This is a registration for a ‘Utility Model’ - a kind of patent-lite. It covers a, rather fanciful, rack-and-pinion, Triplex derailleur and dates from 1943 - making it the earliest record of a Triplex derailleur that I have yet seen.

• Publisher: Oficina Española de Patentes y Marcas
• Inventor: Antonio Bascarán
• Country: Spain
• Date: Priority date December 1943
• Derailleur brands: Triplex
• Derailleurs: unknown