Pistonolas have an unfortunate reputation of not working, and I don't
know if there are any fully operative instruments around.  The only
other Pistonola which I remember being sold the owner had quite a job
to sell.

Strangely enough, Paddy Handscombe (who has a Pistonola innards) has
produced a diagram of the mechanism for the Player Piano Group
bulletin.  He sent it to me a year or two back and I've been waiting
for the article to go with it since then.  He's promised to write
something in the next few days!

The mechanism was clearly designed by someone whose design background
was in petrol engine carburettors: the valves come straight from a
float chamber.  (It's interesting to look at player actions and work
out what discipline their designers came from: Aeolian were clearly
organ builders, while Ampico were engineers.)  Pistonola actions look
like they come from a car.

Paddy tells me that there is an article written by Edwin Evans in the
1920s that says the system played in a very responsive manner, so don't
believe the 'can't work' articles in earlier MMDs!

The system did indeed work at a high tension, but relied on gearing
down to reduce the tension required to play the piano action.
Apparently this is about 3-to-1, so it uses more air but at a lower
tension.  A little basic physics tells us that as the energy required
to operate the piano action stays the same, so the energy exerted by
the player action must also remain the same, therefore its operator
must expend the same energy!  The same high-tension/low-volume vs.
low-tension/high-volume design issue crops up in other instruments.

Julian Dyer