AU2017204418A1

AU2017204418A1 - Strainer

Info

Publication number: AU2017204418A1
Application number: AU2017204418A
Authority: AU
Inventors: Lawrence O'toole
Original assignee: Infrabuild Wire Pty Ltd
Current assignee: Infrabuild Wire Pty Ltd
Priority date: 2016-06-29
Filing date: 2017-06-28
Publication date: 2018-01-18
Anticipated expiration: 2037-06-28
Also published as: AU2017204418C1; AU2017204418B2; AU2022263602A1

Abstract

Disclosed is a wire strainer grab 202 for clamping a wire 204. The grab 202 may form part of a wire strainer. The grab 202 comprises a body 214, a cam 216 mounted to the body 214, and an anvil 218. The anvil 218 comprises first 220a 5 and second 220b bearing surfaces that are both generally rounded, and a recessed surface 222 that extends between the bearing surfaces 220a, 220b. Figure 2A. 9220729_1 (GHMatters) P102499.AU.1 gyIL AK rc 2(6 no D.

Description

Technical Field

This disclosure relates to a strainer and strainer grab for straining or tensioning 5 wire. The strainer and strainer grab may have particular, but not exclusive, use in tensioning fence wires for agricultural purposes.

Background Art

Wire fences are generally formed by installing fence posts and then attaching fence wire between the posts. In many cases the fence wire must be tensioned in order to form an effective barrier, and so as not to sag between the posts.

Tensioning may be performed, for example, by bringing two wire ends together under tension and joining them. This tensioning can be performed by hand, but tools are more commonly used, because they allow higher tensioning to be achieved.

One such tool is a strainer that comprises two grabs (which are each adapted to grip a portion of wire), a chain attached to one of the grabs, and a lever arrangement attached to the other grab that can be moved along the chain to move the grabs towards one another.

Such a device relies on the grabs having a strong grip on the wire ends in order to place the wires under tension and to bring them together. Some devices are not capable of consistently achieving this grip, which can result in slipping of the wires. Other devices achieve this grip, but the large gripping forces and high tension (in the wires) can result in the wires being cut, deformed or severely weakened. This can lead to injury of a user of the device, or can lead to a weak

5 fence construction.

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It is to be understood that, if any prior art is referred to herein, such reference does not constitute an admission that the prior art forms a part of the common general knowledge in the art, in Australia or any other country.

Summary

Disclosed is a wire strainer grab for clamping a wire. The grab comprises a body, a cam mounted to the body, and an anvil. The anvil comprises first and second bearing surfaces. At least one of the bearing surfaces is generally rounded. The anvil further comprises a recessed surface, between the bearing surfaces, for receipt of the wire such that a portion of the wire can be clamped against the recessed surface by the cam. The bearing surfaces support the wire either side of the clamped portion.

Because at least one of the bearing surfaces is rounded, the load passing between the anvil and the wire is able to be better distributed across that bearing surface. Such loads can increase during use as the wire is tensioned; the distribution of the load can help to prevent cutting, deformation or weakening of the wire where it comes into contact with the at least one bearing surface.

The phrase ‘generally rounded’ encompasses faceted surfaces that are made up of a plurality of flat faces and that, due to their size and orientation (i.e. angles between the faces being minimal), result in an overall surface that has a rounded

0 appearance, and that provides the distribution of load discussed above. The phrase ‘generally rounded’ is also not intended to be interpreted as being restricted to a part-circular surface.

In one embodiment both of the first and second bearing surfaces may be rounded. This may provide enhanced protection against cutting, deformation or weakening

5 of a clamped wire.

In one embodiment the clamped portion of wire may be spaced from the portions of wire supported on the bearing surfaces. The spacing of the clamped portion of the wire from the portions supported on the bearing surfaces may allow a smooth

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2017204418 28 Jun 2017 transition (in the wire) between these two supported portions of wire. That is, it may avoid sharp changes in the direction of the wire, which may otherwise create stress concentrations and result in weakening of the wire.

In one embodiment the recessed surface and bearing surfaces may be continuous 5 so as to form a generally smooth surface of the anvil. Again, this may ensure smooth transition of the wire between the clamped portion and the portion supported on the bearing surfaces. It may avoid any sharp edges or comers that could damage (e.g. cut or deform) or weaken the wire.

