Ruediger, one of the finest technical terms dictionary (German/English) that I found was from Siemens AG. Try the Erlangen R&D facility. However, I must admit, even with this dictionary, I ran into some terminology that gave us problems. The German word was "Liboka". This drove us nuts - even the Germans did not know what it meant. Finally, one person solved the riddle and explained to us the methodology of German abbreviations.
LIBOKA = LIcht BOgen KAmmer (Arc Chamber)
GESTAPO = GEshafts STamm POlitzie (Elite special police)
So, even with this dictionary, you may have your work cut out for you. Good Luck!