AU720531B3 - A device for tensioning wire - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A PETTY PATENT Name of Applicant(s): Address for Service: Invention Title: RICHARD DOUGLAS QUIRK CULLEN CO., Patent Trade Mark Attorneys, 239 George Street, Brisbane, QId. 4000, Australia.

A DEVICE FOR TENSIONING WIRE The following statement is a full description of this invention including the best method of performing it known to me: A DEVICE FOR TENSIONING WIRE The present invention relates to a device for tensioning wire. In particular, the present invention is directed towards a device for use in tensioning fencing wire during construction of a fence.

Wire fences formed from wire tensioned between supporting posts are widely used to fence agricultural land. It is known to use wire tensioning or straining device in the construction and repair of wire fences.

Some tensioning devices form a permanent part of the fence and can link two sections of wire together or wire to an anchor post. When fencing large areas, it is necessary to use a large number of these types of devices, which may be relatively expensive.

Wire tensioning tools which can be used to tension wire prior to joining either two lengths of wire or to attach wire to an anchor post are also known. These tools typically have a pair of clamps for engaging loose ends of wires to be joined. Operation of the tool draws the ends together, thereby tensioning the wire. When the wires have been tensioned, the wires are joined.

Correct tensioning of wire in a wire fence is important.

Insufficient tensioning can reduce the strength and performance of the fence.

Excess tensioning can unduly stress or even break the wire. Typically, manufacturers provide specifications for the optimum tensioning of a respective wire. It will be appreciated that there can be considerable variations in the gauge and/or strength of fencing wire. With conventional wire tensioning tools, it is not possible to measure the tension applied.

Generally, an operator may simply estimate a desired degree of tension.

In order to address this difficulty with obtaining an optimum degree of tension, there have been a number of proposals.

One earlier proposal has been to modify of a wire tensioning tool of the type as described above. The tool includes a compressed spring located between the tool body and one of the clamps. The degree of compression of the spring is proportional to the tension in the wire. A graduated arm indicates the degree of compression. In use, the wire is tensioned until a predetermined degree of compression of the spring is reached, as determined by the graduated arm. A disadvantage of such a device is that the spring and arm make the tool quite cumbersome and heavy to use. The spring also interferes with tying the loose ends of the wires together. Also, the free ends of the wires can become caught in the spring.

It is also possible to measure the tension or strain using a separate measuring device. Such a device is independent of the device used to tension the wire. However, use of such devices adds an extra step to the wire tensioning process. This can add to the time and costs for installation or repair of a wire fence.

It is therefore an object of the present invention to provide a wire tensioning tool which may at least partially overcome the above disadvantages or provide the public with a useful choice.

According to a first broad form of the invention, there is provided a device for tensioning a wire, the device having a first attachment means for attaching the device to a wire to be tensioned, a second attachment means for attaching the device to an anchor point, a handle operatively associated with the first and second attachment means, such that pivotal movement of the handle can draw the attachment means together so as to apply tension to the wire and during the pivotal movement torque is transmitted to the handle, the torque being proportional to the tension, the device further including torque indicating means associated with the handle for indicating to a user when a preselected torque has been reached.

The device of the present invention includes first and second attachment means operatively attached to a handle. The attachment means may be the same or different and typically includes a clamp or the like. The second attachment means can attach to an anchor point which may be any suitable point to which a wire may be joined such as a fence post or a second length of wire.

A handle is operatively connected to the respective attachment means such that pivotal movement of the handle can draw the respective attachment means towards each other so as to tension the wire. Suitable operating mechanisms are known and include rack and pinion arrangements.

A preferred operating mechanism has a length of chain attached to a clamp.

The handle has a pair of arms extending from the upper end of the handle, the arms terminating in inwardly facing hooks. The hooks alternatively engage successive links in the chain as the handle is moved backwards and forwards thereby drawing the attached clamp down to the handle. Such arrangements are known in the art as "chain walkers".

The device also includes a torque indicating means which can indicate to a user when a predetermined torque has been reached.

When the handle is moved back and forth, a torque is transmitted through the handle, the torque being proportional to the tension or strain being introduced to the wire. By providing an indication as to when a predetermined torque value has been reached, the wire can be tensioned to a predetermined value.

Mechanisms for indicating when a certain torque has been reached are known. Such mechanisms are used in power wrenches so as to avoid overtightening of nuts or bolts. Such mechanisms may be suitable for use in the present invention.

The torque indicating means is typically housed within the handle. Torque indicating means may operate by providing a moving scale to indicate an increase in torque or a signalling means which is activated when a desired torque has been reached. Alternatively, operation of the tool may be disengaged when a maximum torque has been reached.

