AU621899B2

AU621899B2 - Lifting apparatus

Info

Publication number: AU621899B2
Application number: AU36167/89A
Authority: AU
Inventors: Paul Robert Browne
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-06-10
Filing date: 1989-06-09
Publication date: 1992-03-26
Anticipated expiration: 2009-06-09
Also published as: AU3616789A

Description

PROVISIONAL SPEC IFICAfjb 5 NTS ACT 1952 NO. PI 8734 COMPLETE SPECIFICATION

(ORIGINAL)

FOR OFFICE USE: Clas2i8t9 Application Number.

ILodged: Complete Specification Lodged: Accepted: Published: Priority: Related Art: a I Cj S e-) 4,a~rn of Applicant(s): 1 0;0 Add~ess of Applicant(s): PAUL ROBERT BROWNE Yargalain Calingari

CALINGARI

Wongon Hills Road Western Australia, Australia.

00430 0 0 43 0 0 00 Aetual 0 lnventor(s): PAUL ROBERT BROWNE 0 00 0 0 *00 A44rje. s for Service: 0 mr0Fr-(-1 HfP4 Co PIF-Z Kelvin- Lord-.& co-a-, 4-Dour-o P-1ace-,

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Western-Austral-ia-- 6 0 0 5 Complete Specification for the invention entitled: "LIFTING APPARATUS" The following statement is a full description of this invention, including the best method of performing it known to me/ us 2 -2- The present invention relates to a post puller, particularly envisaged, for use in the removal of "star" picket type posts and the like embedded in the ground.

"Star" pickets are a type of fencing picket commonly used in agriculture for the support of wire fencing.

Previously, to remove a picket various apparatus have been used. However, most of the apparatus of the prior art have resulted in either the picket being bent or buckled or distorted. The pickets are bent due to pulling force being applied along an axis not collinear with an axis of the picket thus providing a bending moment and/or clamping devices that clamp byr applying an unbalanced bending moment to the picket.

A bending moment then distorts the picket. Apertures are provided in the pickets for attachment of wire fencing. Other prior art systems have relied upon attachment to these apertures and the picket is embedded securely in the ground, this has resulted in elongation of the apertures and bending of the picket at the aperture and consequent degradation of the performance of the picket. Bending can occur at ground level or at the location of connection of the picket remover.

It is an object of the present invention to provide a post puller to avoid the aforesaid problems of the prior art.

In accordance with the present invention there is provided a post puller for pulling a post from the ground, said post puller comprising: a first elongate member having first and second ends and provided with a first clamping surface; a second elongate member having first and second ends and provided with a second clamping surface, said first and second elongate members connected together by a pivot means and juxtaposed in such a manner that said respective first ends can overlap and said first and second clamping surfaces cooperate to form a clamp in which said post can be clamped by mutual pivoting of said first and second elongate members in opposite directions about said pivot means, said pivot means disposed to one side of said clamp; p,,LL whereby, in use, applying a lifting force at /J locations proximate respective second ends of said first and 3 second elongate members causes pivoting of said first and second clamping surfaces in opposite directions relative to said pivot means for clamping said post therebetween and generates a clamping force and a pulling force, said clamping force applied transversely to a longitudinal axis of the post and, said pulling force acting substantially coaxially with said longitudinal axis of the post, wherein said clamping force exceeds said pulling force so that the post can be pulled out of the ground without slipping between said first and second clamping surfaces.

The apparatus of the present invention will henceforth be described with reference to star pickets although it is to be understood that it is of general applicability.

The apparatus of the present invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is an upper perspective view of a post puller in accordance with the present invention; Figure 2 is a lower perspective view of the post puller of Figure 1, shown, in use, attached to a star picket; Figure 3 is a part plan view of the post puller of Figure 1; Figure 4 is a side view of the post puller of Figure S1, shown, in use, attached to a star picket; and, Figure 5 is an upper perspective view of a hand lever for use with the post puller of Figure 1.

Shown in the accompanying drawings is a post puller for removing a star picket P (see Figure 2) from in the ground. The post puller 10 comprises a clamp means 11 having a first elongated member 12 having opposite ends 14 and 16.

