[A/S] Re: Overload Devices On Tow Vehicles

[Max Hicks <maxhicks@xxxxxxxxx>]

In 1970, Caravanner Insurance Company, the insurance
division of Airstream, did a study on "why were loss
of control" accidents happening?
They reduced 10 years of data on that type of loss,
that came from over 1,000 "loss of control" accidents,
specifically towing an Airstream trailer, of any
length.
They concluded that "ANY" rear end suspension
modifications, such as air shocks inflated more than
minimum, air lifts inflated more than minimum, load
levelers and overload springs, would "defeat" the
purpose of a "load equalizing hitch." 
Actual duplications of rigging setups were made, and
then the tow vehicle front and rear axle weights were
made along with the trailer weights.
Those weight measurments, conclusively proved, that
rear end suspension modifications that beefed up the
rear end (fulcrum) defeated a proper rated, properly
installed load equalizing hitch. 
They then set out to predict future results of that
type of rigging, which continued to prove their
original conclusion.
Simply measuring the weights of both tow vehicle
axles, with the trailer attached, answers the
question.
They also came up with a formula, and proved it to be
correct.
That formula is, that the rear axle weight cannot be
more than ten percent of the tow vehicle gross weight,
heavier than the front axle. 
That is to say that if the tow vehicle total weight
with the trailer hooked up, was 6000 pounds, then the
maximum rear axle weight could be no more than 3300
pounds and the front axle should be no less than 2700
pounds. Actual test results demonstrated that if these
weight ratio's were adhered to, then a loss of control
accident would not "likely" occur. Part of the test
set up utilized a device called "Safety-Tow." It would
indicate instability, however slight, AND,
automatically apply the trailer brakes, before a
complete loss of control could take place. Some 19
patents were issued for the "Safety-Tow.  
Inflating air lifts or air shocks, will shift these
weight ratio's considerably, as well as overload
springs, of any form.     Max