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
The following quotes come from the "Snow and TT" thread. Since Ed's comments pertain to how the HA works, I am responding here rather than hijack the other thread.
Ed,
When a bow wave exerts a right-directed force on the rear of your TT, the TT responds by exerting a left-directed force on the TV. With a conventional hitch, the force is applied at the ball. The force will push the rear of the TV to the left and the relatively large resulting steering moment will cause the TV to yaw CW. It is primarily the yaw which is sensed by the driver.
With the HA, the lateral force from the TT is applied to the TV at a point closer to the TV's rear axle. The steering moment is considerably reduced and the yaw of the TV also is considerably reduced. The yaw might be reduced enough that the driver does not notice it.
As for the TV seeming to be more stable when towing, this could be due to the TT acting as a "yaw damper" for the TV. In order for the rear of the TV to be pushed to the right, the TT must undergo a CW yaw. The TT's yaw moment of inertia will resist the lateral push from the TV. This resistance will counter some of the bow wave force on the TV. Therefore, the response of the TV should be less when towing. At least, that's how I figure it.
Ron
bettered wrote:Ron Gratz wrote:
When a large truck passes a TT, the first interaction comes from the truck's bow wave. This results in a force which tends to pushes the rear of the TT away from the truck.
If a sway control "stiffens" the connection between TV and TT at the ball, the TV's rear tires and the TT's tires can work together to resist the push on the TT. If there is no "stiffening" of the connection, the TT's tires must provide all of the lateral resistance to the bow wave.
Ron
Interesting observation. With my hitch, I don't get that "initial" wave at all. Zip. The only push I feel is when the bow wave hits the front of my TV as the big guy passes me. Even then it's less of a blip when I'm towing than when I'm not. The whole rig seems more stable towing with the Hensley than not towing at all. Go figure.
Ed,
When a bow wave exerts a right-directed force on the rear of your TT, the TT responds by exerting a left-directed force on the TV. With a conventional hitch, the force is applied at the ball. The force will push the rear of the TV to the left and the relatively large resulting steering moment will cause the TV to yaw CW. It is primarily the yaw which is sensed by the driver.
With the HA, the lateral force from the TT is applied to the TV at a point closer to the TV's rear axle. The steering moment is considerably reduced and the yaw of the TV also is considerably reduced. The yaw might be reduced enough that the driver does not notice it.
As for the TV seeming to be more stable when towing, this could be due to the TT acting as a "yaw damper" for the TV. In order for the rear of the TV to be pushed to the right, the TT must undergo a CW yaw. The TT's yaw moment of inertia will resist the lateral push from the TV. This resistance will counter some of the bow wave force on the TV. Therefore, the response of the TV should be less when towing. At least, that's how I figure it.
Ron
