Hensley Arrow: How does it REALLY work?
There have been several discussions on this hitch that have become somewhat 'controversial'. I am NOT trying to stir this controversy/bashing back up. Instead, I'd like to see a good, intelligent di...
Forum Discussion
Tim,
I hope that you’ll stick around; I can see that you’ve invested a lot of time and energy into this thread, and I appreciate your efforts, as I’m sure that everyone following does. Try not to get too stressed out by those of us who are not engineers challenging your ideas, but also try to keep an open mind. It seems to me that Stressor and I are of very similar opinion as to how the HA works, while you and Ron are of a slightly different opinion. Maybe the truth about how the HA works lies somewhere in between all of our ideas.
Thanks for posting the link to your model video; I think it gives me a much clearer idea of how your theory works. Please allow me to explain where I think that the flaw in your theory lies. In your video model you allow too many degrees of freedom. There are several types of 4 bar linkages, most usually have anchor points to restrict unwanted movement. In your example you allow full unrestricted movement of the linkage by anchoring it only by pivot points at the midpoint of the top and base of the trapezoid. In the HA this is not the case. To demonstrate you’d have to glue or fasten perpendicular members to the model at the midpoint of the base and top of the trapezoid, then move the model again the same way you did before, and watch how wildly the perpendicular members move back and forth. Now for the TT or the TV to be able to move in this fashion they would need to have swiveling casters for wheels. Since the wheels on a TT don’t swivel, they act as an anchor point that is attached to a 20’ (based on TT size) lever arm. Based on that premise if you go to your model again and pin down the TT end of the hitch so that it can not pivot (based on our new anchor point) and apply inward force to either the upper left or upper right corner of the trapezoid in a direction that approximately bisects the corner that you have chosen you see motion that is the same as that of an HA Remember not to pin down the TT end of the model so tight that there cannot be motion as needed through all 4 pivot points in the linkage. The resulting motion is a little bizarre, but the way that the HA moves is a little bizarre.
I realize that I’m a Johnny come lately on this thread, but that is only because I didn’t know it existed, or I definitely would have been here for the duration.
MacMan I too would be interested to see what the Hensley engineers would have to say about our thread.
Dave
I hope that you’ll stick around; I can see that you’ve invested a lot of time and energy into this thread, and I appreciate your efforts, as I’m sure that everyone following does. Try not to get too stressed out by those of us who are not engineers challenging your ideas, but also try to keep an open mind. It seems to me that Stressor and I are of very similar opinion as to how the HA works, while you and Ron are of a slightly different opinion. Maybe the truth about how the HA works lies somewhere in between all of our ideas.
Thanks for posting the link to your model video; I think it gives me a much clearer idea of how your theory works. Please allow me to explain where I think that the flaw in your theory lies. In your video model you allow too many degrees of freedom. There are several types of 4 bar linkages, most usually have anchor points to restrict unwanted movement. In your example you allow full unrestricted movement of the linkage by anchoring it only by pivot points at the midpoint of the top and base of the trapezoid. In the HA this is not the case. To demonstrate you’d have to glue or fasten perpendicular members to the model at the midpoint of the base and top of the trapezoid, then move the model again the same way you did before, and watch how wildly the perpendicular members move back and forth. Now for the TT or the TV to be able to move in this fashion they would need to have swiveling casters for wheels. Since the wheels on a TT don’t swivel, they act as an anchor point that is attached to a 20’ (based on TT size) lever arm. Based on that premise if you go to your model again and pin down the TT end of the hitch so that it can not pivot (based on our new anchor point) and apply inward force to either the upper left or upper right corner of the trapezoid in a direction that approximately bisects the corner that you have chosen you see motion that is the same as that of an HA Remember not to pin down the TT end of the model so tight that there cannot be motion as needed through all 4 pivot points in the linkage. The resulting motion is a little bizarre, but the way that the HA moves is a little bizarre.
I realize that I’m a Johnny come lately on this thread, but that is only because I didn’t know it existed, or I definitely would have been here for the duration.
MacMan I too would be interested to see what the Hensley engineers would have to say about our thread.
Dave
