Abstract:
A pruning device for cutting tree limbs includes a head assembly mounted atop an elongated pole and activated by a tether line. The head assembly can be pivoted to various angles relative to the pole axis without impairing the effectiveness of the tether line to apply pulling force for achieving cutting of upwardly angled tree limbs.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to cutting tools, and more particularly concerns pruning shears mounted upon an elongated handle and equipped with an actuating tether deployed along said handle. 
     2. Description of the Prior Art 
     Conventional tree and shrub pruners are typically comprised of cutting shears mounted atop a pole of fixed or telescopically adjustable length with an actuating rope or cable extending from said shears to the lowermost extremity of the pole. The shears are generally comprised of a stationary member having a hook configuration disposed in the same plane as the pole, and a cutting blade interactive with the stationary member to sever a limb engaged by said stationary member. The pruning shears are manipulated by holding the pole in one hand and the rope in the other hand in order to pull the rope and thereby force the blade against an engaged limb. The blade is returned to a stand-by starting position by virtue of a restoring spring. 
     Representative examples of such pruning devices are described in U.S. Pat. Nos. 4,033,036; 4,096,630; 5,084,975; 5,613,301; 5,743,018; 5,996,232 and elsewhere. 
     Manipulation of the pruning device and actuation of the cutting blade can be difficult, depending upon the height of the limb to be severed, its orientation and location, and the presence of closely adjacent interfering structures. In particular, it is difficult to cut branches which have a nearly vertical orientation because the stationary hook member must engage the branch in such manner that the branch is transversely oriented relative to the pole. Ideally, the branch to be severed is disposed in orthogonal relationship to the pole. 
     When the pruning device is operated at ground level, the operator can walk around the base of the tree to find the best angle of application of the device for the cutting of a particular branch. However, when the operator is on a rooftop or in some other situation which restricts movement relative to the branch to be severed, considerable difficulty is encountered. 
     U.S. Pat. No. 4,033,036 to Morris discloses a pole type pruning device wherein the cutting head can be adjustably pivoted to positions wherein the plane of the hook member is disposed between 0 and 90 degrees relative to the pole axis. However, in achieving such adjustability, the upper structure of his pruning device has been weakened, and the force required to effectively pull the rope has been significantly increased. 
     It is accordingly an object of the present invention to provide a pole type pruning device having a tether-actuated cutting head which is angularly adjustable relative to an elongated supporting pole. 
     It is another object of this invention to provide an adjustable pruning device as in the foregoing object wherein achievement of adjustability does not adversely affect the strength of the pruning device. 
     It is a further object of the present invention to provide an adjustable pruning device of the aforesaid nature wherein achievement of adjustability does not significantly increase the amount of pulling force needed to be applied to said rope to actuate said cutting head. 
     It is yet another object of this invention to provide a pruning device of the aforesaid nature of durable, simple construction amenable to low cost manufacture. 
     These objects and other objects and advantages of the invention will be apparent from the following description. 
     SUMMARY OF THE INVENTION 
     The above and other beneficial objects and advantages are accomplished in accordance with the present invention by a pruning device for cutting tree limbs comprising: 
     1) a support pole elongated upon a straight axis between upper and lower extremities, 
     2) a pruner assembly associated with the upper extremity of said pole and comprised of: 
     a) an engaging member having a base portion and an upper portion having a hook shaped configuration defining a downwardly directed gripping region adapted to rest upon a limb intended to be severed, and 
     b) a cutting member having a lower blade portion and upper lever arm portion, said cutting member being pivotally joined to said engaging member at a site between said blade and lever arm portions, 
     3) tether means secured to said lever arm portion and having sufficient length to extend to a free terminal extremity below the lower extremity of said support pole, whereby pulling motion applied to said tether produces forceful traversal of said blade portion through said gripping region, 
     4) restoring spring means interactive between said engaging member and lever arm portion and biased against the force applied by said pulling motion, and 
     5) a pivot mechanism interactive between the base portion of said engaging member and the upper extremity of said pole, said pivot mechanism comprising: 
     a) a knuckle joint comprised of slideably interactive upper and lower members secured by a threaded tightening bolt upon which rotative motion of said upper member is centered, 
     b) a rotating control wheel positioned at a site below said bolt and centered at 45 degrees of angular displacement from said axis, said wheel having a diameter such as to tangentially receive said tether in a straight vertical path, and 
     c) an upper guide mounted above said control wheel, and a lower guide positioned below said control wheel, said guides permitting sliding motion of said tether in its direction of elongation but preventing lateral displacement thereof, whereby, 
     6) said rotative movement of said upper joint member and attached pruner assembly enables said engaging member to be securably positioned at various angles of between 0 and 90 degrees relative to the pole axis in a path parallel to but displaced from said pole axis, and the pulling functionality of said tether remains effective at all positions of said pruner assembly. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawing forming a part of this specification and in which similar numerals of reference indicate corresponding parts in all the figures of the drawing: 
     FIG. 1 is a right side view of an embodiment of the pruning device of the present invention with portions broken away, and shown in a straight condition typical of conventional pruning devices. 
     FIG. 2 is a fragmentary front view of the embodiment of FIG. 1 shown with its pruning head relocated 90 degrees from the axis of the pole handle. 
     FIG. 3 is a rear view of the embodiment of FIG.  2 . 
