WO2008151365A1

WO2008151365A1 - Manual digging tool

Info

Publication number: WO2008151365A1
Application number: PCT/AU2008/000836
Authority: WO
Inventors: Glenn Raymond Dalby; Robert Andrew Dickson
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-06-12
Filing date: 2008-06-12
Publication date: 2008-12-18
Anticipated expiration: 2009-12-12
Also published as: AU2008261605A1

Abstract

A digging tool having an elongated, transversely flat blade projecting from an elongated handle with a fulcrum member on one side of the blade, and an elongated plate normal to the one side of the blade projecting from the fulcrum member towards the free end of the blade.

Description

MANUAL DIGGING TOOL

FIELD OF THE INVENTION

The present invention relates to a manually-operable digging tool, for example, a manual post-hole digger.

BACKGROUND OF THE INVENTION

Manual post-hole diggers generally consist of a straight bar having a chisel point at one end and a tamper at the other end. In use, the chisel is driven into the ground to cut a hole that is deepened by pushing or pulling the bar so that it pivots against the top edge of the hole. The bar thus acts as a first-class lever with an effort arm above the ground, resistance in the bottom of the hole, and a fulcrum located at the top edge of the hole. The mechanical advantage of the lever is decreased as the hole is deepened because the resistance distance (i.e., the distance between the resistance at the bottom of the hole and the fulcrum at the top edge of the hole) is increased.

It would be desirable to provide a simple and robust manually leverable digging tool with a substantially constant mechanical advantage that is independent of digging depth.

SUMMARY OF THE INVENTION

According to the present invention, there is provided a digging tool having an elongated, transversely flat blade projecting from an elongated handle with a fulcrum member on one side of the blade, and an elongated plate normal to the one side of the blade projecting from the fulcrum member towards the free end of the blade.

The fulcrum member can have an inverted V-shape in longitudinal cross section so that in use the apex of the fulcrum member provides a fulcrum. A reinforcing web can extend normal to the one side of the blade within the valley of the fulcrum member so as to hold the apex thereof spaced apart from the blade. The reinforcing web can be a flat triangular plate.

The blade, handle, fulcrum member, plate, and reinforcing web can be integrally secured together by welding or brazing to form a rigid, solid digging tool having a tool head with high structural strength.

The plate and the reinforcing web can extend longitudinally along the longitudinal centreline of the blade.

The fulcrum member can be a transversely flat flange bent into an inverted curved V-shape in longitudinal cross section.

The free end of the blade can be sharpened or bevelled.

The free end of the plate can be rounded or inclined away from the free end of the blade. The free end of the plate can be sharpened or bevelled.

The blade can be slightly curved longitudinally, and the fulcrum member and the plate can be provided on the convex side of the blade.

The handle can be a straight hexagonal bar.

A tamper can be provided on the free end of the handle.

The present invention also provides a method of digging a hole using the above digging tool. BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be further described by way of example only with reference to the accompanying drawings, in which: Figures 1 and 2 are perspective views of a digging tool of one embodiment of the invention;

Figures 3 and 4 are perspective detail views of the tool head of the digging tool; and

Figures 5 and 6 are side views of the digging tool in use in holes having different depths.

DETAILED DESCRIPTION

Referring to Figures 1 to 4, one embodiment of a digging tool 10 has an elongated, transversely flat blade 12 projecting from an elongated handle 14 with a fulcrum member 16 on one side of the blade 12, and an elongated plate 18 normal to the one side of the blade 12 projecting from the fulcrum member 16 towards the free end of the blade 12.

The handle 14 is, for example, a straight hexagonal bar. A tamper 20 is provided on the upper free end of the handle 14. The blade 12 is slightly curved longitudinally to allow its free end to penetrate the ground generally vertically when the handle 14 is inclined slightly away from the vertical relative to the ground. The fulcrum member 12 and the plate 18 are provided on the convex side of the blade 12. The free end of the blade 12 is sharpened or bevelled to aid ground penetration.

