Hensley Arrow: How does it REALLY work?

bettered wrote:
Hi Ron. I don't know how he could have made both brackets slip if they were properly installed. Once the compression force was relieved on the one side (by the bracket slipping) there would have been nothing in compression on the slipped side to force the other side bracket rearwar.

The actual shear capacity of the bolts is not particularly meaningful because the torque on the U-bolts is what restrains the brackets. The shear bolts have no practical mechanical function. They are extremely mild steel on purpose.

Ed,
The brackets were not properly installed. The shear bolts were not in place. The HA instruction manual states:
"CAUTION
In some cases, damage to the struts can occur if:
Shear bolts are not in place."
and
"---The frame brackets are designed to slide when too much force is put on them from the strut bars. If the brackets don’t slide then it’s possible for the strut bar to be damaged."

This means to me that, in addition to whatever frictional resistance to sliding is developed by the clamping force from the U-bolts, the shear bolts are intended to supply an additional amount of sliding resistance limited to their combined shear capacity.

If the 5/16" shear bolt is Grade-2 rather than Grade-5, it still will have an ultimate shear capacity of about 3000 lbs (or 6000 lbs for two bolts). The bolts do have a practical mechanical function as Don found out when he towed his trailer without them.

If one bracket moves rearward, then the struts are loose and the HA's linkage can "flop" around. If the loose struts allow the linkage to shift to the right, TT thrust can overload the left bracket causing it to move rearward. If the linkage shifts to the left, the right bracket can be overloaded. Both brackets can be pushed rearward.

Ron