> "Action:  Direct electric action (as pioneered by Wicks) would be
> employed for all wind switching.  *** Electric wind valves never
> (well, hardly ever) *** wear out.  They can be driven by TTL (or
> whatever) protocol."

Well, in my experience I have had to work on fairly modern mechanical
instruments, with the electric wind valves fitted ** inside ** the chest,
which have failed due to dirt.  I have also had trouble with relay
magnets due to dirt and rust.  On the other I have worked on proper
pneumatic mechanical instruments which were still working on leather
puffs (pouches) that had been replaced in 1928.  They were still working
(some of them!) in 1978.  That was on the 98-key Gavioli in the Gondola
Switchback at Thursford, Norfolk, UK.

I think the best idea would be to make the instrument as per normal, and
drive the main pneumatic relay with solenoids which are ** very
accessible **, that could be just plugged-in to change them.  It is a
real pain to have to dismantle part of an instrument just because a
modern electric relay has stuck.  However if it was very easy to change
you could live with that.

In the early 1970's, when I was doing some work on a boiler at a factory
that made electric micro switches, they had banks of them on test.  I
asked the man how many operations they expected from the life of the
component.  He said about half a million.   Now I wonder how many times
the snare drum relay had operated between 1928 & 1978 ?? !!

The start (!) of my web site is at  http://homepage.zynet.co.uk/timblyth/

Tim Blyth
Kingsbridge
South Devon
UK