Patent Publication Number: US-11654589-B2

Title: Power operated rotary knife with notched rotary knife blade and trim guide

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority under 35 USC 120 as a continuation application of parent U.S. application Ser. No. 15/628,637, filed Jun. 20, 2017, published as U.S. Pub. No. US-2018-0117782-A9 on May 3, 2018, to be issued as U.S. Pat. No. 10,583,577 on Mar. 10, 2020, which is a continuation-in-part application of U.S. application Ser. No. 15/216,120, filed Jul. 21, 2016, published as U.S. Publication No. US-2017-0021514-A1 on Jan. 26, 2016, issued as U.S. Pat. No. 10,343,296 on Jul. 9, 2019, which claimed benefit of U.S. Provisional Application Ser. No. 62/196,973, filed Jul. 25, 2015. The respective entire contents of the above-identified U.S. application Ser. Nos. 15/628,637 and 15/216,120 and U.S. Provisional Application Ser. No. 62,196,973, U.S. Publication Nos. US-2018-0333880-A1 and US-2018-0162001-A1, and U.S. Pat. Nos. 10,583,577 and 10,343,296, are incorporated herein in their respective entireties by reference for any and all purposes. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a power operated rotary knife including a notched annular rotary knife blade and a notched annular trim guide, the notched trim guide directing elements to be cut into position for cutting between recessed, sharpened regions or cutting portions of the rotary knife blade against recessed shearing portions of the notched trim guide. 
     BACKGROUND 
     Power operated rotary knives are widely used in meat processing facilities for meat cutting and trimming operations. Power operated rotary knives also have application in a variety of other industries where cutting and/or trimming operations need to be performed quickly and with less effort than would be the case if traditional manual cutting or trimming tools were used, e.g., long knives, scissors, nippers, etc. By way of example, power operated rotary knives may be effectively utilized for such diverse tasks as taxidermy; cutting and trimming of elastomeric or urethane foam for a variety of applications including vehicle seats; and tissue removal or debriding in connection with medical/surgical procedures and/or tissue recovery from a body of a human or animal donor. 
     Power operated rotary knives typically include a head assembly and an elongated handle assembly releasably affixed to the head assembly. The handle assembly extends along a longitudinal axis and includes a hand piece having a gripping surface to be grasped by an operator or user to manipulate the power operated rotary knife. The handle assembly may include a central core or other attachment structure to releasably attach the handle assembly to the head assembly. 
     The head assembly includes an annular blade housing and an annular rotary knife blade supported for rotation by the blade housing. The annular rotary blade of conventional power operated rotary knives is typically rotated by a drive assembly which include a flexible shaft drive assembly extending through an opening in the handle assembly. The shaft drive assembly engages and rotates a drive train, such as, for example, a pinion gear supported by the head assembly. The flexible shaft drive assembly includes a stationary outer sheath and a rotatable interior drive shaft which is driven by an electric motor. Gear teeth of the pinion gear engage mating gear teeth formed on an upper surface of the rotary knife blade. Alternately, a pneumatic motor disposed in a throughbore of the handle assembly may be used to drive the pinion gear supported by the head assembly which, in turn, rotates the rotary knife blade. 
     Upon rotation of the pinion gear by the drive shaft of the flexible shaft drive assembly, the annular rotary blade rotates within the blade housing at a high RPM, on the order of 500-1500 RPM, depending on the structure and characteristics of the drive assembly including the motor, the shaft drive assembly, and a diameter and the number of gear teeth firmed on the rotary knife blade. Conventional power operated rotary knives are disclosed in U.S. Pat. No. 6,354,949 to Bads et al., U.S. Pat. No. 6,751,872 to Whited et al., U.S. Pat. No. 6,769,184 to Whited, and U.S. Pat. No. 6,978,548 to Whited et al., all of which are assigned to the assignee of the present invention and all of which are incorporated herein in their respective entireties by reference. 
     SUMMARY 
     In one aspect, the present disclosure relates to a power operated rotary knife comprising: an annular rotary knife blade supported for rotation about a central axis of rotation in a direction of rotation and rotating with respect to a trim guide, the knife blade including an annular body including an inner wall and an outer wall and an upper end and a lower end, the annular body of the rotary knife blade including a bearing surface for rotational support of the rotary knife blade and a driven gear for rotationally driving the rotary knife blade, the rotary knife blade further including a blade section extending from the lower end of the annular body, the blade section including a blade frustoconical wall extending between an upper end of the blade section and a lower end of the blade section, the lower end of the blade section spaced radially inwardly from and axially below the upper end, a plurality of circumferentially spaced apart notches extending from the lower end of the blade section into the blade frustoconical wall, each of the plurality of notches including an opening at the lower end and a central open portion defined by a peripheral wall, the peripheral wall including a cutting portion, the cutting portion of each of the plurality of circumferentially spaced apart notches defining a cutting edge of the rotary knife blade; and a trim guide including a base and a guide section extending radially inwardly and axially downwardly from the base, the guide section extending axially below and being adjacent to the blade section of the rotary knife blade and including a guide frustoconical wall extending between an upper end of the guide section and a lower end of the guide section, the lower end of the guide section spaced radially inwardly from the upper end, a plurality of circumferentially spaced apart notches extending from the lower end into the guide frustoconical wall, each of the plurality of notches including as opening at the lower end and a central open portion defined by a peripheral wall, the peripheral wall including a shearing portion, the shearing portion in overlapping axial alignment with the cutting portions of the plurality of notches of the blade section of the rotary knife blade as the rotary blade rotates about the central axis of rotation. 
     In another aspect, the present disclosure relates to a combination of an annular rotary knife blade and a trim guide for a power operated rotary knife, the combination comprising: the annular rotary knife blade supported for rotation about a central axis of rotation in a direction of rotation and rotating with respect to the trim guide, the knife blade including an annular body including an inner wall and an outer wall and an upper end and a lower end, the annular body of the rotary knife blade including a bearing surface for rotational support of the rotary knife blade and a driven gear for rotationally driving the rotary knife blade, the rotary knife blade further including a blade section extending from the lower end of the annular body, the blade section including a blade frustoconical wall extending between an upper end of the blade section and a lower end of the blade section, the lower end of the blade section spaced radially inwardly from and axially below the upper end, a plurality of circumferentially spaced apart notches extending from the lower end of the blade section into the blade frustoconical wall, each of the plurality of notches including an opening at the lower end and a central open portion defined by a peripheral wall, the peripheral wall including an arcuate cutting portion, the arcuate cutting portion of each of the plurality of circumferentially spaced apart notches defining a cutting edge of the rotary knife blade; and the trim guide including a base and a guide section extending radially inwardly and axially downwardly from the base, the guide section extending axially below and being adjacent to the blade section of the rotary knife blade and including a guide frustoconical wall extending between an upper end of the guide section and a lower end of the guide section, the lower end of the guide section spaced radially inwardly from the upper end, a plurality of circumferentially spaced apart notches extending from the lower end into the guide frustoconical wall, each of the plurality of notches including as opening at the lower end and a central open portion defined by a peripheral wall, the peripheral wall including a shearing portion, the shearing portion in overlapping axial alignment with the cutting portions of the plurality of notches of the blade section of the rotary knife blade as the rotary blade rotates about the central axis of rotation. 
     In another aspect, the present disclosure relates to a power operated rotary knife assembly comprising: a) a hand-held power operated rotary knife including a head assembly and an elongated handle assembly extending from the head assembly along a longitudinal axis, the head assembly including: i) an annular rotary knife blade supported for rotation about a central axis of rotation in a direction of rotation, the annular rotary knife blade including a blade section including a central opening and a plurality of circumferentially spaced apart notches extending from a lower end of the blade section, each of the plurality of notches including an opening at the lower end and a central open portion defined by a peripheral wall, the peripheral wall including a cutting portion, the cutting portion of each of the plurality of circumferentially spaced apart notches defining a cutting edge of the rotary knife blade; ii) a trim guide including a central opening and a plurality of circumferentially spaced apart notches extending from a lower end of the trim guide, each of the plurality of notches including an opening at the lower end and a central open portion defined by a peripheral wall, the peripheral wall including a shearing portion, the shearing portions in overlapping axial alignment with the cutting portions of the plurality of notches of the blade section of the annular rotary knife blade as the annular rotary blade rotates about the central axis of rotation, overlapping central openings the annular rotary knife blade and the trim guide defining a central cutting opening of the head assembly; and iii) a frame body supporting a drive mechanism including a gear member engaging and rotating the annular rotary knife blade; b) a portable power unit including a drive motor assembly and a blower assembly, the drive motor assembly including a driveshaft assembly rotating about a driveshaft central axis of rotation, the blower assembly including a fan and a duct, the fan coupled to and rotated by the driveshaft assembly, the duct including an inlet duct side on one side of the fan and an outlet duct side on an opposite side of the fan, the inlet duct side including an interior region, rotation of the fan causing a vacuum pressure condition within the interior region of the inlet duct side; c) a flexible shaft drive transmission including a rotating flex shaft assembly operatively coupled between the driveshaft assembly of the portable power unit and the drive mechanism of the head assembly of the power operated rotary knife, rotation of the driveshaft assembly about the driveshaft central axis of rotation causing rotation of the flex shaft assembly and rotation of the gear member of the drive mechanism to rotate the annular rotary knife blade; and d) a vacuum assembly including a vacuum hose coupled between the head assembly and the inlet duct side of the duct of the blower assembly, an interior region of the hose in fluid communication with the interior region of the inlet duct side, the vacuum pressure condition within the interior region of the inlet duct side causing a vacuum pressure condition within an interior region of the vacuum hose and a vacuum condition in a region of the central cutting opening of the head assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other features and advantages of the present disclosure will become apparent to one skilled in the art to which the present disclosure relates upon consideration of the following description of the disclosure with reference to the accompanying drawings, wherein like reference numerals, unless otherwise described refer to like parts throughout the drawings and in which: 
         FIG.  1    is a schematic top front perspective view of a first exemplary embodiment of a power operated rotary knife of the present disclosure including a handle assembly, a head assembly, including a notched annular rotary knife blade, a blade housing and a notched trim guide; 
         FIG.  2    is a schematic top plan view of the power operated rotary knife of  FIG.  1   ; 
         FIG.  3    is a schematic bottom plan view of the power operated rotary knife of  FIG.  1   ; 
         FIG.  4    is a schematic top, front perspective view of the head assembly of the power operated rotary knife of  FIG.  1   , including a frame, the notched annular rotary knife blade, a blade housing, and the notched trim guide and with a pivoting thumbpiece assembly removed for clarity; 
         FIG.  5    is a schematic exploded top, front perspective view of the head assembly of  FIG.  4   ; 
         FIG.  6    is a schematic bottom plan view of the frame head assembly of  FIG.  4   ; 
         FIG.  7    is a schematic top plan view of a combination of the notched annular rotary knife blade, the blade housing, and the notched trim guide of the head assembly of the power operated rotary knife of  FIG.  1   ; 
         FIG.  8    is a schematic bottom plan view of the combination of the notched annular rotary knife blade, the blade housing, and the notched trim guide of the head assembly of the power operated rotary knife of  FIG.  1   ; 
         FIG.  9    is a schematic section view of the combination of the notched annular rotary knife blade, the blade housing, and the notched trim guide of the head assembly of the power operated rotary knife of  FIG.  1   , as seen from a plane indicated by the line  9 - 9  in  FIG.  7   : 
         FIG.  10    is a schematic top, front perspective view of the notched annular rotary knife blade of the head assembly of the power operated rotary knife of  FIG.  1   ; 
         FIG.  11    is a schematic top plan view of the notched annular rotary knife blade of the head assembly of the power operated rotary knife of  FIG.  1   ; 
         FIG.  12    is a schematic bottom plan view of the notched annular rotary knife blade of the head assembly of the power operated rotary knife of  FIG.  1   ; 
         FIG.  13    is a schematic section view of the notched annular rotary knife blade of the head assembly of the power operated rotary knife of  FIG.  1   , as seen from a plane indicated by the line  13 - 13  in  FIG.  11   ; 
         FIG.  13 A  is a schematic section view of an end portion of the notched annular rotary knife blade depicted in the section view of  FIG.  13   ; 
         FIG.  14    is a schematic top, front perspective view of the notched trim guide of the head assembly of the power operated rotary knife of  FIG.  1   ; 
         FIG.  15    is a schematic top plan view of the notched trim guide of the head assembly of the power operated rotary knife of  FIG.  1   ; 
         FIG.  16    is a schematic bottom plan view of the notched trim guide of the head assembly of the power operated rotary knife of  FIG.  1   ; 
         FIG.  17    is a schematic section view of the notched trim guide of the head assembly of the power operated rotary knife of  FIG.  1   , as seen from a plane indicated by the line  17 - 17  in  FIG.  15   ; 
         FIG.  18    is a schematic front elevation view of the blade housing of the head assembly of the power operated rotary knife of  FIG.  1   ; 
         FIG.  19    is a schematic section view of the blade housing of the head assembly of the power operated rotary knife of  FIG.  1   ; and 
         FIG.  20    is a schematic top front perspective view of a second exemplary embodiment of a power operated rotary knife assembly of the present disclosure including a power operated rotary knife and a vacuum assembly, the power operated rotary knife including a handle assembly, a head assembly, including a notched annular rotary knife blade, a blade housing, a notched trim guide, and a vacuum connector, the vacuum assembly including the vacuum connector and a vacuum hose coupled to the vacuum connector; 
         FIG.  21    is a schematic longitudinal section view of the power operated rotary knife assembly of  FIG.  20   ; 
         FIG.  22    is a schematic top front perspective view of the power operated rotary knife of  FIG.  20   , the vacuum hose of the vacuum assembly being removed for clarity purposes; 
         FIG.  23    is a schematic exploded perspective view of the power operated rotary knife of  FIG.  22   ; 
         FIG.  24    is a schematic top plan view of the power operated rotary, of  FIG.  22   ; 
         FIG.  25    is a schematic bottom plan view of the power operated rotary knife of  FIG.  22   ; 
         FIG.  26    is a schematic top plan view of a combination of the notched annular rotary knife blade, the blade housing, and the notched trim guide of the head assembly of the power operated rotary knife assembly of  FIG.  20   ; 
         FIG.  27    is a schematic bottom plan view of the combination of the notched annular rotary knife blade, the blade housing, and the notched trim guide of the head assembly of the power operated rotary knife assembly of  FIG.  20   ; 
         FIG.  28    is a schematic section view of the combination of the notched annular rotary knife blade, the blade housing, and the notched trim guide of the head assembly of the power operated rotary knife assembly of  FIG.  20   , as seen from a plane indicated by the line  28 - 28  in  FIG.  26   ; 
         FIG.  28 A  is a schematic enlarged section view of the combination of the notched annular rotary knife blade, the blade housing, and the notched trim guide of  FIG.  28    that is within a dashed circle labeled  FIG.  28 A  in  FIG.  28   ; 
         FIG.  29    is a schematic top plan view of the notched annular rotary knife blade of the head assembly of the power operated rotary knife assembly of  FIG.  20   ; 
         FIG.  30    is a schematic longitudinal section view of the notched annular rotary knife blade of  FIG.  29   , as seen from a plane indicated by the line  30 - 30  in  FIG.  29   ; 
         FIG.  31    is a schematic enlarged section view of an end portion of the notched annular rotary knife blade of  FIG.  29    that is within a dashed circle labeled  FIG.  31    in  FIG.  30   ; 
         FIG.  32    is a schematic top perspective view of the notched trim guide of the head assembly of the power operated rotary knife assembly of  FIG.  20   ; 
         FIG.  33    is a schematic top plan view of the notched trim guide of  FIG.  32   ; 
         FIG.  34    is a schematic bottom plan view of the notched trim guide of  FIG.  32   ; 
         FIG.  35    is a schematic longitudinal section view of the notched trim guide of  FIG.  32   , as seen from a plane indicated by the line  35 - 35  in  FIG.  33   ; 
         FIG.  36    is a schematic top perspective view of the vacuum connector of the head assembly of the power operated rotary knife assembly of  FIG.  20   ; 
         FIG.  37    is a schematic bottom plan view of the vacuum connector of  FIG.  36   ; 
         FIG.  38    is a schematic longitudinal section view of the vacuum connector of  FIG.  36   , as seen from a plane indicated by the line  38 - 38  in  FIG.  37   ; 
         FIG.  39    is a schematic longitudinal section view of the vacuum connector of  FIG.  36   , as seen from a plane indicated by the line  39 - 39  in  FIG.  37   ; 
         FIG.  40    is a schematic bottom perspective view of the vacuum connector of  FIG.  36   ; 
         FIG.  41    is a schematic top front perspective view of a third exemplary embodiment of a power operated rotary knife assembly of the present disclosure including a power operated rotary knife, a vacuum assembly, a flexible shaft drive transmission, a handle extension assembly, a speed control assembly, and a portable power unit including a rotational power source and a vacuum source; 
         FIG.  42    is a schematic top back perspective view of the power operated rotary knife assembly of  FIG.  41   ; 
         FIG.  43    is a schematic side perspective view of a distal portion of the power operated rotary knife assembly of  FIG.  41    including the power operated rotary knife, a distal portion of the vacuum assembly and a rotational speed control/handle assembly, a vacuum hose of the vacuum assembly removed for clarity; 
         FIG.  44    is a schematic top plan view of the distal portion of the power operated rotary knife assembly of  FIG.  43   ; 
         FIG.  45    is a schematic side elevation view of the distal portion of the power operated rotary knife assembly of  FIG.  43   ; 
         FIG.  46    is a schematic longitudinal section view of the distal portion of the power operated rotary knife assembly of  FIG.  43   ; 
         FIG.  47    is a schematic top plan view of the portable power unit of the power operated rotary knife assembly of  FIG.  41   ; 
         FIG.  48    is a schematic side elevation view of the portable power unit of  FIG.  47   ; 
         FIG.  49    is a schematic side perspective view of a vacuum adapter of the vacuum assembly and a peripheral end portion of an input side duct of a blower assembly of the portable power unit of the power operated rotary knife assembly of  FIG.  41   ; 
         FIG.  50    is a schematic exploded side perspective view of the portable power unit of  FIG.  47   ; 
         FIG.  51    is a schematic explode front perspective view of portions of the power operated rotary knife, the vacuum assembly, the flexible shaft drive transmission, the speed control assembly, and the handle extension assembly of the power operated rotary knife assembly of  FIG.  41   ; 
         FIG.  52    is a schematic exploded rear perspective view of portions of the power operated rotary knife, the vacuum assembly, the flexible shaft drive transmission, the speed control assembly, and the handle extension assembly of the power operated rotary knife assembly of  FIG.  41   ; and 
         FIG.  53    is a schematic section view of the distal portion of the power operated rotary knife assembly of  FIG.  43   , as seen from a plane indicated by the line  53 - 53  in  FIG.  46   . 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure relates to a power operated rotary knife, in one exemplary embodiment, shown generally at  100 , in  FIGS.  1 - 3   , including a head assembly  300  having a rotating, notched annular rotary knife blade  500  ( FIGS.  10 - 13   ) and a coacting stationary, notched trim guide  700  ( FIGS.  14 - 17   ). The rotary knife blade  500  is supported by a stationary blade housing  600  ( FIGS.  18  and  19   ) for rotation about a central axis of rotation R of the blade  500 . The blade housing  600  is positioned between the rotary knife blade  500  and the trim guide  700 . Each of the rotary knife  500 , the blade housing  600  and the trim guide  700  are annular, defining central open regions. When the rotary knife blade  500 , the blade housing  600  and the trim guide are assembled and attached to a frame body  310  of the head assembly  300 , as described below, the central open regions of a combination  450  of the blade  500 , blade housing  600  and trim guide  700  define a central cutting opening CO (best seen in the top plan view of  FIGS.  2  and  7   ) of the power operated rotary knife  100 . Cutting and trimming take place with the central cutting opening CO. The central cutting opening CO is actually defined by a combination  480  of the blade  500  and the trim guide  700 . As can be seen in the top plan view of  FIG.  7   , the bottom plan view of  FIG.  8    and the sectional view of  FIG.  9    which depicts the blade/blade housing/trim guide assembled combination  450 , no portion of the blade housing  600  extends radially inwardly far enough to define any portion of the central cutting opening CO. Thus, the central cutting opening CO is defined by intersecting central open regions of the assembled combination  480  of the rotary knife blade  500  and trim guide  700 . 
