Abstract:
A mobile field shredder adapted to move continuously through an orchard, pick up pruned branches from the ground, and shred the branches into sawdust and small shredded pieces. The front end of the shredder includes a pair of counter-rotating feeder rollers for picking up the branches. A shredding chamber receives the branches from the feeder rollers. First and second shredder rollers within the shredding chamber, include plural knife blocks on their respective outer peripheries. The shredder rollers are driven in tandem, in the same direction. A chamber screen is provided at the after end of the shredding chamber, in close proximity to the second shredder roller. The shredder rollers reduce the size of material so it is can pass through perforations in the screen. The consistency and size of the shredded material is such that it rapidly decomposes in the field and enriches the soil in the orchard.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The invention relates generally to devices for shredding pruned plant material into particle size. More specifically, the invention pertains to a self propelled field shredder, adapted to pass through an orchard, pick up pruned branches from the ground, and shred the branches into sawdust and small shredded particles. The consistency and size of the shredded material is such that it rapidly decomposes in the field and enriches the soil in the orchard.  
           [0003]    2. Description of the Prior Art  
           [0004]    Orchard trees, such as almonds, pistachios, and walnuts, are typically pruned at the end of each harvest season. This pruning is undertaken to shape and size the trees, as well as to improve their production. The pruned material may range in size from small twigs to branches up to four inches in diameter. As pruning crews move through the orchard, the cut twigs and branches are simply dropped into piles between rows of the trees. Later, individual piles are pushed by machinery and consolidated into larger piles at the end of the rows. Then, the large piles are burned under controlled conditions, to eliminate all trace of the cuttings.  
           [0005]    This process is labor consuming, because the material has to be moved considerable distances from where it was cut. In addition, agricultural burning of cuttings and like material, has fallen into disfavor, owing to the air pollution it necessarily produces. It appears likely that new Federal and State air pollution standards will severely limit or even eliminate large scale agricultural burning of this sort, in the near future.  
           [0006]    In lieu of burning branch cuttings, chipping or shredding machines have been used in some applications either to cut up or to pulverize pruned material into relatively small pieces.  
           [0007]    A conventional chipper uses knives mounted on a rotating flywheel or a drum. The material is held fast by a stationary shear bar or anvil as the knives pass close by. Chippers may also use infeed rollers to pull material into the machine and force it against the knives and anvil. The small chips produced by the cutting action of the knife and anvil arrangement are discharged through a chute.  
           [0008]    When chippers are used to process tree cuttings, they are mounted on a truck body or on a trailer frame so they can be moved into a position close to the pruning operation. These mobile chippers are used primarily by utility crews for power or telephone service. Workers manually feed the chipper by pushing the branches into a rear positioned hopper. A rotating element, such as a drum or a disc having sharp blades on a cutting surface, aggressively draws branches into the chipper. The processed material may be stored in a bin mounted on the truck, or it may be discharged into a pile on the ground.  
           [0009]    Shredders, by way of contrast, usually employ a rotatable element in conjunction with a screen. The rotatable element hammers, flails, or grinds the material into small pieces. When the pieces are small enough, they pass through perforations in the screen and are discharged. The most common shredder design uses a series of metal strips mounted on a rotating shaft. This type of shredder, known as a “Hammer Mill”, forces the incoming material against a curved, perforated plate until it is broken up and shredded sufficiently to pass through the perforations.  
           [0010]    The chipped, slivered, or shredded material may be used for ground cover or compost. However, the size and consistency of the material discharged by conventional chippers and shredders is such that it will not decompose quickly, and it cannot be added directly to soil to form a homogeneous mixture. This has particular consequences in almond orchards, where any foreign material left on the orchard floor is collected with the nuts during the mechanical harvest of the crop. At the hulling facility, the woody chips and shreds are difficult to separate from the almond hulls. Since almond hulls are sold to dairies as a feed supplement, excessive amounts of fiber, such as that provided by the woody material, reduce the food and economic value of the supplement. Moreover, to the extent that the chips or shreds can be separated from the hulls at the hulling facility, they pose an expensive storage and disposal problem.  