In one embodiment the recessed surface may extend between the bearing surfaces along a generally concave profile. The concave profile may have a generally constant radius.

In one embodiment the recessed surface may comprise a generally V-shaped cross-section. Alternatively, in one embodiment the recessed surface may comprise a generally semi-circular shaped cross-section. The semi-circular or V15 shaped cross-sections may help to centre the wire across the width of the recessed surface. This may help to avoid the wire being dislodged from the recessed surface.

In one embodiment the cam may be pivotally mounted to a body of the strainer grab. The cam may, for example, be mounted to the body by way of a pin

0 extending through the cam and the body.

In one embodiment a clamping edge of the cam may comprise a non-constant radius, which may accommodate clamping of a plurality of wire diameters against the recessed surface. A constant radius cam could result in pinching of the wire when it is not within a narrow range of suitable diameters. The pivot point of the

5 cam may be positioned so as to facilitate this accommodation of wires of various diameters. As the cam is rotated, the gap between the non-constant radius clamping edge and the recessed surface can generally be smallest at a central portion of the recessed surface. This may help to ensure that the wire is not pinched at an edge of the recessed surface.

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In one embodiment the anvil may be secured to the body of the grab. The anvil may be permanently or temporarily secured to the body. The anvil may also be integral with the body. The body may comprise an enlarged portion to accommodate the anvil.

In one embodiment the recessed surface may form the base of a recess defined between the anvil and the body portion. Sidewalls of the recess may be defined by opposing surfaces of the body and anvil.

In one embodiment the anvil may be secured to the body portion by two fasteners, received through aligned holes in the anvil and body portion. The fasteners may be in the form of bolt and nut arrangements, screws, rivets, etc.

In one embodiment the bearing surfaces may be generally concentric with respect to the holes in the anvil. That is, the bearing surfaces may be defined by portions of the anvil that are enlarged to accommodate the holes.

Also disclosed is a wire strainer comprising first and second wire strainer grabs. 15 At least one of the first and second grabs is as defined above. The wire strainer further comprises a chain attached to the first wire strainer grab, and a lever mechanism attached to the second wire strainer grab. The lever mechanism comprises two hook members for hooking into the links of the chain, and a lever arm able to be moved to hook the hook members into the chain links in an

0 alternate manner, so as to move the lever mechanism along the chain.

Brief Description of the Drawings

Embodiments will now be described by way of example only, with reference to the accompanying drawings in which:

Figures 1A and IB show a prior art wire strainer; and

Figures 2A and 2B show an embodiment of the wire strainer disclosed herein.

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Detailed Description

In the following detailed description, reference is made to accompanying drawings which form a part of the detailed description. The illustrative embodiments described in the detailed description, depicted in the drawings and defined in the claims, are not intended to be limiting. Other embodiments may be utilised and other changes may be made without departing from the spirit or scope of the subject matter presented. It will be readily understood that the aspects of the present disclosure, as generally described herein and illustrated in the drawings can be arranged, substituted, combined, separated and designed in a wide variety of different configurations, all of which are contemplated in this disclosure.

Referring to Figure 1, a prior art wire strainer 100 is shown. The strainer 100 comprises first 102a and second grabs 102b, both being adapted so as to be able to clamp a portion of fence wire 104. The first grab 102a is attached or coupled to a chain 106, and the second grab 102b is coupled to a lever mechanism 108. The lever mechanism 108 comprises a lever 110 and biased hook members 112 that are configured to hook into links of the chain 106. In use, the lever 110 may be moved (i.e. levered) back and forth to move the hook members 112, which alternately hook into and move along the chain 106 such that the first 102a and

0 second 102b grabs (and the portions of wire 106 they are clamping) are caused to move towards one another. This enables the wire 104 to be progressively tensioned.

Figures 2A and 2B show a wire strainer grab 202 for clamping a wire 204. The grab 202 may form part of a wire strainer similar to that shown in Figures 1A and

5 IB. Hence, features that are generally consistent between the wire strainer shown in Figures 1A and IB and the grab shown in Figures 2A and 2B have been accorded similar reference numerals. The grab 202 comprises a body 214, a cam 216 mounted to the body 214, and an anvil 218. The anvil 218 comprises first

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220a and second 220b bearing surfaces that are both generally rounded, and a recessed surface 222 that extends between the bearing surfaces 220a, 220b.

