Just when you think you have seen it all, something like this pops up.
This has to be a contender for the largest player action fitted into
an upright piano, in this case, a John Broadwood piano.  The unit
pneumatics contain a primary and a secondary valve.  The exhausters are
on the back, as you can see in the photos at the link below:

  http://www.edgaida.com/broad.html

Enjoy!

Ed Gaida
San Antonio, Texas, where spring has sprung for everything but the
pecan trees!