Abstract:
A turf aerator is provided with three aligned aerator shafts having aerator devices mounted thereon. The innermost shaft is mounted in a frame for free-willing operation and the two outer shafts are each connected to a motor through selectively controlled hydraulic pumps which in turn are connected to hydraulic motors for driving the outermost shafts selectively or simultaneously with the innermost shaft being mounted for free-willing operation.

Description:
BACKGROUND OF THE INVENTION 
   The present invention is directed to a turf aerator and more specifically to an aerator having three separate shafts in axial alignment with each other with the tine assemblies on the middle shaft being mounted for free wheel rotation and the tine assemblies on the left and right shafts being mounted for rotation with the left and right shafts which may be selectively driven or simultaneously driven. 
   Core-type aerators are well known in the art and are generally comprised of a walk-behind unit having a main frame with an internal combustion engine mounted on the top thereof. A transverse shaft is rotatably mounted adjacent a lower rear portion of the frame and has a plurality of discs secured thereto which in turn support a plurality of radially extending core tines. A suitable drive arrangement is provided between the output shaft of the motor and the tine carrying shaft. A pair of adjustable wheels are pivotally mounted on opposite sides of the frame adjacent the rear thereof which may be adjustable in height under the control of an operator walking behind the aerator. Suitable controls are provided on the handle for controlling the drive to the shaft carrying the core tines. In most models of turf aerators, all of the tine carrying discs are simultaneously rotated since they are mounted on a single transverse shaft to which the drive is imparted. At least one turf aerator model is provided wherein the outermost tine carrying discs are mounted on the shaft for a free wheeling operation. 
   The aerator disclosed in U.S. Pat. No. 6,102,129 is of the walk behind type and which is provided with two independent tine carrying shafts which are axially aligned with each other for independent rotation relative to each other. Each shaft is selectively connected to an output shaft of a motor mounted on the frame of the aerator by two separate drive trains each having a clutch arrangement therein. A pair of control levers are mounted on a handle assembly for operating the clutches in each drive train. Thus either or both of the tine carrying shafts may be rotated to facilitate a turning operation of the aerator or while traversing a sloping surface. 
   The aerator disclosed in U.S. Pat. No. 5,680,903 is provided with a series of tine assemblies spaced along a driven shaft driven by a motor. Each tine assembly has a plurality of tines for aeration extending in a substantially radial pattern about the driven shaft. The inner tine assemblies along the middle portion of the driven shaft are secured to the driven shaft to drive the aerator along the lawn as the driven shaft rotates. The outer tine assemblies adjacent the ends of the driven shaft are rotatably mounted on the driven shaft. This permits the outer tine assemblies to free wheel independently and thereby make the aerator more maneuverable and easier to turn. 
   SUMMARY OF THE INVENTION 
   The present invention provides an improved turf aerator having three separate shafts in axial alignment with each other with the tine assemblies on the middle shaft being mounted for free-will rotation and the tine assemblies on the left and right shafts mounted for rotation with the shafts which may be selectively or simultaneously driven. The turf aerator is provided with a platform upon which the operator will stand to operate the turf aerator. An internal combustion engine is operatively connected to two hydraulic pumps which in turn are connected to left and right hydraulic motors respectively, which will impart a drive to the left and right tine carrying shafts respectively. The hydraulic motors also provide a drive to the left and right main wheels of the turf aerator respectively. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of the turf aerator of the present invention. 
       FIG. 2  is a bottom plan view of the turf aerator showing the relationship of the tine carrying shafts relative to the drive wheels. 
       FIG. 3  is an exploded view with the internal combustion engine and hydraulic pumps shown in spaced substantially operative arrangement relative to the hydraulic motors, the tine carrying shafts and the drive for the wheels. 
       FIG. 4  is a view of the tine assembly per se. 
       FIG. 5  is a schematic view showing the hydraulic circuitry interconnecting the various components. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The lawn aerator  10  shown in  FIG. 1  is comprised of a main frame  12  having an internal combustion engine  14  mounted on the upper portion thereof. The main frame  12  is supported by a pair of rotatable driven wheels  16 , two smaller non-driven wheels  18  on the rear position of the frame and two even smaller non-driven wheels  20  mounted on the front portion of the frame  12 . The wheels  18  can be raised and lowered by the lever  22  to stabilize the aerator. 
