Some Duo-Arts had the key-bed shifter pedal pneumatic and some did not.
I have one that has both the shifter pedal pneumatic and the hammer
rail lift pneumatic.

I  will not use the shifter pedal pneumatic as I do not believe it is
the correct way to get the correct expression from the Duo-Art rolls.
Most Duo-Arts did not use these and they are found only in a few
Steinway Duo-Art pianos.  If it was such a good idea then why don't
you find them in every Duo-Art Steinway?

If the piano gets heavy use then the pedal is useless, as the soft felt
parts of the hammer will harden.  Most shifter pedals move the action
just enough to let the less-used portion of the hammer hit the strings,
which is a softer part of the hammer.  That is just my opinion.

Don Teach, Shreveport Music Co
1610 E. Bert Kouns, Shreveport,  LA  71105
dat-smc@juno.com