     The notched annular knife blade  500  and coacting notched trim guide  700  are useful for a number of tasks, including trimming/pruning of plants and, specifically, trimming/mining foliage, branches, stems, stalks, runners, etc. of plants, including nursery stock and production plants in an efficient and effective manner, by utilizing the advantage of a power driven, rapidly rotating rotary knife blade for cutting purposes. Among the plant suitable for trimming and pruning by the power operated knife  100  of the present disclosure include strawberry plants or bushes, which require periodic pruning and trimming of the plants, including trimming of runners (stems sent out by a plant to establish new plants, crowns, etc.) to maximize fruit production. 
     Pruning of strawberry plants by hand using conventional hand tools such as pruning shears, snips, scissors, etc. or having employees use their hands for pruning is both labor intensive and time consuming. Additionally, constant hand manipulations required for operating pruning shears and the like are both tiring for the employee and result in repetitive stress to the employee&#39;s hand. While attempts at using power operated or power driven tools to replace hand pruning operations, such as, for example, the use of power driven string trimmers to prune strawberry plants, have met with limited success because strawberry plants are delicate and the plant and its root structure may be easily damaged by the action of a rapidly rotating plastic line of a string trimmer. Additionally, many commercial growers utilize plastic mats or sheets between strawberry plant rows to inhibit weed growth and protect strawberry plant roots. The whipping action of a rotating plastic line upon inadvertent contact with plastic mat or sheet can displace or damage the mat or sheet thereby undesirably exposing the plant roots and/or damaging the plant roots. 
     The power operated rotary knife  100  of the present disclosure utilizes the advantage of a rapidly rotating rotary knife blade  500  and the stationary trim guide  700  to facilitate effective and efficient trimming or cutting of plant foliage/branches/stems/stalks/runners and the like, etc. (hereinafter interchangeably and generally/collectively referred to as “branch” and/or “branches” and/or “foliage” and/or “foliage material” and/or “material” and/or “materials” throughout this description). Depending on the gearing of a drive mechanism  400  and the rotational speed of a drive motor of the drive mechanism  400  of the power operated rotary knife  100 , a diameter of the rotary knife blade  500  and the gearing characteristics of the driven gear  520  of the blade  500  and other factors, the rotation speed of the blade  500  may be on the order of 500-1500 RPM. The rotary knife blade  500  is supported for rotation about a central axis of rotation R by a blade housing  600  and, when looking at the rotary knife blade  500  and the rotary knife  100  from above (the top plan view shown in  FIG.  2   ) rotates in a counterclockwise direction of rotation CCW (as seen in  FIG.  2   ). 
     The rotary knife blade  500  includes a blade section  550  that extends axially downwardly and radially inwardly from an annular body  510  of the blade  500 . The blade section  550  extends between an upper end  552  and a lower end  554  and has a generally frustoconical shape. The lower end  554  of the blade section  550  defines a lower end  518  of the rotary knife blade  500 . The blade section  550  includes a plurality of notches or notched regions  560  extending inwardly from a bottom or lower end  508  of the blade  500 , that is, the lower end  554  of the blade section  550 . Each of the plurality of notches  560  defines a recessed, arcuate cutting region or portion  580  of the rotary knife blade  500 . Taken together, the recessed, arcuate cutting portions  580  defined by the plurality of notches  560  define a cutting edge  590  of the blade section  550 . The plurality of notches  560  extend inwardly from a bottom end  554  of the blade section  550  of the rotary knife blade  500 . The notches  560  include interior cutting regions which are recessed from the bottom end  554  of the blade section  550 . For each of the plurality of notches  560 , the arcuate cutting portion  580  of the notch  560  is disposed at a trailing end  570  of the notch  560  with respect to the direction of rotation CCW of the blade  500 . In one exemplary embodiment of the rotary knife blade  500  of the present disclosure, the plurality of notches  560  are disposed in an evenly circumferentially spaced arrangement in the blade section  550  of the knife  500 , as best seen in  FIG.  11   , and the number of notches  560  is six. 
     The coacting trim guide  700  includes a planar base  710  and a guide section  720  extending axially downwardly and radially inwardly from the base  710 . The trim guide  700  is positioned and configured such that the guide section  720  extends below and is adjacent to the blade section  550  of the blade  500 , substantially conforming to the generally frustoconical shape of the blade section  550 . The guide section  720  includes an upper end  722  and a lower end  724 . The lower end  724  of the guide section  720  defines a lower end  704  of the trim guide  700 . The guide section  720  includes a plurality of notches or notched regions  730  extending inwardly from a bottom or lower end  724  of the guide section  720 , that is, the lower end  704  of the trim guide  700 . Each of the plurality of notches  730  defines a recessed, shearing regions or portions  740  of the trim guide  700 . For each of the plurality of notches  730 , the shearing portion  740  of the notch  730  is disposed at a leading end of the notch  730  with respect to the direction of rotation CCW of the blade  550 . The shearing portions  740  of the guide section notches  730  are in overlapping axial alignment with the arcuate cutting portions  580  of the blade section notches  560  as the rotary knife blade rotates about the central axis of rotation R. Stated another way, the stationary shearing portions  740  and the rotating cutting portions  580  create a shearing or scissors-like cutting action because they are in overlapping axial alignment as the rotary knife blade  100  rotates about its central axis of rotation R. 
     An extending distal portion  725  of the guide section  720  of the trim guide  700  extends axially below and radially inwardly of the lower end  504  of the rotary knife blade  500  to function as a guard to protect the blade  500  from inadvertent contact with the plastic mat or sheeting used between rows of plants or around the base of a plant to inhibit weed growth and/or protect plant roots. Additionally, the extending distal portion  725  of the guide section  720  advantageously functions to direct a branch or branches into an interior region  745  of one of the plurality of notches  730  as the knife  100  is moved by the operator in a direction orthogonal to the axis of rotation R of the rotary knife blade  500  to cut or trim a branch or branches. That is, the operator moves the knife  100  to position a branch or branches to be cut or trimmed within the central cutting opening CO defined by the rotary knife blade, blade housing, and trim guide combination  450 . The operator then moves the knife  100  in a direction generally orthogonal to the blade axis of rotation R such that the branches are urged against the lower end  724  of the trim guide  700  and slide along a lower end  724  of the guide section  720  and move into the interior region  745  of one of the plurality of notches  730  of the guide section  720 . Typically, the movement of the knife  100  is in the direction of the operator, that is, the operator pull the knife in a rearward or proximal direction RW ( FIG.  1   ) toward himself or herself as the plurality of notches  730  are position toward a forward portion  726  of the guide section  720 . Since the distal portion  725  extends beyond the lower end  504  of the blade, the uncut branch or branches can slide along a lower end  724  of the guide section  720  and move into the interior region  745  of one of the plurality of notches  730  of the guide section  720  as the operator pull the knife  100  toward himself or herself. 
     The trim guide  700  also includes a guard section  750  comprising a peripheral rib  751  which extends axially above and radially outwardly from the base  710 . As can best be seen in  FIG.  15   , the rib  751  extends around most, but not all of the total annulus defined by the trim guide  700 . Additionally, the guard section  550  includes a vertical extension  754  extending axially upwardly from an upper end  751   a  of the rib  751  and a lip  770  extending axially upwardly and radially inwardly from an upper end  754   a  of the vertical extension  754 . The vertical extension  754  and the lip  770  subtend an angle less than an angle subtended by the rib  751 . Both the rib  751 , the vertical extension  754  and the lip  770  of the guard section  750  function as guards to protect the blade  500  from inadvertent contact with plastic mats, portions of plants that are not to be trimmed or cut, and the like. 
     In one exemplary embodiment of the trim guide  700  of the present disclosure, the plurality of notches  730  are disposed in a front or distal portion  726  of the guide section  720  of the trim guide  700 , as can best be seen in  FIG.  16   , and the number of notches  730  is six, evenly spaced apart subtending just over 180 degrees of the total annulus defined by the trim guide  700 . 
     The notches  730  of the trim guide  700  function to direct the plant branches to be cut into recessed shearing portions  740  defined by each of the plurality of notches  730  of the trim guide  700  wherein the recessed arcuate cutting portions  580  of the plurality of notches  560  of the rotary knife blade  500  cut the branches by shearing action as the blade  500  rotates with respect to the stationary trim guide  700 . To cut or trim a branch, the power operated rotary knife  100  is positioned with respect to a plant branch to be cut or trimmed such that the branch extends through the cutting opening CO defined by the power operated rotary knife  100 , the operator then moves the knife  100  in a direction such that the branch is moved within the cutting opening CO and urged against the front or distal portion  725  of the guide section  720  of the trim guide  700 . Depending on the position of the branch within the cutting opening CO, the movement of the rotary knife  100  by the operator will move the branch into one of the plurality of notches  730  of the trim guide guide section  720 . A cutting portion  580  of the rotary knife blade  500  will impact the branch within the interior region  745  of the notch  730 , cutting the branch by a shearing action between the shearing portion  740  of the trim guide notch  730  at the leading end  732  of the notch  730  and the cutting portion  580  of the blade section notch  560  at the trailing end  570  of the notch  560 . 
     While the shearing action of the power operated rotary knife  100  has been described above with respect to trimming, pruning, cutting of plants and, specifically, strawberry plants, one of skill in the art will recognize that the power operated rotary knife  100  of the present disclosure can be advantageously used for any trimming/pruning/cutting task where a shearing-type cutting action between a rapidly rotating rotary knife blade  500  having, recessed sharpened, cutting portions  580 , against a stationary trim guide  700 , having recessing shearing portions  740 , that functions to guide elements to be cut or trimmed into position for cutting by the recessed, sharpened cutting portions  580  of the rotary knife blade  500 . In one exemplary embodiment of the power operated rotary knife  100  of the present disclosure, an outer diameter of the rotary knife blade  500  is approximately 5.09 in. and the blade configuration is a so-called flat blade configuration meaning the blade has a shallow blade cutting profile, as opposed to, for example, a hook blade configuration or a straight blade configuration. As would be understood by one of skill in the art, the configuration and size of the rotary knife blade  500  may vary depending on the elements/branches to be cut, trimmed or pruned. The present disclosure contemplates the use of alternate blade sizes and configurations and corresponding different diameters/sizes and configurations for the trim guide  700  in the power operated rotary knife  100 . 
     Handle Assembly  200   
     The power operated rotary knife  100  of the present disclosure includes the head assembly  300  having an elongated handle assembly releasably affixed thereto. As can best be seen in  FIGS.  1 - 3   , the handle assembly  200  extends along a longitudinal axis LA. The handle assembly  200  includes a hand piece  210  defining an exterior gripping surface  212  adapted to be gripped by an operator of the power operated knife  100  when wielding and manipulating the knife  100 . The hand piece  210  includes the central throughbore defined by an inner surface  224  of the hand piece  210 . The handle assembly throughbore is coaxial with the longitudinal axis LA and is aligned with a throughbore of a throughbore  312  of a frame or frame housing/body  310  of the head assembly. 
     The handle assembly  200  further includes a drive shaft latching assembly  280 . The shaft drive latching assembly  280  releasably secures a flexible shaft drive assembly (not shown) of the drive mechanism  400  to the handle assembly  200  such that motive power may be applied to drive a drive or gear train  402  disposed in the throughbore  312  of the frame  310  and thereby rotate the rotary knife blade  300 . In one exemplary embodiment, the gear train  402  comprises a pinion gear  404  which is rotated by the flexible shaft drive assembly and, in turn, rotates the rotary knife blade  500 . The shaft drive latching assembly  280  includes a latching knob  282  secured to a proximal end  214  of the hand piece  210  and a latching member  284  for releasably securing a coupling of the shaft drive assembly to the handle assembly  200 . 
     The latching knob  282  of the drive shaft latching assembly  280  threads onto a threaded end section (not shown) of the frame tube (not shown) extending from the frame body  310 . When the latching knob  282  is threaded onto the threaded proximal end section of the frame tube, the hand piece  210  is thereby sandwiched and secured to the rearward annular boss  350  of the frame body  310 . 
     Head Assembly  300   
     The power operated rotary knife  100  includes a handle assembly  200  and the head assembly  300  releasably affixed to the handle assembly  200 . As can best be seen in  FIGS.  4 - 6   , the head assembly  300  includes the frame housing or frame  310 , a clamping assembly  330 , the rotary knife blade  500 , the blade housing  600  and the trim guide  700 . The rotary knife blade  500  is supported for rotation about the axis of rotation R by the blade housing  600 . The blade housing  600  defines a rotational plane RP of the rotary knife blade  500 . The blade housing  600 , in turn, is releasably affixed to the frame body  310  by a cover or clamp  332  of the clamp assembly  330 . As is best seen in  FIGS.  6 - 8   , the frame body  310  also supports the drive mechanism  400  of the power operated rotary knife  100 . In one exemplary embodiment, the frame body  310  includes the longitudinally extending, central throughbore  312  which supports the gear train  402  of the drive mechanism  400 . Specifically, the gear train  402  includes a pinion gear  4604  and an input shaft of the pinion gear  404  is supported for rotation within a cylindrical bushing  410  positioned within a front portion  314  of the throughbore  312 . The pinion gear  404  is precisely positioned and oriented by the frame body  310  such that a gear head  406  of the pinion gear meshes with a driven gear  520 , namely, set of gear teeth  522  formed at the upper end  516  of the annular body  510  of the of the rotary knife blade  500  to rotate the knife blade  580  within the blade housing  600 . 
