Cutlery – Cutting tools – Plural cooperating blades
Reexamination Certificate
2000-03-15
2001-01-30
Payer, Hwei-Siu (Department: 3724)
Cutlery
Cutting tools
Plural cooperating blades
C030S245000
Reexamination Certificate
active
06178644
ABSTRACT:
This invention relates to cutting tools, and more particularly, to pruning shears having an extended handle for reaching branches at greater heights, and a cord for remotely activating a shearing mechanism.
BACKGROUND OF THE INVENTION
Conventional tree pruning shears are typically provided with a pole of fixed or adjustable length, a shearing mechanism located at one end of the pole, and an operating cable or cord attached to the shearing mechanism and extending the length of the pole for remote operation of the shearing mechanism.
The conventional shearing mechanism usually includes a capturing hook portion which is adapted to bang from a branch or limb intended to be cut, and a mating pivotal cutting blade. The cutting blade includes a leverage arm from which is attached one end of the operating cord. The pruning shears are manipulated by holding the pole in one hand and the operating cord in the other hand . A limb of interest is “hooked” and held by the hook portion of the shearing mechanism. The operating cord is then pulled which causes the cutting blade to pivot into the “captured” limb. The amount of force required to cut the limb varies, depending on the type of wood, the size of the limb and the location of the cut. However, for the most part, the cutting action requires a great deal of force from its operator.
In addition, generally the operating cord hangs freely outside the pole. During the cutting operation, the operating cord will frequently become snagged on other branches or twigs, reducing the cutting force, and requiring time and effort to untangle the operating cord.
Another technical problem to be solved is related to certain user needs for an extendable pruner, that is one which can be extended and locked into a number of effective operating pruner lengths for a pruner having design benefits as described above.
While these other units may be suitable for the particular purpose for which they were intended, or for general use, they would not be as suitable for the purposes nor include the benefits of the present invention as described herein.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an adjustable length pruner which will effectively cut a branch with minimal effort.
It is another object of the invention to provide an adjustable length pruner in which the possibility of snagging the operating cord is greatly reduced.
It is a further object of the invention that the cutting arm is operated by means of a leverage arm, and the leverage of the cutting arm is greatly increased by the dual-pivotal attachment of the leverage arm and cutting arm.
It is a further object of the present invention to provide a pruner in which the operating cord extends through the interior of the pruner and has a portion operably coupled to a lower longitudinally operating handle of the pruner.
A further object of the present invention is to provide a pruner having an internally extending operating cord as described, which pruner can be extended and secured in a plurality or infinite number of operating pruner lengths.
Yet a further object is to provide a pruner with a shearing mechanism that includes a leverage arm and blade design that produces enormous cutting forces given the longitudinal displacement of the cutting shaft or handle.
A portable pruner for cutting limbs comprises a hollow elongated tube assembly having a longitudinal axis, a lower sliding portion and an upper open end. The sliding portion is telescopically slidable along the longitudinal axis between a first and a second position. A shearing mechanism is attached to the upper open end of the hollow handle and includes a body having a hook adapted to receive and hold a limb. A cutting blade assembly including a leverage arm is pivotally attached to the body and selectively pivots against the hook to cut the selected limb. The pruner includes means for pivoting the cutting blade with respect to the hook wherein the pivoting means is responsive to movement of the sliding portion between the first and second positions.
The upper section of the pruner is tubular. An operating cord extends through the upper open end then through the interior of the tube and has one portion operable by the sliding portion. Another portion of the cord extends beyond the open upper end and operably engages the leverage arm assembly so that longitudinal withdrawal of the sliding portion causes cutting rotation of the leverage arm and cutting blade assembly.
In one exemplary embodiment the upper section or hollow tube has a fixed length.
In another exemplary embodiment, the upper section or hollow tube includes two telescoping segments and an operable clamping or securing device mounted to the outer segment to enable the user to adjust the overall operating pruner length to any desired length within two limits. The device is selectively moveable on one of the two segments and the cord operatively engages the device so that length adjustment of the two segments also accommodates the change in cord length external to the hollow tube. This permits the same, relative operating positions of the handle and hollow tube regardless of the adjusted length of the hollow tube.
Other principal features and advantages of the invention will become apparent to those skilled in the art upon review of the following drawings, the detailed description and the appended claims.
REFERENCES:
patent: 5745998 (1998-05-01), Le et al.
patent: 5933965 (1999-08-01), Linden et al.
patent: 5960546 (1999-10-01), Cooke et al.
patent: 6038773 (2000-03-01), Le et al.
Le Thong Huu
Le Timothy Van
Dreyfus Edward
Le Thong Huu
Payer Hwei-Siu
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