Answering the PM's here...instead of to each one
The WD Bars (round, or square/rectangular/etc) are all off center in reference to the TV Receiver/Shank/DrawBar...'BALL'
The trailer tongue/coupler mounts on that 'BALL' and swings side to side on that 'BALL'...meaning that is the pivot center
Most all WD Hitch systems (except for one...saw a pic of that, but don't note the name, where the WD Spring mechanism is centered between the tongue (between the 'V') has those bars offset from the hitch 'BALL' by some distance. Normally/generally about 2 inches on each side of the ball
When the trailer sways or swings off center line...the spring bar on one side will swing too, but at a different radius. One side will 'shorten' and the other side will 'lengthen'...ever more with greater off center swing/sway
That then has the 'anti-sway' mechanism come into play. They will resist that swing/sway via whatever way their designers decided
The farther away from the 'BALL' center line, the greater the push/pull...but at some distance, it will not allow tight maneuvering (purposely jack-knife).
Yes to that question about the trunnion's that use friction as their anti-sway mechanism...it is just like the old 'friction bar' and note that the tiny ball they mount to is offset from the 'BALL' center
There was a nifty spread sheet chart showing the push/pull, but that is no more with the demise of Photobucket's new "no longer allows posting to other sites' decision