     Frame Body  310   
     The frame body  310  includes a forward or distal blade housing support region  320  and a rearward annular boss  350 . The forward blade support region  320  includes a pair of outwardly extending arcuate arms  322  which define a blade housing mounting region  324  for receiving an arcuate mounting section  650  of the blade housing  600  and a clamping receiving region  326  for receiving the proximal wall of the clamp  332  of the clamping assembly  330 . The clamp  332  is secured to the frame body  310  by a pair of threaded fasteners  334  that extend through respective openings in the arcuate arms  322  of the frame body  310 . The arcuate mounting section  392  of the blade housing  390  is sandwiched between the forward blade housing support region  320  and the clamp  332  to releasably secure the blade housing  600  to the frame body  310 . 
     In one exemplary embodiment, the rearward annular boss  350  of the frame body  310  includes an inner surface defining a rear portion of the central throughbore  312 . The rear portion of the central throughbore  312  includes a threaded section. A frame tube (not shown) threads into and is affixed to the threaded section of the rearward annular boss  350 . The frame tube (not shown) extends rearwardly though a central throughbore of a hand piece  210  of the handle assembly  200  and includes a threaded proximal end section. An outer surface  352  of the rearward annular boss  350  includes a first region  354 , closest to the forward blade support region  320 , and a middle region  356 . The first region  354  includes a pair of exterior grooves on the outer surface  352  that receives a pair of sealing members  382  of the grease cup assembly  380 . The middle region  356  includes a plurality of raised splines  358  and is sized to receive an annular mounting ring  392  of the pivoting thumb support  390 . If desired and depending on operator preference, the pivoting thumb support  390  may be removed from the power operated rotary knife  100  and the knife  100  may be used without the thumb support  390 . In such an alternate exemplary embodiment, the annular mounting ring  392  is replaced with an annular spacer ring (not shown) which is sized to fit on the plurality of raised splines  358  of the rearward annular boss  350  of the frame  310 . Specific details of the structure and function of the pivoting thumb support  390 , the grease cup assembly  380  and attachment structure of the handle assembly  200  to the head assembly  300  are found in U.S. Published Application No. US2014/0259690 to Mascari et al., published Sep. 18, 2014 and U.S. Published Application No. US2014/0250697 to Steele et al., published Sep. 11, 2014, issued as U.S. Pat. No. 9,321,183 on Apr. 26, 2016. Both U.S. Published Application No. US2014/0259690 and U.S. Published Application No. US2014/0250697 are assigned to the assignee of the present invention and both of the aforesaid published applications are incorporated herein in their respective entireties by reference. 
     Drive Mechanism  400   
     The drive mechanism  400  of the power operated rotary knife  100  includes the drive train  402  supported within the central throughbore  312  of the frame body  310 . In one exemplary embodiment, the drive train  402  includes the pinion gear  404 . The input shaft  408  of the pinion gear  404  is supported for rotation by the cylindrical bushing  410  positioned within the front portion of the throughbore  412 . A drive coupling of a flexible shaft drive transmission (not shown), driven by a remote motor drive (not shown), extends through a throughbore of the hand piece  210  of the handle assembly  200  and engages a female coupling defined by the pinion gear input shaft  408  to rotate the pinion gear  404 . The gear head  406  of the pinion gear  404  operatively engages the set of gear teeth of the rotary knife blade  500  to rotate the knife blade  500  within the blade housing  600 . 
     As mentioned above, in one exemplary embodiment, the drive mechanism  400  of the power operated rotary knife  100  may comprise a remote motor drive and a flexible shaft drive transmission which transfers rotational power from the motor drive to rotate a drive train  1550  of the power operated rotary knife  1000 . The flexible shaft drive transmission includes a driver assembly which is received in a central, longitudinally extending throughbore of the handle assembly  200  to rotatably drive the drive train  402  of the drive mechanism  400 . Such a drive mechanism, including a remote motor drive and flexible shaft drive transmission and driver assembly, are disclosed in U.S. Pat. No. 8,968,107 to Rapp et al., issued Mar. 3, 2015 and U.S. Published Application No. US2013/0174424 to Whited et al., published Jul. 11, 2013, issued as U.S. Pat. No. 9,265,263 on Feb. 23, 2016, both of which are assigned to the assignee of the present invention. Both U.S. Pat. No. 8,968,107 and U.S. Published Application No. US2013/0174424 are incorporated herein in their respective entireties by reference. In an alternate exemplary embodiment of the power operated rotary knife of the present disclosure, the drive mechanism  400  may include a pneumatic motor (not shown) disposed within the throughbore of the handle assembly  200 . An output shaft and coupling of the pneumatic motor are operatively coupled to the female coupling defined by the pinion gear input shaft  408  to rotate the pinion gear  404 . Such a pneumatic drive mechanism is disclosed in U.S. Pat. No. 7,207,114 to Rosu et al., issued Apr. 24, 2007 and U.S. Pat. No. 8,756,819 to Whited et al., issued. Jun. 24, 2014, both of which are assigned to the assignee of the present invention. Both U.S. Pat. Nos. 7,207,114 and 8,756,819 are incorporated herein in their respective entireties by reference. 
     Blade Housing  600   
     The rotary knife blade  500  ( FIGS.  10 - 13   ) is supported for rotation about a central axis of rotation R by the annular blade housing  600  ( FIGS.  18 - 19   ). The blade housing includes a split, annularly curved blade support section  610  that surrounds and supports the rotary knife blade  500  about the entire 360 degree circumference of the blade  500  and a mounting section  650  extending axially from the blade support section  610  and provides a mounting structure for releasably mounting the blade  500  and blade housing  600  to the blade housing mounting region  324  of the frame body  310 . The blade housing includes an inner wall  602  and an outer wall  604  and an upper end  606  and a lower end  608 . Adjacent the lower end  608 , the inner wall  602  defines a bearing surface  620 , which in one exemplary embodiment is a radially inwardly protruding bearing bead  622 , extending from an inner wall  602  of the blade housing  600 . The blade housing bearing bead  622  extends into a generally V-shaped opening or bearing race  540  formed in and extending radially into an outer wall of the  514  of an annular body  510  of the rotary knife blade  500  to support the blade for rotation. The blade bearing race  540  comprises two axially spaced apart, generally frustoconical, bearing faces  542  which bear against the blade housing bead  622  to support the blade both axially and radially. The bearing support structure of the bearing bead  622  of the blade housing  600  and the bearing race  540  of the rotary knife blade  500  define the rotational plane RP of the rotary knife blade  500 , which is substantially orthogonal to the blade central axis of rotation R. 
     The mounting section  650  of the blade housing  600  includes an angled split  652  and a pinion clearance region  654 . The pinion clearance region  654  of the blade housing mounting section  650  provides for clearance for the gear head  406  of the pinion gear  404  of the drive mechanism drive train  402 . The angled split  652  of the mounting section  650  is circumferentially offset from the pinion clearance region  654  and provides for expansion of the blade housing diameter for purposes of changing the rotary knife blade  500  when the blade has reached the end of its useful life. Specific details regarding an annular blade housing with an angle split and offset pinion clearance region are disclosed in U.S. Pat. No. 8,661,692 to Whited et al., issued Mar. 4, 2014. U.S. Pat. No. 8,661,692 is assigned to the assignee of the present invention and is incorporated herein in its entirety by reference. 
     The rotary knife blade  500 , the blade housing  600 , and the trim guide  700 , are all annular and, when assembled, define an overlapping sandwiched combination  450 , as shown in  FIGS.  7 - 9   , wherein the blade housing blade support section  610  is radially sandwiched between, on the radial inside, the annular body  510  of the rotary knife blade  500  and, on the radial outside, by the rib  751  of the guard section  750  of the trim guide  700 . 
     Rotary Knife Blade  500   
     The rotary knife blade  500  of the power operated rotary knife  100  includes an inner wall  502  and a radially spaced apart outer wall  504  and an upper end  506  and an axially spaced apart lower or bottom end  508 . The inner wall  502  defines a central opening of the blade  500 . The blade  500  includes the annular body  510  which defines an inner wall  512  (defining part of the inner wall  502  of the blade  500 ), an outer wall  514  (defining part of the outer wall  504  of the blade  500 ), an upper end  516  (defining the upper end  506  of the blade  500 ) and a lower end  518 . The rotary knife blade  500  further includes the blade section  550  extending axially downwardly and radially inwardly (toward the blade axis of rotation R) from the lower end  518  of the annular body  510 . The blade section  550  includes upper end  552  adjacent the annular body lower end  518  and a lower end  554  (defining the lower end  508  of the blade  500 ) and a generally frustoconical wall  556  extending therebetween. 
     The upper end  516  of the annular body  510 , as mentioned above, defines the driven gear  520  of the blade  500 . The driven gear  520  comprises a set of gear teeth formed in a circumference adjacent the outer wall  514  of the annular body. Adjacent the lower end  518  of the annular body, the blade bearing race  540  defining frustoconical bearing surfaces  542  is formed in the outer wall  514  of the annular body, as described above. 
     The lower end  554  of the blade section  550  includes a plurality interrupted arc portions  572  that define a lower edge  509  of the blade  500 . The interrupted are portions  572  are centered about the blade central axis of rotation R and, if connected and continued, would form a circle defining an inner diameter of the blade  500  with a center on the axis of rotation R. Typically, the interrupted are portions  572  would define a cutting edge of the blade, but, in the rotary knife  500  of the present disclosure, the cutting edge  590  of the blade are defined by the recessed, arcuate cutting portions  580  within the plurality of notches  560 . Interrupting the arc portions  572  are the plurality of notches  560  formed at the lower end  554  of the frustoconical wall  556  of the blade section  550  and extending into the frustoconical wall  556 . As can best be seen in  FIG.  11   , each of the notches of the plurality of notches  560 , when viewed in top plan view, defines a generally rectangular cavity  561  defined by a peripheral wall  562  surrounding a central open portion  564  and defining the cavity  561 . The peripheral wall  562 , when viewed with respect to the counterclockwise direction of rotation CCW ( FIG.  7   ) of the rotary knife blade  500 , includes an angled leading portion or end  566 , a generally linear central portion  568 , and a hook-shaped or U-shaped trailing portion or end  570 . 
     The trailing end  570  of the peripheral wall  562  includes an arcuate sharpened region  571  extending approximately from a transition segment  569  of the peripheral wall  562  bridging the linear central portion  568  and the trailing end  570  to a termination point  584  of the trailing end  570  located at the bottom edge  509  of the blade  500 , as defined by the start of the next interrupted are portion  572 . The arcuate sharpened regions  571  may extend to the bottom edge  509  of the blade  500  or be in close proximity to the bottom edge. Both are contemplated by the present disclosure. The arcuate sharpened regions  571  are concave (like the inside of a bowl) in that they are curving in or hollowed inwardly due to the hook-shape of the trailing end  570  of the peripheral wall  562 . The arcuate sharpened regions  571  of the plurality of notches  560  define the respective recessed arcuate cutting regions or portions  580  of the blade  500 . The arcuate cutting portions  580  are recessed in that at least a portion of the arcuate sharpened region  571  is within an interior region  582  (that is, the central open portion  564 ) defined by each of the plurality of notches  560 . It should be appreciated of course that the arcuate cutting portions  580  (and the associated sharpened regions  571 ), instead of being arcuate (by virtue of the hook-shaped trailing end  570  of the peripheral wall  562 ), could be linear or convex and the present disclose contemplates such an alternate embodiment. In one exemplary embodiment of the rotary knife blade  500 , an inner diameter of the blade  500 , as defined by the interrupted arc portions  572  constituting the lower edge  509  of the blade  500 , is approximately 4.0 in., while the outside diameter of the blade, defined by the radial outermost extent of the outer wall  514  of the annular body  510  of the blade is approximately 5.092 in. In one exemplary embodiment, a thickness of the interrupted are portions  572  is approximately 0.038 in. Additionally, in one exemplary embodiment, the number notches in the plurality of notches  560  is six, each of which is spaced equidistantly about an inner perimeter or inner diameter of the blade  500 , each of the notches subtending an angle α (depicted schematically in  FIG.  11   ) with respect to the central axis of rotation R of approximately 35°. 
     Trim Guide  700   
     The trim guide  700 , which is stationary with respect to the rotation of the blade  500 , includes an upper end  702  and a lower end  704  and defines the planar base  710 , the guide section  720  extending axially below and radially inwardly from the base  710 , and the guard section  750 , including the upwardly extending rib  751 , the vertical extension  754  and the radially inwardly extending lip  770 , as previously described. The base  710  includes an attachment tab  718  extending from a rearward portion  712  of the base  710 . The tab  718  includes an aperture  719 . The trim guide  700  is releasably affixed to a bottom surface  321  of the blade housing support region  320  of the frame body  310  by a threaded fastener  800  that extends through the tab aperture  719  and threads into a threaded opening  321   a  of the bottom surface  321  of the blade housing support region  320  of the frame body  310 . 
     The guide section  720  of the trim guide  700  includes an upper end  722  and a lower end  724  and defines a guide section frustoconical wall  721 . The frustoconical wall  721  extends along the frustoconical wall  556  of the blade section  550 . As described above, the extending distal portion  725  of guide section  720  extends axially below and radially inwardly beyond the lower edge  509  of the rotary knife blade  500  and has two functions: 1) to direct a branch or branches into an interior region  745  defined by one of the plurality of notches  730  as the knife  100  is moved by the operator to cut or trim a branch or branches within the central cutting opening CO of the knife  100 ; and 2) to guard the blade  500  from inadvertent contact with the ground or plastic mats or sheets positioned on the ground between rows of plants. 
     In the forward portion  726  of the guide section  720  are the plurality of notches  730  formed the lower end  724  and extending into the frustoconical wall  721 . The lower end  724  of the guide section  720  also includes interrupted are portions  738  that define a lower edge  709  of the trim guide  700 . The interrupted are portions  738  are centered about the blade central axis of rotation R and, if connected and continued, would form a circle defining an inner diameter of the trim guide  700  with a center on the axis of rotation R. Interrupting the are portions  738  in the forward portion  726  of the guide section  720  are the plurality of notches  730  formed at the lower end  724  of the frustoconical wall  721  of the guide section  720  and extending into the frustoconical wall  721 . As can best be seen in  FIG.  15   , each of the notches of the plurality of notches  730 , when viewed in top plan view, defines a generally slanted, concave U-shaped cavity  741  defined by a peripheral wall  742  surrounding a central open portion  743  (the interior region  745 ) and defining the cavity  741 . The peripheral wall  742 , when viewed with respect to the counterclockwise direction of rotation CCW of the rotary knife blade  500 , includes an angled leading portion or end  732 , a generally linear central portion  733 , and an angled trailing portion or end  734 . 
     For each of the plurality of notches  730 , the leading end  734  of the peripheral wall  742  defines a shearing region or portion  740  extending approximately from a termination point  747  of the notch  730  at the lower end  724  of the guide section  720  where the next adjacent interrupted are portion  738  commences and extending to a radially innermost point  746  ( FIG.  16   ) of the peripheral wall  742 . Or, stated another way, the shearing region or portion  740  extends from the termination point  747  of the notch  730  to a radially innermost point  749  ( FIG.  16   ) of the notch  730 , which corresponds to the radially innermost point  746  of the peripheral wall  742 . When viewed in top plan view, the shearing portions  740  defined by the leading ends  734  of the respective plurality of notches  730  define a linear segment  740   a  ( FIG.  15   ) over most of their extent moving radially inwardly from the lower end  724  of the guide section  720  and then transition into a shorter arcuate segment  740   b  as the innermost point  746  of the peripheral wall  742  is approached. The shearing portions  740  of the plurality of notches  730  of the trim guide  700  are recessed in that at least a portion of the shearing portion  740  is within an interior region  745  (that is, the central open portion  743 ) defined by each of the plurality of notches  730 . 
