Patent Document

FIELD OF THE INVENTION 
     The present invention relates generally to the field of pruning tools. 
     BACKGROUND OF THE INVENTION 
     Pole-mounted pruning tools are widely used by arborists and others to control foliage growth at substantial heights. Conventional pruning tools usually comprise an elongated shaft or tube on the upper end of which a head is mounted. The head often includes a lopping mechanism in the form of an outwardly projecting hook-shaped stationary jaw and a pivotal blade. The blade is typically biased in an open position by a spring and usually includes an actuating device near a lower end of the elongated shaft to enable a user to remotely actuate the lopping mechanism of the tool in a lopping mode at substantial distances that are otherwise ordinarily beyond the user&#39;s direct reach. Pruners may also have a cutting device similar to a saw blade also mounted to an upper end of the head portion of the pruner. A user may also operate the tool in a sawing mode whereby the tool is moved in a reciprocating manner to effect a sawing operation. 
     Typical pruning tools are often configured with a head portion having an outwardly extending lever arm or similar structure that provides mechanical advantage for rotating the pivotal blade outwardly to engage the stationary jaw in a closed position as shown by example in U.S. Pat. Nos. 5,613,301 and 5,996,232. These pruning tools have the disadvantage of being susceptible to becoming entangled in, or obstructed by, surrounding foliage when used in either the lopping or sawing modes due to the awkwardness of the outwardly extending structure. Accordingly, it would be desirable to provide a pruning tool having a streamlined head profile that can be easily maneuvered in dense foliage. It would also be desirable to provide such a low profile pruning tool having sufficient mechanical advantage to provide effective cutting capability. It is further desirable to provide a low profile pruning tool having a cutting blade that rotates inwardly to reduce interference with, and damage to, surrounding foliage when used in dense areas. 
     Accordingly, it would be desirable to provide a low profile pruning tool having one or more of these advantageous features. 
     SUMMARY OF THE INVENTION 
     One embodiment of the invention relates to a low profile tree pruning tool having a head assembly coupled to an upper region of an elongated member and a drive mechanism coupled to the head assembly where the pulley is configured to rotate about a fixed axis. A lopping mechanism is coupled to the head assembly and an actuating line couples the lopping mechanism to the drive mechanism. A transfer line couples the pulley to a slide block. A stationary block is rigidly coupled to the elongated member below the head assembly. A tension line has a first end coupled to the slide block and is configured to movably engage the stationary and slide blocks. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevation view of a low profile pruning tool. 
     FIG. 2 is a perspective view of an upper region of the low profile pruning tool. 
     FIG. 3 is a side elevation view of an upper region of the low profile pruning tool in a released position. 
     FIG. 4 is a side elevation of an upper region of the low profile pruning tool in an actuated position. 
     FIG. 5 is a front elevation view of an upper region of the low profile pruning tool. 
     FIG. 6 is a rear elevation view of the slide block taken generally along lines  6 — 6  of FIG.  4 . 
     FIG. 7 is a cross sectional view of the drive mechanism taken generally along lines  7 — 7  of FIG.  5 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIGS. 1 and 2, a pruning tool  10  is shown according to a preferred embodiment of the present invention. Pruning tool  10  provides a tool for pruning, trimming, cutting, lopping, etc. a wide variety of vegetation including plants, trees, shrubs, branches, limbs, foliage, etc. (not shown) that enables a user to remotely prune vegetation that may not otherwise be within reach. 
     Pruning tool  10  includes one or more elongated members  20  in the form of shafts, poles, handles, etc. that may be used singularly (not shown) or configured for coaxially telescoping extension with one or more retainers  22  in the form of a clamp or holder for adjustably securing the elongated members to the height desired for pruning tool  10 . Retainer  22  may be provided with a quick-release latch  23  (shown as a lever) for clamping and releasing a first elongated member  20  to a second elongated member  20  by moving latch  23  between a locked position and an unlocked position. Head assembly  30  is mounted to an upper region of an upper most elongated member  20 . Head assembly  30  is shown attached to elongated member  20  by a threaded fastener  34  but may be attached by any suitable means including press-fit, threaded engagement, adhesive, rivets, pins, etc. Stationary block  26  is mounted to upper most elongated member  20  at a sufficient distance below head assembly  30  to permit free operation of sliding block  32 . Stationary block  26  is shown attached to elongated member  20  by a threaded fastener  36  but may be attached by any suitable means including press-fit, adhesive, rivets, pins, etc. Tension line  28  has a first end attached to sliding block  32  and a second end routed to a convenient actuating location near end cap  24  located at the bottom of the lower most elongated member  20 . Alternatively, the second end of tension member  28  may be attached to a slidable sleeve (not shown) on the elongated member or the second end of tension member  28  may be attached to end cap  24 . 
