Harvesters – Hand rakes – Combined – convertible and attachments
Reexamination Certificate
1999-09-09
2001-11-06
Pezzuto, Robert E. (Department: 3671)
Harvesters
Hand rakes
Combined, convertible and attachments
Reexamination Certificate
active
06311465
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to gardening tools, and in particular to a lawn rake with a debris collection means, to facilitate the collecting and holding of, for instance, leaves or cut grass.
2. Description of the Prior Art
A variety of lawn rakes and similar tools, having bundling capacity, are known. Different designs of lever systems are used, for example in U.S. Pat. No. 5,058,370 (Russell), U.S. Pat. No. 4,545,189 (Nelson), U.S. Pat. No. 2,797,544 (Fite), U.S. Pat. No. 2,504,943 (Zifferer), U.S. Pat. No. 2,891,374 (Richmond), U.S. Pat. No. 2,908,131 (Ross), U.S. Pat. No. 5,058,370 (Russell), U.S. Pat. No. 2,790,296 (Bernstein) and U.S. Pat. No. 5,303,536 (Tolliver). All these designs share the drawback of being relatively heavy to operate, i.e. the lever action upon the bundling element is heavy and requires the user of the garden tool to exert an unnecessarily high force on the lever system, to accomplish the bundling action. A further design of a garden tool, solely used for picking up already raked leaf piles, is described in U.S. Pat. No. 4,848,074 and U.S. Pat. No. RE 33,702 (Allen). The head of the device has a plurality of tines, pivotably connected to a base portion of the head and interconnected so that if one tine is pivoted, all the others follow the motion. The tines are arranged in a circular manner around a hollow handle. A cable, which runs inside the handle and is attached to a manipulating lever on the handle at one end, and attached to one of the tines at the other end, is used to uniformly move the tines inwardly in unison when the lever pulls the cable. The circular arrangement of the tines makes it extremely difficult to actually use this garden tool as a rake, it is suited primarily for bundling and picking-up leaves.
In the majority, there are three significant methods in the design of debris collecting rakes and rake like devices; U.S. Pat. No. 2,504,943, to Zifferer, is typical of the radial pivot to clutch method, whereas U.S. Pat. No. 2,790,296, to Bernstein is typical of the transverse pivot to clutch method.
The transverse method being an attempt to remove the need for a second articulating rake head which is commonly both heavy and difficult to position, whereas the radial method by reason of expectation may have greater capacity.
The third method being the circumferential clutch method described in U.S. Pat. No. Re.33,702, to Allen.
The aforementioned difficulty in applying force to an articulating rake head using levers, necessitates a combination of linkages and fulcrums of greater mechanical advantage than can be applied to a standard hand rake, to apply sufficient force and control to achieve the desired degree of utility. A combination of linkages for articulating a rake head is disclosed in U.S. Pat. No. 4,545,189 to Nelson, whereby the force is applied using a long thin rod placed in the harder to control centre of compression stress, rather than in the more preferential form of tension. The rod is acting on a lever of the third order at an angle that would apply negligible force to the distal end of the rake head during the last quadrant of rotation where it is most needed to clutch the debris. The method of using an additional lever of the second order to increase the mechanical advantage often seemingly fails to provide a product that gains the consumer's satisfaction.
In U.S. Pat. No. 2,797,544 to Fite and U.S. Pat. No. 2,891,374 to Richmond, both describe attempts to hide the large lever in a through the handle mount which may weaken the handle's resistance to stress beyond a reliable point.
U.S. Pat. No. 2,504,943 to Zifferer, describes a light weight grapple, in the form of an arcuate brace as sufficient means to grasp laminated debris, whereas the majority of prior art describe heavy debris collecting rakes, which suffer from ergonomic and mechanical limitations. The resulting force at the grapple is not constant and almost nullified during the last quadrant of rotation where the greatest amount of force is needed and whereby friction, return springs and massive components have consumed the majority of the applied force, making rakes and rake like devices of this type heavy and unwieldy.
SUMMARY OF THE INVENTION
It is an object of the invention to mitigate and/or obviate the above mentioned disadvantages to provide a rake having a collection means attached to the head of the rake. The collection means is light, but will provide sufficient force to hold a grapple securely and tightly pressed towards the tines of the rake, to hold the raked debris, without the user of the rake having to exert excessive force on the rake mechanism or the rake handle.
It is a purpose of the invention to provide an pulley system beyond that of a simple sheave to provide the needed force.
The past state of the art has relied upon lever principles as force amplification elements, whereas, the present invention describes a reeve of pulley elements able to provide the necessary utility whereby the preferred embodiment of the invention combines force multiplying pulleys and levers in a recondite and reliable form, for applying forcible clutching, grasping and compressive action to a debris collecting apparatus.
It is a further purpose of the invention to apply the greatest amount of force by the simplest, most efficient means using tension, thereby allowing the use of light weight, inexpensive flexible elements, reeved through pulleys and integrated mechanical elements. Whereas many pulley combinations are possible, the present invention prefers to transmit, change direction and multiply the force using a minimum of pulley components integrated into a pivotal grapple as a means of force amplification and to achieve efficient debris pile collection.
Sufficient force can be supplied to a grapple of the collection means using a modified “fixed and runner” pulley combination, also called a “gun tackle purchase”, whereby a fixed pulley is located on an axis of a lever, the axis also being the fulcrum of the grapple and a moving runner pulley is located between the fulcrum and the anticipated point of loading, thereby describing a lever of the “third order” integrated to form the pivoting grapple and further collection means.
The reeve of a flexible element, such as a band, cord, rope or string, translates from the fixed pulley, commonly called a “sheave”, to redirect force and thereby avoiding force vectors common in applying force to levers, to a fixed point of the grapple. The fixed point is further improved being modified as the aforesaid runner pulley position, whereby the translation of force is further improved according to the “law of the pulley” whereby the flexible element is anchored to the rake embodiment according to the common formula W=P*n wherein W is the resulting force, P is the applied force and n is the number of strands thereby amplifying the force applied to the third order lever forming a more powerful clutching means.
It is a further purpose of the invention to prevent overrun or dislocation of the flexible element, whereby the fixed pulley has a shroud located on the axis. The shroud may rotate concentrically to the fulcrum axis and the fixed pulley. The shroud preferably has tabs to act as engaging points to start or stop the shroud rotation.
It is a further purpose of the invention to prevent overrun or dislocation of the flexible element, caused by limpidity, i.e. insufficient tension of the flexible element. Friction sufficient to latch the flexible element within the circumferential groove of a pulley, is found in the elastic properties of the interacting elements, whereby the circumferential opening of the pulley groove is of lesser total width than the circumferential root or bottom width of the pulley groove.
Yet a further purpose of the invention is to prevent overrun or dislocation of the flexible element, whereby the circumferential periphery of one pulley enters into the rope guide or slot of the complementary pulley so that the pulleys may rotate continuo
Armstrong R. Craig
Pezzuto Robert E.
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