     As explained above, the cutting action of the knife  100  occurs through the combination  480  of the rotating rotary knife blade  500  and the stationary trim guide  700 . As the blade  500  rotates about its central axis of rotation R, the shearing portions  740  of the guide section notches  730  come into overlapping axial alignment with the arcuate cutting portions  580  of the blade section notches  560 . Additionally, the central open portion  564  or interior region  582  of each of the plurality of notches  560  of the blade section  550  of the rotary knife blade  500  come into overlapping axial alignment with the central open portion  743  or interior region  745  of each of the plurality of notches  730  as the blade  500  rotates about the axis of rotation R. This transitory overlapping alignment of the central open portions  564 ,  743  or interior regions  582 ,  745  define transitory cutting pockets  799  (two of which can be seen in  FIG.  7   ). The uncut branch or branches directed into a transitory pocket  799  by the guide section  720  of the trim guide  700 , that is, guided into a trim guide notch  730 , will be rapidly and efficiently cut by the shearing action of the rotating cutting portions  580  of the blade  500  passing over the stationary shearing portions  740  of the trim guide  700  as the rotary knife blade  500  continues its high speed rotation in the counterclockwise direction CCW. The cutting pockets  799  are transitory in that as the blade  500  continues to rotate about its axis of rotation R, the blade  500  rotates with respect to the stationary trim guide  700 . Thus, as would be understood, new cutting pockets  799  are formed by overlapping interior regions  582 ,  745  and then disappear as cutting of the branch or branches with the cutting pockets  799  occurs by shearing action by virtue of the rotating cutting portions  580  of the blade  500  passing over the stationary shearing portions  740  of the trim guide  700 . Thus, as the blade  500  rotates about the central axis of rotation R, new cutting pockets  799  are constantly formed and old cutting pockets  799  disappear as cutting occurs and branches in the cutting pockets are cut by shearing action. 
     In one exemplary embodiment of the trim guide  700 , an inner diameter of the trim guide  700 , as defined by the interrupted are portions  738  constituting the lower edge  709  of the trim guide  700 , is approximately 3.809 in., while a diameter defined by a radially innermost point of each of the plurality of notches  730  of the guide section  720  is approximately 4.631 in. Additionally, in one exemplary embodiment, the number notches in the plurality of notches  730  is six, each of the notches subtending an angle β (depicted schematically in  FIG.  15   ) with respect to the central axis of rotation R of approximately 20°. 
     Annular, as used herein, means generally ring-like or generally ring-shaped in configuration and includes configuration wherein the ring include or does not include a split extending through a diameter of the ring or annulus. Axially above or axially spaced above, as used herein, means positioned above as viewed with respect to an axis, for example, the central axis of rotation R of the rotary knife blade  500 , even if the two elements are not in axial alignment with respect to the axis. Similarly, the terms axially below or axially spaced below, as used herein, means positioned below as viewed with respect to an axis, for example, the central axis of rotation R of the rotary knife blade  500 , even if the two elements are not in axial alignment with respect to the axis. Axially extending, as used here, means one element extends from and is positioned above or below a second element with respect to an axis, even if the two elements are not in axial alignment with respect to the axis. Similarly, the terms radially offset from, radially outward of, radially inward of, as used herein, means one element is positioned offset from a second element, as viewed along a radius line extending radially from an axis, for example, the central axis of rotation R of the rotary knife blade  500 , even if the two elements are not in radial alignment along the radius line because one element is axially above or axially below the other element 
     Second Exemplary Embodiment Power Operated Rotary Knife Assembly  1000   
     A second exemplary embodiment of a power operated rotary knife assembly of the present disclosure is schematically shown, generally at  1000 , in  FIGS.  20 - 21   . The power operated rotary knife assembly  1000  includes a power operated rotary knife  1100 , generally similar in structure and function to the power operated rotary knife  100  of the first exemplary embodiment, and a vacuum assembly  1900 . The power operated rotary knife  1100  is best seen in the schematic depictions of  FIGS.  22 - 25   , wherein a vacuum hose  1990  of the vacuum assembly  1900  has been removed for clarity. Advantageously, the vacuum assembly  1900  functions to remove, by vacuum suction, cut or trimmed materials (cut elements/branches) from the cutting opening CO of the power operated rotary knife  1100 . The vacuum assembly  1900  (depicted schematically in  FIGS.  20  and  21   ) expeditiously and efficiently removes trimmed branch materials from the cutting opening or cutting region CO (best seen in  FIGS.  26  and  27   ) and, thus, away from the plant being trimmed, keeping the plant and the plant bed areas clean and free from trimmed branch materials is advantageous from a horticultural point of view. Leaving trimmed materials on the remaining branches of the plant or leaving trimmed materials to decay on the ground in the plant bed area is unsightly and potentially could lead to plant disease and/or insect infestation problems. 
     For brevity, the structural details/functions/advantages of those components and assemblies of the power operated rotary knife  1100  which are similar to the corresponding components and assemblies of the power operated rotary knife  100  will not be repeated in detail, all of the structural details/functions/advantages discussed above with respect to the power operated rotary knife  100  are hereby incorporated by reference with respect to the second exemplary embodiment. Explanations regarding the description of the power operated rotary knife  100 , set forth above, are also hereby incorporated by reference with respect to the second exemplary embodiment. Common reference numbers and letters used in the two embodiments are assumed to represent similar concepts and/or structural details. 
     As best seen in  FIGS.  22 - 25   , the power operated rotary knife  1100  includes an elongated handle assembly  1200  extending and centered about a handle assembly longitudinal axis LA, similar to the handle assembly  200  of the power operated rotary knife  100  of the first exemplary embodiment, and a head assembly  1300 , similar to the head assembly  300  of the power operated rotary knife  100 . The head assembly  1300  includes a notched annular rotary knife blade  1500  supported for rotation about a central axis of rotation R by the split blade housing  1600 , similar in operation and structure to the rotary knife blade  500  and blade housing  600  of the power operated rotary knife  100 . Additionally, as with rotary knife blade  500  and the trim guide  700  of the power operated rotary knife  100 , cutting and trimming of branches for the power operated rotary knife  1100  is accomplished by the shearing action of the rotating rotary knife blade  1500  and a notched stationary trim guide  1700 . The configuration of the rotary knife blade  1500  and the trim guide  1700  are generally the same as the counterpart rotary knife blade  500  and trim guide  700  of the power operated rotary knife 100 . The structure differences of the rotary knife blade  1500  and the trim guide  1700  from their counterparts of the first exemplary embodiment are explained below. 
     The head assembly  1300  ( FIG.  23   ) further includes a frame body  1310 , similar to the frame body  310  of the power operated rotary knife  100 , including a forward blade housing support region  1320  and a rearwardly extending annular boss  1350  and a clamping assembly  1330 , similar to the clamping assembly  330  of the power operated rotary knife  100 . As shown in  FIGS.  20  and  21   , the directions forward FW and rearward RW are generally along and with respect to the handle assembly longitudinal axis LA and the directions up UP and down DW are generally along and with respect to the rotary knife blade axis of rotation R. The clamping assembly  1330  includes an arcuate clamp  1332  secured to the frame body  1310  by a pair of threaded fasteners  1334  that extend through respective horizontally oriented openings  1322   a  of a pair of outwardly extending arcuate arms  1322  of the frame body  1310  and thread into respective threaded openings in a proximal wall  1333  of the clamp  1332 . The clamping assembly  1330  functions to secure a split blade housing  1600  to the blade housing support region  1320 , as described with respect to the head assembly  300  of the power operated rotary knife  100 . The forward blade housing support region  1320  of the frame body  1310  includes the pair of outwardly extending arcuate arms  1322 . The arcuate arms  1322  define a blade housing mounting region  1324  for receiving an arcuate mounting section  1650  of the blade housing  1600  and a clamping receiving region  1326  for receiving the proximal wall  1333  of the clamp  1332  of the clamping assembly  1330 . The head assembly  1300  of the power operated rotary knife  1100  also includes a drive mechanism  1400 , similar to the drive mechanism  400  of the power operated rotary knife  100 . 
     In addition to the foregoing, the head assembly  1300  of the power operated rotary knife  1100  further includes a vacuum connector  1910  ( FIGS.  36 - 40   ), which is releasably affixed to the blade housing  1600 . The vacuum connector  1910  is both a part or component of the head assembly  1300  of the power operated rotary knife  1100  and also is a part or component of the vacuum assembly of the power operated rotary knife assembly  1000 . The vacuum assembly additionally includes a flexible vacuum hose  1990  and a vacuum clamp  1995  for affixing a distal or entrance end portion  1991  of the vacuum hose  1990  to an upper or exit end  1914  of the vacuum connector  1910 . The vacuum connector  1910  defines an inverted funnel-shaped interior region  1912  that provides a fluid communication path for the flow of trimmed foliage material from the cutting opening CO of the power operated rotary knife  1100  to an interior region  1992  of a vacuum hose  1990  to provide for efficient remove of trimmed materials by a vacuum drawn in the interior regions  1992 ,  1912  of the vacuum hose  1990  and the vacuum connector  1910  from the cutting opening CO. That is, in the power operated rotary knife  100 , after shearing, cut materials drop generally downwardly from the shearing region toward the ground by action of gravity. By contrast, with the power operated rotary knife assembly  1000 , the vacuum assembly  1900  functions to apply a vacuum suction pressure in the region of the cutting opening CO to draw cut materials into an interior region  1912  defined by the inverted funnel-shaped vacuum connector  1910  and ultimately into the interior region  1992  of a vacuum hose  1990 . Vacuum pressure drawn in the vacuum hose interior region  1992  is communicated through the interior region  1912  of the vacuum connector  1910  and into an interior region of the rotary knife blade  1500 . The vacuum suction pressure is created by a suitable vacuum motor system (not shown) and the cut materials accumulate in a container (not shown) at a proximal end of the vacuum hose  1992 . 
     As mentioned above, the head assembly  1300  includes the notched annular rotary knife blade  1500  ( FIGS.  29 - 32   ), the coacting stationary, notched trim guide  1700  ( FIGS.  32 - 35   ), the blade housing  1600  ( FIGS.  23 ,  28  and  28 A ) and the vacuum connector  1910  ( FIGS.  36 - 40   ). The rotary knife blade  1500  is supported by the stationary blade housing  1600  for rotation about a central axis of rotation R of the blade  1500 . The blade housing  1600  is positioned between the rotary knife blade  1500  and the trim guide  1700 . The trim guide  1700  is secured to the frame body  1310  by a threaded fastener  1800  which passes through an aperture  1719  in a attachment tab  1718  of the trim guide  1700  and threads into a threaded opening  1321   a  of a bottom surface  1321  of the blade housing support region  1320  of the frame body  1310  to secure the trim guide  1700  to the frame body  1310  (similar in structure and function to the fastener  800  and the attachment tab  718  of the trim guide  700  of the power operated rotary knife  100 ). 
     As can be seen in  FIG.  21   , the vacuum connector  1910  is secured to a clamp  1332  of the clamping assembly  1330  by a threaded fastener  1980  ( FIG.  21   ) which extends through a vertically oriented opening  1963  defined in a radially extending boss  1962  of a clamp interface portion  1960  of a lower mounting section  1950  of the vacuum connector  1910 . The threaded fastener  1980  threads into a threaded opening  1342  formed in an upper surface  1340  of the clamp member  1332  to secure the vacuum connector  1910  to the clamp member  1332  and thereby couple the vacuum connector  1910  to the frame body  110 . In one exemplary embodiment, the threaded connector  1980  is a thumbscrew to advantageously allow for easy removal of the vacuum connector  1910  from the remainder of the head assembly  1300 , specifically the clamp member  1332  and the blade housing  1600  for servicing of the vacuum connector  1910 . The vacuum connector  1910  is also secured to the trim guide  1700  by a C-shaped latch  1972  (best seen in  FIGS.  39  and  40   ) extending from an arcuate rim portion  1971  of a trim guide interface portion  1970  of the lower mounting section  1950  of the vacuum connector  1910 . The C-shaped latch  1972  of the trim guide interface portion  1970  latches or hooks on to an axially and radially extending rib  1751 , a vertical extension  1754  and a radially inwardly extending lip  1770  of a guard section  1750  (best seen in  FIGS.  32  and  35   ) of the trim guide  1700 . The C-shaped latch  1972  to the trim guide  1700  is circumferentially opposite of the connection of the thumbscrew  1980  of the radially extending boss  1962  to the clamp member upper surface  1340 . The combined coupling of the C-shaped latch  1972  and the thumbscrew  1980  releasably secure the vacuum connector  1910  to remainder of the head assembly  1300 . 
     As schematically depicted in  FIGS.  26  and  27   , each of the rotary knife blade  1500 , the blade housing  1600  and the trim guide  1700  are annular, defining central open regions CO 1 , CO 2 , CO 3 , respectively. When the rotary knife blade  1500 , the blade housing  1600  and the trim guide  1700  are assembled and attached to the frame body  1310  of the head assembly  1300 , the central open regions of a combination  1450  of the blade  1500 , the blade housing  1600  and trim guide  1700  define the central cutting opening CO of the power operated rotary knife  1100 . Cutting and trimming take place along a periphery of the central cutting opening CO. The central cutting opening CO is actually defined by a combination  1480  of the blade  1500 , and the trim guide  1700 . As can be seen in  FIGS.  21  and  26 - 28 A , no portion of the blade housing  1600  extends radially inwardly far enough to define any portion of the central cutting opening CO of the power operated rotary knife  1100 . Thus, the central cutting opening CO is defined by intersecting central open regions CO 1 , CO 3  of the assembled combination  1480  of the rotary knife blade  1500  and trim guide  1700 . 
     Blade Housing  1600   
     As best seen in  FIGS.  21 ,  23 ,  28  and  28 A , the rotary knife blade  1500  of the power operated rotary knife  1100  is supported for rotation about the central axis of rotation R by the annular blade housing  1600 . The blade housing includes a split, annularly curved blade support section  1610  that surrounds and supports the rotary knife blade  1500  about the entire 360 degree circumference of the blade  1500  and a mounting section  1650  extending axially from the blade support section  1610  and provides a mounting structure for releasably mounting the blade  1500  and blade housing  1600  to the blade housing mounting region  1324  of the forward blade housing support region  1320  of the frame body  1310 . The blade housing  1600  includes an inner wall  1602  and an outer wall  1604  and an upper end  1606  and a lower end  1608 . Adjacent the lower end  1608 , the inner wall  1602  defines a bearing surface  1620 , which in one exemplary embodiment is a radially inwardly protruding bearing bead  1622 , extending from an inner wall  1602  of the blade housing  1600 . The blade housing bearing bead  1622  extends into a generally V-shaped opening or bearing race  1540  formed in and extending radially into an outer wall of the  1514  of an annular body  1510  of the rotary knife blade  1500  to support the blade  1500  for rotation about the axis of rotation R. The blade bearing race  1540  comprises two axially spaced apart, generally frustoconical, bearing faces  1542  which bear against the blade housing bead  1622  to support the blade both axially and radially. The bearing support structure of the bearing bead  1622  of the blade housing  1600  and the bearing race  1540  of the rotary knife blade  1500  define a cutting plane RP of the rotary knife blade  1500 , which is substantially orthogonal to the blade central axis of rotation R. 
     The mounting section  1650  of the blade housing  1600  includes an angled split  1652  and a pinion clearance region  1654 . The pinion clearance region  1654  of the blade housing mounting section  1650  provides for clearance for a gear head  1406  of a pinion gear  1404  of a drive train  1402  of the drive mechanism  1400 . The angled split  1652  of the mounting section  1650  is circumferentially offset from the pinion clearance region  1654  and provides for expansion of the blade housing diameter for purposes of changing the rotary knife blade  1500  when the blade has reached the end of its useful life. Specific details regarding an annular blade housing with an angle split and offset pinion clearance region are disclosed in U.S. Pat. No. 8,661,692 to Whited et al., issued Mar. 4, 2014. U.S. Pat. No. 8,661,692 is assigned to the assignee of the present invention and is incorporated herein in its entirety by reference. 
     The rotary knife blade  1500 , the blade housing  1600 , and the trim guide  1700 , are all annular and, when assembled, define an overlapping sandwiched combination  1450  wherein the blade housing blade support section  1610  is radially sandwiched between, on the radial inside, the annular body  1510  of the rotary knife blade  1500  and, on the radial outside, by a radially outwardly and axially upwardly extending rib  1751  of the guard section  1750  of the trim guide  1700 . The rib  1751  includes a frustoconical section  1752 . A vertical extension  1754  of the guard section  1750  extends from an upper end  1751   a  of the rib  1751  and is disposed axially above the rib  1751 . A radially inwardly extending lip  1770  of the guide section  1570  extends from an upper end  1754   a  of the vertical extension  1754  in a radially inward direction. An angle subtended by the rib frustoconical section  1752  is greater than 180°, while an angle subtended by the upper vertical extension  1754  and the lip  1770  are significantly less than 180°. 
     Rotary Knife Blade  1500   
     As best seen in  FIGS.  29 - 31   , the rotary knife blade  1500  of the power operated rotary knife  1100  of the second exemplary embodiment includes an inner wall  1502  and a radially spaced apart outer wall  1504  and an upper end  1506  and an axially spaced apart lower or bottom end  1508 . The inner wall  1502  defines a central opening of the blade  1500 . The blade  1500  includes the annular body  1510  which defines an inner wall  1512  (defining part of the inner wall  1502  of the blade  1500 ), an outer wall  1514  (defining part of the outer wall  1504  of the blade  1500 ), an upper end  1516  (defining the upper end  1506  of the blade  1500 ) and a lower end  1518 . The rotary knife blade  1500  further includes the blade section  1550  extending axially downwardly and radially inwardly (toward the blade axis of rotation R) from the lower end  1518  of the annular body  1510 . The blade section  1550  includes upper end  1552  adjacent the annular body lower end  1518  and a lower end  1554  (defining the lower end  1508  of the blade  1500 ) and a generally frustoconical wall  1556  extending therebetween. 
