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I want to fix a wire rope horizontally between two trees with a T-connector in the middle of the wire rope to hang a tire swing from.

Something like this:

tree-------wire rope------???-----------------------tree
  I                        I                         I
  I                        I                         I
  I                        I                         I
  I                        I                         I
  I                        I                         I
  I                    tire swing                    I
  I                                                  I
  I                                                  I

I looked for a T-shaped connector but have not found a solution.

What kind of connection can I use to hang the tire swing from the middle of the wire rope? I need something that will not deteriorate during the use of the swing.

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What you're describing is known as a 'low angle bridle.' The problem with this configuration, where a flexible cable runs nearly horizontally and a load is applied in the middle, is that the tension in the top cable gets very big. In fact, to have the top cable be perfectly horizontal would require infinite force at each end, since its own weight is always going to make it sag a little. Just getting pretty close to horizontal requires a really large force. Because it's generally a bad idea, I don't think you'll find a piece of hardware that looks exactly like what you're imagining.

However, if your trees are tall enough, you can make a more typical bridle (Think a Y shape) where the top wire rope goes up as well as out. In conventional rigging, we try to keep the angle between the top two legs below 90 degrees, although there are some exceptions. If you go that route, you'll want the top piece to actually be two separate pieces of wire rope. Connecting the two bridle legs to the vertical drop you'll want to use either an anchor shackle if it's temporary, or a pear shaped link if you can swage the cable in place. (Obviously since your load moves, make sure to mouse the anchor shackle if you go that route!)

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  • $\begingroup$ Thanks, I understand the tension problem. I thought if I buy a 8 milimeter diameter wire rope, it will be enough (the swing would be 6 meters tall). But as I read your comment, maybe its not enough (need to hold the weight of two adults, 150 kilogram). So if you say it's dangerous I must replan the whole thing (Y shape would cause the swing too little). $\endgroup$ – mue114 May 12 '15 at 17:34
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    $\begingroup$ @mue114 one pivot axis of the swing will be the line between the attachments on the trees. The other axis will be through the Y connector. The load one the horizontal will be $\frac{weight}{\sin(\text{angle off horizontal})}$, just pick a decent angle. $\endgroup$ – ratchet freak May 12 '15 at 20:46
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Why does it have to be dead horizontal? With a bit of slack, the cross-rope can be part of the swing as well.

Wire ropes and trees are not a good combination anyway - you'll ring-bark the trunk with a wire rope and kill the top of the tree. Use a regular rope instead (polyprop if you don't want it rotting). With a regular rope, I'd tie an Alpine butterfly and hang the swing off that.

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  • $\begingroup$ If you go with wire, at least pad the end that loops around the tree with a length of plastic tubing or something. $\endgroup$ – Carlton May 12 '15 at 19:18
  • $\begingroup$ The best way to attach wire to a tree is to have a tree service drill a hole straight through the limb where you want the attachment point and put in a long eyebolt. $\endgroup$ – regdoug May 12 '15 at 22:50

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