Given my school-boy French, I am not quite sure what unique invention this patent claims. However, it does include some nice drawings of various deraileurs - most notably the Huret Course Compétition.

• Publisher: L’Institut national de la propriété industrielle
• Inventor: André-Maxime Huret, Roger-Henri Huret and Jacques-André Huret
• Country: France
• Date: French application March 1946
• Derailleur brands: Huret
• Derailleurs: prototype Huret Dural Competition, Huret Course Compétition, Huret Route Touriste