     The upper end  1516  of the annular body  1510 , as mentioned above, defines the driven gear  1520  of the blade  1500 . The driven gear  1520  comprises a set of gear teeth formed in a circumference adjacent the outer wall  1514  of the annular body. Adjacent the lower end  1518  of the annular body, the blade bearing race  540  defining frustoconical bearing surfaces  542  is formed in the outer wall  1514  of the annular body, as described above. 
     The lower end  1554  of the blade section  1550  includes interrupted are portions  1572  that define a lower edge  1509  of the blade  1500 . The interrupted are portions  1572  are centered about the blade central axis of rotation R and, if connected and continued, would form a circle defining an inner diameter of the blade  1500  with a center on the axis of rotation R. Typically, the interrupted are portions  1572  would define a cutting edge of the blade, but, in the rotary knife  1500 , the cutting edge  1590  of the blade is defined by a plurality of recessed, arcuate cutting portions  1580  within the plurality of notches  1560 . Interrupting the are portions  1572  are the plurality of notches  1560  formed at the lower end  1554  of the frustoconical wall  1556  of the blade section  1550  and extending into the frustoconical wall  1556 . As can best be seen in  FIGS.  29  and  30   , each of the notches of the plurality of notches  1560 , when viewed in top plan view, defines a generally rectangular cavity  1561  defined by a peripheral wall  1562  surrounding a central open portion  1564  and defining the cavity  1561 . The peripheral wall  1562  of each notch of the plurality of notches  1560 , when viewed with respect to the counterclockwise direction of rotation CCW of the rotary knife blade  1500 , includes an angled leading portion or end  1566 , a generally linear central portion  1568 , and a hook-shaped or U-shaped trailing portion or end  1570 . 
     As best seen in  FIGS.  29  and  30   , the trailing end  1570  of the peripheral wall  1562  includes an arcuate sharpened region  1571  extending approximately from a transition segment  1569  of the peripheral wall  1562  bridging the linear central portion  1568  and the trailing end  1570  to a termination point  1584  of the trailing end  1570  located at the bottom edge  1509  of the blade  1500 , as defined by the start of the next interrupted are portion  1572 . The arcuate sharpened regions  1571  may extend to the bottom edge  1509  of the blade  1500  or be in close proximity to the bottom edge  1509 . Both are contemplated by the present disclosure. The arcuate sharpened regions or cutting portions  1571  are concave (like the inside of a bowl) in that they are curving in or hollowed inwardly due to the hook-shape of the trailing end  1570  of the peripheral wall  1562 . The arcuate sharpened regions  1571  of the plurality of notches  1560  define the respective recessed arcuate cutting regions or portions  1580  of the blade  1500 . The arcuate cutting portions  1580  are recessed in that at least a portion of the arcuate sharpened region  1561  is within an interior region  1582  (that is, the central open portion  1564 ) defined by each of the plurality of notches  1560 . 
     It should be appreciated of course that the arcuate cutting portions  1580  (and the associated sharpened regions  1571 ), instead of being arcuate (by virtue of the hook-shaped trailing end  1570  of the peripheral wall  1562 ), could be linear or convex and the present disclose contemplates such an alternate embodiment. In one exemplary embodiment of the rotary knife blade  1500 , an inner diameter of the blade  1500 , as defined by the interrupted are portions  1572  constituting the lower edge  1509  of the blade  1500 , is approximately 3.704 in., while the outside diameter of the blade, defined by the radial outermost extent of the outer wall  1514  of the annular body  1510  of the blade is approximately 5.092 in. The inner diameter of the blade  1500  is approximately twice the radius RAD, schematically depicted in  FIG.  11   . In one exemplary embodiment, a thickness of the interrupted are portions  1572  is approximately 0.063 in. Additionally, in one exemplary embodiment, the number notches in the plurality of notches  1560  is six, each of which is spaced equidistantly about an inner perimeter or inner diameter of the blade  1500 , each of the notches subtending an angle α (depicted schematically in  FIG.  29   ) with respect to the central axis of rotation R of approximately 32°. 
     Trim Guide  1700   
     As can best be seen in  FIGS.  32 - 35   , the trim guide  1700  of the power operated rotary knife  1100 , which is stationary with respect to the rotation of the blade  1500 , includes an upper end  1702  and a lower end  1704  and defines the planar base  1710 , the guide section  1720  extending axially below and radially inwardly from the base  1710 , and the guard section  1750 , including the radially outwardly and upwardly extending rib  1751 , the vertical extension  1754  and the radially inwardly extending lip  1770 . As can best be seen in  FIG.  35   , the guard section  1750  of the trim guide  1700  extends axially upwardly and radially outwardly from the base  1710 . The rib  1751  of the guard section  1750  includes the frustoconical section  1752 . The vertical extension  1754  extends axially upwardly from the upper end  1751   a  of the rib  1751 . The lip  1770  extends radially inwardly from the upper end  1754   a  of the vertical extension  1752 . The lip  1770  subtends an angle substantially equal to the angle subtended by the vertical extension  1752 . The base  1710  includes the attachment tab  1718  extending from a rearward portion  1712  of the base  1710 . The tab  1718  includes the aperture  1719 . The trim guide  1700  is releasably affixed to the bottom surface  1321  of the blade housing support region  1320  of the frame body  1310  by the threaded fastener  1800  that extends through the tab aperture  1719  and threads into the threaded opening  1321   a  of the bottom surface  1321  of the blade housing support region  1320  of the frame body  1310 . 
     As can best be seen in  FIG.  35   , the guide section  1720  of the trim guide  1700  includes an upper end  1722  and a lower end  1724  and defines a guide section frustoconical wall  1721 . The frustoconical wall  1721  extends along the frustoconical wall  1556  of the blade section  1550 . The guide section  1720  of the trim guide  1700  includes interrupted are portion  1738  circumferentially spaced apart by a plurality of notches  1730 . In one exemplary embodiment, the notches of the plurality of notches  1730  are spaced equidistant about the lower end  1724  of the guide section  1720  and the number of notches  1730  is ten. The openings or cavities defined by each of the notches of the plurality of notches  1730  are generally a concave, slanted or skewed U-shape. 
     Unlike the trim guide  700  of the power operated rotary knife  100  of the first embodiment, the plurality of notches  1730  are disposed circumferentially in spaced-apart relationship about an entirety (that is around the entire 360° circumference) of the lower end  1724  of the guide section  1720 . That is, in the trim guide  700 , the guide section  720  included the forward portion  725 , subtending just over 180 degrees of the total annulus defined by the trim guide  700 . As shearing action for trimming of branches occurred in a region of the plurality of notches  730  of the guide section  720 , for trimming branches, in the power operated rotary knife  100  of the first embodiment, the operator needed to pull the power operated rotary knife  100  in a rearward or proximal direction RW along the handle assembly longitudinal axis LA toward himself or herself since the plurality of notches  730  were positioned in a forward portion  726  of the guide section  720 . 
     Advantageously, with the trim guide  1700  and the vacuum assembly  1900  of the power operated rotary knife  1100 , the operator may move the power operated rotary knife  100  in any direction, i.e., toward the operator along the longitudinal axis LA of the handle assembly  1200  in the rearward or proximal direction RW, away from operator along the longitudinal axis LA of the handle assembly  1200  in the forward or distal direction FW, or anywhere therebetween, as plurality of notches  730  are spaced about the entire 360° of the guide section  1720  and shearing action is therefore not limited to a forward portion of the guide section but may take place at any circumferential position where a notch  1730  is disposed and shearing action occurs, as explained. Additionally and advantageously, the vacuum assembly  1900  functions to expeditiously and efficiently remove trimmed branch materials from the cutting opening CO region and away from the plant, keeping the plant and the plant bed areas clean and free from trimmed branch materials and possible diseases and other problems associated with leaving trimmed materials on the remaining branches of the plant or left to compost on the plant bed area. 
     The notches  1730  of the trim guide  1700  function to direct the plant branches to be cut into recessed shearing portions  1740  defined by each of the plurality of notches  1730  of the trim guide  1700  wherein the recessed arcuate cutting portions  1580  of the plurality of notches  1560  of the rotary knife blade  1500  cut the branches by shearing action as the blade  1500  rotates with respect to the stationary trim guide  1700 . To cut or trim a branch and then evacuate the cut or severed portions of the branch, the power operated rotary knife  1100  is positioned with respect to a plant branch to be cut or trimmed such that the branch extends through the cutting opening CO defined by the power operated rotary knife  1100 , the operator then moves the knife  1100  in a direction such that the branch is moved within the cutting opening CO and urged against the guide section  1720  of the trim guide  1700 . Depending on the position of the branch within the cutting opening CO, the movement of the rotary knife  1100  by the operator will move the branch into one of the plurality of notches  1730  of the trim guide guide section  1720 . A cutting portion  1580  of the rotary knife blade  1500  will impact the branch within the interior region  1745  of the notch  1720 , cutting the branch by a shearing action between the shearing portion  1740  of the trim guide notch  1720  at the leading end  1732  of the notch  1720  and the cutting portion  1580  of the blade section notch  1560  at the trailing end  1570  of the notch  1560 . 
     As best seen in  FIG.  28   , an extending distal portion  1725  of guide section  1720  extends axially below and radially inwardly beyond the lower edge  1509  of the rotary knife blade  1500  and has two functions: 1) to direct a branch or branches into an interior region  1745  defined by one of the plurality of notches  1730  as the power operated rotary knife  1100  is moved or manipulated by the operator to cut or trim a branch or branches within the central cutting opening CO of the knife  1100 ; and 2) to guard the rotary knife blade  1500  from inadvertent contact with the ground or plastic mats or sheets positioned on the ground between rows of plants. The trim guide  1700  also includes the guard section  1750  including the peripheral rib  1751  which extends axially above and radially outwardly from the base  1710 . The rib  1751  extends around most, but not all of the total annulus defined by the trim guide  1700 . Additionally, the vertical extension  1754  and the lip  1770  extend axially upwardly and radially inwardly from the upper end  1751   a  of the rib  1751 . The vertical extension  1754  and the lip  1770  subtend an angle less than an angle subtended by the rib  1751 . Both the rib  1751 , the vertical extension  1754  and the lip  1770  of the guard section  1750  function as guards to protect the blade  1500  from inadvertent contact with plastic mats, portions of plants that are not to be trimmed or cut, and the like. 
     As best seen in  FIGS.  33 - 35   , the guide section  1720  includes the plurality of notches  1730  formed the lower end  1724  and extending into the frustoconical wall  1721 . The lower end  1724  of the guide section  1720  also includes interrupted are portions  1738  that define a lower edge  1709  of the trim guide  1700 . The interrupted are portions  1738  are centered about the blade central axis of rotation R and, if connected and continued, would form a circle defining an inner diameter of the trim guide  1700  with a center on the axis of rotation R. Interrupting the arc portions  1738  of the guide section  1720  are the plurality of notches  1730  formed at the lower end  1724  of the frustoconical wall  1721  of the guide section  1720  and extending into the frustoconical wall  1721 . As can best be seen in  FIG.  33   , each of the notches of the plurality of notches  1730 , when viewed in top plan view, defines a slightly slanted, concave U-shaped cavity  1741  defined by a peripheral wall  1742  surrounding a central open portion  1743  and defining the cavity  1741 . The central open portion  1743  corresponds to the interior region  1745  of the notch  1730 . The peripheral wall  1742 , when viewed with respect to the counterclockwise direction of rotation CCW ( FIG.  26   ) of the rotary knife blade  1500 , includes an angled leading portion or end  1732  ( FIG.  33   ), a central portion  1733 , and an angled trailing portion or end  1734 . The central portion  1733 , which is generally arcuate, defines a radially innermost section or region  1742   a  of the peripheral wall  1742 . 
     The angled leading end  1734  of the peripheral wall  1742  defines a shearing region or portion  1740  extending approximately from a termination point  1747  at the lower end  1724  of the guide section  1720  where the next adjacent interrupted are portion  1738  commences and extending to a transition point  1748  along the central portion  1733  of the peripheral wall  1742  where the angled leading end  1732  terminates. The transition point  1748  being along the central portion  1733  is one of the radially innermost points of the peripheral wall  1742 . When viewed in top plan view, the shearing portions  1740  defined by the leading ends  1734  of the respective plurality of notches  1730  define a linear segment  1740   a  over most of their extent moving radially inwardly from the lower end  1724  of the guide section  1720  and then transition into a shorter arcuate segment  1740   b  as the transition point  1748  of the peripheral wall  1742  is approached. The shearing portions  1740  of the plurality of notches  1730  of the trim guide  700  are recessed in that at least a portion of the shearing portion  1740  is within an interior region  1745  (that is, the central open portion  1743 ) defined by each of the plurality of notches  1730 . 
     As explained above, the cutting action of the power operated rotary knife  1100  occurs through the combination  1480  of the rotating rotary knife blade  1500  and the stationary trim guide  1700 . As the blade  1500  rotates about its central axis of rotation R, the shearing portions  1740  of the guide section notches  1730  come into overlapping axial alignment with the arcuate cutting portions  1580  of the blade section notches  1560 . Additionally, the central open portion  1564  or interior region  1582  of each of the plurality of notches  1560  of the blade section  1550  of the rotary knife blade  1500  come into overlapping axial alignment with the central open portion  1743  or interior region  1745  of each of the plurality of notches  1730  as the blade  1500  rotates about the axis of rotation R. This transitory overlapping alignment of the central open portions  1564 ,  1743  or interior regions  1582 ,  1745  define transitory cutting pockets  1799 . (Such transitory cutting pockets  1799  are depicted schematically, for example, in  FIGS.  26  and  27   . The uncut branch or branches directed into a transitory pocket  1799  by the guide section  1720  of the trim guide  1700 , that is, guided into a trim guide notch  1730 , will be rapidly and efficiently cut by the shearing action of the rotating cutting portions  1580  of the blade  1500  passing over the stationary shearing portions  1740  of the trim guide  1700  as the rotary knife blade  1500  continues its high speed rotation in the counterclockwise direction CCW. The cutting pockets  1799  are transitory in that as the blade  1500  continues to rotate about its axis of rotation R, the blade  1500  rotates with respect to the stationary trim guide  1700 . Thus, as would be understood, new cutting pockets  1799  are formed by overlapping interior regions  1582 ,  1745  and then disappear as cutting of the branch or branches with the cutting pockets  1799  occurs by shearing action by virtue of the rotating cutting portions  1580  of the blade  1500  passing over the stationary shearing portions  1740  of the trim guide  1700 . Thus, as the blade  1500  rotates about the central axis of rotation R, new cutting pockets  1799  are constantly formed and old cutting pockets  1799  disappear as cutting occurs and branches in the cutting pockets are cut by shearing action. 
     In one exemplary embodiment of the trim guide  1700  of the power operated rotary knife  1100 , an inner diameter of the trim guide  1700 , as defined by the interrupted arc portions  1738  constituting the lower edge  1709  of the trim guide  1700 , is approximately 3.808 in., while a diameter defined by a radially innermost point of each of the plurality of notches  1730  of the guide section  1720  is approximately 4.631 in. Additionally, in one exemplary embodiment, the number notches in the plurality of notches  1730  is ten, spaced about the entirety of the 360° of the central opening CO 3  of the trim guide  1700  and circumferentially spaced apart by ten interrupted are portions  1738  wherein each of the notches of the plurality of notches  1730  subtends an angle β (depicted schematically in  FIG.  33   ) with respect to the central axis of rotation R of approximately 21°. 
     Advantageously, with the trim guide  1700  and the vacuum assembly  1900  of the power operated rotary knife  1100 , the operator may move the power operated rotary knife  100  in any direction, i.e., a rearward or proximal direction RW toward the operator along the longitudinal axis LA of the handle assembly  1200 , a forward or distal direction FW away from operator, or any direction therebetween, as plurality of notches  1730  are spaced about the entire 360° of the guide section  1720  and shearing action is therefore not limited to a forward portion of the guide section but may take place at any circumferential position where a notch  1730  is disposed and shearing action occurs, as explained. Additionally and advantageously, the vacuum assembly  1900  functions to expeditiously and efficiently remove trimmed branch materials from the cutting opening CO region and away from the plant, keeping the plant and the plant bed areas clean and free from trimmed branch materials and possible issues associated with leaving trimmed materials on the remaining branches of the plant or dropping to the ground and decaying on the ground in the plant bed area. 
