John S.

Actually a Helsley or Pullrite will "reduce" the tendency for the towed
vehicle to sway the towing vehicle, but it will not eliminate it, their
websites notwithstanding. They are a better solution that a standard
hitch because the pivot point is moved closer to the rear axle. A
fifth wheel places the pivot point between the wheels, thus further
reducing but not eliminating the ability of the towed vehicle to alter
the direction of the towing vehicle.



> I think you have it there. The TV is the driving force that keeps the sway
> going. And the reason that a 5th wheel or trailers using a Hensley or
> Pullrite hitch pretty much eliminate the problem.
>
> Suppose you pulled a badly loaded but small trailer behind a semi tractor.
> If the trailer deflected due to wind, the truck would not move and would
> pull the trailer back into position. But when pulled by a small vehicle,
> the rear of the TV would be pulled out of position. As it tries to pull
> the trailer back into position and straighten itself out it could put energy
> into the system causing the trailer to swing even further in the opposite
> direction. The rear of the TV also swings even further setting up an
> oscillation.
>
> I talked to a couple that had a new 30 foot trailer and new tow vehicle and
> were using a Hensley hitch. The previous year they started off on vacation
> with a similar set up except using a standard platform hitch. They got
> about 30 miles from home when the trailer began to sway and before they
> could react it rolled.