John is correct in his measurement of the valves, if they are the
ones that run the pedal pneumatics. The reason for the short travel
is to set the speed of the pedals, and keep noise at a minimum.
They don't need the longer travel that the pneumatics have.
However, my book wherein I have kept measurements for over 40 years
shows that the travel for pedals will vary from piano to piano
according to need. The sustaining pedal must move just fast enough
to meet the test roll requirements; much more and the valves get
noisy.
On the other hand, stack after stack shows Aeolian set cross valves
to run within a thousandth of each other, a perfection that's hard to
match, but it's why they were able to jettison the need for primary
valves by 1914.
Bruce Grimes
|