Do early self-leveling suspensions like those for the 450SEL 6.9
shown at: http://www.300sel.com/HydroSuspGuide.pdf
differ in concept from say that of an 1988 560 SEL?
Here's my guess at the differences (based on NO practical experience!) :
It seems to me that the early systems used the nitrogen cells as
springs, and dispensed with coil springs. Damping was achieved by orifices at the cells. The hydraulic struts were designed like hydraulic cylinders, with no damping orifices in the struts. There was fluid only on the top side of the piston.
This would contrast with the later system, where the struts had
damping orifices and the strut piston had fluid above and below it.
Conventional coil springs were used. The nitrogen cells did not
have orifices. The nitrogen cell would not function as a damper,
but would primarily serve for leveling response- maybe also as an auxiliary spring to some extent.
The above are simply assumptions, and I would like to know what's actually going on.