     Vacuum Assembly  1900   
     As best seen in  FIGS.  20 - 23  and  36 - 40   , the vacuum assembly includes the vacuum connector  1910 , which, as described above is also part of the head assembly  1300  of the power operated rotary knife  1100 , a flexible vacuum hose  1990 , which is coupled to an upper or exit end  1925  of the vacuum connector  1910  by a clamp  1995 . In one exemplary embodiment, the vacuum hose is a 4 in. diameter flexible hose or duct which defines the interior region  1992  of the vacuum hose  1990 . 
     The vacuum connector  1910  has a generally inverted funnel shape and includes the lower, larger diameter lower mounting section  1950  and an upper, reduced diameter cylindrical section  1920 , bridged by a tapered middle section  1940  that necks down the diameter between the mounting section  1950  and the cylindrical section  1920 . An inner wall or inner surface  1911  of the vacuum connector  1910  defines the inverted funnel-shaped interior region  1912  that is in fluid communication with the interior region  1992  of the vacuum hose  1990 . An outer wall or outer surface  1913  is radially spaced from the inner wall  1911  and generally conforms to the shaped of the inner wall  1911 . Advantageously, the necked down configuration of the vacuum connector  1910  provides for the funnel shape of the interior region  1912  that proceeds from a larger diameter at a generally cylindrical entry end  1916  of the vacuum connector  1910 , where trimmed branches/foliage material enter the interior region  1912  of the vacuum connector  1910  from the cutting opening CO of the power operated rotary knife  1100  defined by the assembled combination  1450  of the blade  1500 , blade housing  1600  and trim guide  1700 , to a cylindrical exit or upper end  1914  of the vacuum connector  1910 , where trimmed branches and foliage material exit the interior region  1912  of the vacuum connector  1910 . Additionally, the inner surface  1911  of the vacuum connector  1910  is smooth, with minimal discontinuities, to facilitate flow of trimmed foliage materials from the entry end  1916  to the exit end  1914  of the vacuum connector  1910 . The vacuum connector  1910  is centered about a central axis VCA extending though the interior region  1912  of the vacuum connector  1910 . When the vacuum connector  1910  is coupled to the head assembly  1300  of the power operated rotary knife  1100 , the central axis VCA of the vacuum connector  1910  is substantially parallel to but slightly offset by a radial distance schematically shown as distance d in  FIG.  21   , from the central axis of rotation R of the rotary knife blade  1500 . In one exemplary embodiment, an offset distance d between the rotary knife blade axis of rotation R and the vacuum connector central axis VAC is 0.200 in. 
     The lower mounting section  1950  of the vacuum connector  1910  includes a lower end  1952 . The lower end  1952  of the mounting section  1950  includes a lower edge  1958 . The lower end  1952  of the mounting section  1950  corresponds to a lower end  1916  of the vacuum connector  1910 . The lower edge  1958  of the lower end  1952  of the mounting section  1950 , which corresponds to a lower edge  1918  of the lower end  1916  of the vacuum connector  1910 , is defined by an axially lowest peripheral edge  1979  of a C-shaped latch  1972  of the a trim guide interface portion  1970 . A generally proximal portion  1954  of the lower end  1952  includes a clamp interface portion  1960 , while a generally distal portion  1959  of the lower end  1952  includes the trim guide interface portion  1970 . The clamp interface portion  1960  extends peripherally between approximate endpoints  1954   a ,  1954   b  of the proximal portion  1954 , while the trim guide interface portion  1960  includes the remainder of the lower end  1952 . The arcuate trim guide interface portion  1970  and the clamp interface portion  1960 , advantageously function in co-acting relationship to releasably secure the vacuum connector  1910  to the head assembly  1300  of the power operated rotary knife  1100 . 
     The arcuate trim guide interface portion  1970  of the lower mounting section  1950  of the vacuum connector  1910  includes the radially extending arcuate rim portion  1971  that seats on the rib  1751 , the vertical extension  1754  and the lip  1770  of the guard section  1750  of the trim guide  1700 . As can be seen in  FIG.  21   , more specifically, extending from the annular rim  1953  of the trim guide interface portion  1970  of the vacuum connector  1910  is the C-shaped latch  1972  that hooks over and thereby attaches the vacuum connector  1910  to the guard section  1750  of the trim guide  1700 , acting in cooperation with the clamp interface portion  1960 . The arcuate trim guide interface portion  1970  extends radially outwardly from and axially below the entry opening  1914  of the vacuum connector  1910  and subtends an angle of approximately 270° with respect to the central axis VCA of the vacuum connector  1910 . That is, the trim guide interface portion  1970  (approximately) 270° and the clamp interface portion  1960  (approximately) 90° circumscribe the entirety of the circular lower peripheral surface of the vacuum connector  1910  with respect to the vacuum connector central axis VCA. 
     The C-shaped latch  1972  of the trim guide interface portion  1970  is located at and extends from a lower end  1956  of the distal portion  1952  of the lower mounting section  1950  of the vacuum connector  1910 . The C-shaped latch  1972  includes an upper horizontal section  1973 , a vertical section  1975 , and a lower frustoconical section  1977 . When the trim guide interface portion  1960  is latched to the trim guide  1700 , a horizontal wall  1974  of the upper horizontal section  1973  bears against an upper surface  1772  of the radially inwardly extending lip  1770  of the guard section  1750  in the trim guide  1700 , a vertical wall  1976  of the middle vertical section  1975  bears against an outer surface  1753  of the vertical extension  1754  of the guard section  1750  of the trim guide  1700 , and an angled wall  1978  bears against the outer surface  1753  of the frustoconical section  1752  of the rib  1751  of the guard section  1750  of the trim guide  1700 . The axially lowest peripheral edge  1979  of the C-shaped latch  1972  defines the lower edge  1918  of the lower end  1916  of the vacuum connector  1910  and the lower edge  1958  of the lower end  1952  of mounting section  1950 . 
     Additionally, as best seen in  FIG.  40   , the clamp interface portion  1960  of the proximal portion  1954  of the lower mounting section  1950  includes a radially protruding boss  1962  having a planar lower surface  1962   a  and a cylindrical projection  1962   b  extending axially upwardly. The boss  1962  defines a vertical opening  1963 . A threaded connector  1980 , preferably a thumb screw, extends through the boss vertical opening  1963  and threads into a threaded vertically extending opening  1342  in an upper surface  1340  of the clamp  1332  of the clamping assembly  1330  to secure the vacuum connector  1910  to the clamp  1332  of the clamp assembly  1330 . Stated another way, the threaded fastener/thumb screw  1980  extends through the vertically oriented opening  1963  of the radially extending boss  1962  of the clamp interface portion  1960  of the mounting section  1950  and threads into the threaded opening  1342  formed in the upper surface  1340  of the clamp member  1332  to secure the vacuum connector  1910  to the clamp member  1332  and thereby couple the vacuum connector  1910  to the frame body  1310 . 
     The clamp interface portion  1960  further includes a pair of axially extending pedestals  1964   a ,  1964   b  circumferentially flanking the boss  1962 . The pair of pedestals  1964   a ,  1964   b  fit into and engage respective ones of a pair of axially extending slots  1335  formed in the proximal wall  1333  of the clamp  1332 . The clamp interface portion  1960  further includes a contoured opening  1966  sized and shaped to engage the upper surface  1340  of the clamp  1332 . The contoured opening  1966  is defined by the lower edge  1958  of the lower end  1952  of the vacuum connector  1910  in the region of the clamp interface portion  1960 . The contoured opening  1966  of the clamp interface portion  1960  comprises a pair of lateral contoured openings  1966   a ,  1966   b  and a central contoured opening  1966   c . The contoured opening  1966   a  is adjacent the pedestal  1964   a , while the contoured opening  1962   b  is adjacent the pedestal  1964   b . The central contoured opening  1966   c , which includes the generally planar lower surface  1962   a  of the boss  1962 , engages a central portion  1341  of the upper surface  1340  of the clamp  1332 . The contoured opening  1962  is defined by a lower peripheral edge  1964  of the lower mounting section  1950  in the region of the clamp  1332 . The peripheral edge  1964  bears against the upper surface  1340  of the clamp  1332  along a region of contact corresponding to the clamp interface portion  1960 , that is, the portion  1954  of the lower end  1952  of the mounting section  1950  of the vacuum connector  1910  corresponding to the clamp interface portion  1960  to provide a seal between the vacuum connector  1910  and the clamp upper surface  1340  to mitigate loss of vacuum pressure which would otherwise occur if there was a gap or space between the vacuum connector  1910  and the upper surface of the clamp  1332 . 
     Third Exemplary Embodiment—Power Operated Rotary Knife Assembly  2000   
     A third exemplary embodiment of a power operated rotary knife assembly of the present disclosure is schematically shown, generally at  2000 , in  FIGS.  41  and  42   . The power operated rotary knife assembly  2000  includes a power operated rotary knife  2100 , generally similar in structure and function to the power operated rotary knife  1100  of the power operated rotary knife assembly  1000  of the second exemplary embodiment, and a vacuum assembly  2900 , generally similar in structure and function to the vacuum assembly  1900  of the power operated rotary knife assembly  1000  of the second exemplary embodiment. The power operated rotary knife  2100  includes a head assembly  2300 , substantially similar to the head assembly  1300  of the second exemplary embodiment, and an elongated handle assembly  2200  extending along a longitudinal axis LA, substantially similar to the handle assembly  1200  of the second exemplary embodiment, extending away from the head assembly  2300 . The head assembly  2300  includes an annular, notched rotary knife blade  2500  supported for rotation about a central axis of rotation R by a stationary blade housing  2600 . A stationary annular trim guide  2700  is positioned adjacent the rotary knife blade and includes a plurality of notches that provide for a shearing action between overlapping axially aligned cutting portions of the notches of the rotary knife blade and shearing portions of the notches of the trim guide  2700 , as previously described with respect to the rotary knife blade  1500  and trim guide  1700  of the power operated rotary knife  1100  of the second exemplary embodiment. The blade housing  2600  is positioned between the rotary knife blade  2500  and the trim guide  2700  and, like the blade housing  1600  of the second exemplary embodiment, supports the blade  2500  for rotation about its axis of rotation R. 
     Both the rotary knife blade  2500 , the blade housing  2600  and the trim guide  2700  are annular and thus have central open regions or central openings (identified as CO 1 , CO 2 , CO 3  in the second embodiment and shown schematically in  FIGS.  27  and  27   ). As explained with respect to the second embodiment, the annular shapes of the rotary knife blade  2500  and the trim guide  2700  define a generally planar central cutting opening CO of the power operated rotary knife  2100 , as shown schematically in  FIGS.  41 - 46   . As explained with respect to the second embodiment, the blade housing  2600  is not part of the cutting process, being radially recessed from the cutting opening CO. 
     Additionally and advantageously, the power operated rotary knife assembly  2000  of the third exemplary embodiment further includes a portable power unit  3000  ( FIGS.  47 ,  48  and  50   ) and a flexible shaft drive assembly or transmission  3700  ( FIGS.  50  and  51   ) operatively coupling the portable power unit  3000  to a drive mechanism  2400  of the power operated rotary knife  2100 . In one exemplary embodiment, the portable power unit  3000  is both remote from the power operated rotary knife  2100  and is suitable to be carried by an operator as the operator moves along a rows of plants, such as grape vines, performing cutting and/or trimming operations. In this way, the operator is free to move freely and unencumbered along and between rows of plants and advantageously position his or her body and manipulate the power operated rotary knife  2100  such that the central cutting opening CO of the power operated rotary knife  2100  is properly presented to and moved with respect to and through the plant foliage for efficient cutting and trimming operations. That is, advantageously, the portable power unit  3000  is spaced from the power operated rotary knife  2100  so as not to interfere with the operator&#39;s grasping or holding of the knife  2100  or the operator&#39;s manipulation of the cutting opening CO of the knife  2100  in cutting/trimming operations. Nor is the weight of the portable power unit  3000  added to the weight of the power operated rotary knife  2100 , that is, the hand of the operator grasping and manipulating the knife  2100  is not burdened with the weight of the portable power unit  3000 . In one exemplary embodiment, the portable power unit  3000  is mounted on a lightweight support frame  3200  configured to be carried akin to a backpack on the shoulders of the operator utilizing a pair of vertically extending shoulder straps  3220  affixed to a vertical support  3210  of the support frame  3200 . 
     In one exemplary embodiment, portable power unit  3000  comprises a drive motor assembly  3300 , including a rotatably driven crankshaft or driveshaft  3400 , and a blower assembly  3450 , including a centrifugal-type fan  3460 . Advantageously, the drive motor assembly  3300  and the blower assembly  3450  are operatively coupled by and through the rotating driveshaft  3400  of the drive motor assembly  3300  which is common to or a part of both assemblies  3300 ,  3450 . Advantageously, the rotating driveshaft  3400  both provides the rotational power source  3100  to rotate the rotary knife blade  2500  of the power operated rotary knife  2100  about the central axis of rotation R and provides the vacuum source  3150  by rotating the centrifugal-type fan  3460  of the blower mechanism  3450  of the drive motor assembly  3300 . That is, the rotating driveshaft  3400  powers both the rotary knife blade  2500  of the power operated rotary knife  2100  and powers the centrifugal fan  3460  of the blower mechanism  3450 . 
     In one exemplary embodiment, the flexible shaft drive assembly or transmission  3700  includes an outer casing assembly  3710  and a flex shaft assembly  3800 , which is rotatably supported within a tubular throughbore defined by the outer casing  3710 . The outer casing assembly  3710  is stationary with respect to the rotating flex shaft assembly  3800  and includes an outer casing  3715 , a motor end coupling  3720 , at a proximal end of the outer casing  3715 , and the handle assembly coupling  3750 , at a distal end of the outer casing  3715 . The outer casing  3715  comprising a flexible tube including one or more tubular layers of plastic material, such as nylon, and, optionally, also may include one or more layers of braided wire between the tubular layers for added strength and durability. The flex shaft assembly  3800  of the flexible shaft drive transmission  3700  includes a rotating drive transmitting shaft or flex shaft  3802 , a first, driven fitting  3820  at a first, motor or proximal end  3810  of the flex shaft  3802  and the second, male drive fitting  3850  at a second, handle assembly or distal end  3812  of the flex shaft  3802 . When a motor end coupling  3720  of the shaft drive transmission  3700  is in an engaged state (operatively coupled or connected) with a drive motor coupling  3550  of a drive motor coupling assembly  3500  of the drive motor assembly  3300  of the portable power unit  3000 , the first, driven fitting  3820  of the flex shaft assembly  3800  is operatively engaged with a drive fitting  3410  of a drive motor assembly  3300 . Actuation of the drive motor assembly  3300 , when the motor end coupling  3720  of the shaft drive transmission  3700  and the drive motor coupling  3550  of the drive motor coupling assembly  3500  are in the engaged state results in rotation of the flex shaft  3802  and, via an operative interconnection of the second, male drive fitting  3850  of the flex shaft assembly  3800  with the drive mechanism  2400  of the power operated rotary knife  2100 , rotation of the rotary knife blade  2500  about the blade central axis or rotation R. Additional details regarding the structure and function of the flexible shaft drive transmission  3700  are found in U.S. Pat. No. 9,121,438, issued Sept. 1, 2015 to Mascari. The aforesaid U.S. Pat. No. 9,121,438 is assigned to the assignee of the present application and is hereby incorporated herein in its entirety by reference. 
     The power operated rotary knife assembly  2000  of the third exemplary embodiment is advantageously suited for the trimming/cutting of leaves of grape vines. In the production of fine table wines, grape vineyard owners and managers must carefully control the amount of sun that is received by the clusters of grapes growing on grape vines. In order to provide a requisite amount of sun, the leaves of the grape vines often require period pruning through the growing season. The power operated rotary knife assembly  2000  advantageously allows for efficient and effective power-assisted hand trimming of foliage (i.e., leaves, stems of leaves and small runners, etc.) the grape vines that would otherwise block grape clusters from receiving a requisite amount of sunlight. Moreover, because the power operated rotary knife  2100  is capable of being easily and accurately manipulated by the operator using an upward sweeping motion of the power operated rotary knife  2100  with the knife being in the orientation of, for example,  FIG.  41   , undesirable over-trimming and/or damage to the grapes or vines is mitigated. To use the power operated rotary knife assembly  2000 , the operator positions the cutting opening CO of the power operated rotary knife  2100  generally horizontally and vertically below the grape leaf or leaves desired to be cut from the grape vine. The operator then sweeps the knife  2100  generally arcuately upwardly to trim the grape foliage (leaves, leaf stems, runners, etc.). Advantageously, the power operated rotary knife  2100  includes a handle extension  3910  of a speed control/handle extension assembly that is substantially parallel to the central axis of rotation R of the rotary knife blade  2500  and substantially orthogonal to the handle assembly longitudinal axis LA. The operator grips a finger gripping portion  3912  of the handle extension  3910  and advantageously moves the power operated rotary knife in a natural upward, arcuate sweeping motion by bending his or her arm at the elbow. 
