Hello fellow MMDers.  Can anyone tell me why upright Duo-Art soft pedal
pneumatics have a small valve on the side, but never are attached to
anything?  Over the years I have seen a number of uprights, and never
has the little valve to atmosphere been attached to anything.

Before Christmas, I rebuilt a late 1926 Aeolian Duo-Art upright, which
had never been worked on before, and the little valve had no sign of
ever having been attached to anything.  I am now finishing up an early
1916 Steinway upright and again, the little valve exists, but is not
connected to anything.  I can find no mention or note of this valve in
any of the fairly vast collection of Duo-Art printed matter that I own.

I could understand it being in the early units, found not to be very
useful, and left unattached.  But what I do not understand is, if that
were the case, why did it continue to be included in the later units?

If anyone has a plausible idea why it exists or better still a written
explanation from any print material, I would like to know why.

Thanks for any ideas.

Ferdinand Pointer
The Piano Company
Clearwater, FL