The member 12 further comprises a slot 18 formed at the end 14.

Fixed through the slot 18 is a bolt 20 attached to which is one end of a chain 22. The slot 18 and the bolt 20 constitute a first post attachment means 23 for applying a pulling force to the first elongated member 12.

At the other end 16 is located a cut out 24 extending A JP.i therethrough. The cut out 24 is composed of rectangular 4slot 26 extending from the end 16 towards the end 14.

Adjacent an end 28 of the slot 26, intermediate of the length of the member 12 is a narrow slot 30 dimensioned to receive a long longitudinal apertured tang T of the star S 5 picket P as shown in Figures 2 and 4.

Near the end 16 there is a hole 32 extending transversely through the member 12 as shown in Figure 3. The hole 32 receives a bolt 34 or pin or the like.

The clamp'means 11 also comprises a second elongated member 36 having a hole 38 located adjacent an end 40 and extending therethrough. The hole 38 is dimensioned to receive the bolt 34 to pivotally couple the second member 36 into the 1 rectangular slot 26 of the first member 12.

The member 36 has an apertured flange 41 with a bolt 42 to S I I I which is attached another end of the chain 22. The flange 41 and the bolt 42 constitute a second attachment means 44 for applying a pulling force to the second elongated member 36.

Preferably, the distance from the hole 38 to the end 40 is less than the distance from the hole 38 to the flange 41.

This results in a clamping force which is greater than the force pulling the star picket P out of the ground.

"i 'Preferably, the distance from each of the bolts 20 and 42 to the end 28 of the slot 26, that is at a juncture of the slots 26 and 30, is substantially equal. However, it is to be understood that \requality of such distances would still typically result in non bending of the star picket P during removal provided the pulling force is applied to the chain L 22 substantially in line with the axis of the star picket P. Or put another way, provided the pulling force is applied substantially in line with the juncture of the slots 26 and 30. However, it is to be understood that the alignment could deviate slightly without affecting the performance of the post puller 10. The amount of allowable deviation is dependent on the perpendicular distance of the pulling force to the axis of the star picket P, the length of the star picket P that is above the ground and the elastic deformation characteristics of the star picket P.

It has been found that a deviation of about 30mm does not substantially effect operation of the present invention.

It is anticipated that greater deviations could also be allowable. Preferably, the members 12 and 36 can pivot with respect to each other through an angle of more than 100 so as to allow for insertion of the star picket P into the slot Typically, the long apertured tang T of the star picket P is disposed, in use, in the slot 30 but not extending to a closed end 46 of the slot Preferably, the slot 26 comprises two oppositely disposed shoulders 48 which form a clamping surface set at 20 angles to substantially meet with two short longitudinal tangs S of the star picket P.

Preferably, the end 40 of the member 36 forms another clamping surface and is shaped to co-act with the shoulders 48 to grip the star picket P therebetween but prefereably not to grip the star picket P at the juncture of the tangs S.

The hole 38 is located so that the clamping surface will pivot toward the clamping surfaces 48 closer than the B thickness of metal of the star picket P in order to clamp same.

The clamping surface 40 is preferably shaped to achieve transmission of 6 clamping force between the *tA40 and the star picket P as the pulling force is increased. Typically, this is achieved by curving the ie\a40 as shown.

Conveniently, the flange is located intermediate of the length of the member 36 to facilitate striking of an end adjacent the flange 41, with a hammer, to disengage the clamping means 11 from clamped engagement with the star picket P.

Typically, the bolt 34 is made of high tensile steel materials or otherwise large enough to withstand the forces generated.

S Typically, washers 52 are disposed on the bolt 34 between the first and the second elongated members 12 and 35 to avoid slop therebetween and hence to avoid bending of the S 15 bolt 34.

It is envisaged that other forms of attachment means 23 and 44 could be used provided, such as, for example a hole drilled through the members 12 and 36 to receive the shackles in place of the slot 18, bolt 20, flange 41 and the i 20 bolt 42.

In use, the post puller 10 is disposed such that the narrow slot 30 receives the tang T of the star picket P as shown in Figures 2 and 4. Preferably, the slot 18 and the flange 41 are uppermost in this configuration.