           [0011]    While some chipping and shredding machines are designed to be operated in remote field locations, they cannot pick up branches from the ground and feed them into the chipper. Nor are such devices designed to process material while passing through a field. Conventional mobile chippers and shredders are simply parked for on-site operation, and then after finishing, moved on to a new location. No continuous field processing of material spread over a large area is possible.  
           [0012]    Consequently, the need exists for a mobile device, adapted to pass through an orchard or field, and while in motion, continuously shred pruned material arranged in rows or piles.  
           [0013]    The need also exists for a mobile field shredder which can shred branches into particles having a size and consistency whereby they can be deposited directly onto the ground, for rapid decomposition and soil enrichment.  
           [0014]    The need further exists for a mobile field shredder which can produce shredded particles of a selected size and consistency.  
           [0015]    The need also exists for a field shredder which can pick up variably-sized cuttings from the ground, and process them continuously without need for adjustment or interruption.  
           [0016]    Lastly, the need exists for a detachable field shredder which can be front mounted on and coupled to a transport vehicle, providing both mobility and operational power for the shredder.  
         SUMMARY OF THE INVENTION  
         [0017]    The field shredder of the present invention is properly characterized as a shredder, yet has some of the characteristics of a chipper.  
           [0018]    The shredder of the present invention is constructed on a mobile shredder frame. The shredder frame is preferably detachably coupled to the front end of a tractor, or other transport vehicle. In that manner, the tractor may be used for other purposes throughout the growing year and the shredder may be stored until needed, or transported to another location for use with a different tractor.  
           [0019]    Rotary feeder means is mounted on the front end of the shredder frame for picking up the pruned branches from the ground. The feeder means includes an upper feeder roller and a counter-rotating lower feeder roller. The feeder rollers are elongated, have parallel axes of rotation, and are mounted transversely with respect to the direction of travel of the shredder frame. In this manner, the central portions of the rollers are adapted to engage a row of stacked, pruned branches as the mobile frame is moved through an orchard, a vineyard, or other agricultural setting where cuttings are so row-arranged.  
           [0020]    The upper feeder roller has plurality of circumferentially-spaced gripping plates. The plates extend longitudinally along the full length of the roller, and project in perpendicular fashion from its outer periphery. The plates are provided with an outer edge, having teeth or serrations for engaging the branches. The upper feeder roller is mounted on a pair of hydraulically damped sub-frames, pivotally mounted to the shredder frame. In response to variably-sized incoming branches, the upper feeder roller and the sub-frames rotate upwardly or downwardly to accommodate larger or smaller branches.  
           [0021]    The lower feeder roller includes a plurality of radially extending tines for mechanically engaging and lifting the branches from the ground. A guide plate, including plural slots to accommodate rotational passage of the tines therethrough, is located above and slightly rearwardly from the lower feed roller. Branches lifted by the tines are engaged by the gripping plates of the upper roller, and are fed rearwardly, between the gripping plates of the upper roller and the guide plate.  
           [0022]    A shredding chamber, mounted in the central and rear portions of the shredder frame, has a front inlet adjacent the output of the feeder means. The shredding chamber is defined by lateral end plates spanned by upper and lower shrouds. The chamber also includes an acuate, rear-positioned chamber screen, which provides an outlet for the shredded branch particles.  
           [0023]    Housed within the shredding chamber are a first shredder roller and a second shredder roller. The shredder rollers have longitudinal axes of rotation parallel to the upper and lower feeder rollers. The first and second rollers are mounted for rotation on roller drive shafts, passing through both end s of the shredding chamber. Shredder roller pulleys are provided on the end extremities of these drive shafts.  
           [0024]    A gear box is mounted in the central region of the shredder frame, above the shredding chamber. The gear box has an input drive shaft, and a pair of output drive shafts. Rotational power may be provided to the input drive shaft by an engine. This engine may be mounted either on the shredder, or on an auxiliary vehicle which transports the shredder. The output drive shafts extend laterally from either side of the gear box, past both end plates of the shredding chamber. A drive pulley is located on the outer end extremity of each drive shafts. A drive belt interconnects the drive pulley with the roller pulleys for the shredder rollers. The shredder rollers are thereby driven in tandem, in such a manner that their upper portions rotate rearwardly, and their lower portions rotate forwardly.  
