BACKGROUND OF THE INVENTION 
   The present invention relates to a dual drive material turning machine and method. Composting requires that the material being composted be turned or aerated periodically in order to achieve the biodegradation necessary in order to change the material to compost. Therefore, a need has arisen for equipment for quickly and easily turning and aerating the material being composted. 
   Prior compost windrow turners are shown in U.S. Pat. Nos. 4,932,196; 4,976,095; and 5,893,262. These prior compost windrow turners utilize an elevated moving face for lifting the compost material upwardly and for depositing it to the rear of the device. They include a drive mechanism provided by a tractor or other vehicle at one side of the device. 
   One disadvantage of these prior devices is that unusual bending forces are applied to the elevated moving face during the time that the compost turning occurs. This is the result of the drive mechanism being placed at one side of the compost turner. 
   One of the patents, U.S. Pat. No. 4,976,095, shows a plurality of vanes 96 which are connected by a single rod so that they will always remain parallel to each other and can be moved simultaneously by movement of a single rod. Because all of these vanes are parallel to one another, it is not possible to change the shape or configuration of the pile of material being deposited at the rear of the device. 
   Also, in prior devices, sprockets are used at the lower end of the device for tightening the belt which is trained around an upper sprocket and a lower sprocket. Tightening devices have been provided which are positioned between the two upper and lower sprockets and also between the front and rear surfaces of the belt being driven. These tightening devices often encounter material being lifted by the belt assembly, and become dirty and exposed to these materials to the point where they sometimes become inoperative. 
   Therefore, a primary object of the present invention is the provision of an improved drive material turning machine and method for operating the same. 
   A further object of the present invention is the provision of an improved material turning machine which utilizes drive tracks on opposite sides of a belt assembly, with both of the drive tracks being driven to propel the machine through the material being aerated and turned. 
   A further object of the present invention is the provision of an improved dual drive material turning machine and method which minimizes the bending forces applied between the lifting apparatus and the drive train for the machine. 
   A further object of the present invention is the provision of an improved dual drive material turning machine and method which includes two sets of vanes that can be independently adjusted so as to change the shape and form of the windrow being deposited behind the turning machine. 
   A further object of the present invention is the provision of an improved tightening apparatus which is protected from the material being lifted by the machine. 
   A further object of the present invention is the provision of a method for moving the machine through an elongated pit containing the material to be turned and aerated. 
   A further object of the present invention is the provision of a method for guiding the machine along a pair of spaced apart channels during the time that the machine is being propelled through the elongated pit containing the material to be aerated. 
   A further object of the present invention is the provision of apparatus for suspending the machine from a pair of spaced apart rails and for lifting the machine to an elevated position above the material to be aerated and for lowering the machine into contact with the material to be aerated. 
   A further object of the present invention is the provision of a pair of elongated pits positioned in side-by-side relationship so that the machine may progress through one of the pits in a first direction and then reverse itself and progress through the second pit in a direction opposite from the first direction. 
   A further object of the present invention is the provision of a material turning machine which is economical to manufacture, durable in use and efficient in operation. 
   SUMMARY OF THE INVENTION 
   The foregoing objects may be achieved by an apparatus for turning material piled on the ground in a windrow. The apparatus comprises a first track assembly and a second track assembly spaced apart from one another and having continuous tracks, each having elongated track axes spaced apart from one another and approximately parallel to one another. A lift assembly is connected between the first and second tracks and comprises an upper end, a lower end, and a belt trained around the upper and lower ends. The lower end is positioned adjacent the ground and the upper end is positioned in spaced relation above the lower end whereby the belt includes a front belt surface extending upwardly from the lower end to the upper end and rear belt surface extending from the upper end to the lower end. A power source is connected to both of the first and second track assemblies for independently driving the first and second track assemblies. The power source is connected to at least one of the upper and lower ends for causing at least one end to rotate and cause the front face of the belt to move continuously from the lower end to the upper end and to cause the rear face of the belt to move continuously from the upper end to the lower end. In this motion, the belt will engage the material piled on the ground and then carry the material upwardly on the front surface of the belt and then drop the material back onto the ground as the belt passes over the upper end. 
   According to another feature of the invention, frame members are provided adjacent the upper end and have a first group and a second group of vanes mounted thereon in spaced relation to one another adjacent the upper end for engaging and guiding the material as the belt carries the material over the upper end and drops the material back onto the ground. 
