GB2195732A - Wire tensioner - Google Patents

Abstract

A wire tensioner for fencing includes a lateral arm 10, for abutment against a post 74, and a ratchet bar 16 engageable with a non-return pawl 32 such that the bar is moveable only in the direction of arrow 38. A wire 72 to be tensioned and secured to a fence post 74 is secured to the tensioner by main, secondary and tertiary wire clamps 52, 64, 68. Handle 42 is swung so as to cause the pawl 48 to displace the ratchet bar 16 and main clamp 52 away from the fence post 74 so that part of the wire 72 which extrudes past the post 74 is under tension. This is in contrast to known proposals wherein the main clamp is pulled towards the post during tensioning leaving a slack length of wire between the clamp and the post. <IMAGE>

Description

SPECIFICATION Wire tensioner This invention concerns wire tensioners of the kind employed for tensioning fence and like wires where they extend between adjacent supports or posts, to which they are required to be secured, e.g. by stapling, ready for chain-link or like fencing to be secured thereto.

It is already known to provide a construction of wire tensioner comprising an abutment member for abutting against a wire support or post and adapted for a ratchet bar to slide relative thereto, a swingable handle, pivoted to the abutment member, carrying a pawl for engagement with the ratchet bar to displace the latter, a wire clamp being carried by the ratchet bar. In this known construction, the arrangement is such that the wire clamp is drawn towards the abutment member by displacement of the ratchet bar caused by operation of the swingable handle. In other words, the tensioning operation of the tensioner is such as to cause the clamp to close up towards the support or post thereby tensioning a length of wire attached to the clamp.Thus, there is a free short length of the wire, between the clamp and the support or post, which is not tensioned, so that the rest of the wire has to be over-tensioned to ensure that the desired tension is achieved throughout the overall wire length after it has been fastened and the tensioner has been removed. There is also the possibility, where a wire is being secured to round posts, that the tension introduced into the wire being handled creates a turning movement in the tensioner so that the latter tends to swing about the post to which it is applied. The operation of such a tensioner can therefore require a certain degree of skill and experience.

An object of the present invention is to provide a wire tensioner of the kind above referred to in which these difficulties and disadvantages are obviated or minimised, the arrangement in particular providing for the wire to be in tension where it extends past the support or post, so that there is no need to over-tension the wire, and also enabling simple provision to be made for counteracting any tendancy for the tensioner to be swung, by the wire tension, about the post.

With this object in view, the present invention provides a wire tensioner comprising an abutment member for abutting against a wire support or post and adapted for a ratchet bar to slide relative thereto, a swingable handle, pivoted to the abutment member, carrying a pawl for engagement with the ratchet bar to displace the latter, a wire clamp being carried by the ratchet bar, characterised in that said wire clamp is so disposed, upon the ratchet bar, that wire-tensioning displacement of the ratchet bar causes the wire clamp to move away from the abutment member.

The abutment member conveniently comprises a pair of plates between which the ratchet bar extends, a lateral projection or horn being provided to engage the support or post. For slidably locating the ratchet bar relative to a displacement pawl carried by the handle, and a non-return pawl carried by the abutment member and engaging the ratchet, a roller bearing may be so located between the plates that the outer race thereof abuts the ratcher bar.

To minimise the possibility of the tensioner being swung about the support or post by wire tension, the construction is preferably such as to provide wire restraints in dispositions leading up to the wire clamp.

These wire restraints may, if desired, be in the form of secondary wire clamps carried by the ratchet bar.

In order that the invention may be fully understood, it will be described further, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a plan view illustrating a practical embodiment of the wire tensioned according to the invention; Fig. 2 is a sectional and elevation taken approximately as indicated by the line ll-ll of Fig.

1; Fig. 3 is a fragmentary view, to a slightly enlarged scale, comparable with the right hand end of Fig. 1 and illustrating a modification; Fig. 4 is an underneath view of the modification shown in Fig. 3; and Fig. 5 is a view generally similar to Fig. 3 illustrating a further modification.

Throughout the various figures, similar reference numerals have been allocated to similar parts.

