A chain restraint

Abstract

Chain restraint 100 for a pawl operated wire strainer and having a handle 11 with a walker bar 12 extending from the handle, and a pair of pawls 13,14 pivoted on the walker bar. The walker bar and paw

Description

Field of the Invention The present invention relates to agricultural wire strainers and, in particular, to agricultural wire strainers which “walk” along a chain due to the action of pawls attached to a reciprocating walker bar. Background Art Such wire strainers generally take the form of a handle, a walker bar extending from the handle, and a pair of pawls pivoted on the walker bar. By moving the handle backwards and forwards through an arc, so the pawls can be made to walk along the chain. The chain over which the pawls have already moved in order to carry out the straining motion, cascades over the strainer under the influence of gravity. Since the strainer may be held in various orientations depending upon the height of the wire being strained, the height of the fencing contractor or farmer, the stance of the fencing contractor or farmer, and the like, so the chain over which the pawls have already moved may cascade in various different fashions. When the strainer is moving forwardly along the chain, the chain about to be engaged by the pawls is relatively taut and straight and untwisted. It is necessary for the chain to be untwisted (that is having the chain links aligned) for the pawls to walk along the chain. For this reason a swivel (not illustrated) is often located in the chain. A difficulty sometimes arises when the strainer is being released after the wires being strained are interconnected, in that the pawls are required to walk backwardly for at least a small distance, and this is difficult if the un-tensioned chain is not straight and untwisted. Genesis of the Invention The genesis of the present invention is a desire to at least ameliorate the above-mentioned difficulty. It is known from Australian Patent Application No 2008 203 804 in the name of Peter Barrett to provide a guide means 33 which provides a guiding influence to the “excess chain” over which the pawls have walked. The main constituent of this guide means 33 1 06 03 25 is a notch 38 in the walker bar 30 (Fig. 5 of the abovementioned Australian patent application). It is also known from Australian Patent Application No 2018 274 897 ONESTEEL 5 WIRE PTY LIMITED to provide similar notches 24, 224, 225, 226 in a walker bar of a wire strainer. Although provided to increase the arc through which the handle can be reciprocated, such notches also provide a guiding influence for the “excess chain” over which the pawls have already walked. 10 Summary of the Invention In accordance with a first aspect of the present invention there is disclosed a pawl operated wire strainer having a handle, a walker bar extending from the handle, and a pair of pawls pivoted on the walker bar, the walker bar and pawls substantially defining an operating plane of said wire strainer, wherein at least one chain restraining link is 15 pivotally connected to said walker bar, said link having a protrusion which extends outwardly from said operating plane. In accordance with a second aspect of the present invention there is disclosed a 20 connecting link for interconnecting a walker bar with a strain gauge, or a wire gripper, or a hook of a pawl operated chain walking wire strainer having a handle, a walker bar extending from the handle and a pair of pawls pivoted on the walker bar, said connecting link being substantially planar and having a protrusion extending outwardly from the plane of the connecting link. 25 In accordance with a third aspect of the present invention there is disclosed a pair of connecting links each as referred to above wherein said protrusions extend in opposite directions. 30 Brief Description of the Drawings A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: 06 03 25 Fig. lisa partial perspective view of a prior art fence strainer illustrating the handle, walker bar, pawls and coupling links, Fig. 2 is a top view of the prior art fence strainer of Fig. 1, Fig. 3 is a perspective view of a prior art fence strainer in one mode of 5 operation, Fig. 4 is a perspective view of the prior art fence strainer of Fig. 3 in another mode of operation, Fig. 5 is a front perspective view of a chain restraining link of a first embodiment, 10 Fig. 6 is a rear perspective view of the chain restraining link of Fig. 5, Fig. 7 is a perspective view similar to Fig. 3 of a fence strainer having two of the chain restraining links of Figs. 5 and 6, Fig. 8 is a perspective view similar to Fig. 4 of the fence strainer of Fig. 7, Fig. 9 is an enlarged perspective view of the fence strainer of Fig. 8, 15 Fig. 10 is a view similar to Fig. 9 but showing the fence strainer in an inverted position, and Fig. 11 is a view similar to Fig. 9 but showing the strainer being partially released from the chain. 20 Detailed Description As seen in Fig. 1, a prior art fence strainer 10 has a handle 11 of indefinite length from which extends a walker bar 12. Two pawls 13, 14 are pivoted on the walker bar 12. In between the pawls 13, 14 are two connecting links 16 and 17 which connect to a hook, strain gauge, wire gripper or the like (all not illustrated in Fig. 1) depending 25 upon the configuration of the strainer 10. From Fig. 2, it will be seen that the connecting links 16, 17 are substantially flush with the side surfaces of the pawls 13, 14 and define a pair of operating planes 18, 19 which will be referred to hereafter. 