           [0025]    The first roller is provided with a plurality of knife blocks, strategically located in semi-helical rows on the outer periphery of the roller. The second roller is similarly equipped with knife blocks, but the height of these blocks is somewhat greater than the height of the knife blocks on the first roller. Each of the knife blocks has a sharp leading edge, which is arranged in spaced relation from the upper and lower shrouds and the arcuate chamber screen. These knife blocks both cut and shred the incoming branches, as they pass through the shredding chamber, first rearwardly from the first roller to the second roller, and then forwardly from the second roller to the first roller.  
           [0026]    The residence time of material within the shredding chamber determines the size and consistency of the discharged particles. If the perforations within the chamber screen are enlarged in size, the residence time will be reduced and the particle size increased. If the perforations within the chamber screen are reduced in size, the residence time will be increased and the particle size decreased. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0027]    [0027]FIG. 1 is a perspective view of the field shredder of the present invention mounted upon the forward end of a tractor, the apparatus shown progressing through an orchard and about to encounter a pile of branch prunings;  
         [0028]    [0028]FIG. 2 is a perspective view of the field shredder taken from an elevated angle, the outer housing covers being raised and two cover plates of the upper chamber shroud being removed to show the pair of shredder rollers within the shredding chamber;  
         [0029]    [0029]FIG. 3 is a fragmentary, perspective view of the right-hand end of the shredder, as viewed in FIG. 2, the end shroud being removed to show the drive pulley and the shredder roller pulleys;  
         [0030]    [0030]FIG. 4 is a side elevational view of the right-hand end of the shredder in a lowered, operational position;  
         [0031]    [0031]FIG. 5 is a view as in FIG. 4, but with the shredder in a raised, disabled position, for maneuvering and transport;  
         [0032]    [0032]FIG. 6 is a fragmentary, side elevational view of the right-hand, front-end portion of the shredder, showing the upper feeder roller in a lowermost position;  
         [0033]    [0033]FIG. 7 is a view as in FIG. 6, but showing the upper feeder roller in a raised position, in response to forces provided by a large, incoming branch;  
         [0034]    [0034]FIG. 8 is a transverse, cross-sectional view of the shredder, showing the upper and lower feeder rollers, and the first and second shredder rollers within the shredding chamber;  
         [0035]    [0035]FIG. 9 is a perspective view of the showing the physical characteristics of the major components of the shredder, including the feeder rollers, the shredder rollers, and the chamber screen;  
         [0036]    [0036]FIG. 10 is an inset detail of a typical knife block affixed to the periphery of the first shredder roller; and,  
         [0037]    [0037]FIG. 11 is an inset detail of a typical knife block affixed to the periphery of the second shredder roller. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0038]    Turning now to FIG. 1, the field shredder  11  of the present invention is preferably detachably mounted on the forward end of a transport vehicle  12 . The transport vehicle  12  may be either a conventional or a specially designed tractor. If it is a conventional tractor, the shredder may be independently powered, or it may be powered by hydraulic or electrical sources on the tractor. If vehicle  12  is specially designed, as disclosed herein, the shredder  11  is powered by the same engine which drives the transport vehicle  12 .  
         [0039]    The shredder  11  includes a mobile shredder frame  13  upon which the major components of the present invention are mounted. The front end of frame  13  is provided with an upper feeder roller  14  and a lower feeder roller  16 . Both feeder rollers are elongated in configuration, having parallel axes of rotation. The axes of the feeder rollers are oriented transversely, however, with respect to the forward direction of travel of the shredder frame and the transport vehicle.  
         [0040]    The feeder rollers are particularly well adapted to pick up individual branches  17  of variable size, from a row or pile  18  of pruned branches or other cuttings. The row of branches was previously formed when crews of workers passed through an orchard of trees  19 , and so placed the cuttings during the pruning process. Other than arranging the cut branches in a row between the trees so that they can be accessed by the shredder  11 , no other manipulation or handling of the branches is necessary for them to be processed by the shredder  11 .  