     FIG. 4 is a sectional view taken in the direction of the arrows upon the line  4 — 4  of FIG.  1 . 
     FIG. 5 is a schematic view showing how the pruning device of this invention acts upon a branch of a tree that is directed at a sharp upward angle. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIGS. 1-5, an embodiment of the pruning device  10  of the present invention is shown comprised of support pole  11  elongated upon a straight axis  12  between upper and lower extremities  13  and  14 , respectively, and pruner assembly  15  mounted atop said upper extremity. 
     Support pole  11  may be a single integral member of strong, light construction, but is preferably comprised of upper and lower telescopically interactive members capable of causing the pole to have adjustable lengths between about 8 and 16 feet. The pole may be fabricated of tubular aluminum or fiberglass components resistant to outdoor weathering factors. 
     Pruner assembly  15  is comprised of engaging member  16  having a base portion  17  and an upper portion  18  having a hook shaped configuration defining a downwardly directed gripping region  19  adapted to rest upon a limb  20  intended to be severed. Said gripping region may have a diametric size ranging between about 2 and 4 inches. A cutting member  21  having a lower blade portion  22  and upper lever arm portion  23 , is joined by pivot pin  24  to said engaging member at a site between said blade and lever arm portions. The mounting of said cutting member is such that, when said lever arm portion is moved downwardly, blade portion is caused to traverse said gripping region in an upward motion. In certain embodiments, a saw may extend upwardly from engaging member  16 . 
     Tether means  25 , which may be a supple rope, cable or chain, is pendently secured to said lever arm portion. Said tether means has sufficient length to extend to a free terminal extremity  26  below the lower extremity of said support pole. Forceful downward pulling upon said tether means produces the aforesaid movement of said cutting member with consequent severing of limb  20 . In the illustrated embodiment, the pulling force applied to said tether is augmented by pulley wheels  43 ,  44  and  45  operating between engaging member  16  and lever arm portion  23 . 
     Restoring means in the form of coil spring  27  interacts between engaging member  16  and lever arm portion  23  to return blade portion  22  to its starting or stand-by position away from interaction with gripping region  19 . 
     A pivot mechanism  28  is interactive between base portion  17  of engaging member  16  and upper extremity  13  of pole  11 . The exemplified embodiment of said pivot mechanism is comprised of knuckle joint  29  including slideably associated upper and lower members  30  and  31 , respectively, secured by a threaded tightening bolt  32 . Said upper member is adapted to undergo controlled rotative motion about bolt  32 , carrying with it said pruner assembly. 
     In the exemplified embodiment, upper member  30  of said knuckle joint is considered a male component having downwardly directed plate  34  centered on axis  12 , and opposed concave bearing shoulders  50 . Lower member  31  is considered a female component having paired plates  35  which slideably receive plate  34  and terminate in convex bearing surfaces  51  slideably interactive with shoulders  50 . In alternative embodiments, the male and female components can be in reversed positions. 
     Bolt  32  is shown to penetrate an aperture  37  in one of paired plates  35  and an aligned aperture  38  in associated plate  34 , and threadably engages a threaded hole  39  in the opposite paired plate  35 . A knurled manipulating knob  40  and abutment collar  41  are disposed upon one extremity of bolt  32 . By virtue of such arrangement, pruner assembly  15  can be rotated to angular positions between 0 and 90 degrees relative to axis  12 , and secured in said positions by tightening force applied to knob  40 . In some embodiments, one or both surfaces of plate  34  may be provided with radially extending ridges adapted to engage matching ridges in paired plates  35 . Such feature will provide greater stability of a chosen and locked angular position. It should be noted that the aforesaid construction enables gripping region  19  to move in a path which is parallel to axis  12  but laterally displaced therefrom. 
     A rotatable control wheel  46  is attached to lower member  31  at a site below bolt  32 , and centered at 45 degrees of angular displacement from axis  12 . Said control wheel has a diameter such as to tangentially receive tether rope  25  in a straight vertical path thereof. 
     Pulley wheel  45  serves as an upper guide positioned above upper joint member  30  in orthogonal relationship to control wheel  46 . A stationary lower guide  48  is mounted below wheel  46  in vertical alignment with pulley wheel  45 . Said upper and lower guides span control wheel  46  and bolt  32 , and permit sliding motion of the rope longitudinally, namely along the length of the rope, but not laterally. 
     When pruner assembly  15  is rotated and locked in a position oriented at 90 degrees relative to pole axis  12 , the pruning device is well suited for the cutting of branches that are upwardly oriented at almost vertical angles. The reason is that the cutting blade functions best when orthogonally disposed to a branch within the gripping region. Similarly, other angular positions of the pruning assembly can be chosen for operating on differently directed branches. 
     It is to be noted that, even in the maximum 90 degree dislocation of the pruner assembly, the effectiveness of the rope is undiminished in applying pulling force to lever arm portion  23 . The reason for such retained efficiency is that the apex of the angle defined by the taut rope is centered upon the threaded extremity of bolt  32 , and the path of the rope does not encounter frictional restraints in its angled path. 
     While particular examples of the present invention have been shown and described, it is apparent that changes and modifications may be made therein without departing from the invention in its broadest aspects. The aim of the appended claims, therefore, is to cover all such changes and modifications as fall within the true spirit and scope of the invention.