30 Turning now to Fig. 3, the connecting links 16, 17 of the fence strainer 10 are connected to a conventional strain gauge 21 which is in turn connected to a conventional wire grabber or gripper 22. The strain gauge 21 is preferably of the type 06 03 25 illustrated in Australian Design Registration No 2020 15808 and the wire gripper 22 is preferably of the type illustrated in US Patent No 11, 680, 422. The pawls 13, 14 are inter-engaged with a chain 24 and can be walked along the chain 24 by reciprocally moving the handle 11 through an arc in known fashion. In the mode of operation 5 illustrated in Fig. 3, the “excess” chain 24’ (which is the chain upon which the pawls 13, 14 have already walked) drops down between the pawls 13, 14. However, in the mode of operation illustrated in Fig. 4, the same excess chain 24’ passes over the walker bar 12 and the upper one of the two connecting links 16, 17 10 and then drops down under the influence of gravity. It will be appreciated that the configuration of the excess chain 24’ in the arrangement illustrated in Fig. 4 is very dependent upon the orientation of the fence strainer 10. For example, if the handle 11 is lifted upwardly, then the “excess” chain 24’ can drop over the distal pawl 13. 15 After the fence wire has been strained, and often knotted or otherwise secured by means of a fastener such as those sold under the trade marks GRIPPLE (Registered Trade Mark) or BOBEX (Registered Trade Mark), it then becomes necessary to remove the strainer 10 from the chain 24. This is done by, paradoxically, increasing the strain and removing the leading pawl (14 in Figs. 3 and 4) from engagement with 20 the chain 24. This action requires the previously leading pawl to be disengaged from the chain and re-engaged behind what was the trailing pawl. This requires manual intervention in the case of the mode of operation illustrated in Fig. 3, and is difficult to do in the mode of operation illustrated in Fig. 4 if the chain 24 between the pawls 13,14 is not straight and untwisted. It is towards ameliorating this difficulty that the 25 present invention is directed. As illustrated in Figs. 5 and 6, a chain restraint 30 is illustrated which is incorporated into a connecting link which replaces the connecting link 16, 17. It will be seen that the chain restraint 30 has a link body 31 with apertures 32, 33 in either end. In 30 addition, the chain restraint 30 has an inverted L-shaped arm 35 which preferably has a length which exceeds the length of one of the links in the chain 24. 06 03 25 As seen in Fig. 7, a strainer 100 of the preferred embodiment preferably has two of the chain restraints 30 which replace the connecting links 16, 17 and thus interconnect the walker bar 12 with the strain gauge 21. 5 The chain restraints 30 enable the chain 24 to be passed between the link body 31 and the arm 35 and then draped downwardly under the influence of gravity as illustrated in Fig. 8. As a consequence, the chain 24” between the trailing pawl 13 and the chain restraint 30 is maintained both straight and untwisted as it is being fed into the pawls. It will be appreciated from Fig. 8 that as the pawls 13, 14 walk along the chain 24 and 10 thereby increase the tension in the chain 24, that portion of the chain 24” between the chain restraint 30 and the nearer pawl 13,14 will retain the straight and untwisted character which it had prior to being walked over by the pawls 13, 14. This is because the arm 35 of the chain restraint 30 provides a chain guide. 15 As seen in Fig. 10, the orientation of the fence strainer 100 and, in particular its handle 11, can be changed without dislodging the chain 24” from the chain restraint 30. This is particularly important when working with wires closely adjacent the ground where, in effect, it is necessary to invert the normal operation of the fence strainer 100. If the handle 11 is not pointing generally upwards, it is unable to be 20 reciprocated, and the strainer 100 thereby operated. Irrespective of the orientation of the fence strainer 100, gravity always acts downwardly on the excess chain 24’ on the side of the chain restraint 30 further from the walker bar 12. As a consequence, the fence strainer 100 and its handle 11 can be 25 moved into a variety of configurations without dislodging the excess chain 24’ from the chain restraint 30. Thus, the chain 24” between the chain restraint 30 and the pawls 13, 14 always remains taut, straight and untwisted. It will be apparent that the arms 35 of the chain restraints 30 extend or protrude 30 beyond the operating planes 18, 19 as illustrated in Fig. 2. The arms 35 therefore constitute two protrusions which extend outwardly beyond the respective operating planes and in opposite directions. 06 03 25 The foregoing describes only one embodiment of the present invention and modifications, obvious to those skilled in the fencing arts, can be made thereto without departing from the scope of the present invention. For example, the features and advantages disclosed to one facet of the invention may be utilised, mutatis 5 mutandis, in other facets of the invention. It will be apparent to those skilled in the fencing arts that although two of the chain restraints 30 are preferable, most of the operational benefits can be achieved by means of a single chain restraint 30. 10 Furthermore, it is not necessary for the chain restraint to have the configuration of replacing a connecting link 16, 17 since a protrusion could be directly connected to, or formed on, the walker bar 12. However, a particular advantage of the chain restraint 30 of the preferred embodiment is that it is able to be retrofitted to existing fence 15 strainers which are already in the hands of previous customers. The term “comprising” (and its grammatical variations) as used herein is used in the inclusive sense of “including” or “having” and not in the exclusive sense of “consisting only of’. 06 03 25

