Hensley Arrow: How does it REALLY work?

TeryT wrote:
I'm confused: If it doesn't lock up on the trailer side, what explains the fellow in the video pushing on the side of Hensley model mock-up? Is he not pushing that hard?

Actually in my experience I know it doesn't lock, as I've seen the trailer moving somewhat, while not feeling it much in the TV. But I still wonder about that video & why it appears locked up.

Tery,

The guy is pushing at a point between the "TT" wheels and the hitch. Part of his push is distributed to the "TT" wheels and part to the hitch. The lateral force which goes to the hitch is applied to the "TV" very close to the "TV's" rear wheels due to the forward projection of lateral force by the HA's linkage. The front wheel on the "TV" is either a caster wheel or a wheel fixed at 90 degrees to the longitudinal axis of the "TV" and it cannot resist any lateral force.

Two things could cause the "TT" to swing relative to the "TV" under the test conditions:
1. The rear wheels on the "TT" could slide to the right relative to the "TV". However, the lateral push on the "TT" wheels is not sufficient to overcome the static friction forces on those wheels.
2. The rear wheels on the "TV" could slide to the right relative to the "TT". However, the lateral push on the "TV" rear wheels is not sufficient to overcome the friction forces on those wheels.

If the "TV's" rear overhang were representative of real life (i.e. the point of application of lateral force being about 2' behind the "TV's" rear wheels), then the guy's push would cause a CCW torque on the "TV" and it would yaw CCW because the front wheel would offer no resistance.

Since the non-representative test fixture causes the "TT" lateral force to be applied at the "TV's" rear wheels, there is no moment which would cause a relative yaw between the "TT" and "TV. Since there is no moment, there is no yaw and the hitch appears to be "locked".

Ron