Abstract:
An airboat having aquatic vegetation shredder includes an airboat having a buoyant hull and an aquatic vegetation shredding assembly supported on the hull. The airboat is driven by a propulsion assembly including a propeller that revolves in the air. These features cooperatively provide a low draft vessel that is capable of relatively higher forward speeds than other aquatic vegetation shredders and particularly effective in shallow water environments. Various alternative configurations of the shredding assembly are disclosed including upright and fore-and-aft shaft orientations for the cutting assembly and a drum and knife cutting assembly.

Description:
RELATED APPLICATIONS 
   This is a continuation application of U.S. Ser. No. 09/769,661, filed Jan. 25, 2001 now abandoned, which is hereby incorporated by reference herein. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates generally to equipment for shredding, harvesting, destroying or otherwise processing aquatic vegetation. More specifically, the present invention concerns an airboat provided with an aquatic vegetation shredding assembly. 
   2. Discussion of Prior Art 
   Aquatic vegetation can be devastating to both marine operations and the aquatic ecosystem. Unfortunately, most conventional expedients are ineffective in destroying or otherwise controlling such vegetation. These problems have previously been identified in our U.S. Letters Patents, both of which are assigned of record to the assignee of the present invention and are identified as follows: U.S. Pat. No. 6,023,920 entitled APPARATUS FOR DESTROYING AQUATIC VEGETATION; and U.S. Pat. No. 6,116,004 entitled AQUATIC VEGETATION DESTROYER. 
   Our prior inventions address these problems by providing, among other things, a design that is particularly successful in delivering vegetation to the shredding assembly and a design for shredding vegetation both generally at the water surface and well below the water surface to ensure that at least most of the plant is shredded. We have now determined that, in some instances, it would also be beneficial to have an aquatic vegetation shredder that is particularly designed for use in shallow water and in no water conditions (e.g., changes in the water level of a body of water may leave aquatic vegetation growing on dry land). 
   OBJECTS AND SUMMARY OF THE INVENTION 
   Responsive to these and other problems, an important object of the present invention is to provide a device that is capable of eliminating the troubles presented by aquatic vegetation, as noted in our U.S. Letters Patents. It is also an important object of the present invention to provide a machine that is capable of destroying aquatic vegetation in or around shallow water and no water conditions. Another important object of the present invention is to provide an aquatic vegetation shredder that can shred vegetation generally at the water surface as well as below the water surface. 
   In accordance with these and other objects evident from the following description of the preferred embodiment, the present invention concerns an airboat provided with an aquatic vegetation shredding assembly. The airboat has a buoyant hull, and an aquatic vegetation shredding assembly is supported on the hull. The airboat is driven by a propulsion assembly including a propeller that revolves in the air. These features cooperatively provide a low draft vessel that is capable of relatively higher forward speeds than other aquatic vegetation shredders (e.g., the airboat with assembly can transport to and from off-shore shredding locations in less time than current shredders) and particularly effective in shallow water and no water environments. 
   Other aspects and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments and the accompanying drawing figures. 

   
     BRIEF DESCRIPTION OF THE DRAWING FIGURES 
     Preferred embodiments of the invention are described in detail below with reference to the attached drawing figures, wherein: 
       FIG. 1  is a top plan view of an aquatic vegetation shredder constructed in accordance with the principles of the present invention, wherein the apparatus comprises an airboat supporting an aquatic vegetation shredding assembly; 
       FIG. 2  is a side elevational view of the machine shown in  FIG. 1 ; 
       FIG. 3  is an enlarged front cross sectional view of the machine taken generally along line  3 — 3  of  FIG. 2 , particularly showing the aquatic vegetation shredding assembly having the generally horizontal cutters mounted on respective upright shafts; 
       FIG. 4  is an enlarged, fragmentary side view of the bow end of the machine, particularly illustrating the primary frame of the shredding assembly swung downwardly to orient the cutters at a forwardly and downwardly sloped angle relative to horizontal; 
       FIG. 5  is an enlarged, fragmentary side view of the bow end of the machine similar to  FIG. 4 , but illustrating the cutting assembly swung upwardly relative to the primary frame to reposition the cutters in the horizontal orientation; 
