After reading all the fine details about roll changers that have been
posted, it might be nice to see two of them in operation.  Art Reblitz
and I collaborated to post a YouTube video of a very nicely restored
Wurlitzer CX, which his shop did.  Art wanted some detailed shots of
the changer in action, and we were able to do that.  Art's camera
delivered fine HD pictures, and we cut the action down to the most
salient aspects of that wonderful mechanism.  You can see this top
drawer restoration in action at

  http://www.youtube.com/watch?v=omoos87WEPg 

On my web site featuring Aeolian organ Opus 1280, I have posted a short
movie that demonstrates the Aeolian Organ Concertola.  The video predates
HD camcorders, but it still shows the basic operation clearly.  Watch
using QuickTime player at

  http://www.aeolianorgan.com/aeolian/Movie.html 

The unique feature of the Aeolian changer was that it did not require
a special roll.  Wurlitzer changers required a roll with the loading wire
rod permanently attached to the roll leader.  On the Aeolian, the rods
were part of the changer mechanism.

But that feature was also a big headache.  The rods were held in the
rotating drum by spring clips.  To engage the spring clips after rewind,
the roll had to move briskly resulting in a sudden stop when fully
rewound, which could cause the roll tab to tear off.  Slowing the
rewind speed to save the tab often resulted in incomplete spring clip
engagement.  Then as the drum revolved, the rods fell out and dangled
down inside.  What happened next was unpredictable, but as the rod
moved about, various jambs would occur.

Two air motors drive the Concertola: one is for drum movement, and the
other is for play and reroll.

Art mentions the late patent by Tolbert F. Cheek assigned to Aeolian in
1934.  That patent eliminated the rods.   A  "wand" arm pulled the
roll, by a special tab, down to engage the take-up spool.  The system
worked, but very few mechanisms were sold.

Bob Taylor
Missouri