     Referring to FIG. 2, head assembly  30  is shown according to a preferred embodiment. Head  30  includes a lopping mechanism  40  in the form of cutting jaws having a stationary jaw and a pivoting jaw. Head  30  may be unitarily formed with a stationary hook portion  42  portion having an upward curvature to form the stationary jaw portion of the lopping mechanism  40 . Head  30  includes a rotatable pivoting blade  44  that has a curved jaw portion and a lever portion  45  and operates in cooperation with hook portion  42  in a shearing relationship where blade  44  passes beyond the cutting surface of hook  42  to lop-off foliage captured between hook portion  42  and the jaw portion of blade  44  when lopping mechanism  40  is actuated. Pivoting blade  44  may also be removably attached to head  30  to facilitate replacement after suitable wear. Hook portion  42  and blade  44  are configured as a pair of downwardly extending jaws, whereby the open jaws of the pruning tool  10  may be placed over, and then lowered onto, a branch, limb, stem, etc. so that the foliage to be lopped provides support to pruning tool  10  during the lopping operation. Blade  44  is shown pivotally attached to head  30  by threaded fastener  46  but may be pivotally coupled by any suitable means including pins, bushings, bearings, etc. In an alternative embodiment, hook portion  42  may be in the form of an anvil (not shown) where hook portion  42  and blade  44  cooperate in a clamping operation where hook  42  and blade  44  contact each other in an abutting relationship. 
     Saw blade  54  may be removably attached to head  30  by a guide tab  56  on head  30  corresponding to mating aperture (not shown) on saw blade  54  and retained by threaded fastener  60  shown as a through-bolt and wing nut. Alternatively, saw blade  54  may be permanently mounted to head  30  or removably attached to head  30  by any suitable means to ensure stable operation when used in the sawing mode. 
     Referring further to FIGS. 2 and 5, head  30  includes a housing having two mating housing half portions  70  and  71 . Housing portion  70  is integrally formed with a support portion  48  that is coupled to, and supports, a drive mechanism  50  in the form of a pulley assembly, and a semi-circular sleeve  90  that is adapted to fit over member  20 . Housing portion  71  is integrally formed with a hook portion  42  and a semi-circular sleeve  92  that is adapted to fit over member  20  and adjoin sleeve  90  to form a tight seam. Housing portion  71  may also include stiffening webs  52  to maintain sufficient structural rigidity while minimizing overall weight of head  30 . In a particularly preferred embodiment, housing portion  70  is made of “NYLON” and formed by an injection molding process, but may be composed of any other suitable plastic or polymer that is lightweight, strong and rigid. Housing portion  71  is made of zinc and formed in a die cast process, but may be steel or aluminum or any other suitable material having the necessary strength and toughness for pruning service. 
     Referring to FIGS. 3 and 4, the actuating components of head  30  are shown according to a preferred embodiment. Slide block  32  increases the mechanical advantage of a user pulling on tension line  28  by having three interfaces. The first interface on slide block  32  is a fixed connection to transfer line  66 . The second interface on slide block  32  is a fixed connection to a first end of tension line  28 . The third interface on slide block  32  is a pulley  64  that receives tension line  28  after tension line  28  is routed from the second interface and through a pulley  62  on stationary block  26 . Slide block  32  and stationary block  26  are preferably made of NYLON or plastic, but may be made of any material suitable for transferring the tensile loading on tension line  28  to transfer line  66 . 
     At the first interface, tension line  28  is fixed using any suitable means shown schematically as a knot or crimped plug (not shown) at a first end to slide block  32 . Tension line  28  is then routed downward to stationary block  26  and through rotatable pulley  62  where the tension line&#39;s  28  direction of force is reversed. Tension line  28  is then routed upward to slide block  32  and through the rotatable pulley  64  where the tension line&#39;s direction of force is again reversed. The second end of tension line  28  is routed downward where it is accessible for user-actuation by pulling downward. The second end of Tension line  28  may be left unattached for increased flexibility or the second end may be attached to the bottom end, or any lower portion, of the lower most elongated member  20  where it may be conveniently grasped and pulled by a user. Pulleys  62  and  64  increase the mechanical advantage of the user when pulling the second end of tension line  28  in a generally downward direction (i.e. relative to head  30  and along the axis of elongated member  20 ) to move slide block  32  in a similar downward direction. Single pulleys are shown on stationary block  26  and slide block  32  however multiple pulleys (not shown) may be provided to increase the available mechanical advantage. 