       FIG. 6  is an enlarged, fragmentary top view of the bow end of a second embodiment of the present invention, wherein the machine includes cutters similar to those shown in  FIGS. 1-5  but are rotatable in an upright plane; 
       FIG. 7  is an enlarged, fragmentary side view of the bow end of the machine shown in  FIG. 6  having a portion of the hood removed; 
       FIG. 8  is an enlarged front cross sectional view of the cutting assembly taken substantially along line  8 — 8  of  FIG. 7 ; 
       FIG. 9  is an enlarged, fragmentary side view of the bow end of the machine shown in  FIG. 6  particularly illustrating the shredding assembly in a lowered position; 
       FIG. 10  is an enlarged, fragmentary top view of the bow end of a third embodiment of the invention, wherein the machine includes a laterally extending drum carrying multiple flail-type knives; 
       FIG. 11  is an enlarged, fragmentary side view of the bow end of the machine shown in  FIG. 10 , with a portion of the frame being removed; 
       FIG. 12  is an enlarged front elevational view of the cutting assembly taken substantially along line  12 — 12  of  FIG. 11 ; and 
       FIG. 13  is an enlarged, fragmentary side view of the bow end of the machine shown in  FIG. 10 , particularly illustrating the shredding assembly in a lowered position. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Turning initially to  FIG. 1 , the aquatic vegetation shredder  10  selected for illustration includes an airboat  12  and an aquatic vegetation shredding assembly  14  mounted to the bow end of the airboat  12 . The airboat  12  includes a low draft hull  16 . The hull  16  has a generally rectangular, box-like configuration and includes a top deck wall  18 , a downwardly spaced bottom wall  20 , opposite port and starboard sidewalls  22  and  24 , and opposite bow and stem endwalls  26  and  28 . The top deck wall  18  is a solid surface providing a sealed hull  16  to prevent the hull  16  from filling with water and shredded debris. As shown in  FIG. 2 , the bottom wall  20  slopes upwardly at the bow end of the airboat  12  converging with the bow endwall  26 . As shown in  FIG. 2  by the dashed water line, the airboat hull  16  is a low draft hull displacing relatively small amounts of water when in operation. In the preferred embodiment, the hull  16  has a bow-to-stern length of approximately twenty feet and a width or beam of approximately eight feet. The eight foot beam allows the airboat  12  to be trailered on a standard tractor pulled semi-trailer without any overwidth problems. However, the principles of the present invention are equally applicable to various other hull designs having a multitude of varied dimensions so long as the draft allows the airboat  12  to operate in shallow water and no water conditions. For example, the airboat could have a double-hull, or triple-hull design and accommodate twin or triple engines respectively. 
   Those ordinarily skilled in the art will appreciate that airboats are commonly operated in shallow waters having vegetation protruding through the surface (e.g., a swamp) or in no water conditions where vegetation exists. Sometimes this vegetation will capture or seize the airboat. It is therefore desirable to slicken the bottom of the airboat hull. As is commonly done on airboats to slicken the hull, the bottom wall  20  of the airboat hull  16  is coated with polyethylene. However, the principles of the present invention are equally applicable to various other methods of slickening the hull  16  including coating the hull  16  with materials other than polyethylene or utilizing sprayers that forwardly spray slickening agents such as soap or diesel fuel on the hull and/or the vegetation. In some environments the aquatic vegetation can become so entangled and dense that the vegetation forms a virtual floating island. It is desirable for the airboat  12  to have a slickened hull  16  that enables the airboat  12  to operate on these floating islands. It is also desirable for the airboat  12  to operate in no water conditions, for example on and around the banks of a body of water or where the water level in a body of water changes leaving aquatic vegetation growing on dry land. 
   At the stern end of the airboat  12  is a cage  30  housing an internal combustion engine  32  drivingly coupled to a propeller  34 . The cage  30  is configured and constructed as is commonly known in the art. The engine  32  can be variously sized and powered so long as it produces the required propeller rotation to adequately propel the total weight of the airboat  12  and shredding assembly  14 . In the usual manner, the engine  32  is supported, so that it rests above the surface of the top deck wall  18 . The engine  32  is drivingly coupled to the propeller  34  in the usual manner. The propeller  34  includes a hub  36  and a plurality of fan blades  38  coupled to the hub  36 . The blades  38  and the hub  36  are configured in a known manner so that the pitch angle of each of the blades  38  can be varied. That is, rotation of the propeller  34  in the same rotational direction can propel the airboat  12  both forwardly and rearwardly depending on the pitch angle of the blades  38 . 