   A platform  24  for the operator is mounted on the frame  12  substantially between the driven wheels  16  and the rear non-driven wheels  18  as best seen in  FIG. 2 . An operating treadle  26  is mounted at the forward side of the platform  24  when the treadle is depressed by the operator, the engine can be controlled by the throttle lever  25 . When the treadle  26  is not depressed, the engine can only operate at idle speed regardless of the operation of the throttle lever  25 . 
   A pair of operating handles  30 ,  32  are pivotably on the frame  12  and are operatively connected to a left hydraulic pump  34  and a right hydraulic pump  36 , respectively, as viewed in  FIG. 3  by links  50  and  52 . The internal combustion engine  14  is provided with an output shaft  38  having a pair of pulleys  40  mounted thereon. Rotation of the drive shaft  38  is imparted to the left and right hydraulic pumps  34 ,  36  by means of respective belts  42 ,  44  which are entrained about pulleys  46  and  48  of the left and right hydraulic pumps  34 ,  36 . A pair of control links  50  and  52  are connected to the respective control handles  30  and  32  at one end thereof. The opposite ends of the links  50 ,  52  are operatively connected to the hydraulic pumps  34 , 36  respectively, one of the connections being shown in  FIG. 1 . Thus, the output and pressure of the hydraulic fluid from the left and right hydraulic pumps to the left and right hydraulic motors may be varied to vary the speed of the hydraulic motors. The details of such hydraulic pumps and hydraulic motors are well known in the art and are not shown in detail in the present disclosure. The left hydraulic motor  54  and right hydraulic motor  56  are mounted on the frame  12  above the tine assembly  58  as best seen in  FIG. 3 . A pair of sprocket wheels  60 ,  62  are mounted on the output shaft of the left hydraulic motor  54  and a pair of sprocket wheels  64 ,  66  are mounted on the output shaft of the hydraulic motor  56 . The drive wheels  16 ,  16  are each provided with a sprocket wheel  68 ,  70 . A chain  72  is entrained about the sprocket wheel  62  on the output shaft of the left hydraulic motor  54  and the sprocket wheel  70  on the left drive wheel  16  as viewed in  FIG. 3 . A chain  74  is also entrained about the sprocket wheel  66  on the drive shaft of the right side hydraulic motor  56  and the sprocket wheel  68  on the right drive wheel  16  as viewed in  FIG. 3 . Thus the drive wheels  16 ,  16  are driven by the hydraulic motors  54 ,  56 . 
   The tine assembly as best seen in  FIGS. 2–4  is comprised of a transverse frame  76  having four depending supports  78 ,  80 ,  87 , and  84 . A first shaft  86  is rotatably mounted between the dependent supports  78 ,  80  and a pair of conventional tine assemblies  88 ,  90  are connected to the shaft  86  for rotation therewith. A sprocket wheel  92  is also mounted on the shaft  86  and is driven by means of a chain  93  which in turn is driven by the sprocket wheel (not shown) on shaft  95  which is driven by chain  94  and sprocket wheel  60  driven by the left side hydraulic motor  54 . A second shaft  96  is mounted for rotation between the supports  87 ,  84  and a pair of conventional tine assemblies  98 ,  100  are mounted on the shaft  96  for rotation therewith. A sprocket wheel  102  is also mounted on the shaft  96  and is driven by a chain and sprocket wheel (not shown) on a shaft (not shown) similar to shaft  95  which is driven through a chain  104  trained about the sprocket wheel  64  which is driven by the right side hydraulic motor  56 . A third shaft  106  is rotatably mounted between the supports  80 ,  87  and a pair of tine assemblies  108  and  110  are rotatably mounted on the shaft  106  independently of each other. The shaft  106  is not driven and accordingly the tine assemblies  108 ,  110  simply free wheel and receive their rotation by contact with the ground as the turf aerator moves along the ground. The left and right shafts  86 ,  96  may be selectively or simultaneously rotated by the hydraulic motors  54 ,  56  under the control of the levers  30 ,  32 . As a result the rotation of the left and right tine assemblies may be conveniently selected to assist the operator in turning the turf aerator or traversing a slope with the turf aerator. 
     FIG. 5  is a schematic showing of the hydraulic circuitry interconnecting the hydraulic motors to the hydraulic pumps. In addition to the hydraulic motors and the hydraulic pumps a reservoir tank  120 , a filter  122  and a control valve  124  are provided. In addition to controlling the hydraulic pumps and hydraulic motors the control valve also controls a cylinder  126 . 
   The foregoing and other objects and features of the inventions will be more obvious in view of the following claims for raising and lowering the tine assembly.