My guess is it works the same way as Deadly Dave's, aldot: you need to unscrew that lock ring, then the two drive plates and clutches can slide sideways off the square that is driving them. I think your shaft is probably similar to Dave's, but they used lock rings instead of hexagonal nuts to retain the clutches. Is there a thread protruding slightly on the other side of the clutches as well as the one you have shown? That would make it even more likely your shaft design is the same as Dave's. If so, you might be able to use nuts when you reassemble it.
