Torsion Free Subframe Explanation?

So I'm reading up on these Torsion Free subframe concepts and I was hoping someone with a lot of knowledge could possibly elaborate for me. Basically my main question is regarding HOW the subframe moves independently from the trucks frame. Every subframe design I've seen has 2 pivoting mounts bolted parallel to the trucks frame (usually towards the middle of the subframe) and 2 pivoting mounts bolted perpendicular to the trucks frame (usually at the front and back of the subframe). Because these mounts pivot in opposite directions (90 degrees from eachother), how does the subframe move independently from the trucks frame?
 
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