As shown in Figs. 1 and 2, a preferred embodiment of the wire tensioner according to the invention comprises an abutment member in the form of a lateral arm 10 formed integrally with a main plate 12 which is riveted to a secondary plate 14, the two plates 12, 14 together forming a guide body between the plates 12, 14 of which is a gap through which extends a ratchet bar 16 which is slidably guided by a guide shoe 18 located on rivet 20 and outer race 22 of a roller bearing 24 located on rivet 26.

The edge of the bar 16 presented to the roller bearing 24 is linear. The opposite edge of the bar 16 is formed with alternating ratchet teeth 28 and notches 30 with which co-operate a non-return pawl 32 loaded by a respective spring 34 and pivotally mounted on rivet 36 which also contributes to the securement together of the two plates 12 and 14.

The shape of the teeth and notches 28, 30 and of the pawl 32 is such that the bar 16 may be displaced to the right as indicated by arrow 38 in Fig. 1 but is prevented from mov ing to the left in a direction opposed to the arrow 38 once the pawl 32 has engaged into one of the notches 30, such latter movement being permitted only upon manual disengagement of the pawl 32 by use of a protrusion 40 thereon.

The rivet 20, in addition to contributing to the securement together of the plates 12, 14, serves as a pivot connecting a handle 42 swingably to the plates 12, 14, the rivet 20 extending through limbs 44, 46 of a bifurcated end of said handle 42. Pivotally mounted between the limbs 44, 46 by a pivot 47 is a main pawl 48 of the tensioner, this pawl 48 being loaded by a respective spring 50 into engagement with the ratchet teeth 28.

A main wire clamp 52 of the tensioner is provided on a lateral extension 54 provided at that end of the bar 16 which is behind the lateral arm 10 considered in the direction in which the bar 16 moves (i.e. the direction 38), and this clamp 52 comprises a camshaped law 56 pivotally secured to the extension 54 at a spacing from a fixed anvil 58, and having a side arm 60 engaged by a spring 62 which acts rotationally to load the jaw 56 so as to engage against the anvil 58.

The ratchet bar 16 also has, at its other end, a secondary wire clamp 64 whose construction is similar to that of the clamp 52 and which is mounted on respective ateral extension 66 of the bar and has its respective parts indicated by similar reference numerals.

The main plate 12 also carries a wire guide in the form of a tertiary wire clamp 68 which is mounted upon a spacer block 70 and is similar in its construction. The clamps 52 and 64, the parts thereof again having been allocated similar reference numerals.

The manner of operation of the wire tensioner will readily be understood from the foregoing description and the drawings. Let it be assumed that it is required to tension a wire 72 (see particularly Fig. 1) and secure it to a fence post 74, the left hand end (as viewed in Fig. 1) of the wire being anchored at some distance away from the post 74, the tensioner is applied to the post 74 by the lateral arm 10 as shown, and the wire 72 is engaged with the tensioner by way of the main wire clamp 52, the respective jaw 56 being pivoted against the action of the spring 62 by means of its side arm 60 to permit the wire 72 to be entered between the jaw 56 and the anvil 58.

It is not essential for the wire 72 also to be engaged with the secondary wire clamp 64 and the tertiary wire clamp 68, but it is preferably so engaged.

For applying tension to the wire 72, the handle 42 is manually swung about its pivot 20, initially in a clockwise direction as indicated by arrow 76 in Fig. 1, to displace the bar 16 in the direction 38, and then back again, during which the bar 16 is prevented from returning by the non-return pawl 32.

This is continued until the desired tension is achieved. The function of the secondary wire clamp 64 is to locate the tensioner relative to the wire 72 during the tensioning operation and to prevent the tension in the wire 72 tending to cause the tensioner to swing about an axis provided by the post 74. The tertiary wire clamp 68 contributes to preventing swinging of the tensioner, but of course it does not grip the wire 72 during movement of the ratchet bar 16 in the direction of arrow 38, but allows the wire 72 to pass between its jaw 56 and anvil 58. Should, however, the bar 16 move in the direction opposed to the arrow 38, the clamp 68 clamps the wire 72 and retains the tension therein.

