WO2001011939A1

WO2001011939A1 - Novel post hole digger

Info

Publication number: WO2001011939A1
Application number: PCT/US1999/018465
Authority: WO
Inventors: Porter T. Pickren
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-08-13
Filing date: 1999-08-13
Publication date: 2001-02-22
Anticipated expiration: 2002-02-13
Also published as: AU5561699A

Abstract

The subject invention provides a post hole digger which facilitates the digging of deep uniform diameter post holes. The post hole digger accomplishes this by crossing the handles to close the shovel blades. This allows the handles to stay within the diameter of the hole opening, removing the need to increase the diameter of the hole opening as the depth of the hole is increased.

Description

DESCRIPTION

NOVEL POST HOLE DIGGER

Background of the Invention

The present invention relates to a new and improved manual post hole digger. The improved manual post hole digger permits the user to more conveniently produce a vertical hole with an essentially constant hole diameter through the length of the hole, enabling the user to dig deep holes. A common type of manual post hole digger is the clamshell post hole digger.

Previously known clamshell post hole diggers typically comprise a pair of sharpened shovel blades mounted on pivotally connected elongated handles. The post hole digging is accomplished by thrusting the blades into the ground then spreading the handles apart forcing the shovel blades together gripping the soil. The soil is then removed from the hole and dumped to the side. This process is repeated until a hole of the desired depth is attained.

The principal problem with this type of clamshell post hole digger is, as the hole is dug deeper the handles cannot be spread sufficiently far apart to grip the soil. Therefore, the diameter at the hole opening must be increased as the depth of the hole is increased.

Many attempts have been made to design clamshell post hole diggers which can dig a deep hole without the need to increase the diameter at the opening of the hole. Such diggers are provided by: Luck (U.S. Pat. No. 5,669,648), Alienate (U.S. Pat. No. 5,478, 128), Robinson (U.S. Pat. No. 5,427,424), Bumham (U.S. Pat. Nos. 5,320,363, 5,273,331), Arens (U.S. Pat. No.2,710,765),Rice (U.S. Pat. No.2,654,626), Sonnenberg

(U.S. Pat. No.2,435,473), Loos, etal. (U.S. Pat. No. 2,230,498), Mayeda, etal. (U.S. Pat No. 2,028,680), McDowell (U.S. Pat. No. 1,888,929) and Theriot (U.S. Pat. No. 1,706,332). These devices are complex and difficult to operate. The devices often contain numerous parts that become worn and damaged from the soil and debris. There remains a need for a low cost, simply built, reliable, and easy to use clamshell post hole digger. Brief Summary of the Invention

One objective of the present invention is to provide an improved clamshell post hole digger that enables the user to dig essentially constant diameter holes.

Advantageously, the present invention enables the user to use either abduction or adduction to dig deeper post holes without having to increase the diameter of the hole opening as the depth of the hole increases.

The post hole digger of the present invention utilizes a unique cross-handled design which enables the user to close the blades of the post hole digger without having the handles wider than the diameter of the top of the hole. In a specific embodiment, the present invention comprises the following components, two sharpened shovel blades, two hinge brackets, and two elongated handles. Preferably, on the hinge brackets there are an offset handle mounting plate, shovel blade mounting plate, and an axial pivot point, where the offset handle mounting plate and the shovel blade mounting plate are on opposite sides of the axial pivot point. The elongated handles are secured to the offset mounting plates on the hinge brackets.

The shovel blades are secured to the shovel blade mounting plate. The hinge brackets are secured together at the axial pivot point with the shovel blades opposing each other. In a preferred embodiment the shovel blades are made of stainless steel.

The offset configuration allows the elongated handles to be pushed or pulled towards each other and cross without coming into contact. Through this crossing the shovel blades close and the elongated handles stay within the diameter of the hole opening. This enables the user to dig a deeper constant diameter post hole.

A further objective of the present invention is to decrease the user's fatigue. The user can change from abduction to adduction and back to abduction by changing the position of the hands on the elongated handles. The switching from abduction to adduction allows the user to use different muscles and decrease fatigue.

A further aspect of the present invention pertains to markings on one, or both, of the elongated handles which show the depth of the hole. By having ruled handles, the user can easily dig a hole of a desired depth. Thus, one aspect of the present invention is a cross-handled post hole digger with ruled handles. The ruled handles of the present invention can also be used with a standard post hole digger. Other objectives of the present invention are to provide a low cost, simply built, reliable, and easy to use clamshell post hole digger.

Brief Description of the Drawings Figure 1 depicts a full view of a post hole digger of the present invention. Figure 2 depicts the elongated handles crossing, within the diameter of the hole, to close the shovel blades.

Figure 3 depicts ruled elongated handles which indicate the depth of the hole. Figure 4 depicts a full view of the post hole digger of the present invention.

