Abstract:
Pruners and loppers have dual mode operation in that the blade is closed with a single squeeze or with multiple squeezes and a rotatable selector selects the desired mode. The blade has a rocker arm with ratchet teeth formed in a window in the arm. The scissor handle has a radius arm which ends in a pawl which can engage the ratchet nearer the pivot axis of the blade or further from it.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a Continuation of U.S. Ser. No. 13/884,662, filed on Jun. 21, 2013, now allowed, which is a national stage application of International Application No. PCT/AU2011/001466, filed on Nov. 14, 2011, and claims priority benefit of Australian Patent Application No. 2010101247, filed Nov. 12, 2010. These applications are incorporated by reference herein in full. 
     
    
     TECHNICAL FIELD OF THE INVENTION 
       [0002]    This invention concerns ratchet primers for use inter alia in gardening. The invention is applicable to pruners known as secateurs worked by one hand and to toppers with extended handles which require two handed operation. 
       BACKGROUND OF THE INVENTION 
       [0003]    Ratchet pruners are a boon to gardeners, especially female gardeners, because they do not require a strong grip to sever stalks close to the opening capacity of the pruners. The repeated squeezing action of the operator&#39;s hand allows the cut to be made in three or four stages. While thick stalks or dried stalks all yield to the blade using multiple ratchet strokes, the time taken to prune by this ratchet mechanism is considerably greater and progress is slower. 
         [0004]    Carrying an ordinary pruner and a ratchet pruner does not generally speed the operator&#39;s work because it may not be until the resistance to cutting is felt by the operator that the choice of which tool to use becomes apparent. 
       SUMMARY OF THE INVENTION 
       [0005]    In one aspect the invention provides a dual mode ratchet pruner which in a first mode closes a blade with a single squeeze by an operator and in a second mode requires multiple squeezes by the operator to close the blade, wherein the position of a mode selection control selects which of said first and second modes the pruner would operate in. 
         [0006]    Preferably:
       the pruner has two handles for manual scissor-like actuation,   the blade has:
           a blade pivot whereby the blade is pivotally connected to a first of said handles, and   a rocker arm with ratchet teeth extending away from the pivot;   
           the second of said handles is pivotally connected to said first handle distant from said blade pivot; and   a pawl activated by scissor action of the handles is able to apply force to those of the teeth nearest the blade pivot or those furthest from the blade pivot.       
 
         [0013]    Preferably the pawl is a radius arm pivoted to said second handle and said pawl is biased to operate in said first mode. 
         [0014]    Preferably the ratchet is formed by a window in the rocker arm and the pawl is free to apply force to a first end of the window to produce said first mode and to the opposite end of the window to produce said second mode. 
         [0015]    Preferably said mode selection control comprises a cam which acts on the pawl. 
         [0016]    More preferably
       said mode selection control comprises a shaft portion having a cam cross section, and   said shaft is rotatable by a lever on one of said handles to thereby select which of said modes the pruner would operate in.       
 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    The invention is now described with reference to the accompanying drawings, in which: 
           [0020]      FIG. 1  is a side view of a pruner according to one embodiment of the invention, shown in the closed position; 
           [0021]      FIG. 2  is a side section view of the pruner of  FIG. 1  open and ready to cut in the multi-stage cut mode; 
           [0022]      FIG. 3  is an exploded view of the primer in  FIG. 1 ; 
           [0023]      FIG. 4  is an enlarged view of the mode selection area of the primer with the parts set in its multi-stage cut mode; and 
           [0024]      FIG. 5  is the view shown in  FIG. 4  but with the parts set in the pruner&#39;s single cut mode. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0025]    In this description the primer will be described oriented for use as shown in  FIG. 1  with its cutting blade uppermost and pointing forwards. The region encircled by dashed lines and indicated at  40  in  FIG. 2  is shown in respective enlarged views in  FIG. 4  and  FIG. 5 . 