   Hingedly supported on the cage  30  in the usual manner are lateral steering rudders  40  and  42 . The engine  32 , propeller  34  and steering rudders  40  and  42  are conveniently controlled from a cab  44  adjacent the cage  30 . In the usual manner, the cab  44  includes a rudder guide  46 , a seat  48 , and the supporting framework  50 . However, the cab  44  further includes a cab guard (not shown) that separates the cage  30  from the seat  48  so that when the propeller  34  is propelling the airboat  12  rearwardly, the airboat  12  operator seated in the seat  48  is shielded from the moving air generated by the propeller  34 . It is within the ambit of the present invention to include alternative variously constructed propulsion means (e.g., multiple propellers, bow mounted propeller, etc.). As previously discussed, the propulsion means could include multiple engines. In addition, the cab could be located at the bow end of the airboat and include a windshield. 
   Those ordinarily skilled in the art will appreciate that the illustrated airboat  12  is similar in many respects to standard airboat constructions. It is therefore within the ambit of the present invention to utilize a commercially available airboat and make any necessary modifications to it. A suitable airboat is available under the designation TRAILBOSS from Marshland Marine of Baytown, Tex. It has particularly been determined that the 20′×8′ Model and the 24′×8′ Model of the TRAILBOSS is well suited for use in the illustrated embodiment. 
   The aquatic vegetation shredding assembly  14  is mounted to the airboat  12  at the bow end. In particular, a frame  52  swingably mounted to the airboat  12  includes a starboard pair of fore-and-aft arms  54  and  56  and a port pair of fore-and-aft arms  58  and  60 . As shown in  FIG. 2 , the starboard pair of arms  54  and  56  are joined at their rearward ends and form two sides of a triangle. The port pair of arms  58  and  60  are similarly configured. The starboard and port pairs of arms are fixedly connected by transverse bars  62 ,  64  and  66  (see FIGS.  1  and  5 ). Transverse bar  66  is fixed between fore-and-aft arms  56  and  60  adjacent their forward ends. Transverse bar  64  is fixed between fore-and-aft arms  54  and  58  adjacent their forward ends. The starboard and port pairs of arms are pivotally attached to the hull  16  by bracket assemblies  68  and  70  respectively, and are disposed outwardly from the hull  16  so as to permit swinging of the frame  52  below the top deck wall  18 . Transverse bar  62  is fixed between bracket assemblies  68  and  70 . Perhaps as best shown in  FIG. 5 , swinging of the frame  52  is controlled by a double-acting hydraulic piston and cylinder assembly  72  pivotally mounted to the transverse bar  62 . A cable  74  is connected between the hydraulic assembly  70  and the transverse bar  66 , such that the frame  52  swings downwardly as the assembly  72  extends, and the frame  52  swings upwardly as the assembly  72  retracts. It will be noted that the cable  74  partially entrains a pulley  76  rotatably mounted to the hull  16  by a stand  78 . 
   As previously described, the starboard arms  54  and  56  form two sides of a triangle (as do the port arms  58  and  60 ). Attached to the forward ends of the starboard and port arms, completing the triangle, are the end arms  80  and  82 . Pivotally mounted to the frame  52 , between the endarms  80  and  82 , is a cutting assembly  84  (see FIGS.  1  and  2 ). The cutting assembly  84  is pivotally mounted to the frame  52  on pivots  86  and  88 . As shown in  FIG. 3 , the assembly  84  includes an upper horizontal support member  90 , a downwardly spaced lower horizontal support member  92 , and vertical support members  94 ,  96 ,  98  and  100 . Rotatably coupled to the assembly  84  are upright shafts  102  and  104 . The shafts  102  and  104  are each rotatably supported on the horizontal support members  90  and  92  by a pair of pillow block bearings  106 ,  108  and  110 ,  112  respectively. Rigidly fixed to the lower end of each of the shafts  102  and  104  is a corresponding hub  114  and  116 . Swingably mounted to each of the hubs  114  and  116  are a plurality of cutting blades  118 ,  120  and  122 ,  124  respectively. The blades  118 ,  120 ,  122 , and  124  are each bolted to the corresponding hub  114  or  116  so that when the hub  114  or  116  rotates, they project in a generally radial orientation (as shown in FIG.  1 ); however, they are deflectable out of the general radial orientation. That is, if the blade  118 , for example, strikes a rigid object (relative to the typical vegetation being shredded) such as a tree trunk, the blade  118  parries off the trunk. It is believed this mounting configuration prevents the blades  118 ,  120 ,  122  and  124  from becoming prematurely deformed and worn thereby extending the overall life of the cutting assembly  84 . The blades  118 ,  120 ,  122  and  124  are pitched such that shredded vegetation is lifted away from the corresponding blade once cut. Because lifted vegetation may fall onto the shafts  102  and  104  and into the airboat  12 , the shredding assembly  14  includes a vegetation shield (not shown) fixed to and extending along the face of the cutting assembly  84  and fixed to and extending between the bottom of arms  54  and  58  along the portion thereof that extends beyond the hull  16 . The vegetation shield is designed to limit the amount of cut vegetation that falls against the shafts  102  and  104  and back into the airboat  12 . The vegetation shield may be variously constructed and utilize alternative materials and designs (e.g., a rubber matting tied to the primary frame with rope). 
