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Correct use of wire rope (‘bulldog’) grips

Wire rope grips are used for forming an eye in the end of steel wire rope, with or without a thimble to support the rope structure.

On the subject of wire rope grips, (West 1997, p67) states:

Wire rope (or ‘bulldog’) grips are only suitable for permanent fixed stays or guys.

They can be one of the most dangerous fittings used by riggers if not used correctly. If the bolts are overtightened the rope will be crushed or if the bolts are under tightened slipping will occur.

At least three wire rope grips should be used, with the saddles on the live part of the rope, and the U-bolt pressing on the less heavily loaded tail of the rope. They should be spaced at least six rope diameters apart.

Do not use them on temporary stays or guys that have to be shifted and re-fastened because the the severe crushing and punishing action of the U-bolt. Do not use sections that are damaged by the clip and then straightened out to take the load.

Do not use bulldog grips on any load hoisting ropes. When connecting a lizard to a stay or guy, make sure that the crowns of the U-bolts press upon the lizard. Although they will (be) damaged, they are easily replaced.

Correctly applied bulldog grips may form an eye with 80 per cent of the breaking strength of the rope. If not correctly applied, they have no reasonable safe value.

Do not use a grip that is the wrong size or that has been strained or damaged.

Do not use a bulldog grip to directly connect two straight lengths of rope. If this is necessary, join two thimbles and then use the grips to make two thimble eyes.

Credibility and application of the reference

The reference (West 1997) was published as a training manual by Workcover (the agency responsible for OHS in NSW), and serves as a de-facto practices manual. If an accident occurs in this jurisdiction, and advice of the manual was ignored, it would more difficult for the rigger(s) to argue that they had not significantly contributed to the adverse outcome.

Ham radio and wire rope grips

In my experience, wire rope grips are almost always misused in ham radio antenna applications.

A better solution is often a swaged eye terminal, it is smaller, less likely to foul, and properly done, stronger.

References

West, D ed. 1997. A Guide to Rigging. Sydney: Workcover New South Wales.


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