[A/S] Re: Thanks to everyone!

["FKlingener" <jfklingener@xxxxxxxxxxxx>]

> ...
> I had anticipated that I might need or want some sort of sway 
control hitch.

When we discuss these things, it's good to differentiate between 
'weight equalization' and 'sway control' devices.

The former are fundamentally spring systems that apply a torque across 
the hitch.  Their net effect is to decrease the static load on the 
rear axle of the tow vehicle and distribute it between the trailer 
axle(s) and the front axle of the tow vehicle.  They have no damping 
beyond inherent friction of their parts.

'Sway control' devices usually have some damping function that resists 
'sway.'  When people say 'sway' they're usually talking about an 
oscillation in yaw (the heading angle viewed from above) between the 
trailer and the tow vehicle.  Word niceties aside, everyone recgnizes 
sway when they're trying to control a tow rig.

It's an unhappy situation, because the weight distribution systems 
will seem to 'control sway' in combinations that that otherwise have 
too much weight on the ball.

> ...  but I see that there are many
> different choices available.  I'm sure when you are pulling a 25' to
> 30' rig, sway control takes on a whole new dimension!!  The Bambi 
19"
> grosses only 4500 lbs, which is not terribly intimidating.  On the
> other hand, my half-ton, short bed pickup is not the beefiest tow
> vehicle out there, either.

My 16'CCD/Jeep Cherokee is practically undrivable without the Reese 
load-equalization hitch (http://www.reese-hitches.com/
hi_pef_trunnion_bar_wd.htm), but sway control would be useless.

The things that dominate the yaw oscillation model (the things that 
determine whether you'll have white knuckles crossing the high bridge 
with oncoming wide loads) are the yaw moments of inertia of the 
vehicles (which go as the square of the length) and the wheelbase of 
the tow vehicle.  

It's hard to generalize.  I think the best that can be done is to ask 
for advice places like this as long as everyone speaks the same 
language.  It'd be particularly helpful to provide URLs to the 
equipment you're discussing.

Hth,
Fred Klingener