Hensley Arrow: How does it REALLY work?

MacMan wrote:
......That 20 inches has to still allow some lever action for movement, compared to the Pull-Rite or fiver. Still, no tests that I have ever seen will say that a TT equipped with a Pull-Rite or a fiver exibit less sway or reaction than a Hensley. In most instances, they are equal, or perhaps I should say, "Perceptibly Equal." Maybe that 20 inches of difference is reduced enough from the normal hitch distance to pivot point to make all of the difference?

This is an excellent point. It is quite possible that, once the "steering moment" induced by the TT on the TV falls below a certain threshold, sway will appear to be eliminated whether the lever arm in 24" or 12" or zero. However, if unexpectedly large forces on the TT cause the moment to be above the threshold, then sway might occur.

...With the linkages in the Hensley, The hitch almost has to pivot slightly backwards to make its pivot sideways, to allow turns.

The ball is at is most rearward position when the TT and TV are aligned straight ahead. Any turning action will cause the ball to move to the side (up to 5") and slightly forward as the TT swings.

...When the TV is pulling the trailer, the trailer, due to inertia, will try to resist forward movement, making the tendency of the TT to stay in place (or essentially backwards from the moving TV). This allows a natural backwards movement of the pivot in the black and orange parts of the Hensley.

If lateral forces on the TT cause it to swing to the side, the pulling force (tension) in the linkage will tend to move the ball back to center.

...Now, if the TT is to infulence movement on the TV, It must actually move forward relative to the TV. Now, since TTs are not equipped with engines, the only way that it can move forward is due to the TV stopping quickly, or when going downhill, if the TT tends to gain speed quicker than the TV.

The TT can exert lateral force on the TV via the linkage even in the absence of any longitudinal force between TT and TV. There does not have to be relative movement.

...Anyone with a Hensley Hitch knows, and is told in the manual, to set the boost higher on your brake control to prevent this forward (and sideways) movement of the TT on the hitch. I suppose the same thing could happen going down a steep grade if you were to decelerate, and engine braking was holding the TV back without the trailer brakes, although I have never heard of this being an issue. Perhaps this is because the differences in inertia between TV and TT are not great enough going downhill, and these differences only come in to play when the brakes on a TV are applied without the TT brakes coming on strong enough.

It is important that the TT should not push on the TV. With the HA, if there is an angle of just a few degrees between TT and TV, the VPP can move as much as 19" to the side of the TV's centerline. This means that the forward thrust from the TT is acting on the TV with a moment arm of about 19". This can induce a large "steering moment" on the TV just as a lateral force can.

...Perhaps an illustration could be used similar to a motorcross bike swingarm linkage type rear suspension.

Off hand, I don't see how the HA linkage would be similar to a motorcycle swingarm; but, I'll have to give it more thought

...I hope I have been able to add to this enjoyable discussion, and hope that my response was not totally stupid.

Your comments were certainly of value -- nothing the least bit stupid.

Ron