         [0041]    To effect efficient pick-up and feed of the branches  17  into the shredder  11 , the outer periphery of upper feeder roller  14  is provided with a plurality of circumferentially-spaced gripping plates  21 . The plates  21  extend longitudinally along the full length of the roller  14 , projecting outwardly in perpendicular fashion. The plates  21  have an outer edge with teeth  22 , or serrations, adapted for engaging the outer surface of the branches  17 .  
         [0042]    A drive shaft  23  extends from both ends of upper feeder roller  14 . One end of the drive shaft  23  passes through a first rotatable end of a respective L-shaped sub-frame  24 , for connection to a hydraulic motor  26 . The other end of the drive shaft  23  passes through a bearing located in the first rotatable end of a sub-frame  24  on the other side of the shredder  11 . Each sub-frame  24  is pivotally mounted by means of a bolt  27  to the shredder frame  13 . A hydraulic damper  28  extends between each of the second rotatable ends of sub-frames  24  and the shredder frame  13 .  
         [0043]    Similarly, a drive shaft  29  extends from both ends of the lower feeder roller  16 . One end of the drive shaft  29  passes through a respective support plate  31 , for connection to a hydraulic motor  32 . The other end of the drive shaft passes through a bearing located in a respective support plate  31  on the other side of the shredder  11 . Both hydraulic motors  26  and  32  are preferably powered by a hydraulic pump and associated control valves (not shown), located on transport vehicle  12 .  
         [0044]    Lower feeder roller  16  includes a plurality of radially extending tines  33  for initially engaging and lifting the branches  17  from the ground. Although not critical, it should be noted that adjacent rows of tines are arranged in alternating offset relation along roller  16 . Thus, rows 1 and 3 are in vertical alignment, but they are horizontally offset with respect to rows 2 and 4. It has been determined that this arrangement provides a suitable compromise between the need to have a sufficient number of tines to engage the stack of branches, without having so many tines that pickup efficiency is impaired.  
         [0045]    An elongated guide plate  34 , provided with a plurality of slots  36  to accommodate rotational passage of the tines  33 , is located above and slightly rearwardly from the lower feed roller  16 . As will be noted particularly from a review of FIGS. 7 and 8, the feeder rollers  14  and  16  are counter-rotating. The tines  33  of the lower feeder roller engage the lower portion of the row or pile of branches. Owing to their upward rotation when encountering branches, the tines are effective to lift the branches upwardly and rearwardly. Concurrently, the gripping plates  21  engage the upper portion of the row of branches, and drive the branches downwardly and rearwardly. The guide plate  34  is located at the confluence of these forces at the material input of the feeder rollers, ensuring that the branches are maintained in substantially horizontal relation, as they are picked up and actively driven into the shredder  11 .  
         [0046]    The pruned branches  17  vary in diameter from finger size to approximately 4″. Therefore, the shredder feeding mechanism must be able to accommodate these varying sizes, efficiently and without sustaining damage. If the gap between the feeder rollers were maintained at a distance corresponding to the maximum diameter of the branches, no damage would occur from large incoming branches. However, pickup efficiency would suffer for small branches, owing to the greater than optimum distance between operative elements of the feeder rollers and the small branches. If the gap between the feeder rollers were set at a distance corresponding to the minimum diameter of the branches, the pickup efficiency would be very good for small branches. Unfortunately, upon encountering a large incoming branch, the tines and the gripping plates of the feeder rollers might be damages.  
