This is the first of two patents filed by a Boris Mikhailov who appears to work for a mysterious body called Enterprise P/I B-8916 (ПРЕДПРИЯТИЕ П/Я В-8916). To add to the mystery, Enterprise P/I B-8916 held a number of other highly specialist scientific patents that seem completely unrelated to bicycles. As far as I can tell, Enterprise P/I B-8916 may have been based in Zheleznodorozhny, an eastern suburb of Moscow. The word ‘Zheleznodorozhny’ means something like ‘Railway’, and the local railway station is famous as the one at which Anna Karenina threw herself under the wheels of a train - a snippet of knowledge that you should feel free to use to impress your friends at all those literary supper parties that you undoubtedly attend.
This patent appears to be for a variant of Suntour’s Quick Cage, that allows you to quickly and easily remove the chain from the derailleur. I can’t add much to this, except to comment that the base derailleur design seems to owe something to the Huret Eco (2490), and the inventor clearly has a love of Origami.
Finally, and bizarrely, the patent makes reference to page 158 of Fred DeLong’s 1974 ‘DeLong’s Guide to Bicycles and Bicycling’ although it calls him ‘Tred De long’.