I rebuilt an Autopiano for a nice lady near the beginning of my career.
I've not been on MMD in a vocal way although I have been "one of you
all" for twenty years.  Anyway, I have always admired the function of
that particular Autopiano.

I've rebuilt just about every kind of player since but have never come
across a piano with as nice a manual pump as that old Autopiano.  With
the design of the pump and the double valve design along with a good
tight regulation all the way through, that finished restoration would
play barely audible notes on 1 inch of vacuum!

The best part (to me) was the bypass valve built into the one side
(I think it was the right side bellows) which enabled high suction
that was produced by the player pianist to go past the equalizer and
straight to the stack.  I've never seen it since in a manually pumped
player.

I am currently in the process of rebuilding a Pratt Read whose
stationary boards of its bellows are completely shot.  I must make new
ones.  I thought that, as long as I had to remake so much anyway, it
would be nice to include that expression functionality to this unit.
I can easily come up with my own design to make this sort of "direct
drive" to the stack from the bellows and around the reservoir/equalizer
myself but would really love to take another look at how Autopiano made
theirs, and I have no literature that contains data on that valve nor
can I find any reference to it on-line or in the Archives.

After all folks, it's been twenty years since I rebuilt that pump and
my brain ain't what she used to be.  Does anybody have a picture,
schematic or description of how that valve worked?  If so, I'd love
to hear about it.

David Rodgers