Hensley Arrow: How does it REALLY work?

bettered wrote:
I agree with you Ron. But before we can get into sliding friction, we have to get past static friction. Now I'm not claiming to be an expert on tire dynamics, but even though the contact patch is moving (forward), I'm thinking it has a static friction coefficient in the lateral direction (sideways).

As long as the tire is rolling, it is not considered static in any direction, because the contacted surface area is constantly changing.

bettered wrote:
It is only after the TT has broken loose that it can apply any translation or turning movement to the rear bar of our 4-bar system. Forces yes, but movement of the rear link without tires going sideways - can't happen.

For the most part you're right, Ed. However, since in the real world there are always tolerance gaps and wear on interfacing materials, I'm certain that there is a slight amount of play in the linkage, some units more than others. This would allow some translation to occur without any rotation of the rear bar, resulting in no moment to be applied to the tires from the hitch. Besides, the rotational angle changes very little in the first inch or two of translation on each side of center anyway.

In addition, I'm having a hard time imagining what kind of forces outside of a broadside hit at the axles that could result in anything other than a moment on the CG of the TT. I've already shown above how a lateral force resulting from the moment of a TT results in a reactive COUNTER moment generated by the trans-rotation of the hitch linkage. We just don't know how much of a reactive moment the hitch CAN generate given its relatively minimal leverage and unknown compressive strength.

I think it might be more useful to identify specific hazardous conditions and analyze the various reactions using a HA. For example, if lateral slippage of the tires is a concern, pick a possible cause so we can start with those inputs.

Tim