Sounds like something that might be associated with the "Tank" style of "freehub". This is an old French brandname and there were several companies that made versions of it under license, Cyclo being the largest (maybe) but Maxi-Car and others, too.
It would be much more useful to not rely on written descriptions but to post some pictures of the thing, shot from both sides. That might ring bells with folks who don't know it by this Merveille brand but have seen another version of it.