Abstract:
An inexpensive and readily available pruning blade for pruning crop growth, such as grape vines following harvest, has a disc-like base plate. The base plate has ordinary small diameter radial Skil-saw blades mounted around the periphery. The saw blades are fixed rotationally on the base plate by a clamp and have a portion of the saw teeth extending beyond the base plate periphery so that rotation of the base plate induces cutting action by the saw teeth at the periphery of the base plate. When the extending saw teeth become dull, the clamp is loosened, the saw blade is rotated through an arc sufficient to expose sharp teeth at the base plate periphery, and the clamp is tightened.

Description:
SUMMARY OF THE INVENTION 
     The disclosed invention relates to apparatus for mounting on a mobile vehicle for pruning branches of vines and bushes or trees in a ground growing crop including a pruning blade and means carried on the mobile vehicle for mounting the pruning blade for rotational movement in a predetermined position relative to the vines and bushes. The pruning blade includes a base plate that has a periphery and a center of rotation adapted to engage the means for mounting. Also included is a plurality of cutting members having peripheral cutting surfaces together with means for releasably fixing the plurality of cutting members around the periphery of the base plate in spaced position so that portions of the peripheral cutting surfaces extend beyond the base plate periphery. 
     In another aspect of the invention, a pruning blade is adapted to be mounted on a rotating drive shaft for use in mechanically pruning vines and bushes of a row-grown field crop, wherein the blade includes a flat base plate having a periphery and a centrally located opening for engagement by the rotating drive shaft. Also included is a plurality of cutting members having peripheral cutting surfaces, and means for releasable fastening the cutting members in spaced relation around the periphery of the base plate so that the peripheral cutting surfaces extend beyond the periphery of the base plate. 
     In a further aspect of the invention, apparatus is provided for pruning branches of vines and bushes of a ground growing crop wherein a vehicle for traversing the ground has a power source with a driver connected to the power source. A drive shaft is coupled to the driver at one end and has an opposing free end for positioning adjacent the crop. The improvement includes a base plate having a periphery and a centrally located attachment point for accepting and affixing the base plate to the drive shaft free end. A plurality of cutting members has peripheral cutting surfaces. Also included is means for releasably fastening the cutting members in spaced relation around the periphery of the base plate so that the peripheral cutting surfaces extend beyond the periphery of the base plate. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective of a preferred embodiment of the present invention. 
     FIG. 2 is an elevation of a mobile vehicle illustrating one manner of using the present invention. 
     FIG. 3 is a diagrammatic depiction of another manner of using the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Continuing efforts are made to reduce the costs of producing crops such as wine grapes. The cost of pruning an acre of wine grapes runs from $200-$250 when the pruning is done with hand labor. There are currently in existence several styles of mechanized pruning machines. Some machines use sickle-style cutters, much like the sickle cutters used to harvest hay. Other mechanized pruning machines have used large radial-style saw blades and yet other pruning machines have used a straight steel blade much like that seen on a lawnmower. 
     The foregoing mechanical pruning machines have several weak points. One of the things that growers of wine grapes want is a clean, smooth cut. It is undesirable to have a cut that shatters the end of the wood. As blades wear and become dull, the quality of the cut decreases. Large radial style saw blades in pruners have to be removed and resharpened. This requires a grower to have extra sets of large radial style saw blades which are very expensive. Without the extra sets the grower must idle his pruning crew while the saw blade is being sharpened. Further, as a vineyard is being pruned, the blades or cutters may come into contact with steel stakes as well as very hard, high tensile strength wire. The blades are immediately dulled when they contact such items. 
     The present invention uses the most common radial saw blade made. Seven and one quarter-inch Skil-Saw blades are preferred. They are inexpensive and readily available. Moreover, multiple 7-¼ inch saw blades are much cheaper than one large diameter saw blade. Additionally, it proves to be very expensive to re-sharpen large diameter saw blades. Referring now to FIG. 1 of the drawings, the pruning blade assembly of the present invention is shown at  10  having a base plate  11 . A plurality of holes  12 , some of which are visible in FIG. 1, are arranged about the periphery of the base plate  11 . There is also an inner circle of holes  13  in the base plate as well as a center opening  14 . 
