Hensley Arrow: How does it REALLY work?

bettered wrote:
---At risk of re-opening the thread on a technical level, I'm wondering if the geometry/resultant force issue becomes critical as a result of the VPP's lateral travel reaching its extreme OR if it becomes significant when "hitting the stop" (collapse of one of the two links) occurs, causing a "jerk" load on the TV's rear wheels as was Garfield's experience. My expectation (not my experience) would be that the latter would be a more likely LOC event.

Ed,

BOTH situations can result in jackknife forces and moments being applied to the TV if there is sufficient deceleration of the TV and the TT is not being braked sufficiently.

At an articulation of only a few degrees with the VPP at or close to its lateral extreme, TT thrust will tend to steer the TV. If the thrust is great enough or the TV has too short a wheelbase, a jackknife might result. This situation might be the more dangerous because an articulation of a few degrees can exist at or near highway speeds. This HA phenomenon could explain how the "Hensley jackknife" occurred.

The other phenomenon (which you have called, "hitting the stop") is likely to occur only at lower speeds because it requires an articulation angle of 15 degrees or more. At an articulation of more than 10 degrees, the HA's VPP has moved rearward close to the location of the ball coupler. This means the HA now is acting pretty much like a conventional hitch -- TT forces are being applied very close to the ball coupler. Except, there is one very important difference. If the TT is pushing against the HA and if there is "collapse" of the linkage, the "hitting the stop" will cause an impact load which can be considerably greater than the static push from the TT. It sounds very much as though this second HA phenomenon is what Garfie|d experienced.

Ron