   According to another feature of the present invention, each of the vanes in the first and second groups have a flat vane surface. The first and second groups of vanes each are independently adjustable to change the direction of the flat vane surfaces so as to direct and guide the material in the desired direction as it passes over the upper end of the lift assembly. 
   According to another feature of the present invention, the upper end includes at least one upper sprocket and the lower end includes at least one lower sprocket. The belt is trained around the upper and lower sprockets. A belt tightening apparatus extends between the upper and lower sprockets and is longitudinally extensible to expand the distance between the upper and lower sprockets and thereby tighten the belt trained around the upper and lower sprockets. 
   According to another feature of the present invention, the belt tightening apparatus comprises a hydraulic cylinder enclosed within a hydraulic cylinder protective housing so as to protect the hydraulic cylinder from coming in contact with the material. 
   The foregoing objects may be achieved by a method for turning a quantity of material resting on the ground. The method comprises moving a continuous belt around the upper end and the lower end so the belt moves along a front surface from the lower end to the upper end and then along a back surface from the upper end to the lower end. The method includes driving a first track connected to one side of the belt and a second track connected to the opposite side of the belt so as to move the belt towards the material resting on the ground. The material on the ground is engaged with the moving belt. It is carried upwardly on the front surface of the belt from the lower end to the upper end and is dropped to the ground as the material passes over the upper end. 
   According to another feature of the present invention, the material is engaged after it passes over the upper end of the belt assembly with a first group and a second group of spaced apart vanes. Each of the vanes has a vane surface and uses the vane surface to guide the material as it drops to the ground. 
   According to another feature of the present invention, the positions of the vanes are adjusted independently of one another so as to change the direction of guidance provided by the vane surfaces to the material as it drops to the ground. 
   According to another feature of the present invention, the quantity of material is contained within an elongated pit. The belt assembly is positioned within the first elongated pit so that it has a lower end engaging the material within the first elongated pit and an upper end above the lower end. A continuous belt is trained around the upper and lower ends. The belt is continuously moved so that it progresses from the lower end to the upper end on the front face of the belt and moves from the upper end to the lower end on a back face of the belt. The material is lifted on the front face of the belt assembly as the belt assembly moves from the lower end of the belt assembly to the upper end of the belt assembly. The material is deposited back in the first pit after the belt assembly has carried the material from the lower end of the belt assembly to the upper end. 
   According to another feature of the present invention, a second pit includes a quantity of material therein also. The method further comprises moving the belt assembly into the second pit after engaging and lifting all the material in the first pit. Then the material in the second pit is engaged with the lower end of the belt assembly and is lifted upwardly and deposited back into the second pit after the material has reached the upper end of the belt assembly. 
   According to another feature of the present invention, the first and second pits are positioned side-by-side and the method comprises moving the belt assembly in a first direction along the length of the first pit and moving the belt assembly in a second direction opposite from the first direction along the length of the second pit. 
   According to another feature of the present invention, the belt assembly is held completely above the material within the first pit and then the lower end of the belt assembly is moved downward into contact with the material within the first pit. 


   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of the dual drive material turning machine of the present invention. 
       FIG. 2  is a front elevational view thereof. 
       FIG. 3  is a sectional view taken along line  3 — 3  of  FIG. 1 . 
       FIG. 4  is a sectional view taken along line  4 — 4  of  FIG. 3 . 
       FIG. 5  is a sectional view taken along line  5 — 5  of  FIG. 2 . 
       FIG. 6  is a partial perspective view showing the detail of the chains and the attached belt crossbars which comprise the belt. 
       FIG. 7  is a top plan view of a pair of pits located in side-by-side relation. 
       FIG. 8  is a sectional view taken along line  8 — 8  of  FIG. 7 . 
       FIG. 9  is a view similar to  FIG. 8 , but showing the belt assembly in its lowered position. 
   


   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIG. 1 , the numeral  10  generally represents one embodiment of the machine of the present invention. Machine  10  includes a first drive assembly  12  and a second drive assembly  14  which are positioned on the opposite sides of a lift or belt assembly  16 . The first drive assembly  12  includes a first engine  18  and a cab  20 . A stairway or ladder  22  leads to the cab  20 . A first track assembly  21  includes a front wheel  24 , a back wheel  26  and a first track  28  trained around the front and back wheels  24 ,  26 . A plurality of idler wheels  30  are positioned between the front and back wheels  24 ,  26 . 