     A number of small diameter radial saw blades  16  are seen positioned in spaced relationship around the periphery of the base plate  11 . The small diameter saw blades are held in position by means of fasteners  17  that extend through centrally located holes (not shown) located on an axis of rotation of each of the small diameter saw blades and through one of the holes  12  in the base plate. The fasteners  17  are engaged at a free end by a threaded nut (not shown) if they extend to the opposite side of the base plate, or by threads formed in the holes  12 . Any other holding device will serve. While each individual small radial saw blade  16  is held in position on the periphery of the base plate  11  by a fastener  17 , each blade  16  is prevented from rotating about its axis by another fastener  18  that extends through one of the holes  13  in the base plate. The fastener  18  is engaged at the opposite side of the base plate by a holding device such as a nut or the like (not shown). FIG. 1 illustrates a washer-like member  19  that is placed under the head and around the shank of the fastener  18 . The edge of the washer  19  extends radially from the fastener  18  to overlap the periphery of an adjacent saw blade  16  and thereby fix the saw blade rotationally. 
     It may be seen from FIG. 1 that a greater or fewer number of saw blades  16  may be affixed on the periphery of the base plate  11  depending on the cutting requirement for the pruning job to be undertaken. Adding a greater number of smaller diameter saw blades to the periphery of the base plate  11  will provide a cutting edge that is more continuous for certain pruning purposes and placing a smaller number of saw blades  16  on the periphery of the base plate will provide fewer teeth for the pruning operation in accordance with different desired pruning results. Moreover, the tooth design on the saw blades  16  may be changed to provide either a coarse cut or a fine cut or a combination of several types of blade teeth may be provided, again depending on the pruning job requirements. In any event, when the exposed teeth extending from the periphery of the base plate  11  become dulled through use or as a result of contact with objects other than the vines or branches to be pruned, the fastener  17  may be loosened as necessary and then the fastener  18  may be loosened to relieve pressure on the washer  19 . The saw blade  16  may then be rotated through an arc to present new and sharp teeth along the portion of the saw blade that extends outwardly from the periphery of the base plate  11 . Since only a portion of the blade is in use at any one time, the saw blades may be rotated as described herein several times to provide a new group of sharp saw teeth for performing the pruning operation before the saw blade needs replacement. Common 7-¼ inch Skil-saw blades cost less than $3.00 each. A 30-40 inch diameter pruning saw blade costs anywhere from $300 to $500. The saw blades  16  may simply be discarded once the teeth are dulled after several positions of the saw blade are assumed, while the more expensive large diameter pruning saw blades are so expensive that they are usually sent to be re-sharpened. 
     FIG. 2 is a rudimentary drawing of a crop harvester, similar to a harvester used to harvest vine-grown crops such as grapes. The harvester includes an inverted “U” shaped frame  20  that has wheels  21  for contacting the ground  22 , thereby allowing the harvester to traverse over the ground. A power source  23  is mounted on the harvester frame providing power which is transferred to a driver  24 , such as a hydraulic motor having an output shaft  26  extending therefrom. The output shaft  26  in the embodiment shown extends along an axis  27  (FIG. 1) that passes through the center of rotation of the pruning assembly  10 . 
     In the depiction of FIG. 2 a vine row, represented by the single vine trunk  28  and attached branches, is approached from both sides and the top by pruning assemblies  10  that are driven to rotate about their axes  27  when connected to the ends of the shafts  26 . The pruning assemblies  10  are positioned toward and away from the vines to be pruned by a known positioning assembly  29 , one for each pruning assembly. The positioning assemblies are represented in FIG. 2 as hydraulic cylinders that position each pruning assembly  10  closer to or farther from the row of vines to be pruned. FIG. 2 is representative of one configuration of pruning assemblies  10 , it being understood that one or two pruning assemblies may be all that is required for any particular pruning operation. The entire operation is controlled from an operator&#39;s station  31  located on top of the inverted “U” shaped frame  20 . 
     FIG. 3 shows an articulated arm that includes a first arm section  32  and a second arm section  33 . The second arm section  33  is depicted as part of the hydraulic positioning assembly  29  shown in FIG.  2 . One end of the arm  32  is mounted at a pivot  34  attached to a frame  36  on a mobile vehicle used in harvesting operations. The free end of the arm  32  has a pivot  37  thereon to which is attached the second arm section  33 . Power is provided from a power source, similar to that described in FIG. 2, to a driver such as a hydraulic motor  38  (similar to motor  24 ) that is mounted near the free end of the articulated arm. An output shaft  39  extends from the motor  38  and provides rotational drive for the pruning assembly  10 . The pruning assembly is thereby rotated about the axis  27  at a predetermined speed depending upon the requirements of a particular pruning operation. It should be noted that the positioning devices shown as items  29  in FIG.  2  and as item  33  in FIG. 3 are controlled by positioning sensors (not shown), sometimes termed “row finders” in harvesting machinery parlance. These devices are included in this disclosure solely for the purpose of showing the environment in which the invention is useful as disclosed and claimed herein. 
     Although the best mode contemplated for carrying out the present invention has been shown and described herein, it will be understood that modification and variation may be made without departing from what is regarded to be the subject matter of the invention.