   Pivoting of the assembly  84  is controlled by a hydraulic piston and cylinder assembly  126  pivotally mounted between the transverse bar  64  and the upper horizontal member  90  (see FIGS.  1  and  5 ). In its unactivated position as shown in  FIG. 4 , the cylinder assembly  126  maintains the cutting assembly  84  vertically alligned and generally parallel with the endarms  80  and  82 . As the cylinder assembly  126  retracts from the unactivated position, the cutting assembly  84  pivots toward the position shown in FIG.  5 . In this way, the cutting assembly  84  can be pivotally adjusted in order to achieve the desired positioning of the cutting blades  118 ,  120 ,  122  and  124  relative to the surface of the water. For example, as shown in  FIG. 5 , the cutting blades  118 ,  120 ,  122  and  124  are generally parallel to the surface of the water. Although not shown, it will be appreciated that the cylinder assembly  126  may be extended, rather than retracted, from the unactivated position shown in  FIG. 4  thereby causing the cutting assembly  84  to pivot away from the position shown in FIG.  5 . It will be appreciated that the cutting assembly  84  can be positioned (via assemblies  72  and  126 ) to shred aquatic vegetation located below the surface of the water (e.g., root structures). 
   Each of the upright shafts  102  and  104  is driven by a reversible, variable speed hydraulic motor  128  and  130 , respectively, mounted to the stem side of the assembly  84  on the corresponding motor mount  132  and  134 . The motor mounts  132  and  134  are each rigidly fixed to the upper horizontal member  90  and to a corresponding motor mount support  136  and  138 . The motor  128  is connected to and powered by a hydraulic power unit  140  (only partially shown). In the usual manner, the unit  140  includes a pump  142  driven by an engine  144  and a fluid reservoir  146  (see FIG.  2 ). A suitable engine is available from General Motors Corporation as Model No. ZZ4, rated at 350 horsepower. The unit  140  is connected to the motor  128  by the fluid circuit lines  148  and  150  (only partially shown). A drive sprocket  152  mounted on the output shaft of the motor  128  is entrained by a chain  154  that extends forwardly to wrap around a driven sprocket  156  fixed to the shaft  102 . The shredding assembly  14  further includes chain guards (not shown) mounted to the cutting assembly  84  that prevent shredded debris from falling in and around the chains. The motor  128  preferably rotates the shaft  102  (and the attached blades  118  and  120 ) in a clockwise direction when viewed from above, as in FIG.  1 . The motor  130  is essentially identical to the motor  128  and similarly connected to the shaft  104  by a chain and sprocket drive. However, the motor  130  preferably rotates the shaft  104  (and the attached blades  122  and  124 ) in a counterclockwise (opposite of the shaft  102 ) direction when viewed from above, as in FIG.  1 . It is believed that with the shafts  102  and  104  configured to rotate in the preferred directions, the shredded vegetation is thrown away from the center of the boat, as is desirable. The motors  128  and  130 , however, are independently operable and reversible thereby allowing for selective and varied rotation of the shafts  102  and  104 . The principles of the present invention equally apply to vegetation shredders that utilize alternative forms of directing the cut vegetation away from the center of the boat, for example, both of the cutters could rotate in the same direction and present a staggered configuration such that cut vegetation is passed from blade to blade until it is thrown to one side of the airboat  12 . It is also entirely within the ambit of the present invention to utilize a single cutter rather than multiple cutters as illustrated. 