   A second engine  32  includes a second track assembly  33  having a second track  34 . Similar front, rear, and idler wheels (not shown) support the second track assembly  33 . 
   The lift or belt assembly includes first and second side walls  36 ,  38 .  FIG. 4  shows the internal structure within the belt assembly  16 . 
   An internal frame assembly  40  is comprised of four longitudinal frame tubes  42 . The number of frame tubes may be varied without detracting from the invention. An upper cross frame  46 , a middle cross frame  48  and a lower cross frame  50  extend transversely with respect to the longitudinal frame members  42 . Also a cross strip member  51  extends transversely to the longitudinally members  42 . Welded to the cross strip member  51  are a plurality of spaced apart wheel support strips  44  which extend parallel to the longitudinally extending frame members  42 . 
   Extending upwardly from the upper cross frame  46  are a plurality of upper mounting ears  52  having upper bosses  54  mounted thereon. Extending through the upper bosses  54  is an elongated upper sprocket shaft which is rotatable within the bosses  54 . A plurality of sprockets  58  are rigidly attached to the sprocket shaft  56  and are adapted to rotate in unison therewith. A hydraulic motor  60  is drivingly connected to the shaft  56  for rotating the sprockets  58 . Motor  60  is supported by a motor support frame  61  that is rigidly connected to the internal frame assembly  40 . The number of sprockets  58  may vary without detracting from the invention. 
   At the lower end of internal frame assembly  40  are mounted a plurality of lower sprockets  62  which are rotatably mounted within sprocket mounts  64 . Welded to each sprocket mount  64  is an extensible tube  66  which is telescopically received within the elongated longitudinally extending tubes  42 . Also contained within each of the tubes  42  is a hydraulic cylinder  68  having a cylinder rod  70  extending therefrom. A hydraulic hose  72  extends within the middle cross frame  48  which is hollow, and provides hydraulic fluid to each of the hydraulic cylinders  68 . It can be seen from  FIGS. 3 and 4  of the drawings that the walls of tubes  42  protect the cylinder  68  and the cylinder shaft  70  as well as the hydraulic hose  72  from the material being conveyed by the belt  76 . Support wheels  74  are mounted between the strips  44  and are rotatable so as to provide support to the upper surface  122  of the belt  76 . Thus the belt  76  extends upwardly from lower sprocket  62  toward the upper sprocket  58 . Then the belt returns in a downward path from the upper sprocket  58  along a rear face  124  of the belt  76  to the lower sprocket  62 . 
   The belt  76  is shown schematically in  FIGS. 1 and 2 , but its structure and the structure of the chains which guide the belt around the sprockets  58 ,  62  are shown in  FIGS. 5 and 6 . The chains  78  include chain links  79  which are interconnected by a plurality of mounting flanges  80 . Each mounting flange  80  includes an upper horizontal surface  81  for receiving a plurality of cross bars  82 . Each belt cross bar  82  is formed from an L-shaped angle  84  having a plurality of vertical portions  86 . Together, the chains  78 , the mounting flanges  80 , and the belt cross bars  82  form the belt  76 . 
   The bolts  88  bolt the belt cross bars  82  to the upper flat surfaces  81  of the mounting flanges  80 . Thus each L-shaped angle  84  comprises and independent segment of the entire belt  76 . It should be noted that the vertical flanges  86  of each angle  82  are positioned in alternating relationship so that the vertical flanges of one angle  82  are positioned between the vertical flanges  86  of the adjacent angle  82 . 
   A vane assembly  89  is supported by a pair of spaced apart upstanding frame members  90 . Extending between the upper ends of the frame members  90  is a vane cross tube  92 . A first group of vanes  94  is mounted to the cross tube  92  and a second group of vanes  96  is also mounted to the cross tube  92 . The two groups of vanes  94 ,  96  are pivotally mounted to the cross tube  92  for pivotal movement about vane axes  98 . 
