The Wurlitzer Automatic Roll Changer as it was installed in most
American coin pianos is a Ferris wheel type magazine, holding six
five-tune rolls which automatically thread and play sequentially after
each roll completes all five tunes.  A selector knob on the side of the
piano's case allowed a customer to pick the particular roll he wanted
_only_ if the last roll was finished playing and re-rolled.  If a roll
was between tunes or the piano was otherwise operating, this knob
remained locked and the customer was unable to select a particular
roll.  The piano then played the next tune on that roll.

Wurlitzer Automatic Roll Changer rolls have a special leader which is
not tapered to a hook like most piano rolls.  For automatic changing
purposes, the roll changer rolls are completely straight across the
end.  Inside the very end of the roll is trapped a thin wire which
runs completely across the it, and extending out about an inch and a
half from both sides.  It is with this wire across the leader that the
roll changer threads rolls.

At the end of the last tune on a roll, the machine goes into re-roll
just like any other roll mechanism.  However, in this case, the roll
comes completely off the take up spool and is then locked into place on
the roll magazine by a spring-loaded latch on each side of the
magazine.  This is done so the roll remains spooled tightly until it is
time to play it again, and also keeps the leader wire in position for
the roll changing process.

At this point, all the rolls are spooled into the magazine, and the
roll changer makes 1/6 of a revolution bringing the next roll into play
position, however not threading it, and the transmission shift back
into play.  If there are no other credits on the piano, the instrument
then shuts off, which through an interlock the selector knob on the
side of the case is unlocked, allowing the next customer to select the
roll he wishes to play, if desired.

By rotating the knob, the Ferris wheel magazine supporting the rolls
inside the piano is turned, bringing the roll the customer wants to
hear into playing position.  If no roll is selected by the customer,
then the next roll that the changer has already placed into position
will thread and play when the instrument is started.

If credits were left on the piano at the finish of re-roll, or if the
customer inserts a coin to start the piano, the process of threading
the next roll to play begins.  The roll magazine locks into position
simultaneously locking out the manual selector knob, and the take up
spool begins to turn.  The small latches on the sides of the roll
magazine are opened, allowing the leader wire to be freed.

The wire extending through the leader of each roll extends out past
the edges of the roll magazine itself, and small arms are positioned
on each side of the roll magazine to pull down on the wire of the roll
that is now in play position.  This process begins the threading of
the roll by guiding the paper down toward the take-up spool.  Slots
cut into the side flanges of the now-turning take up spool pull the
roll leader by its wire into it, wrapping the paper around the spool.

The piano then plays all the tunes on that roll before going into
re-roll and repeating the roll changing process automatically.  If the
piano were set to play free, the piano would play all the tunes on all
six rolls in sequence, changing the rolls automatically without
stopping.

John D. Rutoskey