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
What a great thread!!
I’ve been lurking around this and other similar forums for several years trying to dig up any information that I can find regarding how the HA works. This is the first time I’ve felt compelled to jump in (Long time listener…First time caller). I think that this is the first HA thread that I’ve ever seen on any forum that has had so many people working together to understand this hitch. I was up until 3:30 AM last night following this thread.
To date I have spent numerous hours contemplating how this hitch works, and I have a theory that I’d like to bounce off all of you to see if there might be any validity to it.
Here goes… I think that the virtual pivot point, or projected pivot point is a mistake in the theory of how this hitch works, in my opinion there is no VPP or PPP. In my theory there are 4 pivot points, each of which move together in a way controlled by “linkage design” to allow turning initiated only by the TV not the TT.
Simple to say, a little more difficult to explain…
If you look at the 4 bar linkage diagrams posted several times above (sorry don’t know how to post a diagram), and ignore the theoretical pivot point part of them. Now look at the trapezoid linkage shape in the straight diagram, and compare that to the trapezoids shape in the turning diagram. Notice how the right side linkage collapses to the left when a right turn is initiated by TV (top of the trapezoid rotating CW), try to imagine how the same thing will occur with the left side linkage when the TV initiates a left turn (top of the trapezoid rotating CCW). The explaining gets a little more difficult from here. If you imagine trying to initiate a turn in either direction with the TT, notice that the force created by turning the TT(base of the trapezoid CW or CCW) causes a force that would be pushing directly on the linkages. The trapezoid CANNOT collapse like when turning is initiated by the TV. I make this motion easier for myself to visualize by imagining picking up the TV and turning it with a hinging type motion at the trapezoid, then by doing the same thing with the TT. With the TT the hinging can’t occur. Within this visualization turning motion created by the TT (base of the trapezoid) is eliminated causing the TT to follow behind the TV like a box truck. Not to say that cross winds cannot affect the TV/TT combo, but it will be handled more like a box van or straight truck.
The pictures of the “model” above(the ones with the man) came from the Hensley video, in that video he effortlessly turns the TV part of the model while no turning motion at all can be initiated by the TT part of the model(like a straight truck or box van). The motion that he can and cannot apply to the model is not influenced by the wheel positions or caster types or angles, but by the hitch linkage design.
By the way I just bought a HA off EBay a couple of weeks ago and am really looking forward to using it. First trip is July 4th to the Outer Banks, about an 8 hr drive from here, should be a good test.
Feel free to let me know what you think of my theory, or ask for more info if I wasn’t clear enough (sleep deprived). I’m sure that we can figure this out.
Thanks for your time,
Dave
I’ve been lurking around this and other similar forums for several years trying to dig up any information that I can find regarding how the HA works. This is the first time I’ve felt compelled to jump in (Long time listener…First time caller). I think that this is the first HA thread that I’ve ever seen on any forum that has had so many people working together to understand this hitch. I was up until 3:30 AM last night following this thread.
To date I have spent numerous hours contemplating how this hitch works, and I have a theory that I’d like to bounce off all of you to see if there might be any validity to it.
Here goes… I think that the virtual pivot point, or projected pivot point is a mistake in the theory of how this hitch works, in my opinion there is no VPP or PPP. In my theory there are 4 pivot points, each of which move together in a way controlled by “linkage design” to allow turning initiated only by the TV not the TT.
Simple to say, a little more difficult to explain…
If you look at the 4 bar linkage diagrams posted several times above (sorry don’t know how to post a diagram), and ignore the theoretical pivot point part of them. Now look at the trapezoid linkage shape in the straight diagram, and compare that to the trapezoids shape in the turning diagram. Notice how the right side linkage collapses to the left when a right turn is initiated by TV (top of the trapezoid rotating CW), try to imagine how the same thing will occur with the left side linkage when the TV initiates a left turn (top of the trapezoid rotating CCW). The explaining gets a little more difficult from here. If you imagine trying to initiate a turn in either direction with the TT, notice that the force created by turning the TT(base of the trapezoid CW or CCW) causes a force that would be pushing directly on the linkages. The trapezoid CANNOT collapse like when turning is initiated by the TV. I make this motion easier for myself to visualize by imagining picking up the TV and turning it with a hinging type motion at the trapezoid, then by doing the same thing with the TT. With the TT the hinging can’t occur. Within this visualization turning motion created by the TT (base of the trapezoid) is eliminated causing the TT to follow behind the TV like a box truck. Not to say that cross winds cannot affect the TV/TT combo, but it will be handled more like a box van or straight truck.
The pictures of the “model” above(the ones with the man) came from the Hensley video, in that video he effortlessly turns the TV part of the model while no turning motion at all can be initiated by the TT part of the model(like a straight truck or box van). The motion that he can and cannot apply to the model is not influenced by the wheel positions or caster types or angles, but by the hitch linkage design.
By the way I just bought a HA off EBay a couple of weeks ago and am really looking forward to using it. First trip is July 4th to the Outer Banks, about an 8 hr drive from here, should be a good test.
Feel free to let me know what you think of my theory, or ask for more info if I wasn’t clear enough (sleep deprived). I’m sure that we can figure this out.
Thanks for your time,
Dave