Claims

1. A pawl operated wire strainer having a handle, a walker bar extending from the handle, and a pair of pawls pivoted on the walker bar, the walker bar and pawls substantially defining an operating plane of said wire strainer, wherein5 at least one chain restraining link is pivotally connected to said walker bar,said link having a protrusion which extends outwardly from said operating plane.

2. The strainer as defined in claim 1 wherein said protrusion is formed on a link 10 interconnecting said walker bar with a strain gauge, or a wire gripper or ahook.

3. The strainer as defined in claim 2 wherein said protrusion comprises an arm of substantially inverted L-shaped configuration.

154. The strainer as defined in claim 3 wherein said arm has a transverse extent approximately equal to the length of one link of the chain.

5. The strainer as defined in any one of claims 1-4 and having a pair of said20 protrusions each extending from said plane in opposite directions.

6. The strainer as defined in claim 5 wherein each of said protrusions is formed on a corresponding one of a pair of links.25 7. The strainer as defined in claim 6 wherein each of said protrusions comprisesan arm of substantially inverted L-shaped configuration.

8. The strainer as defined in claim 7 wherein said arm has a transverse extent approximately equal to the length of one link of said chain.

309. A connecting link for interconnecting a walker bar with a strain gauge, or a wire gripper, or a hook of a pawl operated chain walking wire strainer having a handle, a walker bar extending from the handle and a pair of pawls pivotedon the walker bar, said connecting link being substantially planar and having a protrusion extending outwardly from the plane of the connecting link.

10. A pair of connecting links each as defined in claim 9 wherein said protrusions 5 extend in opposite directions .

11. The connecting link or pair of connecting links as claimed in claim 9 or 10 wherein the or each protrusion comprises an arm of substantially inverted L-shaped configuration.

012. The connecting link or pair of connecting links as claimed in claim 11 wherein said arm has a transverse extent approximately equal to one length of a link of a chain upon which said wire strainer walks.06 03 25

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