I'm building a trike and plan to use a few bolted connections to allow it to fold up.

I have seen bolt sleeves like this on hang gliders. The tube is swaged on both ends and the bolt can be snugged up with a nylock without crushing the large tube. My guess is that the tube also increases the bearing area and reduces the liklihood of ovalizing the hole. On a hang glider most bolted connections like this are subject to pivoting when the glider is folded.

Is anyone familiar with how these tubes are installed? Are they a commercial product or DIY?

My guess is that one end is flared with something like a modified brake line flare tool, and the second end is crushed by tightening a bolt through the tube. Probably needs an outer sleeve inside the big tube to keep that part of the small tube from expanding when the second end is flared - but that"s 100% speculation.

Name: Bolt Sleeve.jpg Views: 1630 Size: 104.9 KB