         [0026]    As shown in the drawings, the pruner  1  has a handle  2  having a hollow mid-section  4  which extends into a grip  6  at one end and a jaw member in the form of a curved anvil  8  at the opposite end. The handle  2  is formed mostly of die cast aluminium with an engineering grade plastic material  3  forming a gripping portion which provides thermal insulation for the user&#39;s hand. At the base of the anvil  8  at the front of the handle  2  is a pivot  10  which joins the handle  2  to a die cast scissor-type handle which forms the lower guard handle  12  of the pruner. The handle  12  has a hollow portion  13  at its front end and the gripping area  11  is of plastic material which provides thermal insulation. The pivot  10  is a flat-headed pin fastened by a washer  7  and a circlip  9 . 
         [0027]    The hollow mid-section  4  of the handle  2  has a slot  14  which accommodates a blade  16  having a cutting edge  17  towards one end and a rocker arm  18  towards the other end. The blade  16  is mounted on a pivot pin  20  which bridges the slot  14  and screws into the right hand side of the handle  2 . A rat-trap-type spring  21  around the pivot pin  20  biases the handles to open the pruner. The cutting edge  17  of the blade  16  bears onto a narrow bed  22  of hard polymer material inset into the working face of the anvil  8 . The rocker arm  18  extends into a V-shaped space  24  lying between handles  2  and  12 . 
         [0028]    The endmost zone of the rocker arm  18  is perforated to create a ratchet window  26  having rounded ends  28  and  29  and four ratchet teeth  30 . 
         [0029]    The upper part of the scissor handle  12  is hollow and the opposing walls  32  are joined by a thrust pin  34 . The thrust pin  34  acts as a pivot for a bifurcated thrust link  36  and is retained by a lock washer  35 . The thrust link has a pair of cranked side plates  37  having, at one end, respective bores  39  to accommodate the thrust pin  34  and, at the other end, a pawl pin  38  connecting the side plates  37 . The pawl pin  38  projects through the ratchet window  26  and is retained by a nut  41  on its threaded end. The opposing walls  32  of the handle  12  also support a mode selector  45  which has a cam  42  lying between the walls  32  and contacting a planar web portion  43  on the thrust link  36  which joins the top edges of the side plates  37 . A rat-trap-type spring  44  is coiled around the thrust pin  34  with one tail of the spring bearing against the underside of the web portion  43  and the other tail of the spring bearing against the base of the hollow portion  13 . The spring  44  urges the bifurcated thrust link  36  into contact with the cam  42  at all times and biases the ratchet into the single cut mode at one end of the window. 
         [0030]    The cam  42  has a shaft portion  50  having a cylindrical face portion  52  and a longitudinal flat face portion  54 . Engagement of the flat face portion  54  with the web portion  43  allows the pawl pin  38  to reach the end  28  of the window  26  which lies closer to the blade  16 . When the selector  45  is rotated so that the cylindrical face portion  52  is in engagement with the web portion  43  of the thrust link, this has the effect of moving the pin  38  to the end  29  of the window further from the blade, wherein the pin  38  is free to engage the ratchet teeth  30  and yield a multi-stage cut in the general manner of a conventional ratchet primer. 
         [0031]    The shaft  50  carries a lever  51  at one end which lies within a sector-shaped depression  56  on the outside face of the handle  12 . When the lever is rotated between its extremes within the depression  56 , the shaft  50  rotates between its positions where it is the flat face  54  or the cylindrical portion  52  which bears against the thrust link. 
         [0032]    The end of the rocker arm  18  has a hook  46  which is captured by sliding a latch mechanism  48  on the scissor handle so that the pruner can be closed and kept closed. 
         [0033]    Whilst the above description includes the preferred embodiment of the invention, it is to be understood mat many variations, alterations, modifications and/or additions may be introduced into the constructions and arrangements of parts previously described without departing from the essential features or the spirit or ambit of the invention. 
         [0034]    For example although the pruners described with reference to  FIGS. 1 to 5  are anvil-style pruners, the invention is also applicable to bypass-style pruners. 
         [0035]    It will be also understood that where the word “comprise”, and variations such as “comprises” and “comprising”, are used in this specification, unless the context requires otherwise such use is intended to imply the inclusion of a stated feature or features but is not to be taken as excluding the presence of other feature or features. 
         [0036]    The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that such prior art forms part of the common general knowledge.