In use, the recessed surface 222 can receive a wire 204 such that a portion 224 of the wire 204 can be clamped against the recessed surface 222 by the cam 216.

Although not apparent from the figures, the recessed surface 222 comprises a generally V-shaped cross section (i.e. the cross-section being generally in the same plane as the cam). This centres the wire 204 when clamped against the recessed surface 222 and helps to prevent dislodgement of the wire from the recessed surface 222 as it is being clamped (i.e. it is guided towards the bottom of the V). When clamped in this way, the bearing surfaces 220a, 220b support the wire 204 at either side of the clamped portion 224, and the clamped portion 224 of wire 204 is generally spaced from the portions 226 of wire 204 that are supported by the bearing surfaces 220a, 220b. Because the bearing surfaces 220a, 220b are rounded, the force passing between the anvil 218 and the wire 204 is distributed across the bearing surfaces 220a, 220b. Such forces increase during use as the wire 204 is tensioned, and the resultant distribution of the load can help to prevent cutting, deformation or weakening of the wire 204 where it comes into contact with the bearing surfaces 220a, 220b. This weakening, deformation or cutting may also be somewhat reduced by the spacing of the clamped portion 224 of wire

0 204 from the portions 226 that are supported by the bearing surfaces 220a, 220b, because the spacing allows smooth transition of the wire 204 between these portions 224, 226.

The recessed surface 222 and bearing surfaces 220a, 220b are formed so as to be generally continuous. This provides a generally smooth upper surface of the anvil

5 218. In particular, the recessed surface 222 of the illustrated embodiment extends between the bearing surfaces 220a, 220b along a generally concave profile.

The anvil 218 is formed of a steel plate structure that is removably mounted to the body 214 of the grab 202 (which is also in the form of a steel plate structure) by two fasteners 228 extending through holes 230 that extend through the anvil 218

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2017204418 28 Jun 2017 and the body 214 of the grab 202. The anvil could instead be printed, cast or machined as a single piece.

An edge of the body 214 is enlarged to accommodate the mounting of the anvil 218 thereto. The recessed surface 222 forms a base of a recess 232 that is defined between the anvil 218 and the body 214. That is, the recessed surface 222 defines a ledge extending from a face of the anvil 218 and, when the anvil 218 is mounted to the body 214, this ledge (i.e. the recessed surface 222) is sandwiched between the face of the anvil 218 and face of the body 214 so as to define the recess 232.

The anvil 218 is shaped so as to be enlarged around the holes 230. This 10 strengthens the anvil 218 in these regions and also forms the bearing surfaces

220a, 220b, which are defined by edge surfaces of the enlarged portions (i.e. such that the bearing surfaces 220a, 220b are generally concentric with the holes 230).

The open end of the recess 232 is generally aligned with the cam 216, which is pivotally mounted to the body 216 so that it can be pivoted into a clamping position in the recess 232, where it can clamp the wire 204 against the recessed surface 222. A clamping edge 234 of the cam (i.e. the edge of the cam 216 that clamps the wire 204 against the recessed surface 22) is curved. The curvature of the clamping edge 234 is formed such that it does not have a constant radius. This, in combination with the location of the pivot point of the cam 216, allows the grab

0 202 to clamp wires of various diameters, while ensuring that the clamping point of the various wires is located generally centrally along the profile of the recessed surface 222. That is, the non-constant radius means that, as the clamping edge 234 is rotated towards the recessed surface 222, the point where the gap is smallest between these features is generally central to the recessed surface 222.

5 This is not the case with a constant-radius clamping edge, which can result in pinching of a clamped wire.

The cam 216 and the body 214 are each pivotally connected to respective arm members 236, which are in turn pivotally connected to one another such that the cam 216, body 214 and arm members 236 form a parallelogram arrangement.

