[VAC] Re: Brake controllers

["Harvey Barlow" <harveybarlow@xxxxxxxxxxxxx>]

Bob,

Most vintage Airstreams are presently being towed by modern tow vehicles or
were towed with one prior to being acquired by their current owners so most
have probably already had their umbilical cords converted.  The only ones
that will likely be exceptions are vintage trailers that are towed behind
vintage tow vehicles.

The term "hydraulic brake controller" can be easily misunderstood.
Airstream may have once offered trailers that actually had hydraulic brakes
that tapped into the tow vehicle's braking system.  I believe Airstream also
offered trailers with vacuum operated brakes some years ago.  As far as I
know, current offerings and most of the old ones still in service use
electric trailer brakes.  Tow vehicles must provide 12 volt power with a
capability of approximately 3 amps per trailer brake when braking is
desired.  That is done by a brake controller that senses application of
truck brakes and applies trailer brakes.

The question is how the brake controller is actuated.  Most currently
available brake controllers use the tow vehicle's stop light switch to
activate an electronic circuit which switches 12 volt power with high
current capability to the trailer.  Some current offerings use a cable
attached to the tow vehicle's brake pedal arm to manually operate a rheostat
in the brake controller.  The old-fashioned Kelsey-Hayes brake controllers
that have been discussed several times recently tap into the tow vehicle's
hydraulic brake line.  Hydraulic pressure routed to the K-H controller
actuates an electric rheostat which provides measured trailer braking.

All will provide trailer braking on demand and will work with utility
trailers, cargo trailers, horse trailers, or travel trailers using electric
trailer brakes.

Opinions differ on which type of brake controller works best.

Harvey Barlow