A preferred torque indicating means includes a spring operated mechanism housed within the handle. Typically the handle includes a tube which has a shaft inserted into the tube. One end of the shaft extends from the top of the tube and engages with or forms a tool head. The attachment means are connected to the tool head. The shaft is pivotally connected to the tube near the open end of the tube. The other end of the shaft is within the tube and abuts an arm or member which is biased into the abutment position by a compressed spring. When the handle is moved back and forth, torque is transmitted to the shaft. When the torque matches the force of the compressed spring there is relative movement between the shaft and arm which produces an audible click or sound which alerts an operator to the fact that a torque limit has been reached.

Typically, the torque indicating means can be adjusted to vary the maximum torque which can be reached.

By way of example only, the present invention will now be described with reference to the accompany figure which represents a preferred device of the present invention.

The figure illustrates a wire tensioning tool 11. The tool 11 has an upper wire engaging head 12 and a handle 13. The wire engaging section has two clamps 14, 15 for attaching about the lengths of wire 16, 17 to be joined. Clamp 14 is fixed to section 12 by a short length of chain 18. Clamp io 15 is attached to a longer section 19 of chain. Head 12 has a pair of parallel arms 20, 21 having inwardly facing hooked ends 22, 23. The upper arm 20 is shown as engaging a link 24 of chain 19.

Pivotal movement of handle 13 allows arms 20, 21 to alternatively engage links of chain 19, thereby drawing clamp 15 closer to the tool head 12, thereby drawing wires 16, 17 together.

Handle 13 includes an open-ended tube 30. A shaft 31 extends from the open end 32 of tube 30. The extending end of shaft 31 is threadably engaged with tool head 12. The shaft 31 is pivotally attached to tube about a pivot point (not illustrated) located adjacent the open end 32. The tool includes an alignment pin (not illustrated) for use when threading the handle 13 to the head 12. The alignment pin enables the handle to be fitted such that in use, pivotal movement of the shaft 31 about the pivot point is in the same plane as the arms 20, 21 of the tool head 12.

The opposite end of the tube 31 has an end cap 33 threadably attached thereto. The end cap 32 houses a compression spring 34. The degree of compression of the spring 34 can be adjusted by rotating end cap 33. Typically, the end cap 33 has graduations (not illustrated) which correspond to the degree of compression of the spring 34. It can be seen that springs may easily be replaced by simply unscrewing the end cap 33.

The handle also includes an arm 35 located within the tube 31 and which extends from the spring 34 to shaft 32.

The arm 35 is tapered towards the spring 34 and terminates in disc 36 which contacts and compresses the spring. The other end 37 of the arm 35 is bevelled and abuts.

In use, clamps 14 and 15 are clamped to wires 16, 17. The handle 13 is pushed backwards and forwards so as to "walk" the arms 20, 21 along chain 19. This motion draws clamp 15 towards the tool head 12. As tension is increased on the wires, torque is transmitted to the handle by shaft 32. Pivotal movement of shaft 32 relative to tube 31 is initially prevented by contact of its lower end 38 with arm 35. When the torque equals to match the compression force of the spring, the shaft moves to produce an audible click which may be heard by an operator thereby indicating that a desired wire 0io tension has been reached. (The desired tension may be adjusted by adjusting the compression of the spring as described above.) The ends of the two wires can then be joined, the action of the arms 20, 21 reversed so as to release the tension until the chain is slack, thereby allowing disengagement of the clamps 14, 15 from the wires 16, 17.

It can be seen that the device of the present invention allows an operator to easily detect when a desired wire tension has been reached. The indicating means forms part of the wire tensioning tool. and does not require any additional tools, actions or measurements. The device of the present invention also allows wires to be tensioned to a reproducible degree. This may be desirable in the construction of a multi-strand fence.

It will be appreciated that various changes and modifications may be made to the present invention as described and claims herein without departing from the spirit and scope thereof.

Claims (3)

1. A device for tensioning a wire, the device having a first attachment means for attaching the device to a wire to be tensioned, a second attachment means for attaching the device to an anchor point, a handle operatively associated with the first and second attachment means, such that pivotal movement of the handle can draw the attachment means together so as to apply tension to the wire and during the pivotal movement torque is transmitted to the handle, the torque being proportional to the tension, the device further including torque indicating means associated with io the handle for indicating to a user when a preselected torque has been reached.

2. The device of claim 1, which includes a tool head to which the first and second attachment means are connected, the handle is mounted to the tool head and houses the torque indicating means.

3. The device of claim 1 substantially as hereinbefore described with reference to the figure. DATED this 9th day of February 2000 Richard Douglas QUIRK By his Patent Attorneys 2n CULLEN CO.