One method for changing the length of pullrods for one pedal "on the fly", based on which other pedals are pushed, is to use a free-hanging lever on a bent bellcrank axle and connect two halves of a pullrod via it. Somewhat like what's shown in this sketch...
![Image](http://www.gunlaug.no/msc/img/varpitchpedal.png)
Two such levers that looks like bellcranks, are shown rotating freely on a round axle, and since the axle is bent and the in and outgoing pullrods are offset, the angle the axle is rotated to by its locked "angle control bellcrank" that is connected to bellcrank shafts for other pedals, determines the effective length of the pullrods for this pedal.
"A" shows the bent axle i what I call "normal pitch" position.
"B" shows the bent axle in its extreme left position for "lowest pitch".
"C" shows the bent axle in its extreme right position for "highest pitch".
I expect a rotation of max +/-45° off neutral to me enough to cover the necessary pitch range for JI tuning of an activated pedal in any pedal combination, since no pitch adjustment larger than +/-20 cents should be necessary.
I will use adjustable end-stop screws to control and tune the pitch for max angle both ways - shortest and longest pullrods, but haven't decided if I should spring-load it for "normal pitch" or even if a "normal pitch" is needed. I have found "2-pitch pullrods" to be enough when testing on my old Dekley, which means simply using a spring to pull the angle back to an end position may be enough.
Since the length of the freehanging bellcranks and the angle controlling bellcrank is about the same as normal bellcranks in a PSG, the force needed to change pitch will be very small.
Since the variation in length of the pullrods is very small, +/- a millimeter or so should be enough, such a variable pitch changer has to be as precisely made and moving as a regular bellcrank axle, but it can be made thinner and lighter because of the low load that will be put on it.
I will need one such adjustable pullrod in my Dekley to begin with, to control pitch of string 5 and 10 with A pedal engaged. I expect 2 or 3 such angled axles to cover all, or nearly all, "unusable" chords in a regular JI tuned E9 PSG.
Now, I'll be really happy if any of you can find the flaws in my logic so far. Got to be some, and I want them to be found and corrected early...
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