I believe that Torpedo derailleurs were copies of German Fichtel & Sachs derailleurs possibly manufactured under license in Italy. Two companies seem to be involved, both based in Milano Italy. I am a little unclear about exactly what role each company may have played:

• From about 1950, the Italian distributor for Fichtel & Sachs was a company called Enea Rossi. This company still exists. I have seen various pieces of literature issued by Ebea Rossi that prominently feature the brand Torpedo but seem careful not to mention Fichtel & Sachs. Of course, Torpedo was a sub-brand that was widely used by Fichtel & Sachs in the German market, but, unlike the Italian products and literature, both the German Torpedo products and the relevant German literature also prominently featured the words Fichtel & Sachs.
• Erlotti also produced immaculoate copies of Fichtel & Sachs derailleurs. These are branded 'Erlotti licensed from Fichtel & Sachs'.