Thanks to all the posters so far. There seems to be two common threads running through the comments:
Sway Control Systems are a "safety" apparatus that IS necessary
and those that say:
There nice to have but not really necessary with the right rig and set up. So why not use one?
What brought this to my mind was the disconnect between the relative weights of a class 8 tractor vs it's fully loaded 53'trailer and the relative weights of the average Travel Trailer setup. And the fact that our parents and their parents often towed large heavier trailers with just a stock sedan.
Your average Class 8 tractor weighs in at somewhere between 16k and 20K LBS. The trailer fully loaded would weigh between 60-65K This all together would give you a fully loaded 80k# vehicle. (approx)
That means that 60,000 lbs can be safely towed by a vehicle that weighs one third as much. I don't believe that the physics change as the numbers decrease. Of course there are many differences in the set ups of these two vehicle types. (pivot point to the trailer axle CL (center line) is the most important) But essentially they are a tow vehicle and a trailer.
My Dodge P/U weighs in at 9000# my trailer at 6292 empty and 8000# fully loaded...Maybe this is why I dont need sway control. But even if you have a big 5th wheel and a 3/4 ton p/u you should still be within the 1/3 - 2/3rds of the scenario above.
As for Tractor trailers swaying on the road. Doubles and triples do sway but it's because they are attached with two pivot points very close together and a steerable (ie turning) axle under the front of the trailer (s). Wind will definitely move a 53 foot trailer sideways, but I dont consider that "Sway" That is wind effect working on a gigantic sail made up of the side of the trailer. Sometimes empty a trailer will bounce from side to side on an uneven road surface but that isnt sway either.
So I am interested in what REALLY causes sway in these recreational rigs.
My guess is uneven loading, too short a distance from Pivot point to C/L of trailer axle, driving habits.
I notice that the European and Australian trailer tongues are quite a bit longer than most of ours and this would help reduce the tendency to sway as it increases the distance from pivot point to axle C/L. If you look at most older trailers from the 50's and 60's you will note that the axles on virtually all of them are much further back than the modern ones. This I believe is one reason many of those older trailers, which were quite heavy, could be towed by your average sedan.
After WWII my entire extended family, Mother, Father, Aunts and Uncles and Grandmother emigrated from Michigan to Southern California and they all pulled a house trailer as they were called then. My grandmother drove her '32 ford coupe pulling a quite big trailer...all the way down Route 66 to San Bernardino, Calif. No body had a sway control system....so what has changed? We have much bigger tow vehicles, lighter trailers, six or 8 speed transmissions instead of three or four, Were using huge diesel engines instead of a flat head six...It just doesnt add up to me.
