There here have been several requests about tubing various coin
operated pianos.  I have never seen a factory tubing diagram but
have seen tracker bar scales.  Some have asked about tubing one of
these before the restoration has begun or a partial restoration was
attempted.  If you completely disassemble the entire player system
and restore every part then you should have some understanding how
each part functions.

A coin-operated piano works on the same basic principal as any
other player piano.  In very simple terms, suction is used to operate
each pneumatic via a valve.  Primary valves are not usually found
in a coin piano.  Suction is supplied at all times to the rewind
pneumatic and the valve that works the pneumatic to add credits in
the coin mechanism or the coin mechanism may be operated mechanically
by a spring.  Suction to other valves -- like those that work the
sustain pedal, soft pedal, mandolin rail, extra instrument such as
xylophone -- have suction applied only when the roll is in the play
position.

In a Seeburg there are several nipples coming from the top of box
that has the reservoir bellows attached to it.  One of these always
supplies suction as long as the pump is running so that suction goes
to the rewind control and to the coin accumulator valve that can add
coin credits.  The vacuum is cut off to the other nipples during rewind
and if you ever restored this part then you will know how it works.
Since the Seeburg has two little pneumatics in it, one of them will
move a wheel inside to add credits (plays) while the other pneumatic
moves the wheel to [subtract credits and] turn off the electricity.

Some Cremona pianos work by similar method while most use a spring
to move the counting wheel for credits.  The stack cut-off or vacuum
cut-off to the stack is done on top of the pump in a Cremona by
mechanical means.  The rewind pneumatic closes and pulls on a rod that
closes the pump vacuum off from the stack.  There is still vacuum to
the rewind pneumatic valves.

The Wurlitzer APP roll uses a mechanical method to count credits and
place piano into play position in many instruments while some use a
combination of pneumatics and mechanical methods.

The tracker bar scale tells you the hole in the tracker bar that is
connected to the various valves that work the various pneumatics.
Example hole one as you look at the front of the tracker bar will be
number one on the tracker scale.  In some pianos there are separate
valve boxes on each side of the piano (Seeburg K or E) while others
use valves in the stack to control pneumatics such as the soft pedal
or sustain (Cremona, Wurlitzer).

If you take the whole player action apart and rebuild each piece then
you will have a better understanding of how each part works.  Generally
the shortest path to the nearest valve is the valve that works the
appropriate pneumatic and that is where the tubing will run.

For example: the sustain pedal valve is close to the sustain pneumatic
and not on the other side of the piano.  You don't usually see tubing
crisscrossing all over the piano -- usually it is very neatly done.
An exception may be certain Seeburg Juniors with all the valves in one
unit, but the tubing is still very neat.

The part that cuts off or stops suction to the stack is usually
connected to the rewind pneumatic.  It may be a pallet valve or
a nipple at the rewind pneumatic that works the cut-off at the pump
or on the distribution box.  In some Wurlitzer pianos it is a valve
that lets air into the stack so it doesn't have enough vacuum during
the rewinding process.

More questions?  Send them to MMDigest.

Don Teach - Shreveport Music
Shreveport, Louisiana