How does the Hensley Arrow differ from a conventional friction sway system?
As noted above, sway is eliminated by making the vehicle combination act like a straight truck. The way a friction system works is to try its best to keep a trailer from becoming a trailer. By shear force it tries to create a straight truck. The problem of sway is between the joint of the trailer and the tow vehicle. Eliminate the joint and you will never have sway, it is 100% impossible. So in theory, so far so good, friction works just fine. Now, add this part of the story: The same sway bar that keeps the trailer straight, also keeps the trailer at any given angle. For any number of reasons (lane changes, truck air wave, emergency maneuvers, etc.), when sway starts, you have created an angle between the trailer and the tow vehicle. The sway bar is now working with the same amount of force to keep the trailer in the sway (or at the angle), as it was when it was trying to keep it out of sway. It is actually a very simple physics fact, the friction device is the worst possible design (
