The SACIE Trionfo is a nicely made, single-pulley, pull-chain, derailleur somewhat reminiscent of the derailleurs that Fichtel & Sachs manufactured from the early 1930s. These derailleurs were licensed for production in Italy by a company called Erlotti that produced derailleurs under the Torpedo brand name. These Torpedo derailleurs were manufactured in quantity and were amongst the commonest derailleurs in Italy during the 1940s and early 1950s. It would be natural for others to produce something similar but not identical - hence the SACIE Trionfo.
I have no real information about the date of this derailleur. It could date from any time from the mid 1930s until the mid 1950s. My guess, based on very little, is that it dates from around 1950. It is stamped with 'SACIE' on the cable stop, 'SACIE TRIONFO' on the wing nut and on the outside of the main arm, and 'Brevetto N. 1819' on the inside of the main arm. Unfortunately, the website of the Italian Patent Office is everything you would expect from an organ of the Italian State - being achingly stylish, but utterly function-free, and you cannot search online for any clues arising from the phrase 'Brevetto N. 1819'. Five stars - but no useful movement.