christofoo -- That's because I was wrong.
I wasn't looking at it right. Normally you have four linkage bars that constrain the moving item (your classic street rod front end). In this case the two bars swap function with the other items.
For the sake of the lurkers [behold the magic]:
a related concept is the three-hinged arch
https://en.wikipedia.org/wiki/Arch#F...vs_hinged_arch