….I raised the issue of the Al-ko ATC system because the way it works is an insight into snaking.
It senses an abnormal lateral force present in the caravan and applies all of the caravans brakes at the same time.
The force this creates is one of tension on the tow ball of the tow car.
I maintain that the harmful forces present at the tow ball during a snake are forces of compression relative to the tow car and they are expressed laterally.
The caravan is forcing the rear axle of the tow car offline as I have said before.
Do not underestimate these forces, they are forces of inertia arising from yawl oscillations set off by external influences.
These may be aerodynamic or mechanical (bow waves, side winds, ruts, steering input, etc)
Poor loading of the caravan will amplify these forces.
Hence the often given advice against placing heavy loads at the front or back of the caravan.
The ATC counteracts these harmful forces of compression by applying tension on the tow ball, the snake decays causing the brakes on the caravan to be released.
If you watch this video you will see that during snaking, the rear axle of the model tow car is thrown off line as I describe.
It does not remain virtually rock steady as you suggest.
http://www.youtube.com/watch?v=PFzrWHTG5e8
I maintain that
if the rear axle of the tow car could be made to remain rock steady and not move off line then the snake could not happen.