Originally Posted by
noimagination
I suppose that's cheaper (for Bike Friday) than paying an engineer to design a proprietary releasable trailer-bike connector.
(This is a relief - I couldn't figure out why one would want to connect a compressed air source to a trailer hitch.)
Well, you could use a socket-wrench U-joint, but you'd have a hard time drilling or welding to it. More probably, it would be a Heim joint (aka spherical rod end) with threads attaching it to trailer tongue, and on the bike a bracket that would hold the rod end in double-shear horizontally, hole vertical, with a clevis pin through both, held with cotter pin or ring. In that orientation it would provide unlimited lateral swing for tight turns, and limited vertical misalignment, of the trailer tongue.