Hi,  Does anyone have diagrams or schematics or photographs showing
how the keys of an upright Pianola were attached so as to animate when
the roll played?  I have a 'UK' Aeolian half Duo-Art Steck which of
course never had animated keys.  I believe that the American Pianolas
did (a lot of the pianola examples on YouTube have animated keys).

I have numerous diagrams showing the cross-section of a pianola showing
the pneumatic stack and hammer action but none of them appear to show
this linkage (if it is a 'linkage').  Is it also true that with some
players this function could be turned on or off?
 
I realise that if you were to weight the keys at the front they would
fall forward as the whippen lifts, but I imagine this is not how a
factory built one works.  Any info would be appreciated.

Jim Perkin