Active suspension

[dmiller@iea.com (Doug Miller)]

>In a message dated 97-01-22 12:39:29 EST, you write:
>
><< Is this a TRUE active suspension? >>
>
>Not by your stated definition.  My recollection is that it actively, and
>quickly, switches between two hydraulic circuits which control damping and
>spring rate.  It is active in responding with spring and damping rates
>appropriate to changing road conditions, but it is still a passive victim of
>what ever the road throws at it.


Yes, that would be more likely for public consumption. *Nobody* has put a
true active suspension on the street for the consumer.  A true active
suspension must be able to power the tire/wheel assemblies both up and down
with its own energy at high cycle rates.  All the systems so far (many
labeled "active") are traditional suspensions that can vary the damping
rates (typically changing orifice sizes in the shock for different flow
resistance) and/or the spring rates (more complex and more expensive).  The
Citroens could independently "lift a leg" for tire changing, but this was
not a system designed to interact with the road surface under way (puttin'
on the Nomex suit against flames ;-)  ).

The amount of horsepower required to power such a system is pretty draining
for a typical car. The Active Corvette (Lotus technology used) I have
driven and worked with took over 30hp in steady state, and the computer
took up 50% of the available rear luggage space.  A pretty severe penalty,
and it ensures that such a system would probably appear on a car with
plenty o'power.


Doug Miller
dmiller@iea.com
97A6Q Wagon, 93 LandCruiser w/diff locks (and well used skidplates), 71
LeMans Sport V8 Convertible.