   It has been determined that some forms of aquatic vegetation can be adequately destroyed by simply mowing it down; that is cutting off the majority of the green portion of the plant growing at or above the water surface without cutting the root system. It is believed that keeping the plant mowed down causes the plant to lose its ability to photosynthesize. This mowing method of shredding vegetation may require several passes to keep the vegetation adequately mowed down. In this regard, vegetation shredders that are slow moving are undesirable. In addition, because the root systems are not being cut, a vegetation shredder that has a cutting mechanism that can operate at or above the water surface, and therefore not drain power from the watercraft, is highly desirable. Some applications, however, also require the root systems to be cut after the above-water portion of the vegetation has been mowed and therefore it is desirable to have a shredding assembly that can perform both of these cutting applications. Accordingly, in use, the illustrated airboat having aquatic vegetation shredder  10  is designed for relatively higher speed forward travel, with the shredding assembly  14  mowing down a path through the vegetation as the airboat  12  is propelled by the propeller  34 . The shredding assembly  14  is positioned so that the blades  118 ,  120 ,  122 ,  124  when rotated, project at or near the surface of the water (including below the water surface). In high speed conditions, the blades are preferably positioned so as not to drain the forward power of the airboat  12 . The rotation of the shafts  102  and  104  in the preferred opposite directions throws the mowed vegetation away from the airboat  12 . The cutting assembly  84  can be pivotally adjusted to position the blades to project below the water surface to allow shredding of vegetation growing below the water surface (e.g., root systems). In this manner, the shredder  10  can be used to shred the aquatic vegetation at the roots (either in the initial pass or on a subsequent pass after the upper potion of the vegetation has been mowed off). 
   In addition to a relatively higher speed of forward travel, the aquatic vegetation shredder  10  is well suited for operation in shallow water and no water conditions. Many forms of aquatic vegetation grow in shallow waters. Aquatic vegetation also grows in no water conditions, for example when the water level of a body of water changes leaving the vegetation growing on dry land. As previously noted, the principles of the present invention are equally applicable to various other shredding assembly constructions. 
   One such variation is illustrated in  FIGS. 6-9 , as an aquatic vegetation shredder  200  including an airboat  202  and an aquatic vegetation shredding assembly  204  mounted to the bow end of the airboat  202 . The shredder  200  is generally similar to the machine  10  shown in  FIGS. 1-5 ; however, the cutters of the shredding assembly  204  are disposed in a generally vertical plane and are rotatable about fore-and-aft axes. It will be appreciated that the airboat  202  is substantially similar to the airboat  12  and therefore the airboat  202  will not be described further herein. In a similar manner, the shredding assembly  204  is constructed in a somewhat similar manner as the shredding assembly  14  and therefore the similar features of the assembly  204  will only be briefly discussed. The assembly  204  is swingably mounted to the airboat  202  by a frame  206  pivotally mounted on bracket assemblies  208  and  210 . The frame  206  includes starboard fore-and-aft arms  212  and  214 , port fore-and-aft arms  216  and  218 , and transverse bar  220  (see FIGS.  6  and  7 ). The shredding assembly  204  includes a cutting assembly  222 ; unlike the shredding assembly  14 , cutting assembly  222  is rigidly fixed to the frame  206  thereby obviating the need for endarms, any pivot-enabling structure, and multiple transverse bars. Similar to shredding assembly  14 , swinging of the frame  206  is controlled by a piston and cylinder assembly  224 , including a cable  226 , a pulley  228  and a stand  230 ; however, the cable  226  is fixed to the cutting assembly  222  rather than a transverse bar (see FIG.  9 ). 