   A first vane tie link  100  is connected at the forward ends of vanes  94  and a second vane tie link  102  is connected at the forward ends of vanes  96 . The connection between the first and second vane tie links  100 ,  102  and the two groups of vanes  94 ,  96  is accomplished by a plurality of tie pins  104  that protrude upwardly from the upper edges of the vanes  94 ,  96 . A first hydraulic cylinder  106  includes a first cylinder rod  108 , and a second hydraulic cylinder  110  includes a second cylinder rod  112 . The cylinders  106 ,  108  are connected to the cross bar  92  by a pair of cylinder mounts or ears  114 . The first and second rods  108 ,  112  are connected to the links  100 ,  102  respectively by means of devises  116 . The first group of vanes  94  and the second group of vanes  96  are independently movable with respect to one another. Extension or retraction of the hydraulic cylinders  106 ,  110  cause movement of the vanes  94 ,  96  respectively. It is possible to turn the vanes  94  towards the center and the vanes  96  towards the center so as to create the desired configuration for a windrow of the material  118  being turned. It is also possible to keep them parallel to one another or to direct them outwardly as desired for the resulting configuration of the windrow formed by the material after it has been aerated. Other configurations such as slanting them all the same direction may be used. 
   Referring now to  FIGS. 7–9 , a modified form  126  of the machine is shown. The machine  126  includes a belt assembly  28  which is substantially the same as the belt assembly described for  FIGS. 1–6 . However, the belt assembly  128  includes an upper shaft  130  which is rigidly mounted thereto and which includes crank arms  132  rigidly connected to its opposite ends. A crane head  134  includes a pair of spaced apart downwardly extending belt flanges  136  which rotatably support the upper shaft  30 . Also extending downwardly from crane head  134  are a pair of spaced apart cylinder flanges  138  between which a cylinder  140  is mounted. Cylinder  140  includes a rod  142  which is connected to the end of crank arm  132 . Cylinder  140  is rotatably mounted between the cylinder flanges  138  for pivotal movement about the axis  143 . 
   The crane head  134  is mounted for movement along a crane channel  144  which has channel teeth  148  adjacent its lower end. A plurality of idler rollers  150  are positioned below the channel teeth  148  and a drive gear  152  is positioned above and in engagement with the channel teeth  148 . The drive gear  152  is driven by a hydraulic motor (not shown) which causes movement of the crane head  134  along the length of crane channel  144 . 
   An elongated first pit  154  is shown in  FIG. 7  to be positioned adjacent a second elongated pit  155 . As can be seen in  FIG. 7 , the tracks  144  extend on opposite sides of the pit  154  and then turn back and extend along the opposite sides of second pit  155 . Within the pits  154 ,  155  are materials  156  to be composted. These materials require turning, and they rest upon the pit bottom or floor  158 . 
     FIG. 8  illustrates the belt assembly in its elevated position with the rod  142  extended from the hydraulic cylinder  140 .  FIG. 9  illustrates the belt assembly  128  in its lowered position. It should be noted that bottom roller  160  is mounted on the bottom end of belt assembly  128  and is adapted to roll along the surface or bottom of  158  of pit  154 . 
   The belt assembly  128  is initially in its elevated position shown in  FIG. 8 . The cylinder  140  is retracted and the belt assembly  128  moves to its lowered position shown in  FIG. 9 . At the same time the belt within the belt assembly is actuated to rotate and the material is lifted upwardly on the belt and dropped from the upper end of the belt downwardly back into the pit. The crane head  134  moves slowly in the direction shown by arrow  162  in the first pit  154 . When the left end of the pit  154  is reached, the belt assembly  128  is again elevated to its upper position and the belt is moved around and reversed in direction so that it fits within the second pit  155  moving from left to right as viewed in  FIG. 7 . The belt assembly  128  is then lowered and the crane head  134  continues to move the belt assembly  128  to the right through the material being composted.  FIG. 7  shows the tracks turning towards yet a third pit (not shown). But the tracks may be arranged in a variety of configurations. For example, they could be a loop that turns back to the first pit  154  after completion of the turning of compost in the second pit  155 . Other methods and means may be used for mounting the belt assembly and for passing it through the pits containing the material to be composted. 
   The invention has been shown and described above with the preferred embodiments, and it is understood that many modifications, substitutions, and additions may be made which are within the intended spirit and scope of the invention. From the foregoing, it can be seen that the present invention accomplishes at least all of its stated objectives.
A machine for turning material piled on the ground in a windrow comprises first and second track assemblies spaced apart from one another and having a lift assembly therebetween. The lift assembly lifts the material upwardly and deposits it to the rear. The first and second track assemblies are individually driven so as to eliminate bending forces on the intermediate lifting assembly. Extensible belt tensioners are provided for tensioning the belt, and these extensible belt tensioners are protected from the material being elevated and aerated. The method involves moving the belt assembly along a first pit containing the material to be composted and then reversing the belt assembly for returning in the opposite direction along an adjacent pit containing materials.