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
Stressor wrote:
The pendulum analogy works, but the hitch is not like a pendulum linkage in that the TT ends of the linkage can only move side to side in response to a lateral force applied along the side of the travel trailer.
The TT end of the linkage (the rear, upper, orange part of the HA) can move side to side and also can rotate (yaw). In fact, it only can move if it simultaneously translates and rotates. This is exactly what a pendulum does. As any given point on the pendulum rod moves to the side, the rod simultaneously changes its angle relative to vertical. If a lateral force is applied to the TT, the TT will swing to the side until the yaw angle is sufficient for the tires to develop an equal opposing force via their slip angles.
How does the lateral force get transferred through the linkage from the travel trailer end to cause the VPP to move? And the answer is apparently that it does not, because the VPP does not move as a result of forces applied to the travel trailer. Where do the forces go? And how do they get there?
See above. A lateral force imposed on the TT causes it to yaw relative to the direction of travel. This changes the angle between TT and TV and it is that change in angle which causes the VPP to move. The lateral force on the TT produces the change of angle and the change of angle causes the VPP to move. Of course, steering the TV to a different heading also will change the angle.
If I replaced the Hensley Arrow with a rigid linkage, call it a Pullrite, would the forces be distributed to the same places in the same manner?
If the PullRite's pivot point were at the same location as the HA's VPP and the effective tongue lengths were the same, the answer is Yes. The PullRite does not provide a "rigid" connection between TT and TV because it allows pivoting at its actual pivot point. The HA does not provide a "rigid" connection between TT and TV because it allows pivoting at its virtual pivot point. Both hitches provide a rigid connection (within the capability of the struts) at the ball coupler; but the pivoting which otherwise would occur at the ball simply occurs at a different location.
Ron
