Karl and Stephen,

> The instruments are operated from punched cards on the principle of a
> player-piano roll, but considerably more robust (and folded up Z
> fashion).  There were various standard systems referred to as '84
> keys', '101 keys', '112 keys' and so-on, and technical developments on
> the action side (I believe a change from exhaust pneumatic to vacuum
> pneumatic) led to some being described as 'keyless' - e.g. '84
> keyless'.

Folding book operated organs are either keyed or keyless.  A keyed organ
uses mechanical fingers or keys that extend up through the holes in the
cardboard to operate the notes and functions.  The keys are mechanically
connected to valves located below them which then operate the organ
notes and functions.  The keyless system uses a tracker bar similar to
a player piano.  All keyless book organs that I know of use a presurized
system (rather than vacuum in the player piano).  In the keyless system,
when a tracker hole is uncovered by a hole in the cardboard, a valve is
triggered pneumatically which then is used to operate the organ notes
and functions.  The two systems can be readily identified just by
looking at the holes in the cardboard.  The mechanical key system uses
rectangular holes in the cardboard.  The keyless system uses chains of
round punched holes.  A few American band organs such as Wurlitzer used
a vacuum system on a paper roll operated tracker bar to control the
organ.  This required two pumps, one for pressure to blow the pipes and
one to supply the vacuum for the tracker bar.  Most other organs,
street, dance and fair organs used a pressurized system, whether keyed
or keyless, and whether book or paper roll operated.

I hope this clarifies the key and keyless systems for organ playing.  I
enjoyed Stephen's viewpoint regarding the various organs, pipework,
tuning and visual effects.  Sometimes we get too close to this stuff and
miss the humor in it.

Bob Conant
Endicott, NY
FOPS, KVD, MBSI, AMICA