Originally Posted by lz4005
There is some info on them at
http://www.sheldonbrown.com/harris/schlumpf.html and more if you follow the links to the manufacturer's site. They are an internal planetary gear.
In the manufacturer's faq section they specifically say they will not work on fixed gear bikes. The reverse pressure will esplode them or something. Would be great for a 700c coaster bike, though.
Coaster brake? I'd imagine the backward pressure from coaster brakes would do the same exploding.
If you meant SS freewheel then that seems OK.