There are a number of U.S. patents for roll changers.  The patents
for the Wurlitzer roll changer and the Aeolian Concertola are in
Class/Subclass 84/120 Music/Instruments/Automatic/Selectors/Plurality
of Sheets/Single Tracker.  The Wurlitzer roll changer is patent number
1,110,001 patented September 8, 1914 and the Aeolian Concertola are
Patent Number 1,808,808 patented June 9, 1931 and Patent Number
1,984,462 patented December 18, 1934.

These patents can be viewed in Google Patents and if you have the
appropriate TIFF plug-in for your browser they can be viewed and
downloaded from the U.S. Patent and Trademark Office web site.

Joe Orens