Detailed Disclosure of the Invention The present invention pertains to an improved post hole digger which allows the user to dig deep, uniform diameter post holes without the need to widen the top of the hole. The post hole digger of the present invention utilizes a unique cross-handled design which enables the user to close the blades of the post hole digger without having the handles wider than the diameter of the top of the hole. In addition to allowing the user to dig uniform diameter holes, the unique cross-handled design of the post hole digger of the subject invention makes it possible for the user to use either adduction or abduction in operating the digger. Thus, the user is able to dig more (or deeper) holes without tiring.

A further aspect of the subject invention pertains to depth indicators on one or both of the handles of a post hole digger. These depth indicators are typically in the form of a ruled handles which show the depth of the hole in feet and inches, or in metric units or in other units. The present invention, which is best understood with reference to Figures 1 to 3 , will now be discussed in greater detail. The present invention as shown in Figure 1 is a post hole digger 1. Referring to Figures 1 through 3, a preferred embodiment of the present invention comprises the following components: two elongated handles 2, two hinge brackets 3 each with a offset handle mounting plate 4, a shovel blade mounting plate 5, and a axial pivot point 6, where the offset handle mounting plate 4 and the shovel blade mounting plate 5 are on opposite sides of the axial pivot point 6, and two shovel blades 7 each with a sharpened end 8 and a shovel mounting member 9.

In a specific embodiment the elongated handle 2 is about 4 feet to 6 feet in length with a diameter of approximately % inch to about 2 inches. Most preferably the handles are about 1 inch to 1.25 inches. The elongated handles 2 are mounted to the offset handle mounting plate 4 on the hinge brackets 3. The elongated handles 2 are mounted to the offset handle mount plates 4 such that the elongated handles 4 are offset about 3 inches to 5 inches from each other. Most preferably the offset between the elongated handles is about 3.5 inches to 4 inches in length. The shovel blades 7 are mounted to the hinge brackets 3 by mounting the shovel mounting member 9 to the shovel blade mounting plate 5. The hinge brackets 3 are attached together by a pivot pin 10 at the axial pivot point 6 with the shovel blades 7 opposing each other. By moving the elongated handles 2 towards and away from each other, about the axial pivot point 6, causes the shovel blades 7 to close and open. In a preferred embodiment, the elongated handles 4 are substantially straight.

Substantially straight is defined as meaning when a user grips the elongated handles 4 and thrust the post hole digger 1 into the ground, a majority of the applied downward force is translated linearly through the elongated handle 4 into the shovel blades 7.

The precise location of the axial pivot point can be moved up or down to achieve the desired blade closing characteristics. A person skilled in the art, having the benefit of the instant disclosure would appreciate that by moving the pivot point away from the tips of the blades, it is possible to enhance the closure of the blades. This embodiment would be appropriate in, for example, sandy soil where full closure of the blades is desirable. On the other hand, a lower axial pivot point (closer to the tips of the blade) could be utilized in firm soils where complete closure of the blade tips is not critical. In one embodiment, the post hole digger is provided with multiple pivot point placements from which the user can choose the appropriate pivot point for a particular use. This can be accomplished by, for example, moving the pivot pin to one of the alternate axial pivot point placement locations. To operate the post hole digger 1, the user grasps and holds the elongated handles

2 parallel to each other. The user then thrusts the sharpened ends 8 of the shovel blades 7 into the ground. As shown in Figure 2, by moving the elongated handles 2 towards each other, crossing without coming into contact, about the axial pivot point 6 the shovel blades 7 close and grip the soil. The user lifts the post hole digger 1 out of the hole while maintaining pressure on the elongated handles 2. Once the post hole digger 1 has been removed from the hole, the user positions the clam shell post hole digger 1 and moves the elongated handles 2 away from each other, uncrossing, to open the shovel blades 7 and release the soil.

When moving the elongated handles 2 the user can change from abduction to adduction and back to abduction by changing the position of the hands. The switching from abduction to adduction allows the user to use different muscles and decrease fatigue. The cross-handled design of the present invention allows the user to close the blades to grasp soil using a motion wherein the user's arms and hands are in front of the body in a powerful position. This is in contrast to previous post hole diggers which required the user to extend his arms widely in order to grasp the soil. The user repeats this process until the hole has reached the desired depth.

In one embodiment one or both of the elongated handles 2 are ruled 11 to indicate the depth of the hole. This embodiment is shown in Figure 3. The ruling may be in inches and/or metric. The ruling embodiment of the present invention can be used with a standard post hole digger in addition to the cross handled digger described herein. In another embodiment the elongated handles 2 can have the ability to increase in length, to allow for the digging of deeper holes. The increase in the length of the elongated handles can be accomplished by different means including, but not limited, to the attaching of extensions to the elongated handles and designing the elongated handles with the ability to telescope, to increase and decrease in length. The elongated handles 2 can be tapered having a larger diameter at the top and tapering to a smaller diameter at the base. The larger diameter at the top of the elongated handles 2 allows the user to better grip the elongated handles 2 and decrease fatigue. Alternatively, the handles may taper with the smaller diameter at the top. The top of the elongated handles 2 can be fitted with grips to allow the user to better grip the elongated handles 2. The post hole digger 1 can be made out of any material that is suitable for outdoor use. In a preferred embodiment, the post hole digger of the present invention is made of a material which is durable, substantially non-corroding and light weight. Examples of such materials include, but are not limited to, aluminum, stainless steel, fiberglass, wood, and composite materials. Thus, the present invention post hole digger 1 is low cost, simply built, reliable, and easy to use. In a preferred embodiment, the blades of the post hole digger are made from high carbon steel. The material for connecting the blades to the handles may be, for example, CQMS milled steel.