         [0047]    The operation of a mechanism previously described, handles these varying branch sizes without serious compromise. By securing the upper feeder roller  14  to a pivotally mounted sub-frame assembly, variable thicknesses for branches are easily accommodated. For example, in FIG. 8, relatively small incoming branches  17  are effectively drawn into the shredder, as the sub-frame and attached upper feeder roller, have dropped to a lower position. With the gap distance between the rollers reduced, effective contact between the tines, the gripping plates, and the branches is maintained. In FIG. 7, a relatively large branch  17  is being drawn into the shredder, causing subframe  24  to pivot upwardly, effectively increasing the gap distance between the rollers. No damage to the rollers or their operative elements occurs. As this pivoting action, both upwardly and downwardly can be abrupt, hydraulic damper  28  is provided to smooth out the rate of rotational movement of the sub-frame, in both directions.  
         [0048]    Having described the branch feeding mechanism, we can now turn attention to the material shredding components of the shredder  11 . A shredding chamber, generally designated by the numeral  37 , is within and mounted to the central and rear portions of the shredder frame  13 . Shredding chamber  37  has a front inlet  38 , adjacent the material output of the feeder rollers, for receipt of branches  17  (See, FIG. 8). Chamber  37  has a volume which is generally defined by lateral end plates  39 , an upper chamber shroud  41 , and a lower chamber shroud  42 . Shrouds  41  and  42  span end plates  39 , and provide upper and lower walls for the chamber. It should be noted that in FIG. 2, two detachable cover plates of the shroud  41  have been removed so that the inner details within chamber  37  can be seen. These cover plates are provided for inspection and maintenance of the internal components of the shredder chamber. However, in normal operation of the shredder, these cover plates are secured in place so that shroud  41  provides a continuous upper wall for the chamber  37 .  
         [0049]    The shredding chamber  37  also includes an acuate, rear-positioned chamber screen  43 , most clearly shown in FIG. 9. Chamber screen  43  is semi-circular in cross-section, and includes a plurality of perforations  44  along its length. These perforations, which may range from a size of ½″ to 1½″, provide an outlet for the shredded branch particles. Arcuate reinforcement ribs  46  are provided around the outer periphery of screen  43 . Without ribs  46 , the screen  43  would distort or fail, owing to the tremendous forces imposed on the screen during the shredding operation.  
         [0050]    Housed within the shredding chamber  37  are a first shredder roller  47  and a second shredder roller  48 . Shredder rollers  47  and  48  have longitudinal axes of rotation which are generally parallel to the axes of rotation of the upper and lower feeder rollers  14  and  16 . First shredder roller  47  is mounted for rotation on a roller drive shaft  49 , passing through both end plates  39  of the shredding chamber. Similarly, second shredder roller  48  is mounted for rotation on a roller drive shaft  51 , which also passes through end plates  39 . Shredder roller pulleys  52  are provided on both ends of shafts  49  and  51 . Pulley cover  53  has been removed in FIGS. 3, 4, and  5  to show these pulleys. In normal operation of the shredder  11 , as shown in FIG. 1, pulley cover  53  encloses these pulleys and their related components.  
         [0051]    A gear box  54  is mounted in the central, upper portion of the shredder frame  13  (See, FIG. 2). The gear box  54  has an input drive shaft  56 , and output drive shafts  57  and  58 . Rotational driving forces are provided to the input drive shaft  56  by an engine (not shown). This engine may be mounted either on the shredder frame  13 , or within the transport vehicle  12 . The output drive shafts  57  and  58  extend laterally from either side of the gear box  54 , through and past both end plates  39  of the shredding chamber. A drive pulley  59  is located on the outer end extremity of each output drive shaft. A toothed drive belt  61  interconnects the drive pulley  59  with the roller pulleys  52  for the shredder rollers. The shredder rollers  47  and  48  are thereby driven in tandem, at both ends, in such a manner that their upper portions rotate rearwardly, and their lower portions rotate forwardly (See, FIG. 8).  
         [0052]    The first shredder roller  47  is provided with a plurality of knife blocks  62 , strategically located rows which are longitudinally offset to define semi-helical paths on the outer periphery of the roller  47 . By semi-helical, it is meant that consecutive knife blocks in only three or four rows of the knife blocks are longitudinally offset to define a helical path. Then, the next consecutive knife block in the first row defines the beginning of another semi-helical path. Offsetting the knives in this fashion distributes the cutting forces more evenly around the shredder rollers.  
