracted and preferably has the side extension wings  30  retracted into the inoperative position and locked into place with the position control apparatus  35 . The transverse orientation of the screed machine  10  must be level, which can be authenticated by observing the pendulum  49 . If the sight level  49  indicates that the screed machine  10  is not level, the stone base at which the screed machine  10  is to start operation must be manually leveled so that the screed machine  10  starts operation in a transversely level orientation. The screed control mechanism  40  is powered on and switched into the automatic mode of operation. The screed machine  10  is then ready for movement along the path corresponding to the location at which the structure, which in this example would be a pre-cast concrete wall, would subsequently be erected. 
         [0060]    Operation of the screed machine  10  is preferably accomplished by two people. One person grasps the handle  16   a , which can be pivotally positioned through manipulation of the position control device  18  to locate the handle  16   a  at a convenient height, and pulls the screed machine along the desired path. The second person utilizes a shovel to assure that a supply of the stone base is piled in front of the wedge portion  28  of the screed member  25  entirely across the transverse width of the screed member  25 . If the screed machine  10  is moved and operated without a supply of stone base in front of the screed member  25 , the screed member  25  can leave a section of the path of the stone base below the desired grade. If the supply of the stone base in front of the screed member  25  is too great, the screed machine  10  will be more difficult to pull along the desired path. Accordingly, the stone base needs to be rough graded to within about an inch or so of the desired final grade before the screed machine  10  is utilized. 
         [0061]    As the first person pulls on the handle assembly  16 , the screed machine  10  is dragged along the desired path of the stone base that is to be finally graded. The laser signal received by the laser receiver  45  identifies the elevation along which the laser receiver  45  is to travel. As the laser receiver  45  moves up or down outside of a predetermined range, corresponding to the screed member  25  changing elevation, electrical power is directed to the linear actuator  47  by the control mechanism  48  to cause the base  42  of the mast  41  to be raised or lowered accordingly. As a result, the screed member  25 , which is connected to the base  42  of the mast  41  moves vertically to keep the position of the screed member  25  at the desired elevation. The depth of the screed member  25  from the wedge portion  28  to the linear portion  26  keeps the stone base level without ridges and valleys caused by the vertical adjustment of the screed member  25  through operation of the control mechanism  48 . 
         [0062]    When the screed machine  25  approaches a corner on the desired path along which the stone base is to be finally graded, it is desirable to widen the transverse width of the path being graded on the stone base to affect the turn at the corner, as will be described in greater detail below. To increase the transverse width of the graded path, the operator needs to depress the actuation lever  39  on the side extension wing  30  corresponding to the inside of the turn to be made so that the side extension wing  30  can be rotated outwardly into an appropriate operative position, whereupon the actuation lever  39  can be released and the side extension wing  30  locked into place. Because the bottom edge of the side extension wings  30  are co-planar with the linear portion  26  and wedge portion  28  of the screed member  25 , the side extension wing  30  simply widens the path being graded by the screed machine  10 . 
         [0063]    One skilled in the art will recognize that the side extension wings  30  increase the drag on the screed member  25  and, therefore, increases the force required to move the screed machine  10 . If additional assistance is required to move the screed machine  10  along the path being graded, the other person, or persons, helping the operator can grasp the grips  13  and assist in pushing the screed machine  10 . At the turn, the screed machine  10  is moved along the path to be graded until the distal tip of the side extension wing  30  that has been deployed into the operative position has cleared the path to be graded after the turn. 
         [0064]    When the screed machine  10  has been moved to a position where the deployed side extension wing  30  the location of the jack  50  is at or near the center of the new path on the stone base to be graded after the turn. The operator deactivates the control mechanism  48  by either turning the control mechanism  48  off or switching the control mechanism  48  into manual mode, and then activates the actuator  53  to extend the jack  50  and engage the bottom plate  54  on the graded surface of the stone base immediately below the screed machine  10 . Continued extension of the jack  50  will raise the screed machine  10 , as is reflected in  FIGS. 12 and 13 . Balance of the machine  10  is maintained because the jack  50  is located at the center of gravity of the machine  10  and also by the operator holding the handle  16 . 
         [0065]    Once elevated off of the stone base, the machine  10  can be pivoted about the vertical axis defined by the bottom plate assembly  51  due to the swiveled bottom plate  54 . Accordingly, the screed machine  10  can be aligned on the next path to be graded. The extra transverse width of the screed member  25  provided by the extension of the wing  30  graded off a sufficient portion of this next path that the entire screed machine  10  will be placed on a leveled surface to start operation along this next path to be graded. When the screed machine  10  is properly aligned on the next path, the side extension wing(s)  30  are repositioned to the inoperative position and the jack  50  is retracted to place the rollers  15  and the screed member  25  back onto the stone base. The control mechanism  48  can then be switched back to the automatic mode and the screed machine  10  can be pulled along this next path as described above until reaching the next turn. 
         [0066]    When finished, the entire perimeter on the stone base corresponding to the erection of the pre-cast concrete walls into a foundation will be graded to a level elevation as defined by the laser level and the paths on the stone base compacted by the weight of the screed machine  10  exerted on the rollers  15 . The pre-cast concrete walls can be erected on the graded paths with full support from the graded stone base. Similarly, the screed machine  10  can be used to grade and compact the stone base for a sewer line, the primary difference being that the laser level will be set on the slope gradient for the sewer line and the automatic function of the control mechanism  48  will properly adjust the screed machine to grade the stone base along the desired slope gradient. 
         [0067]    It will be understood that changes in the details, materials, steps and arrangements of parts which have been described and illustrated to explain the nature of the invention will occur to and may be made by those skilled in the art upon a reading of this disclosure within the principles and scope of the invention. The foregoing description illustrates the preferred embodiments of the invention; however, concepts, as based upon the description, may be employed in other embodiments without departing from the scope of the invention.

Summary:
A screed machine is formed with a forwardly positioned screed assembly including a wedge portion and pivoted wing members. The frame is supported on two rollers spaced behind the screed assembly, which is mounted on a mast for vertical movement in conjunction with a laser receiver that provides a signal from a laser level indicating the final desired grade of the stone base. The machine can be turned at a corner by extension of a jack stand to elevate the machine for rotation about the axis defined by the centrally located jack stand so that the screed machine can be redirected into a different direction without disturbing the final grade of the stone base. The screed machine is manually moved along the stone base by an operator pulling on the handle pivotally connected to the frame. A sight line provides a monitor for the lateral orientation of the screed assembly.