The fulcrum member 16 has an inverted V-shape in longitudinal cross section so that in use the apex 22 of the fulcrum member 16 provides a fulcrum. The fulcrum member 16 is a transversely flat flange bent into an inverted curved V-shape in longitudinal cross section. The transverse extent of the fulcrum member 16 is slightly less than the transverse extent of the blade 12. - A -

A reinforcing web 24 extends normal to the one side of the blade 12 within the valley of the fulcrum member 16 so as to securely hold and maintain the apex 22 thereof spaced apart from the blade 12. The reinforcing web 22 is, for example, a flat triangular plate that extends between the outer surface of the blade 12 and the inner surface of the fulcrum member 16. The reinforcing web 22 resists deformation and separation of the fulcrum member 16 so as to maintain the apex 22 as a fulcrum even after repeated use of the digging tool 10 in dry, hardened ground or soil. The plate 18 and the reinforcing web 22 extend longitudinally along the longitudinal centreline of the blade 12.

The free end of the plate 18 is rounded or inclined away from the free end of the blade 12. The free end of the plate 18 is sharpened or bevelled. The plate 18 reinforces the blade 12, and acts as a lead-in to facilitate entry of the fulcrum member 16 into the ground. The lead-in provided by the plate 18 stops the full force of ground impact from being directly transmitted to the fulcrum member 16. As such, the plate 18 aids retention of the fulcrum member 16 on the blade 12 even after repeated use of the digging tool 10 in dry, hardened ground or soil.

The blade 12, handle 14, fulcrum member 16, plate 18, and reinforcing web 22 are formed, for example in metal, and are integrally secured together, for example by welding or brazing, to provide a rigid, solid digging tool 10 having a tool head with high structural strength that is sufficient to withstand repeated use of the digging tool 10 in dry, hardened ground or soil. Other equivalent materials and constructions may also be used.

Referring to Figure 5, the digging tool 10 is used by driving the blade 12 into the ground to open a hole 26, for example, a post-hole. As illustrated by Figure 6, the hole 26 is then deepened by levering the handle 10 against the side of the hole 26 about the fulcrum provided by the apex 22 of the fulcrum member 16. As is clear from comparing Figures 5 and 6, the resistance distance of the digging tool 10 (i.e., the distance between the resistance of the free end of the blade 12 at the bottom of the hole 26 and the apex 22 of the fulcrum member 16 against the side of the hole 26) remains substantially constant as the hole 26 is deepened. The mechanical advantage of the digging tool 10 therefore advantageously remains substantially constant independent of the depth of the hole.

Embodiments of the invention therefore provide a simple and robust leverable digging tool with a substantially constant mechanical advantage that is independent of digging depth.

The embodiments have been described by way of example only and modifications are possible within the scope of the claims which follow.

Claims

1. A digging tool having an elongated, transversely flat blade projecting from an elongated handle with a fulcrum member on one side of the blade, and an elongated plate normal to the one side of the blade projecting from the fulcrum member towards the free end of the blade.

2. A digging tool according to claim 1, wherein the fulcrum member has an inverted V-shape in longitudinal cross section so that in use the apex of the fulcrum member provides a fulcrum.

3. A digging tool according to claim 1 or 2, further including a reinforcing web that extends normal to the one side of the blade within the valley of the fulcrum member so as to hold the apex thereof spaced apart from the blade.

4. A digging tool according to claim 3, wherein the reinforcing web is a flat triangular plate.

5. A digging tool according to claim 3 or 4, wherein the blade, handle, fulcrum member, plate, and reinforcing web are integrally secured together by welding or brazing to form a rigid, solid digging tool having a tool head with high structural strength.

6. A digging tool according to any preceding claim, wherein the plate and the reinforcing web extend longitudinally along the longitudinal centreline of the blade.

7. A digging tool according to any preceding claim, wherein the fulcrum member is a transversely flat flange bent into an inverted curved V-shape in longitudinal cross section.

8. A digging tool according to any preceding claim, wherein the free end of the blade is sharpened or bevelled.

9. A digging tool according to any preceding claim, wherein the free end of the plate is rounded or inclined away from the free end of the blade.

10. A digging tool according to any preceding claim, wherein the free end of the plate is sharpened or bevelled.

11. A digging tool according to any preceding claim, wherein the blade is slightly curved longitudinally, and the fulcrum member and the plate are provided on the convex side of the blade.

12. A digging tool according to any preceding claim, wherein the handle is a straight hexagonal bar.

13. A digging tool according to any preceding claim, further including a tamper provided on the free end of the handle.

14. A method of digging a hole using a digging tool according to any one of claims 1 to 13.