Hensley Arrow: How does it REALLY work?

Thanks for the kind words Ed B. And Tim, I think we mostly agree on the function of the strut bars, but I think the overlooked aspect of the assembly is that the struts keep everything aligned by placing all the pieces under compression. When you snug up the struts, keeping the hitch head, stinger, etc. all aligned you do that by "expanding" the strut. That means all the potential moving parts in the four bar linkage are being held in place by forces coming from the outside of the assembly, all pushing against each other in (approximate) balance. That, in conjuction with the fact that the front and rear linkage bars are different lengths, is what makes the hitch head to appear to be virtually "locked"

Now comes the hard part. How do you explain the "bump" that can happen if the TT brakes don't engage soon enough , or at all, when slowing down. It would seem that scenario would add even more compression to the hitch assembly. My only guess is that it's velocity dependant (i.e., it only happens when the TT slows down really quickly relative to the TT) and that the mass of the TT at those velocities is enough to cause the rear link to translate to one side or the other. And the beauty of it all is that since the head translates as opposed to the TT swinging, the net force vector on the TT/TV assembly is still pretty much straight ahead so even in a panic stop you don't end up swerving or swaying into your buddy in the adjacent lane.

Andy