Upon the desired tension being achieved, the wire 72 is secured to the post 74, for example by means of a staple or the like (not shown), the spacer block 70 ensuring that the wire 72 passes clear of the plate 12 and the latter does not obstruct the securing operation.

It is particularly important to note that since the main operative wire clamp of the tensioner is the wire clamp 52, the operation of the tensioner is such that such clamp 52 moves relatively away from the post 74 during the tensioning operation, and that part of the wire 72 which extends past the post 74 is under tension. This is in contrast to prior known proposals wherein the main clamp is pulled towards the post during the tensioning and leaves a slack wire length between it and the post.

Figures 3 and 4 illustrate a modification which differs from the embodiment of Figs. 1 and 2 in the form of the main clamp 52. As shown, this comprises two approximately semicircular jaws 80 symmetrically mounted upon the lateral extension 54 on respective pivot pins 82 so as to be freely pivotable.

Each such jaw 80 has a respective peg 84 projecting through a respective window 86 in the extension 54, and a tension spring 88, operative to load the jaws 80 towards one another is connected to these pegs 84 by its ends. Since the jaws 80 are effectively eccentrically mounted by their pivot pins 82, the gripping effect thereof on the wire 72 increases with increase in tension of the wire, as the tensioner is progressively actuated in a manner similar to that above described, and particularly effective gripping of the wire is achieved.

Fig. 5 illustrates a further modification of the main clamp 52. A clamping plate 90 is provided attached to the extension 54 by way of two releasble bolts 92, 94.

The bolts 92, 94 are provided with respective butterfly nuts (not shown) so that the clamping plate 90 is displaceable relative to the extension 54. In use the wire 74 is placed between the plate 90 and the extension 54 and between the two bolts 92, 94 such that the wire 74 passes over one bolt 94 and under a second bolt 92. The nuts (not shown) are tightened thus securing the wire 74 between the plate 90 and the extension 54. A similar modified clamp 52 can also be substituted for the secondary clamp 64. Furthermore by extending the clamping plate 90 and the extension 54 vertically and providing further securing bolts multiple wire strands may be clamped and tensioned simultaneously.

The invention is not confined to the precise details of the foregoing example, and variations may be made thereto. Obviously, the form of the wire clamps, the ratchet bar, the slide and the ratchet pawls may differ in their practical details, as has already been mentioned, the secondary and tertiary wire clamps can be omitted, or they may, if desired, be replaced by simple wire guides. The shape and size of the two plates may also be altered to enclose more or less of the ratchet bar, pawls and wire clamps. The wire clamps may be proportionally longer than illustrated in the drawings or may be 'scythe' shaped about their respective pivotal point. Other variations are also possible.

Claims (7)

1. A wire tensioner including an abutment member for abutting against a wire support or post and adapted for a ratchet bar to slide relative thereto, a swingable handle, pivoted to the abutment member, carrying a pawl for engagement with the ratchet bar to displace the latter, a wire clamp being carried by, the ratchet bar, characterised in that said wire clamp is so disposed upon the ratchet bar, that wire tensioning displacement of the ratchet bar causes the wire clamp to move away from the abutment member.

2. A wire tensioner as claimed in claim 1 wherein the abutment member comprises a pair of plates between which the ratchet bar extends, a lateral projection or horn being provided to engage the support or post.

3. A wire tensioner as claimed in claims 1 or 2 further including a non-return pawl carried by the abutment member and engaging with the ratchet.

4. A wire tensioner as claimed in claims 2 or 3 in which a roller bearing is provided located between the plates such that its outer face abuts the ratchet bar to provide for slidable location of the ratchet bar relative to the pawl carried by the handle.

5. A wire tensioner as claimed in any preceding claim further including one or more wire restraints disposed leading up to the wire clamp.

6. A wire tensioner as claimed in claim 5 wherein the wire restraints are secondary wire clamps carried by the ratchet bar.

7. A wire tensioner substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.