Abstract:
A sod harvester having a sod hold down with at least one free wheeling elastic belt that maintains a downward pressure on sod slabs carried on a conveyor belt with the free wheeling elastic belt moving in unison with the conveyor belt through frictional engagement between sod slabs on the conveyor belt and the free wheeling belt or between the conveyor belt and idler pulleys, which rotationally support the elastic belt, to enable the hold down to prevent or inhibit slippage of the sod slabs on the conveyor belt during sod slab transfer thereon.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     None 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     None 
     REFERENCE TO A MICROFICHE APPENDIX 
     None 
     BACKGROUND OF THE INVENTION 
     The concept of on-the-go sod harvesters that can in a continuous operation cut a sod slab from a sod field and then stack the cut sod slab on a pallet, which can then be transferred to a work site by another vehicle, are known in the art. Typically, the sod harvester includes a set of knives that cuts a flat sod slab from the sod field. The sod slab, which may be left in slab form, is typically elevated upward from the sod field on a conveyor belt that discharges the sod slab onto a sod transfer mechanism. The sod slab is subsequently transferred to a sod pallet for further handling. The sod pallet with a stack of sod slabs thereon can then be transferred to a work site where the sod slabs are removed from the pallet and applied to the field. Examples of sod harvester for on-the-go harvesting are shown in Tvetene et al. U.S. Pat. Nos. 6,296,063; 6,783,318 and 6,364,027. 
     Occasionally, during the sod harvesting process the conditions of the sod soil may effect how the sod slab can be elevated from ground level to a location where the sod slabs can be stacked for delivery to a work site. Typically, the sod slabs are carried on a conveyor belt, which operates at an acute angle with respect to the horizon. Some times soil conditions cause the sod slab to slip on the sod conveyor, which can either jam the sod conveyor or cause damage to the sod slab. The failure of the sod slab to smoothly follow the sod slab conveyor requires operator correction and increases the time to complete the sod harvesting process as well as increases the spoilage due to a sod slab being damaged as the conveyor belt elevates the sod slab from ground level to the sod stacking mechanism in the sod harvester. 
     SUMMARY OF THE INVENTION 
     A sod harvester having a sod hold down with at least one free wheeling elastic belt that maintains a downward pressure on sod slabs carried on a conveyor belt with the free wheeling elastic belt moving in unison with the conveyor belt through frictional engagement between sod slabs on the conveyor belt and the free wheeling belt or between the conveyor belt and idler pulleys, which rotationally support the elastic belt, to enable the hold down to prevent or inhibit slippage of the sod slabs on the conveyor belt during sod slab transfer thereon. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a sod harvester with an elevating sod slab conveyor and a sod hold down with a plurality of sod slabs conveyed from a low end of the sod slab conveyor to a high end of the sod slab conveyor; 
         FIG. 2  is an isolated side view of the elevating sod slab conveyor and sod hold down of  FIG. 1  as a plurality of sod slabs are being conveyed from a low end of the sod slab conveyor to a high end of the sod slab conveyor; 
         FIG. 2A  is an isolated side view of the elevating sod slab conveyor and sod hold down of  FIG. 2  without sod slabs being conveyed from a low end of the sod slab conveyor to a high end of the sod slab conveyor; 
         FIG. 2B  is an isolated view of a set of hanging pulleys in the sod hold down for engaging an inside face of a set of elastic belts in the sod hold down; 
         FIG. 3  is an enlarged partial side view of the top end pulleys and an elastic belt in the sod hold down showing the position of the elastic belt and the idler pulleys as sod slabs are conveyed up the sod slab conveyor; 
         FIG. 3A  is an enlarged partial view of the top pulleys and elastic belt in the sod hold down showing the position of the elastic belt and the idler pulleys in the sod hold down without sod slabs being conveyed up the sod slab conveyor; and 
         FIG. 4  is a top view of the sod hold down with a set of pulleys and a pair of elastic belts located in a parallel condition above a plurality of sod slabs, which are carried by the sod slab conveyor. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  is a side view of a sod harvester  10  having a sod slab-elevating conveyor  12  that elevates sod slabs, which have been cut from a sod field  9  by sod cutter  11 , to a transfer conveyor  13  within the sod harvester that delivers the sod slabs to a sod stacking mechanism within the sod harvester. A driver  50  located in a cab within the sod harvester  10  drives the sod harvester as well as observes the transporting of sod slabs from a first ground end  12   c  of the sod slab conveyor  12  to a higher elevation at an opposite end  12   d  of sod slab conveyor  12 . 
