To Earl's comments on the Barco joints, they are basically a full turn
style rotary joint. As such there is a dynamic seal (pair) above and below
the rotary connection to allow fluid (or gas) passage and allow single or
multiple turns. Problem is that in pneumatic applications (brakes) there
is nothing to lubricate the seals and the joint loses containment
integrity very quickly. Since they are single plane ie +/- x, to "3D"
the connection you need another in in the y +/- plane. More to the Chama
situation, there is (or at least was) an FMC division in Brea, CA that
manufactured an oil field version (similar construction) of the Barco
style joint.