[VAC] Electrical actuators & airstream Brakes etc.

["Carol and Oliver Filippi" <ofilippi@xxxxxxxxxxxxx>]

Chris,

There will be a lot more electrically actuated components on future
vehicles.

The planned introduction of a high voltage electrical system (I can't recall
the voltage off hand) is the handwriting on the wall.  This technology is
much more compatible with computer control, but with 12 volts it is hard to
build any powerful direct electrical  actuators, hence the higher voltage
level.  Meanwhile, we'll have to live with the old electrically activated
drum brakes.

The disk brakes on the late 70's Airstreams were less than great design, and
of course required a vacuum tank to provide the power boost to generate
sufficient pressure to the disk brake caliper pistons.  If you stay with
disk brakes, you are going to have to generate some very high forces (and
pressures) to make them work.

Drum brakes do not require high actuating forces to function.  Rather, they
get their stopping power from the force generated by the friction of the
forward brake shoe against the drum, which is then transmitted to the rear
shoe.  As goofy as the electromagnet actuated drum trailer brakes are, the
do work very well and are simple.  If a new technology replaces this, it
will have to be simple, reliable and modest in price - a tall order for any
product.

Obviously, if one extends the hydraulic brake line from the tow vehicle to
the trailer, and then  the line breaks, the tow vehicle's brakes go with it.
Thus any safe hydraulic system will have to isolate the tow vehicle's
hydraulic system from that of the trailer, yet couple them so far as changes
in pressure on the tow vehicle are concerned.  Until such a design is
available, connecting the tow vehicle hydraulic brake system directly to the
trailer brake system is a dicey proposition.

Oliver Filippi