     Referring to FIGS. 5 and 7, drive mechanism  50  is partially enclosed within housing portions  70  and  71  and includes a double pulley having a transfer sheave  72  and an actuating sheave  74 , each in the form of a pulley or grooved wheel, that are rotationally coupled for pivoting movement about an axis defined by through-bolt  60 . Housing portions  70  and  71  include openings for travel of actuating line  76  and transfer line  66  during pulley rotation, yet provides sufficient enclosure to minimize intrusion of foreign materials during operation such as dirt and foliage. Transfer sheave  72  has a larger diameter than actuating sheave  74 , thus providing increased mechanical advantage to the user for actuating lopping mechanism  40 . Preferably the ratio of transfer sheave  72  diameter to actuating sheave  74  diameter is approximately 1.23 inches to 0.64 inches, however other ratios may be used to acquire the desired mechanical advantage depending on the overall size of head  30  and the number of pulleys provided on stationary block  26  and slide block  32 . Actuating sheave  74  may be oriented eccentrically (not shown) relative to transfer sheave  72  to provide a cam-like motion producing a varying degree of rotational mechanical advantage throughout the rotational range of sheaves  72  and  74 . 
     Transfer line  66  has a first end attached in a non-slip manner such as a knot or a crimped plug (not shown) to transfer sheave  72  so that a portion of transfer line  66  is wound along a portion of the circumference of sheave  72 . A second end of transfer line  66  is attached in a non-slip manner, shown schematically as a knot but may be a crimped plug (not shown) or other suitable retainer, to an upper portion of slide block  32  as shown in FIGS. 4 and 6. A downward motion imposed on slide block  32  by pulling downward on tension line  28  will partially unwind transfer line  66  from sheave  72 , thereby imparting a anti-clockwise rotation on sheaves  72  and  74  as shown in FIG.  4 . An actuating line  76  has a first end attached in a non-slip manner shown schematically as a pin  82  to actuating sheave  74  so that a portion of actuating line  76  is wound along a portion of the circumference of sheave  74 . A second end of actuating line  76  is attached to a lever portion  45  of blade  44 , whereby anti-clockwise rotation of sheaves  72  and  74  will further wind actuating line  76  on actuating sheave  74 , thereby pivoting blade  44  inwardly toward hook portion  42  about the axis of connector  46  to actuate lopping mechanism  40 . 
     Referring further to FIGS. 3 and 4, lever portion  45  of blade  44  is biased toward an open position by a spring  78  that has a first end coupled to blade  44  and a second end attached to housing portion  71 . Spring  78  is preferably an extension-type coil spring having hooks at each end for attachment through retainer aperture  94  in blade  44  and retainer aperture  96  in housing portion  71 . Alternatively, a torsion spring or leaf spring (not shown) may be used to return blade  44  to an open position or an extension spring may be fastened between a lower end of the lever portion  45  of blade  44  and a lower portion of head  30 . 
     Sheaves  72  and  74  are integrally formed in a preferred embodiment but may be separately produced and linked in any suitable manner for unitary rotation. Sheaves  72  and  74  are preferably made of an acetal plastic in an injection molding process, but may be made of any material suitable for supporting and transferring the actuating force from a user applying a downward force to transfer line  28  to lopping mechanism  40 . Sheaves  72  and  74  may include a bearing or bushing (not shown) to reduce operational friction of pruning tool  10 . Actuating member  76  is shown as a chain attached to sheave  74  by a link or pin  82  but may be a cable, cord, wire, rope, strap, etc. Transfer member  66  is shown as a strap having a flattened rectangular cross section and is preferably made of polyester, but may have any suitable shape and be of any appropriate material for transferring the user input force to actuating line  76 . Tension member  28  is shown as a rope or cord and is preferably made of polypropylene, but may be made of any suitable material for repeated use in transferring a user input force to slide block  32 . 
     It is also important to note that the construction and arrangement of the elements of the pruning tool as shown in the preferred and other exemplary embodiments is illustrative only. Although only a few embodiments of the present inventions have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g. variations in sizes, dimensions, structures, shapes and proportions of the various elements, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited in the claims. For example, multiple pulleys may be used in the sliding and stationary blocks to further increase the available mechanical advantage for a user. Further, sprockets may be substituted for the sheaves to engage corresponding chain links on the actuating and transfer lines. Accordingly, all such modifications are intended to be included within the scope of the present invention as defined in the appended claims. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. In the claims, any means-plus-function clause is intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the preferred and other exemplary embodiments without departing from the spirit of the present inventions as expressed in the appended claims.

Technology Category: 1