     A vacuum suction or vacuum pressure condition (schematically represented as arrow VPCCO in  FIGS.  41  and  43 - 45   ) drawn by the blower assembly  3450  of the portable power unit  3000  and transmitted by the vacuum assembly  2900  to a region COR of the cutting opening CO of the power operated rotary knife  2100  tends to advantageously gently pull or draw the foliage (i.e., grape leaves) to be trimmed which are adjacent or above the cutting opening CO into the cutting opening where they are efficiently and effectively cut by the shearing action of the rotary knife blade  2500  and the trim guide  2700 . That is, in the cutting opening region. COR of the cutting opening CO, the vacuum suction VPCCO at the cutting opening CO will draw or pull foliage to be trimmed into the cutting opening CO and, in cooperation with the movement of the power operated rotary knife  2100  by the operator, the foliage will be moved into contact with the overlapping axially aligned cutting portions of the notches of the rotary knife blade  2500  and shearing portions of the notches of the trim guide  2700  causing efficient cutting of the foliage. The trimmed or cut grape leaves, cut grape leaf stems, cut grape vine runners, etc. (generally, trimmed foliage or trimmed foliage material) is advantageously routed through the vacuum assembly  2900  and subsequently passes through a spiral turbine or spiral duct  3470  of the portable power unit  3000  and is then blown toward the ground upon exiting an exit opening  3484  of a blower or outlet side duct  3482  of the spiral duct  3470 . Blowing of the trimmed foliage material on the ground adjacent the grape vines is generally acceptable and, thus, there is no reason to collect the trimmed foliage. However, as one of skill in the art would recognize, the provision of a collection receptacle coupled to the blower side duct exit opening  3484  could be added to the lightweight support frame  3200 , or otherwise supported by the operator&#39;s body, if it was desired to collect the trimmed foliage material rather than blowing the trimmed foliage to the ground. It is within the contemplation of the present disclosure to provide such a collection receptacle for the power operated rotary knife assembly  2000 , if desired. 
     For brevity, the structural details/functions/advantages of those components and assemblies of the power operated rotary knife assembly  2000  which are similar to the corresponding components and assemblies of the power operated rotary knife assembly  1000  or the power operated rotary knife  100  will not be repeated in detail, all of the structural details/functions/advantages discussed above with respect to the power operated rotary knife assembly  1000  and the power operated rotary knife  100  are hereby incorporated by reference with respect to the third exemplary embodiment. Explanations regarding the description of the power operated rotary knife assembly  1000  and power operated rotary knife  100 , set forth above, are also hereby incorporated by reference with respect to the third exemplary embodiment. Common reference numbers and letters used in the three embodiments are assumed to represent similar concepts and/or structural details. 
     Overview 
     As best seen in  FIG.  51   , the head assembly  2300  of the power operated rotary knife  2100  includes a frame body  2310 , a clamping assembly  2330 , along with a rotating, notched annular rotary knife blade  2500  and a coacting stationary, notched trim guide  2700 . The rotary knife blade  2500  is supported by the stationary blade housing  2600  for rotation about a central axis of rotation R of the blade  2500 . The blade housing  2600  is positioned between the rotary knife blade  2500  and the trim guide  2700  and is releasably secured by the clamping assembly  2330  to a forward or distal blade housing support region  2320  of the frame body  2310 . When the rotary knife blade  2500 , the blade housing  2600  and the trim guide  2700  are assembled and attached to a frame body  2310  of the head assembly  2300 , the central cutting opening CO is defined by a combination of the blade  2500  and the trim guide  2700  where cutting and trimming take place, as previously described. 
     The power operated rotary knife  2100  further includes the elongated handle assembly  2200  defining and extending along a handle assembly longitudinal axis LA, which is substantially orthogonal to and intersection the rotary knife blade central axis of rotation R. The head assembly  2300  releasably affixed to a distal end of the handle assembly  2200 , as previously described. The head assembly  2300  of the power operated rotary knife  2100  also includes a drive mechanism  2400 , similar to the drive mechanism  1400  of the power operated rotary knife  1100 . The frame body  2310  supports a drive mechanism  2400  of the power operated rotary knife  2100  which is operatively coupled to the rotary knife blade  2500  to rotate the blade  2500  about its central axis of rotation R. In one exemplary embodiment, the drive mechanism  2400  comprises a pinion gear  2404  rotatably supported in a throughbore  2312  of the frame body  2310 . As previously described with respect to the pinion gear  404  of the power operated rotary knife  100  of the first exemplary embodiment, the pinion gear  2404  rotates about a pinion gear axis that is substantially coincident with the handle assembly longitudinal axis LA and includes a gear head  2406  that operatively engages a driven gear of the rotary knife blade  2500  to rotate the blade about the blade central axis of rotation R. 
     Similar to the vacuum assembly  1900  of the power operated rotary knife assembly  1000  of the second exemplary embodiment, the vacuum assembly  2900  includes the vacuum connector  2910 , which is both part of the vacuum assembly  2900  and is also part of the head assembly  2300  of the power operated rotary knife  2100  and a flexible vacuum hose  2990 . A distal or entrance end portion  2991  of the vacuum hose  2990  is coupled to an exit end  2925  of the vacuum connector  2910  by a clamp  2995 . In one exemplary embodiment, the vacuum hose  2990  is a 4 in. diameter flexible hose or duct which defines an interior region  2992  of the vacuum hose  2990 . 
     As noted above, the power operated rotary knife assembly  2000  of the third exemplary embodiment further includes a portable power unit  3000  and a flexible shaft drive assembly or transmission  3700  operatively coupling the portable power unit  3000  to the drive mechanism  2400  of the power operated rotary knife  2100 . Advantageously, the portable power unit  3000  provides: a) a rotational power source  3100  that is operatively coupled via the flexible shaft drive assembly or transmission  3700  to the drive mechanism  2400  of the power operated rotary knife  2100  to rotatably drive the rotary knife blade about its central axis of rotation R; and b) a vacuum source  3150  that is operatively coupled to a proximal or exit end portion  2996  of the vacuum hose  2990  of the vacuum assembly  2900  to draw vacuum pressure in the interior region  2992  of the vacuum hose  2990 . In one exemplary embodiment, both the rotational power source  3100  and the vacuum source  3150  are provided by the single drive motor assembly  3300 . As noted previously, the drive motor assembly  3300  includes the rotating crankshaft or driveshaft  3400  which provides the rotational power source  3100  and the blower mechanism  3450  which provides the vacuum source  3150 . Advantageously, the driveshaft  3400  powers the blower mechanism  3450 . 
     In one exemplary embodiment, as best seen in  FIG.  50   , coupled to a distal end portion  3402  of the driveshaft  3400  is a multi-engagement face drive fitting  3410 . The rotation of the driveshaft  3400  provides rotational power through the drive fitting  3410  to rotate the cooperating driven fitting  3820  mounted to the motor or proximal end  3810  of the flex shaft  3802  of the flex shaft assembly  3800  of the flexible shaft drive transmission  3700 . Rotation of the flex shaft  3802  causes rotation of the male drive fitting  3850  at the distal or handle assembly end  3812  of the flex shaft  3802 . The male drive fitting  3850 , in turn, is operatively coupled to an input shaft  2408  at a back end of the pinion gear  2404  of the drive mechanism  2400  of the power operated rotary knife  2100 . A gear head  2406  of the pinion gear  2404  engages a rotary driven gear of the rotary knife blade  2500 . Thus, rotation of the driveshaft  3400  causes rotation of the rotary knife blade  2500  about the blade central axis of rotation R. 
     As can best be seen in  FIGS.  45 ,  46  and  50   , the flexible shaft drive transmission  3700  includes a first end adjacent the drive motor assembly  3300 , an opposite or second end, adjacent the power operated rotary knife handle assembly  2200 , and a flexible, elongated central portion. When driven by the drive motor assembly  3300 , the flex shaft  3802  of the flex shaft assembly  3800  rotates about an axis of rotation which is substantially congruent with a central longitudinal axis LASDT of the flexible shaft drive transmission  3700 , which is also the central longitudinal axis LASDT of the flex shaft assembly  3800 . That is, the central longitudinal axis LASDT of the shaft drive transmission  3700  is substantially congruent with a center line though the flex shaft  3802  and also defines a central longitudinal axis of the flexible shaft drive transmission  3700 . In the region of the handle assembly  2200 , the central longitudinal axis LASDT is substantially aligned with and coincident with the longitudinal axis LA of the handle assembly  2200  and, in the region of the motor driveshaft  3400 , the central longitudinal axis LASDT is substantially aligned with and coincident with a central axis is rotation of the driveshaft  3400 . 
     In one exemplary embodiment, the handle assembly coupling  3750  includes a driver assembly  3770  ( FIG.  51   ). As seen in  FIG.  46   , when fully inserted into a frame tube of the handle assembly  2200 , the driver assembly  3770  positions the male drive fitting  3850  of the flex shaft assembly  3800  into driving engagement with the input shaft  2408  at a back end of the pinion gear  2404  of the drive mechanism  2400  of the power operated rotary knife  2100 . The handle assembly  2200  includes a drive shaft latching assembly  2280  to releasably secure the driver assembly  3770  to the handle assembly  2200 . In one exemplary embodiment, a slidable latching member 2284  supported by a latching knob  2282  engages an annular recess of the driver assembly  3770  to releasably secure the driver assembly  3770  to the handle assembly  2200 . The latching knob  2282  of the drive shaft latching assembly  2280  threads onto a threaded proximal end section of the frame tube extending from the frame body  2310 . When the latching knob  2282  is threaded onto the threaded proximal end section of the frame tube, the hand piece  2210  of the handle assembly  2200  is thereby sandwiched and secured to a rearwardly or proximally extending annular boss of the frame body  2310 . 
     Drive Motor Assembly  3300   
     As previously noted, in one exemplary embodiment of the present disclosure, the remote, portable power unit  3000  comprises the drive motor assembly  3300  and the blower assembly  3450 . The driveshaft  3400  is part of both the drive motor assembly  3300  and the blower assembly  3450  and provides both the rotational power source  3100 , in conjunction with the flexible shaft drive transmission  3700 , to rotate the rotary knife blade  2500  about its axis of rotation R and provides the vacuum source  3150 , in conjunction with the centrifugal fan  3460 , the spiral turbine or duct  3470  and the vacuum assembly  2900 , to provide vacuum pressure at the cutting opening CO of the power operated rotary knife  2100 . 
     In one exemplary embodiment of the present disclosure, the portable power unit  3000  is a modified version of a commercially available outdoor power equipment product, namely, a power leaf blower, modified to both provide the rotational power source  3100  operatively coupled to the drive mechanism  2400  of the power operated rotary knife  2100  to rotate the rotary knife blade  2500  about the blade central axis of rotation R and supply the vacuum source  3150  operatively coupled to the vacuum assembly  2900  to draw vacuum pressure in the vacuum hose  2990  and vacuum connector  2910 . In one exemplary embodiment, the power leaf blower is an ECHO power backpack leaf blower, ECHO model number P9580T, available from Echo Incorporated, 400 Oakwood Road, Lake Zurich, Ill. 60047-1564. 
     As best seen in  FIGS.  41 ,  42 ,  47  and  48   , the drive motor assembly  3300  is portable in that it is mounted to the support frame  3200 . The support frame  3200  includes the pair of vertically extending shoulder straps  3220  to allow the user to carry the support frame  3200  and, therefore, the drive motor assembly  3300  on his or her back, similar to a mountaineering backpack. One of skill in the art will recognize that the drive motor assembly  3300  may include various sources of motive power including portable internal combustion engines, portable electric motors, portable pneumatic motors, etc. In one exemplary embodiment, the drive motor assembly  3300  comprises a 2 cycle internal combustion engine  3310 , being both light weight for portability and ease of carrying by the operator, as mounted to a horizontal support  3230  of the support frame  3200 , and providing sufficient power output, via the rotating driveshaft  3400  of the engine  3310 , to both provide the rotational power source  3100  for driving the rotary knife blade  2500  via the flexible shaft drive transmission  3600  and the power operated rotary knife drive mechanism  2400  and provide the vacuum source  3150  for rotating the centrifugal-type fan  3460  of the blower mechanism  3450  to generate appropriate vacuum pressure in the interior region  2992  of the vacuum hose  2990  of the vacuum assembly  2900  and appropriate vacuum pressure in the region of the cutting opening CO of the power operated rotary knife  2100  so as to effectively and efficiently draw foliage into the cutting opening and then route the cut or trimmed foliage material through the vacuum connector  2910  and the vacuum hose  2990  away from the cutting opening CO and ultimately exiting through the exit opening  3484  of the outlet or blower side duct  3482  of the blower assembly  3450  of the portable power unit  3000 . 
     As best seen in  FIGS.  47 ,  48  and  50   , the internal combustion engine  3310  includes the rotating crankshaft or driveshaft  3400 , which is part of a driveshaft assembly  3401 . The driveshaft assembly  3401  extends generally horizontally though openings on opposite sides of an engine or motor crankcase  3320  of the engine  3310  and rotates about a horizontally oriented central axis of rotation DSR of the driveshaft  3400 . The term horizontally oriented assumes that engine  3310  is oriented in a vertical position, that is, a vertical axis of the engine  3310  extending though the engine sparkplug  3326  would be orthogonal to the driveshaft central axis of rotation DSR. The driveshaft  3400  is rotated by a reciprocating piston slidably supported within a cylinder (not shown) in conventional fashion. The driveshaft  3400  includes a central portion  3420  including an enlarged, disk-shaped counterweight  3422 , a first, distal end portion  3402  and a second, proximal end portion  3408 . An extending coupler  3404  is affixed to the distal end portion  3408  of the driveshaft  3400  to extend an axial length of the driveshaft  3400  in the direction of the flexible shaft drive transmission  3700  for purposes of enabling the driving engagement of a multi-engagement face drive fitting  3410  of the engine  3310  with a mating multi-engagement face driven fitting  3820  affixed to a proximal or motor end  3810  of the flex shaft assembly  3800  of the flexible shaft drive transmission  3700 . In one exemplary embodiment, the extending coupler  3404  is affixed, by press fitting, into an opening formed in the distal end portion  3402  of the driveshaft  3400 . The extending coupler  3404  protrudes though an opening  3324  in a first side or a front wall  3322  of the motor case  3320 . A collar  3407  is affixed to a distal end portion  3406  of the extending coupler  3404 . The multi-faced drive fitting  3410 , in turn, is affixed to the collar  3407 . The multi-faced drive fitting  3410 , the collar  3407  and the extending coupler  3404  are all components of the driveshaft assembly  3401  and all of the components of the driveshaft assembly  3401  rotate about the driveshaft central axis of rotation DSR. 
     Additionally, affixed to the front wall  3322  of the motor case  3320  is a generally annular pedestal  3510 , which is part of a drive motor coupling assembly  3500 . The pedestal  3510  serves as a mounting base for a flange  3555  of the drive motor coupling  3550 . The pedestal  3510  is secured to the motor case  3320  by a plurality of threaded fasteners  3512  which extend though openings of the pedestal  3510  and thread into aligned threaded openings in the motor case  3320 . In turn, the drive motor coupling  3550  is secured to the pedestal  3510  by a plurality of threaded fasteners  3557  which extend through aligned openings of the flange  3555  of the drive motor coupling  3550  and thread into aligned threaded openings in the pedestal  3510 . At a distal end  3551  of the drive motor coupling  3550  there is an opening  3553  defined by a tapered collar  3552 . The tapered collar  3552  receives and, via a latching mechanism of the drive motor coupling  3550 , releasably holds and secures a mating tapered coupling body  3722  of the motor end coupling  3720  of the outer casing assembly  3710  of the flexible shaft drive transmission  3700 . When the tapered coupling body  3722  is secured within the tapered collar  3552  of the drive motor coupling  3550 , the drive fitting  3410  of the driveshaft assembly  3401  engages and rotates the driven fitting  3820  of the flex shaft assembly  3800  of the shaft drive transmission  3700 . As best seen in  FIGS.  47 ,  48  and  50   , in the engagement region of the drive and driven fittings  3410 ,  3820 , the driveshaft central axis of rotation DSR and the central longitudinal axis LASDT of the flex shaft assembly  3800  are substantially aligned and coincident. The drive motor coupling  3550  includes a release latch  3560  which, when depressed by the operator, releases the tapered coupling body  3722  of the motor end coupling  3720  from the tapered collar  3552  of the drive motor coupled coupling  3550  and allows for disengagement of the drive fitting  3410  of the driveshaft assembly  3401  and the driven fitting  3820  of the flex shaft assembly  3800  of the shaft drive transmission  3700 . Additional details of the various components of the drive motor coupling  3550  and the motor coupling  3700 , the drive fitting  3410 , the driven fitting  3820 , as well as other components of the flexible shaft drive transmission  3700  may be found in the aforesaid U.S. Pat. No. 9,121,438 to Mascari, which is incorporated herein in its entirety. 
