Automatic music roll changers are complex and fascinating mechanisms
that are quite reliable when restored carefully.  I've been studying
U.S. patents as part of my research for the new book on coin pianos
and orchestrions that Dave Bowers and I are co-authoring.  My shop
has also restored 25 roll changers of various brands over the years,
giving insight into their mechanical design.

In response to recent postings regarding roll changers, I thought
it would be fun to write a brief history here.  I'd like to thank
Dave Bowers, Glenn Grabinski, Terry Hathaway, Juergen Hocker, Thomas
Jansen, Dana Johnson, and Rusty King for sharing much information
with me.

_Types of Changers_

Each manufacturer of automatic roll changers had its own patents
with different patentable concepts, and manufactured the changers
(or machined and assembled the parts) in-house.  Two basic types of
roll changers were made in quantity: those with one take-up spool
(Wurlitzer, Philipps, Hupfeld, and the Aeolian Concertola), and
those with a separate take-up spool for each roll (National Automatic
Music Co., installed in National roll-changing pianos and Welte
Multi-Reproducer attachments for reproducing pianos and organs).

Most roll changers had a roll storage magazine in the shape of
a Ferris wheel, so that concept was common to most of the different
companies' patents.  What differed were methods of handling play,
rewind, change, and shutoff.

_Wurlitzer_

Wurlitzer licensed U.S. patent #769,671 from William Verstraelen
and Christian Alter, both of New York City.  This patent was for
an automatic self-playing zither with a Ferris wheel roll magazine,
filed in September 1903 and granted in September 1904.  No extant
device resembling the patent drawings is known to exist.  Perhaps
Wurlitzer licensed the patent thinking it would offer protection
against other domestic companies making roll changers, although
Philipps and Hupfeld concurrently manufactured roll changers with
Ferris-wheel roll magazines with different controlling mechanisms.

The Wurlitzer-made six-roll changer was covered in detail by U.S.
patent #1,110,001, filed by Wurlitzer employee Frank McCormick in
September 1912 and granted in September 1914.  The first Wurlitzer
changers were made and installed in 1910.  Each one had a serial
number, usually stamped into the front or top edge of the right
side casting.  The highest number found to date is #5236, giving
this device the distinction of being by far the most common and
commercially-successful roll changer.

The Wurlitzer changer had the roll magazine on top.  This permitted
a compact installation in a keyboard-style piano, with the lower
body small enough to fit between the piano action and the cabinet
front, and the Ferris wheel overhanging the piano hammers.  The entire
play/rewind/change cycle was triggered by one rewind pneumatic, with
all further action sequenced by cams and clutches.  In other words,
the entire cycle is driven by the rotation of one input shaft.

_Philipps_

Philipps developed its own six-roll changer for use in large
keyboardless orchestrions around 1903-1904, patented it in 1905, but
didn't regularly install it until 1908 or 1909.  (For more details,
see http://mechanicalmusicpress.com/history/pianella/wpo_idex.htm .)
Wurlitzer PianOrchestras were imported from Philipps in Germany from
1903 to 1914.

The large six-roll Philipps changer installed in many Wurlitzer
PianOrchestras has a large take-up spool on top, with the Ferris wheel
or magazine underneath, as the PianOrchestra cabinet has ample room
for this configuration.  As in the Wurlitzer-made changer, the entire
rewind/change/play sequence is triggered by a rewind pneumatic, with
one input shaft driving the whole cycle.  While the Wurlitzer and
Philipps changers have similarities, there are also many differences
in the design of the individual parts.

Most Wurlitzer PianOrchestras have a six-roll Philipps changer, but
most surviving Philipps orchestrions not sold by Wurlitzer are
keyboard-style instruments with single roll spoolboxes or smaller roll
changers with fewer than six rolls.  Very few of the large six-roll
PianOrchestra-style changers exist in Philipps orchestrions remaining
in Europe.  The smaller Philipps changers have the magazine on top as
in Wurlitzer changers, to fit into compact keyboard-style piano
cabinets.

_Hupfeld_

Hupfeld built several styles of roll changers.  The Ferris wheel
style roll changer most commonly found in Pan Orchestra and Helios
orchestrions was covered in two German patents, #299,980 and 301,815,
granted in July 1916.

The control mechanisms in this changer are very different from the
Wurlitzer and Philipps changers.  Instead of having one input shaft
for driving the entire play/rewind/change cycle, the Hupfeld system
makes use of pallet valves, control valves, and pneumatics to engage
one portion of the cycle after the other.

A wind motor loads the roll leader onto the take-up spool and turns the
spool.  Another input shaft driven by a takeoff from the crankshaft
rotates the magazine when a pneumatic engages a clutch.  This system
provides ample power to rotate the massive magazine (in the case of
a 10-roll Pan roll changer), but allows for easy tempo adjustment,
as in a player piano.

_Aeolian Concertola_

The Aeolian Concertola was covered by U.S. patent #1,808,808, filed
by Joseph Dickinson in 1928; granted and assigned to the Aeolian
Company in 1931, much later than the others.  The Philipps patent had
expired in 1922 and the McCormick patent for Wurlitzer would expire in
1931, so there was little concern about an infringement claim.  (Only
a handful of coin pianos and orchestrions with roll changers were made
after 1928 anyway.)  Interestingly, Tolbert F. Cheek, who invented
primarily for the Welte-Mignon Corporation of New York, was granted
U.S. patent #1,984,462 in December 1934 for an improvement to the
Concertola mechanism, and he assigned it to the Aeolian-Skinner Organ
Co.

_National & Welte_

The National Piano Manufacturing Co., maker of National and Welte roll
changers, had at least seven U.S. patents on its roll changer, granted
between 1913 and 1917.  With its separate take-up spool for each roll,
it had an entirely different mechanical design than the others.

Art Reblitz
http://www.mechanicalmusicpress.com/