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This arrangement is biased such that the cam 216 and the recessed surface 222 are urged towards one another (i.e. in the clamping position). In use, a user may compress the parallelogram arrangement to move the cam 216/body 214 connection towards the arm member 236/arm member 236 connection. This action causes the cam 216 to move away from the recessed surface 222, which forms a gap for receipt of a wire 204 to be clamped. Upon release of the arrangement, the parallelogram expands (due to it being biased) to its natural position and the cam 216 clamps the wire against the recessed surface 222. Such an arrangement means that, in use, tension on the wire 204 tends to urge the cam

216 and recessed surface 222 towards one another such that the grip on the wire

204 increases.

Variations and modifications may be made to the parts previously described without departing from the spirit or ambit of the disclosure.

For example the recess may take any shape suitable for receipt, and clamping of, a 15 wire. The shape and size of the recess may be determined based on the shape and size of the wire it is intended to clamp.

The anvil may be permanently (e.g. integrally) or temporarily connected to the body of the grab. The anvil may not enclose the recessed surface, and instead, the recessed surface may form an exposed upper surface of the anvil. The anvil may be a flat plate and the upper edge of the flat plate may define the recessed surface and the bearing surfaces.

The anvil may be formed of metal (e.g. steel) or plastic, and may have a surface coating so as to be resistant to corrosion, wear, etc. The anvil may be formed by metal printing, machining, casting, etc.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word “comprise” or variations such as “comprises” or “comprising” is used in an inclusive sense, i.e. to specify the presence of the

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2017204418 28 Jun 2017 stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

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Claims

Claims

1. A wire strainer grab for clamping a wire comprising: a body;

a cam mounted to the body; and an anvil comprising:

first and second bearing surfaces, at least one of the bearing surfaces being generally rounded; and a recessed surface, between the bearing surfaces, for receipt of the wire such that a portion of the wire can be clamped against the recessed surface by the cam, the bearing surfaces supporting the wire either side of the clamped portion.
2. A wire strainer grab as claimed in claim 1, wherein the first and second bearing surfaces are rounded.
3. A wire strainer grab as claimed in claim 1 or 2 wherein the clamped portion of wire is spaced from the portions of wire supported on the bearing surfaces.
4. A wire strainer grab as claimed in any one of the preceding claims wherein the recessed surface and bearing surfaces are continuous so as to form a generally smooth surface of the anvil.
5. A wire strainer grab as claimed in any one of the preceding claims wherein the recessed surface extends between the bearing surfaces along a generally concave profile.
6. A wire strainer grab as claimed in claim 5 wherein the concave profile has a generally constant radius.

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7. A wire strainer grab as claimed in any one of the preceding claims wherein the recessed surface comprises a generally V-shaped cross-section.
8. A wire strainer grab as claimed in any one of claims 1 to 6 wherein the recessed surface comprises a generally semi-circular shaped cross-section.
9. A wire strainer grab as claimed in any one of the preceding claims wherein the cam is pivotally mounted to a body of the strainer grab.
10. A wire strainer grab as claimed in claim 9 wherein a clamping edge of the cam comprises a non-constant radius to accommodate clamping of a plurality of wire diameters against the recessed surface.
11. A wire strainer grab as claimed in claim 9 or 10 wherein the anvil is secured to the body of the grab.
12. A wire strainer grab as claimed in claim 11 wherein the body comprises an enlarged portion to accommodate the anvil.
13. A wire strainer grab as claimed in claim 11 or 12, wherein the recessed surface forms the base of a recess defined between the anvil and the body.
14. A wire strainer grab as claimed in any one of claims 11 to 13 wherein the anvil is integral with the body portion.
15. A wire strainer grab as claimed in any one of claims 11 to 13 wherein the anvil is secured to the body portion by two fasteners, received through aligned holes in the anvil and body portion.
16. A wire strainer grab as claimed in claim 15 wherein the bearing surfaces are generally concentric with respect to the holes in the anvil.
17. A wire strainer comprising:

first and second wire strainer grabs, at least one of the first and second grabs being as claimed in any one of the preceding claims;

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2017204418 28 Jun 2017 a chain attached to the first wire strainer grab; and a lever mechanism attached to the second wire strainer grab, the lever mechanism comprising:

two hook members for hooking into the links of the chain; and a lever arm able to be moved to hook the hook members into the chain links in an alternate manner, so as to move the lever mechanism along the chain.

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