       FIG. 2  shows an isolated side view of a sod slab hold down  15  and  FIG. 4  shows a top isolated view of the sod slab hold down  15  that resiliently maintains sod slabs in alignment with a conveyor belt  12   b . In the example shown in  FIG. 2  and  FIG. 4  a set of two free wheeling elastic belts  30  and  30   c  are brought into top engagement with the sod slabs on the conveyor to hold the sod slabs in conveyor alignment as the sod slabs are conveyed from end to end of the conveyor  12 . The top engagement of the sod slabs with the elastic belts not only holds the sod slabs in place it also causes the elastic belts to move in unison with the sod slabs on the conveyor belt  12   b  thus avoiding damage to the sod slabs from the elastic belt contact. A suitable elastic belt  30  or  30   c , which have an inherent resiliency, are O-ring belts as they are elastomeric and can stretch and contract in response to external forces on the belt although other types of belts may be used without departing from the spirit and scope of the invention. 
     The side view in  FIG. 2  shows that sod hold down  15  includes, a first end frame upright  15   a  attached to conveyor  12 , a middle frame upright  15   b  attached to conveyor  12  and a second end frame upright  15   c  attached to conveyor  12 , with each upright extending above an endless conveyor belt  12   b  on the sod slab conveyor  12  to provide support for a free wheeling sod hold down  15 . Sod hold down  15  includes a first set of idler pulleys  19  and  21  that are rotatably mounted on arm  18 , which is pivotally supported at a first end of the conveyor  12  by a pivot pin  15   d  in frame upright  15   a . A second set of idler pulleys  25  and  27  are rotatably mounted on frame upright  15   c . Pulley  25  is rotatably mounted on upright  15   c  and pulley  27  is rotatably mounted on pivotable arm  26  through an axle  22   a . Arm  26  is pivotally supported by frame upright  15   c  though a pivot pin  26   a  that allows the arm  26  with pulley  27  thereon to pivot thereabout in response to the presence or absence of a sod slab on the conveyor belt  12   c . A first elastic belt  30  extends from the first set of pulleys  19  and  21  to the second set of pulleys  25  and  27  with the elasticity of belt  30  urging the first set of pulleys  19  and  21  and pulley  27  in the second set of pulleys  25  and  27  toward each other through the pivoting of arm  18  around pivot pin  15   d  and arm  26  around pivot pin  26   a . In this example frame  15   b  includes a circumferentially grooved pulley  39  ( FIG. 2B ), which is located on an inside face of belt  30 , to maintain a top portion of belt  30  in an out of the way condition above the sod slabs on the conveyer  12  as well as a second circumferentially grooved pulley  39   c , which is located on an inside face of belt  30   c , to maintain a top portion of belt  30   c  in an out of the way condition above the sod slabs on the conveyer  12 .  FIG. 2  shows the lower portion of elastic belt  30  has an outside face  30   a  in engagement with sod slabs  9   a ,  9   b ,  9   c  and  9   d  on the conveyor belt  12   b  to maintain the orientation of the sod slabs as the conveyor belt  12   b  elevates the sod slabs thereon for delivery to the sod transfer conveyor  13 . In this example the engagement of the pulley  22  and the engagement of the elastic belt  30  with the sod slabs causes the belt  30  to travel in unison with the conveyor belt while at the same time maintaining the sod slabs in position for later transfer within the sod harvester. That is, the elasticity of the hold down elastic belt  30  maintains the hold down belt  30  in a motion transfer engagement with the conveyor belt  12   b . Similarly, the elasticity of the hold down elastic belt  30   c  maintains the hold down belt  30   c  in a motion transfer engagement with the conveyor belt  12   b.    
       FIG. 2A  is identical to  FIG. 2  except  FIG. 2A  shows the side view of the sod hold down  15  without any sod slabs on the conveyor belt  12 . Note, the peripheral contact of pulley  22  with the conveyor belt  12   b  as well as the face  30   a  of belt  30 , which is caused by the resiliency of the elastic belt  30 . In this example the conveyor belt  12   b  rotates in a counter clockwise direction while the elastic belt  30  on the free wheeling sod hold down  15  is driven in a clockwise direction through frictional engagement with conveyor belt  12 . As can be seen in  FIG. 2A  that with or without sod slabs the conveyor belt  12   b  rotates the drive belt  30  since the drive belt  30  is in a free wheeling mode as the pulleys supporting drive belt  30  are idler pulleys as opposed to drive pulleys although there may be some beneficial assist from pulley  21  and  27  through contact of the idler pulleys with either the conveyer belt or the sod slabs. In the example shown each of the idler pulleys include a circumferential groove therein to maintain a positive tracking of an elastic belt therein. 