A vertical pulling force is then applied to the chain 22 substantially in line with the axis of the star picket P as shown in Figure 4. Since the pulling force is substantially colinear with the axis of the star picket P, bending of the AL picket P is unlikely to occur.

7 Also, the pulling force causes the members 12 and 36 to pivot upwardly about the bolt 34. The members 12 and 36 continue their pivotal motion until the ad40 contacts the picket P and clamps it against the The pulling force is applied until the picket P is removed from the ground. The clamping force increases with the K applied pulling force and, by virtue of the location of the slots 18 and the flange 41 is always larger than the pulling force. It has been found that in the case of difficult extraction, the picket P may become locked to the post puller 10 after removal. The picket P may be subsequently released by striking the member 36 with a hammer or the like adjacent the end Conveniently, the pulling force may be applied by attaching S 15 the chains to the bucket of a front end loader or a three point hydraulic linkage of a tractor or the like.

The post puller 10 of the present invention provides a relatively easy way of removing star pickets P without bending them or elongating their apertures and where the clamping force increases with and remains greater than the pulling force required.

Modifications and variations such as would be apparent to a skilled addressee are deemed within the scope of the present invention. For example, the chain 22 could be replaced by a cable or rope or two pivotally connected rods or metal straps or the like. Also, a stop could be provided to limit rotation of the second elongated member 36 with respect to the first elongated member 12 so as to limit the clamping force placed on the star picket P and to use such further C_ 27 t 4 a t a

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i i 8 force in pulling the star picket P. Further, it is envisaged that, in use, one of the short tangs S could be located in the narrow slct 30 and the long tang T located against one of the shoulders 48. Still further, it is envisaged that a hand operated lever device 54 (such as shown in Figure 5) could be used to provide the pulling force.

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Claims

1. A post puller for pulling a post from the ground, said. post puller comprising: a first elongate member having first and second and provided with a first clamping surface; a second elongate member having f irst and second ends and provided with a second. clamping surface, said first and second elongate members connected together by a pivot means and. juxtaposed in such a manner that said. respective first ends can 1 overlap and said first and. second clamping surfaces cooperate to form a clamp in which said post can be clamped by mutual pivoting of said first and second elongate members in opposite directions about said pivot means, said pivot means disposed to one side of said clamp; 115 locations proximate respective second ends of said first and second elongate members causes pivoting of said first and s econd clamping surfaces in opposite directions relative to said pivot means for clamping said post therebetween and. generates a clamping force and a pulling force, said clamping force applied transversely to a longitudinal axis of the post A and, said pulling force acting substantially coaxially with said longitudinal axis of the post, wherein said clamping force exceeds said pulling force so that the post can be pulled out of the ground without slipping between said first and second clamping surfaces.

2. A post puller according to claim 1, in which said first elongate member is provided. with a cut out in which said. first clamping surface is formed, said. cut out adapted to receive the first end of said. second. elongate member, and. wherein the locations at which said lifting force is applied are substantially equidistant from said first end of said second elongate member and the distance from the first end of said second. elongate member to said pivot means is less than the distance from said pivot means to the location on the C LL~ second elongate member at which said lifting force is applied. S-

3. A post puller according to claim 2, wherein said first and second clamping surfaces, when facing each other, i define a space having a shape which is substantially i complimentary to the cross sectional shape of the post. i 5

4. A post puller according to claim 3, in which the cut i out comprises a rectangular slot adapted to receive the second elongate member and further includes a narrow slot extending from the rectangular slot for receiving a first tang of a star r picket post to be pulled from the ground and the cut out having 1 0 two shoulders formed proximate the juncture of the rectangular slot and the narrow slot, the shoulders forming said first clamping surface against which second and third tangs of the Sstar post can be clamped by said second clamping surface.

A post puller according to any one of the preceding claims wherein the second clamping surface is formed at the first end of the second elongate member.

6. A post puller substantially as herein described with reference to and as illustrated in any one of the accompanying drawings. Dated this 24th day of December 1991. i PAUL ROBERT BROWNE By Its Patent Attorneys: GRIFFITH HACK CO. Fellows Institute of Patent Attorneys of Australia.