         [0053]    Knife blocks  62  include a first knife edge  63  and a second knife edge  64 . Blocks  62  are preferably welded to the outer periphery of roller  47  for strength. After the shredder has been operated for some time, the knife blocks are examined. If the first knife edges of the blocks  62  are determined to be dull, the entire roller  47  may be removed from the shredding chamber, and reversed, end-for-end. When this is done, the second knife edge  64  is now primarily exposed to the incoming material, and efficient operation of the shredder will resume.  
         [0054]    The second shredder roller  48  is similarly equipped with a plurality of knife blocks  66 , each having a first knife edge  67  and a second knife edge  68 . However, the height of knife blocks  66  is preferably somewhat greater than the height of the knife blocks  62 , located on the first shredder roller  47 . This preference stems from the determination that if the cutting and shredding action of first shredding roller is too aggressive, it will load and stress the shredder. By stepping the height of the knife blocks  62  and  68 , the material is successively and more smoothly, cut and shredded into smaller pieces.  
         [0055]    The sharp leading edge of each of the knife blocks is arranged in spaced relation from the upper shroud  41 , the lower shroud  42 , and the arcuate chamber screen  43 . These knife blocks both cut and shred the incoming branches, as they pass through the shredding chamber, first rearwardly from the first roller to the second roller, and then forwardly from the second roller to the first roller. Any piece of material which is too large to be forced through the perforations in the screen  43  will be carried around the shredder rollers through the bottom portion of the shredding chamber, and passed through the cutting and shredding process again.  
         [0056]    The residence time of material within the shredding chamber determines the size and consistency of the outputted particles. If the perforations within the chamber screen are enlarged in size, the residence time will be reduced and the particle size increased. If the perforations within the chamber screen are reduced in size, the residence time will be increased and the particle size decreased.  
         [0057]    The shredder  11  includes outer housing covers  69  and  71 , as best viewed in FIG. 2. Covers  69  and  71  are hingeably affixed along one edge to shredder frame  13 . During normal operation of the shredder, covers  69  and  71  are closed to keep debris and dirt off of the upper shroud  41  and the gear box  54 . The shredder also includes a brace rod  72 , extending from the forward end of the transport vehicle  12  to the forward end of the shredder frame  13 . Because the shredder is suspended off the forward end of the vehicle  12 , considerable downward forces are developed. Brace rod  72  is effective to counteract these forces, much in the same fashion as a suspension rod does, extending from the rear of a tractor to a three-point tractor attachment.  
         [0058]    When the shredder  11  is used in the field, it is normally in a lowered position, so it can effectively pickup branches from the ground (See, FIG. 4). However, when the end of a row is reached, or when the shredder is being moved from orchard to orchard, it is desirable to raise the shredder to an elevated position, to lessen the chance of damage to the lower feeder roller  16  or the tines  33 . For that purpose, the transport vehicle disclosed herein employs an adjustable height suspension assembly  73 , for the front wheels  74  of the transport vehicle.  
         [0059]    Suspension assembly  73  includes a bracket  76 , and axle plate  77 , and a hydraulic ram  78 . Bracket  76  extends from the shredder frame  13  and includes a pivot bolt  79  at its lower end. Axle plate  77  is pivotally attached to bracket  76  through the pivot bolt  79 . Axle plate  79  supports wheel  74  about an axle  81 . Hydraulic ram  78  extends between an upper portion of bracket  76  and axle plate  77 . When hydraulic ram  78  is retracted, the front end of vehicle  12  and the shredder  11  are in a lowered position, as shown in FIG. 4. When hydraulic ram  78  is extended, plate  77  pivots about bolt  79 , in effect raising the front end of the vehicle and the shredder, as shown in FIG. 5. In this manner the shredder  11  can be lowered and raised as necessary so that both shredding and offsite transport can be accommodated.  
         [0060]    It will be appreciated that I have disclosed a mobile field shredder having the capability to lift branches, arranged in piles and rows on the ground of an orchard, and continuously shred the branches into particles of a size and constituency that they will readily decompose and enrich the orchard soil.