       FIG. 4  is a top view of sod hold down  15  revealing a third set of pulleys  19   c  and  21   c , an elastic belt  30   c  and a fourth set of pulleys  25   c  and  27   c , which are identical to the first set of pulleys  19  and  21 , the elastic belt  30  and the second set of pulleys  25  and  27 . In this example pulleys  19 ,  21 ,  25  and  27  as well as elastic belt  30  are located in a first vertical plane and the pulleys  19   c ,  21   c ,  25   c  and  27   c  as well as elastic belt  30   c  are located in a second plane, which is parallel to the first vertical plane with both elastic belt  30  and elastic belt  30   c  coacting to maintain sod slabs in position as the sod slabs are transported along the conveyor  12 . 
       FIG. 4  shows that the pulleys  21   c  and  19   c  are mounted on a pivotable arm  18   c , which pivots about a pivot pin  15   d  ( FIG. 2 ) on upright  15   a  and that pulley  27   c  is mounted on a pivotable arm  26   c  that pivots about a pivot pin  26   a  ( FIG. 2 ). The side-by-side mounting of the elastic belt  30  and elastic belt  30   c  provide contact with the sod slabs on spaced apart locations on the sod slab to maintain the sod slab in proper orientation as it is transferred along conveyor belt  12 . Although a set of side-by-side free wheeling elastic cord belts  30  and  30   c  are shown it is envisioned that a single wide belt may be used without departing from the spirit and scope of the invention. 
       FIG. 3  shows a partial side view of hold down  15  showing pulleys  19  and  21  and arm  18  of sod hold down  15  when sod slabs  9   a  and  9   b  are located on conveyor belt  12   b . Note, in this position the arm  18 , which supports idler pulley  19  and idler pulley  21  makes an angle Θ 2  with the upright  15   a.    
       FIG. 3A  shows an identical partial side view of hold down  15  showing idler pulley  19  and idler pulley  21  and arm  18  of sod hold down  15  when there are no sod slabs present on conveyor belt  12   b . Note, in this position the arm  18 , which supports pulley  19  and  21  makes an angle Θ 1  with the upright  15   a.    
       FIG. 3A  (without the sod slabs) shows arm  18  pivoted at an angle Θ 1  about pivot pin  15   d  while  FIG. 3  (with the sod slabs) shows arm  18  pivoted at an angle Θ 2  about pivot pin  15   d  where the angle Θ 2  is greater than the angle Θ 1 . In this example the downward or counter clockwise pivoting of arm  18 , which is illustrated by  FIG. 3  and  FIG. 3A  is generated through the elasticity of the belt  30 . That is, by placing elastic belt  30  in tension through engagement with the set of idler pulleys on the opposite ends of hold down  15  generates a counter clockwise torque on arm  18  that brings the belt  30  into engagement with the top of the sod slabs with sufficient force so as to maintain the sod slabs in place on the conveyor belt  12  as the sod slabs are carried thereon. Similarly, by placing elastic belt  30   c  in tension through engagement with the set of idler pulleys on the opposite ends of hold down  15  generates a counter clockwise torque on arm  18   c  that brings the belt  30  into engagement with the top of the sod slabs with sufficient force so as to maintain the sod slabs in place on the conveyor belt as the sod slabs are carried thereon. Likewise the clockwise torque on pivotable arm  26  from elastic belt  30  brings elastic belt  30  into contact with sod slabs on the conveyor belt  12 . In this example the operation of elastic belt  30   c  is identical to elastic belt  30 . 
     Thus the invention includes a method of transferring a sod slab along a conveyor  12  while maintaining the sod slab in a conveying condition by elevating the sod slab onto a conveyor belt  12   b  and bringing a hold down belt  30  or  30   c  supported by a set of idler pulleys into engagement with a top surface of a sod slab on the sod conveyor belt  12   b  with sufficient force to hold the sod slab proximate the conveyor and rotate the hold down belt in unison with the conveyor belt through frictional engagement of the hold down belt with a top surface of the sod slab on the conveyor belt. In the example shown the elasticity of the belts are used to pivot the idler pulleys  21  and  27 ,  21   c  and  27   c  toward each other and bring the belts down into contact with the sod slabs. That is, the elastic belt  30  is used to pivot the arm  18  and arm  26  toward each other through the pulleys  21  and  27 , which are located on opposite ends of the hold down  15 . An alternate method is to pivot arm  18  and arm  26  toward each other using an external tensioner such as a spring or the like between arm  18  and arm  26  or between arm  18  and upright  15   a  and between arm  26  and upright  15   c  that causes the arm  18  and arm  26  to pivot toward the sod slabs to bring the belt into top engagement with the sod slabs on the conveyor. With the use of an external tensioner in the form of springs or the like either one or more of an inelastic belt or an elastic belts may be used as a hold down for the sod slabs.