The materials and dimensions for the preferred embodiments are typically as described herein. It should be understood and readily apparent that there exists a wide latitude in the exact dimensions of the present invention, and the physical dimensions can be readily altered to suit the need of the task. The foregoing is considered as illustrative only of the principles of the present invention. It would be apparent to those skilled in the art, having the benefit of the instant disclosure, that many changes and substitutions can be made to the preferred embodiment without departing from the spirit and scope of the present invention.

It should be understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application and the scope of the appended claims.

Claims

Claims 1. A post hole digger comprising two shovel blades and two elongated handles each of which is operatively attached to one of said shovel blades wherein said elongated handles extend parallel to each other when said shovel blades are open and said elongated handles cross without coming into contact with each other when said shovel blades are closed.

2. The post hole digger, according to claim 1 , wherein said elongated handles and said shovel blades are mounted to hinged brackets which are joined together at an axial pivot point with said shovel blades opposing each other such that said elongated handles can move towards each other and cross without coming into contact with each other to close said shovel blades.

3. The post hole digger, according to claim 2, wherein said post hole digger further comprises a means for adjusting said axial pivot point, such that said axial pivot point can be adjusted closer to or away from the sharpen ends of said shovel blades.

4. The post hole digger, according to claim 1 , wherein said elongated handles and said shovel blades are secured together using hinge brackets which contain an offset handle mounting plate, a shovel blade mounting plate, and an axial pivot point and wherein said offset handle mounting plate and said shovel blade mounting plate are on opposite sides of said axial pivot point.

5. The post hole digger according to claim 4, wherein said elongated handles are mounted to said offset handle mounting plate, such that said elongated handle are offset 3 inches to 5 inches.

6. The post hole digger, according to claim 1, wherein said elongated handles are substantially straight.

7. The post hole digger, according to claiml , wherein said elongated handle are 4ft to 6ft in length.

8. The post hole digger, according to claim 1 , wherein said elongated handle are 3/4 inch to 2 inches in diameter.

9. The elongated handles, according to claim 8, wherein said elongated handles are linch to 1.25 inches in diameter.

10. Said post hole digger, according to claim 1 , wherein said elongated handles are ruled to indicate the depth of said hole.

11. The post hole digger, according to claim 1 , wherein said elongated handles are tapered.

12. The elongated handles, according to claim 11 , wherein the diameter of a top end of said elongated handles is larger then the diameter of a bottom end of said elongated handles.

13. The elongated handles according to claim 11, wherein the diameter of a bottom end of said elongated handles is larger then the diameter of a top end of said elongated handles.

14. The post hole digger, according to claim 1 , wherein said elongated handles are fitted with grips about a top end.

15. The post hole digger, according to claim 1, wherein said elongated handles have a means for allowing changes in the length of said elongated handles.

16. The post hole digger, according to claim 1, wherein said elongated handles are made of a durable, substantially non-corroding, and light weight material.

17. The post hole digger according to claim 16, wherein said elongated handles are made from a material selected from the group consisting of aluminum, stainless steel, fiberglass, wood, and composite materials.

18. A post hole digger comprising two shovel blades, wherein each of sad shovel blade has a hinge bracket and an elongated handle operatively attached thereto, wherein said elongated handles are straight and extend parallel to each other when said shovel blades are open; wherein said hinge brackets are joined together at an axial pivot point, with said shovel blades opposing each other such that said elongated handles are offset 3 to 5 inches, to allow said elongated handles to move towards each other and cross to close said shovel blades, such that said handles have sufficient clearance between them as they cross so that the hands of a person operating said post hole digger, when placing one hand on each of said elongated handle, will pass without the hands contacting to obstruct the movement of said elongated handles.

19. A method for digging constant diameter post holes by utilizing a post hole digger comprising elongated handles attached to shovel blades, wherein said elongated handles extend parallel to each other when said shovel blades are open and cross without coming into contact with each other when said shovel blades are closed, comprising the steps of: a) grasping and holding said elongated handles parallel to each other and thrusting the sharpened ends of said shovel blades into the ground, b) moving said elongated handles toward each other, eventually crossing without coming into contact, thereby closing said shovel blades and gripping the soil, and c) lifting said post hole digger out of said hole while maintaining pressure on the elongated handles, positioning then moving said elongated handles away from each other, uncrossing said elongated handles, to open said shovel blades and release the soil.