In the park this week…Renewing Stock Fencing in Polo Field

Fencing at CharlecotePark needs to be checked regularly and maintained to keep it in good order to prevent our animals going where we don’t want them to go! After many years of service one of the fences in Polo Field, an area where we graze our Jacob Sheep, has come to the end of its useful life and needs to be fully replaced as it has become uneconomical to effect constant repairs. We are now replacing a 136m stretch of fencing along the boundary of an area we call Polo 3.

 Our new Jacob lambs have been moved into the Polo 2 area allowing the Park and Garden team to work on the Polo 3 fence without disturbing the lambs.

Photo 1

All the old fencing and gates have been removed. A new gate (photo 1) has been installed and a rope strung between the gate post and the far edge of the field giving us our straight line (photo 2).

Photo 2

The fence itself is a high tensile steel mesh stock fence supported by round wooden fence posts. The posts are driven into the ground at 5m spacing (photo 3), following the guide rope, using a ‘post knocker’ which fits on to the front of the tractor (photo 4) and is powered by the tractor’s hydraulics. The very heavy hammer easily drives the posts into the ground.

At each end of the run there will be box strainers. Given the length of this run it is also necessary to have a double box strainer in the middle of the run. Box strainers are very strong sections of posts to which the mesh is securely stapled. The wire mesh is then tensioned, to ensure there is no give in it if the sheep push it, before being stapled to the next box strainer.

A box strainer is made by inserting a horizontal rail in between a strainer post and a standard fence post. To ensure the horizontal rail is a good fit, its ends are sawn into a square taper. A corresponding square tapered hole is chiselled into each of the supporting posts and the rail is fitted into the chiselled holes.

A single strand wire is then looped diagonally, twice, between the bottom of the strainer post and the top of the normal post and the ends of the wire are joined using a Gripple clamp. The wire is tensioned using a hand tensioning tool to pull the wire through the Gripple, which allows the wire to pass freely in one direction whilst gripping it securely in the other direction to prevent the wire being pulled back out.

As the name implies, these box strainer sections take the considerable ‘strain’ of the tensioned wire mesh. If an attempt was made to tension the wire mesh stapled only to a standard fence post, the the force of the tensioning would simply pull the fence post out of the ground. Having secured one end of the mesh to a box strainer it is tensioned by clamping a metal tensioning frame to the mesh just after the next box strainer. A ratchet winch is then attached between the tensioning frame and an immovable object, in our case the tow bar of a Gator vehicle. The winch is then ratcheted by hand until the fence reaches the desired tension. The mesh is then securely stapled to the box strainer before the winch and the frame are removed.

To complete the fence a single wire is positioned above the mesh. This provides the height which prevents the sheep from leaping the fence to escape or, indeed, the rams leaping into the field where the ewes are when they feel frisky!

The single strand wire is secured to the box strainer and tensioned at the next box strainer using a monkey strainer. The monkey strainer is clamped to the wire and its chain is secured on the box strainer. As the handle of the monkey strainer is ratcheted, the unique arms of the tool (shown on the right of the picture) ‘walk’ along the chain (like a monkey climbing a rope) pulling the wire to the desired tension when it can then be securely stapled to the box strainer.

Once tensioned and stapled securely at each strainer, the wire mesh and the single wire need only be loosely stapled to the wooden fence posts in between the box strainers to keep it in position.

The finished fence is incredibly strong and well able to withstand any pushing and shoving of our biggest sheep, or, indeed, our even bigger rams!

John, Park Volunteer

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