Hi All,  Thanks to Larry Lobel and a recommendation from Robbie Rhodes,
some information about player pianos, which came from the Tuners'
Journals of the late twenties, can now be found at Player-Care.com.

According to the author, Wilberton Gould, who wrote the series of
articles:

  "A great many player mechanics do not give the least thought to what
actually takes place when the pneumatic strikes the blow upon the piano
action.  Until they do they are only groping in the dark.  It is needless
to say that player mechanics do not know what causes the pneumatic to
collapse, because they do.  Unfortunately, however, there are many who
cannot express themselves as they would like to, and I will endeavor to
give a brief resume of the active agents which perform that function."

What I have found most interesting about these articles is the viewpoint
from which the author explains the various actions taking place within
the player system.  Instead of looking at the vacuum as the force which
is doing the work, he explains things in terms of the pressure, or the
force exerted on various parts by the weight of the atmosphere.  While
this is indeed the most correct way of looking at things, it is a
perspective that I don't recall reading about before now.

It's also interesting to note that over the years I've heard many
people say that it's difficult to understand how a player piano operates
because it's hard to visualize vacuum doing work -- other than cleaning
the floors... ;-)  However, when everything is explained in terms of
pressure, I must admit that it is easier to comprehend things like the
actions of the pouches, valves, and pneumatics.  As one who struggled
somewhat in my early years to truly understand how these things
actually worked, I wish I had read these articles 30+ years ago...

To access the three articles that have been completed so far, go to:
  http://www.player-care.com/technical-articles.html 

Over the coming weeks and months, I hope to be adding more articles by
this author.

Musically,
John A Tuttle
Player-Care.com
Brick, New Jersey, USA