Hensley Arrow: How does it REALLY work?

I have read through most of the thread again tonight and am of the opinion that we may all be on the same page as far as how the HA works except on one point…the VPP. Maybe it’s my misunderstanding, but I don’t think that the VPP is relevant to the way that the HA prevents sway. To me the VPP, as Tim, and Ron have explained it is just the intersection point of the sides of the trapezoid as the linkage moves through its range of motion. Please don’t take this as a knock, but rather as my misunderstanding of this part of the theory. Feel free to try to explain the VPP, and it’s affect on sway control to me, in terms that I might understand, and I’ll try to explain my thoughts to you in a way that you might understand. While I’m not an engineer, I have been a CAD operator for nearly 15 years doing design and CNC programming, and I was a machinist for more than 10 years before that, so I’m no stranger to mechanics and mechanical principles. Linkages are used to control, restrict, or enhance motion. I think I have a pretty good understanding of how the HA works, but I can’t get the VPP part of it. I too have mounted up my HA and played with it to “see what makes it tick”, and it does move exactly as Tim illustrates in his drawings. I just believe that the design of the linkage that limits the TT’s ability to cause sway, not the VPP.

Please don’t be offended by anything that I’ve said, I’m just trying to help provide a clear understanding of how the HA works for everybody, myself included.

Dave