   The cutting assembly  222  includes upper and lower horizontal support members  232  and  234 , and vertical support members  236  and  238  (see FIG.  8 ). Similar to the cutting assembly  84 , the cutting assembly  222  includes shafts  240  and  242 , hubs  244  and  246 , and swingable cutting blades  248 ,  250 ,  252  and  254 . The blades  248 ,  250 ,  252  and  254  are configured like the blades  118 ,  120 ,  122 , and  124  so they project in a generally radial orientation and are deflectable out of the general radial orientation. Unlike the upright shafts  102  and  104 , the shafts  240  and  242  have a fore-and-aft orientation (see FIG.  7 ). In order to accommodate the fore-and-aft orientation, assembly  222  includes lateral support members  256  and  258 , each having a three-sided configuration and being fixed to the lower horizontal support member  234  (see FIG.  6 ). The port-side lateral support member  258  extends forwardly from the bow end of the airboat  202  a further distance than does the starboard-side lateral support  256  in order to support the longer length of the shaft  242  relative to the shaft  240  for reasons that will be described below. Each of the shafts  240  or  242  is rotatably supported on the lower horizontal support  234  and the corresponding lateral support  256  or  258  by a respective pair of pillow block bearings  260  and  262  or  266  (the second bearing supporting the shaft  242  is not shown). The cutting assembly  222  includes a vegetation shield assembly  268 . The shield assembly  268  includes a knockdown plate  270  rigidly coupled to the upper horizontal support  232  and extending forwardly therefrom. The shield assembly  268  further includes a hood  272  extending outwardly and downwardly from the upper horizontal support  232  and adjoining the lateral support members  256  and  258  (see FIGS.  8  and  9 ). The plate  270  and the hood  272  form a vegetation barrier between the cutting area defined by the blades  248 ,  250 ,  252 ,  254  and the airboat  202 , when the shredding assembly  204  is in operation. It is believed this configuration enhances the cutting action of the shredding assembly  204 . 
   Similar to the shredding assembly  14 , the shredding assembly  204  is powered by a hydraulic power unit (not shown) that drives hydraulic motors  276  and  278 . The motors  276  and  278  are mounted to the top of the knockdown plate  270  and have output shafts configured to accommodate the fore-and-aft orientation of the shafts  240  and  242 . That is, the motors  276  and  278  are drivingly connected to the shafts  240  and  242  by the corresponding chains  280  and  282  that extend downwardly to the shafts  240  and  242 . The motors  276  and  278  are operable to rotate the shafts  240  and  242  in varied directions such that the rotational direction of the shafts  240  and  242  can be the same or the opposite direction relative to each other. As previously discussed, the axial length of the shaft  242  is longer than the axial length of the shaft  240 . This configuration provides for offset rotational planes of the blades  248  and  250  relative to the blades  252  and  254 . As shown in  FIG. 6 , a portion of the blades  248  and  250  (when rotating) will overlap a portion of the blades  252  and  254  (when rotating); however, the offset rotational planes of the cutters prevents blade contact. It is believed this overlapping relationship allows for the maximum amount of cut vegetation to be directed away from the center of the airboat  202  as is desirable. As previously discussed, unlike the cutting assembly  84 , the cutting assembly  222  is rigidly (not pivotally) fixed to the frame  206  and repositioning of the cutting assembly  222  can consequently be effected only by swinging the frame  206 . Depending on the conditions, it is believed that the cutting blades  248 ,  250 ,  252 ,  254  need not be directly perpendicular to the surface of the water in order to provide the desired shredding of aquatic vegetation. As shown in  FIGS. 6 and 9 , swinging of the frame  206  adjusts the orientation of the cutting assembly  222  so that shredding of the vegetation can occur at, above or below the surface of the water. 
   Another variation of the shredding assembly is embodied in the aquatic vegetation shredder  300 , as illustrated in  FIGS. 10-13 . The shredder  300  includes an airboat  302  and an aquatic vegetation shredding assembly  304  mounted to the bow end of the airboat  302 . It will be appreciated that the only significant difference between the shredder  300  and the shredder  200  shown in  FIGS. 6-9  is the cutting assembly  306 . The assembly  306  includes a drum  308  rotatably supported on a support assembly  310 , a plurality of knives  312  swingably supported on the drum  308 , and a vegetation shield  314 . A similar arrangement is disclosed in our U.S. Pat. No. 6,116,004, entitled AQUATIC VEGETATION SHREDDER, which is hereby incorporated by reference herein as is necessary for a full and complete understanding of the present invention. The cutting assembly  306  is powered by a hydraulic power unit (not shown) and two end-mounted hydraulic motors  316  and  318 . The motors  316  and  318  are operable to selectively rotate the drum  308  in either a clockwise direction or a counterclockwise direction relative to the axis of rotation. 
   The preferred forms of the invention described above are to be used as illustration only, and should not be utilized in a limiting sense in interpreting the scope of the present invention. Obvious modifications to the exemplary embodiments, as hereinabove set forth, could be readily made by those skilled in the art without departing from the spirit of the present invention. 
   The inventor hereby states his intent to rely on the Doctrine of Equivalents to determine and assess the reasonably fair scope of the present invention as pertains to any apparatus not materially departing from but outside the literal scope of the invention as set forth in the following claims.