     Blower Assembly  3450   
     As best seen in  FIG.  50   , the centrifugal fan  3460  is affixed to the proximal end portion  3408  of the driveshaft  3400 . The fan  3460  is disposed outside of a back wall of the motor case  3320  and is positioned within the spiral turbine or duct  3470  of the blower assembly  3450 . The fan  3460  includes a planar backing plate  3494 . A plurality of arcuate vanes  3496  extension from a back side of the backing plate  3494 . The proximal end portion  3408  of the driveshaft  3400  extends thought an opening in a back wall of the motor case  3320  and fits into a stubshaft  3490  extending distally from a mounting bracket  3492  of the fan  3460  to affix the fan  3460  to the driveshaft assembly  3401 . The fan  3460  is supported for rotation about the driveshaft central axis of rotation DSR within a large central, generally cylindrical region  3471  (best seen in  FIGS.  47  and  48   ) of the duct  3470 . Rotation of the driveshaft  3400  causes rotation of the fan  3460  and flow of air through the spiral duct  3470 . A portion of the spiral duct  3470  that is routing air to the fan  3460  will be in a vacuum condition, while a portion of the spiral duct  3470  on the exhaust or outbound air side of the fan  3460  will be in a higher pressure condition. Accordingly, the spiral duct  3470  will include an inlet or input or vacuum side duct  3472 , providing air to the fan  3460  and the central region  3471  of the duct  3470  in which the tan  3460  rotates, and a generally arcuate shaped output or blower side duct  3476 , receiving blown air from the fan  3460  and the central region  3471  of the duct  3470  in which the fan rotates. Stated another way, the inlet, input or vacuum side duct  3472  is on the inlet side of the fan  3460  to provide air to the fan  3460  (and thus the interior region  3476  of the inlet side duct  3472  is in a vacuum pressure condition), while the output or blower side duct  3476  is on the outlet side of the fan  3460  receives blown air from the fan  3460  (and thus the interior region of the output side duct is in a high pressure condition). Typically, the output or blower side duct would be attached to a blower wand for purposes of blowing leaves, yard debris and dirt and the like. However, in the application of the present disclosure, the inlet or vacuum side duct  3472  is utilized to draw vacuum pressure in the vacuum assembly  2900  of the power operated rotary knife assembly  2000 . The output or blower side duct  3476  includes an exit opening  3484  that trimmed foliage exits and is blown downwardly towards the ground. As the central region  3471 , the inlet or input or vacuum side duct  3472  and the output or blower side duct  3476  are all in fluid communication, trimmed foliage material therefore enters an inlet opening  3474  of the vacuum or inlet side duct  3472  moves through the central region  3471  of the spiral duct  3470  and exits the blower assembly  3450  at a downwardly directed exit opening  3484  of the output or blower side duct  3476 . 
     As best seen in  FIG.  49   , to provide fluid communication and transmission of vacuum pressure an interior region  3476  of the inlet or input side duct  3472  and the interior region  2992  of the vacuum hose  2990  of the vacuum assembly  2900 , the vacuum assembly  2900  further includes an generally funnel shaped vacuum adapter  2930  which provides a substantially sealed, airtight connection between the respective interior regions  3476 ,  2992  of the inlet side duct  3472  of the blower assembly  3450  and vacuum hose  2990 . A distal or inlet end portion  2932  of the vacuum adapter  2930  is generally cylindrical to snuggly receive a proximal end portion  2996  of the vacuum hose  2900 . A clamp  2936  overlaps and seals the proximal end portion  2996  of the vacuum hose  2900  to the inlet end portion  2932  of the vacuum adapter  2930 . Similarly, a proximal or outlet end portion  2934  of the vacuum adapter  2930  is configured in a generally rectangular in cross section to engage and snuggly fit against and seal with a peripheral edge  3478  defining the inlet opening  3474  of the vacuum or inlet or input side duct  3472  of the blower assembly  3450 . The outlet end portion  2934  of the vacuum adapter is secured to the peripheral edge  3478  of the input side duct  3472  with a pair of threaded fasteners  2998  ( FIG.  49   ). Accordingly, with the vacuum adapter  2930 , the vacuum pressure generated by the centrifugal fan  3460  is communicated from the interior region  3476  of the input or inlet side duct  3472  though an interior region  2938  of the vacuum adapter  2930  through the interior region  2992  of the vacuum hose  2900  though the interior region of the vacuum connector  2910  to the region of the cutting opening CO of the power operated rotary knife  2100 . Additionally, because the aforesaid interior regions are in fluid communication and the respective interior regions are substantially axially or longitudinally aligned, the trimmed foliage material flows generally smoothly along a passageway from the cutting opening CO through the vacuum connector  2910 , the vacuum hose  2900 , the vacuum adapter  2930 , and the spiral duct  3470 , to exit the blower assembly  3450  at the exit opening  3484  of the output side duct  3476 . 
     The blower fan  3460 , being rotated by the motor driveshaft  3400 , generates a vacuum pressure condition within the interior region  3476  of the inlet or vacuum duct side  3472  of the blower duct  3470 . This, in turn causes a vacuum pressure condition within an interior region  2992  of the vacuum hose  2990  and a vacuum condition in the region COR of the central cutting opening CO of the head assembly  2300 . Thus, when the operator manipulates the power operated rotary knife  2100  such that the cutting opening CO is presented to foliage to be trimmed, the vacuum pressure condition VPCCO at the cutting opening CO causes the foliage to be drawn into the cutting opening CO where it is cut by the overlapping cutting regions rotating rotary knife blade  2500  and the stationary trim guide  2700 . Stated another way, the blower fan  3460 , being rotated by the motor driveshaft  3400 , generates a flow of air through the interior region of the inlet duct side of the blower duct toward the fan  3460 , this, in turn causes a flow of air within an interior region  2992  of the vacuum hose  2990  and through a region COR of the central cutting opening CO of the head assembly  2300  in a proximal or rearward direction toward the inlet duct side  3472  and toward the fan  3460 . Thus, when the operator manipulates the power operated rotary knife  2100  such that the cutting opening CO is presented to foliage to be trimmed, the flow of air into the region COR of the cutting opening CO causes foliage to be drawn into the cutting opening CO where it is cut by the overlapping cutting regions rotating rotary knife blade  2500  and the stationary trim guide  2700 . The flow of air cause the trimmed foliage material to move within the aligned interior regions  2992 ,  3476  of the vacuum hose  2990  and the blower inlet duct side  3472  and ultimately be blown out of an outlet duct side  3482  of the blower duct  3470 . 
     Speed Control Assembly  3950   
     Advantageously, the drive motor assembly  3300  includes a speed control assembly  3950 , best seen in  FIGS.  45 - 46  and  51 - 53   , which allows the operator to easily control both the rotational speed of the rotary knife blade  2500  and the vacuum pressure drawn in the vacuum hose  2990 , including the vacuum pressure present in the region of the cutting opening CO. In one exemplary embodiment, the speed control assembly  3950  includes a finger operated throttle or speed control trigger  3952 . By depressing or releasing the speed control trigger  3952  appropriately, the operator controls the rotational speed of the driveshaft  3400  of the engine  3310  of the drive motor assembly  3300 . That is, the speed control assembly  3950  includes a speed control cable  3960  operatively coupled between the speed control trigger  3952  and a carburetor  3312  of the drive motor assembly  3300 . In one exemplary embodiment, the speed control assembly  3950  includes a mechanical connection between the trigger  3952  and the motor carburetor  3312 , however, one of skill in the art would recognize that the speed control assembly  3950  could be modified to utilize electronic, as opposed to mechanical controls and it is within the contemplation of the present disclosure to include non-mechanical speed control assemblies. 
     By depressing and releasing finger pressure applied to the speed control trigger  3952 , a position of the trigger  3952  changes with respect to the handle extension  3910  and the rotational speed of the driveshaft  3400  changes with the position of the trigger  3952 . As previously explained, the rotational speed of the driveshaft  3400  is proportional to and determines the magnitude of the rotational speed of the rotary knife blade  2500  and the magnitude of the vacuum drawn in the vacuum hose  2990  and the vacuum connector  2910  of the vacuum assembly  2900 . Advantageously, for ergonomics and ease of operator use, the speed control assembly  3950  is integral with the handle extension  3910  of a handle extension assembly  3900 , that is, the trigger  3952  is positioned to protrude forwardly in a direction generally aligned with and parallel to the handle assembly longitudinal axis and toward the rotary knife blade central axis of rotation R. The trigger  3952  is pivotally mounted just below an upper bulbous or enlarged portion  3914  of the handle extension  3910  which is configured to be used as a thumb rest by the operator during cutting and trimming operations and in proximity to an upper end  3913  of a central, generally cylindrical, finger gripping portion  3912  of the handle extension  3910 . The position of the trigger  3952  permits actuation of the trigger with the operator&#39;s index finger which provides for accurate control of the trigger  3952  while providing for a firm grip by the remainder of the operator&#39;s hand on the cylindrical gripping region  3912  and the overlaying of the operator&#39;s thumb on the upper bulbous thumb rest portion  3914 . 
     Additionally and advantageously, the speed control assembly  3950  includes a second, thumb controlled multi-position switch  3955  that is mounted to a generally planar side  3915  of the upper bulbous-shaped thumb rest portion  3914 . The second thumb switch  3955  of the speed control assembly  3950  advantageously functions, in one position, as a kill switch to turn off the engine  3310 , as desired by the operator. In a second position, the thumb switch  3955  functions as a trigger position lock wherein a specific trigger position of the finger trigger  3750  is locked in by moving the thumb switch  3955  to the second position. In the second position. i.e., the trigger position lock position, advantageously, the operator does not have to maintain constant pressure of his or her index finger on the trigger during, for example, long periods of cutting or trimming operations. This allows the operator to rest his or her index finger and to change gripping positions on the handle extension  3910  to mitigate hand fatigue. 
     The speed control assembly  3950  additionally includes the speed control cable  3960  that operatively couples the finger trigger  3750  and thumb switch  3955  to the carburetor  3312  of the engine  3310  allowing throttle control of the engine  3310  via the position of the finger trigger  3750  and, therefore, control of the rotational speed of the driveshaft  3400 . Advantageously, the operator, via the finger operated speed control trigger  3750  can control the speed of rotation (RPM) of the rotary knife blade  2500 . For example, the operator releases the speed control trigger  3750  when, for example, the operator is walking between rows of plants or otherwise not engaged in cutting or trimming operations with the power operated rotary knife  2100 . Thus, the rotation of the rotary knife blade  2500  is at a reduced rotational speed, i.e., at an idle rotational speed. By contrast, when cutting and trimming operations are being performed, the operator fully depresses the trigger  3750  so that the rotary knife blade  2500  is rotating at full rotational speed for ease of cutting. Similarly and advantageously, because the finger operated speed control trigger  3750  is essentially a throttle control trigger for the drive motor assembly  3300 , the further the trigger  3750  is depressed by the operator, the faster the driveshaft  3400  of the drive motor assembly  3300  rotates and the faster the centrifugal fan  3460  rotates. A magnitude of the vacuum pressure drawn or generated within the vacuum hose interior region  2992  is directly proportional to the rotational speed of centrifugal fan  3460  and therefore directly proportional to the rotational speed of the driveshaft  3400 . Thus, advantageously, the operator can control both the speed of rotation of the rotary knife blade  2500  and the vacuum pressure drawn in the vacuum hose interior region  2992  by the speed control trigger  3750 . 
     Handle Extension Assembly  3900   
     The handle extension assembly  3900  includes the handle extension  3910 , as described above. Additionally, as best seen in  FIGS.  52  and  53   , the handle extension assembly  3900  provides a mounting structure  3920  to mount the handle extension  3910  such that it extends from the hand piece  2210  of the handle assembly  2200 . The handle extension  3910  extends along a handle extension axis HEA. Advantageously, the handle extension  3910  may be positioned with respect to the hand piece  2210  such that the handle extension axis HEA intersects and extends orthogonally with respect to the handle assembly longitudinal axis LA and is substantially parallel to the rotary knife blade central axis of rotation R. The mounting structure  3920  advantageously allows the operator to position and orient the handle extension  3910  in a comfortable and ergonomically beneficial position for the operator such that as the power operated rotary knife  2100  is positioned and manipulated by the operator to move in a natural upward, arcuate sweeping motion by bending his or her arm at the elbow while gripping the cylindrical finger gripping portion  3912  of the handle extension  3910 . For cutting/trimming operations on grape vines in an upward, arcuate sweeping motion, the power operated rotary knife  2001  will be positioned for use as shown in  FIGS.  41 - 43   , that is, the knife  2001  is oriented for use such that the vacuum connector  2910  is positioned below (in the direction B as shown in  FIG.  45   ) the head assembly  2300  and the rotational plane RP of the rotary knife blade  2500  and the handle assembly longitudinal axis LA. Stated another way, the orientation of the power operated rotary knife  2100  will be opposite of the orientation of the power operated rotary knife  1100 , as shown in  FIG.  21   . Similarly, the handle extension  3910  is mounted to the handle assembly hand piece  2210  such that it extends above the rotational plane RP of the knife blade and the handle assembly longitudinal axis LA. 
     To securely affix the handle extension  3910  to the handle assembly hand piece  2210  in the desired orientation and position, the handle extension assembly  3900  further includes a mounting structure  3920  which couples a lower, mounting or base portion  3918  of the handle extension  3910  to the handle assembly hand piece  2210 . In one exemplary embodiment, the mounting structure  3910  includes an annular collar  3922  having a central throughbore  3926  defined by a cylindrical inner surface  3930  of the collar  3922 . As best seen in  FIG.  43   , the diameter of the central throughbore  3926  of the collar  3922  is sized to snuggly overlie a portion  2213  of an exterior surface  2212  of the hand piece  2210 . The latching knob  2282  of the handle assembly  2200  must be removed to slide the collar  3922  over the hand piece  2210 . The collar  3922  includes a threaded opening  3928  extending radially between the cylindrical inner surface  3930  and a cylindrical outer surface  3932  of the collar  3922 . A set screw  3924  is threaded into the opening  3928  and bears against the exterior surface  2212  of the hand piece  2210  to secure the collar  3922  and therefore the handle extension  3910  in the desired rotational position with respect to the cutting opening CO of the head assembly  2300  of the power operated rotary knife  2100 . 
     The mounting structure  3920  further includes a c-shaped clamp  3940  which wraps around and overlies the cylindrical outer surface  3932  of the collar  3922  and includes a pair of spaced apart uprights  3944 , defining a pair of aligned threaded openings  3946 . The base portion  3918  of the handle extension  3910  also includes a threaded aperture  3918 . A threaded fastener  3924  is threaded through the pair of aligned threaded openings  3946  of the clamp uprights  3944  and through the handle extension threaded aperture  3918 . Prior to tightening the threaded fastener  3924 , the handle extension  3910  may be pivoted about a handle extension pivot axis HEPA. Thus, the operator may pivot the handle extension  3910  to find a pivot position of the handle extension  3910  that is most comfortable for the operator. As the threaded fastener  3924  is tightened, the uprights  3944  of the flexible clamp  3940  tighten around and secure the handle extension  3910  in place and a body  3948  tightens around the outer surface  3932  of the collar  3922  to securely couple the handle extension  3910  to the collar  3922 . The handle extension pivot axis HEPA is intersected by the handle extension axis HEA and is offset from and transverse to the handle assembly longitudinal axis LA and the rotary knife blade axis of rotation R. However, advantageously, in any rotational position and in any pivot position of the handle extension  3910 , the handle extension axis HEA intersects handle assembly longitudinal axis LA thereby making is easy for the operator to manipulate the power operated rotary knife  2100  for cutting and trimming operations. 
     As used herein, terms of orientation and/or direction such as front, rear, forward, rearward, distal, proximal, distally, proximally, upper, lower, inward, outward, inwardly, outwardly, upwardly, downwardly, horizontal, horizontally, vertical, vertically, axial, radial, longitudinal, axially, radially, longitudinally, etc., are provided for convenience purposes and relate generally to the orientation shown in the Figures and/or discussed in the Detailed Description. Such orientation/direction terms are not intended to limit the scope of the present disclosure, this application, and/or the invention or inventions described therein, and/or any of the claims appended hereto. Further, as used herein, the terms comprise, comprises, and comprising are taken to specify the presence of stated features, elements, integers, steps or components, but do not preclude the presence or addition of one or more other features, elements, integers, steps or components. 
     What have been described above are examples of the present invention. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the present invention, but one of ordinary skill in the art will recognize that many further combinations and permutations of the present invention are possible. Accordingly, the present invention is intended to embrace all such alterations, modifications and variations that fall within the spirit and scope of the appended claims.