Hi All,  I need to know how the make a simple one-way valve.  Please
follow my (long) explanation and see if you can help me from my
description.

I am re-tubing my late 20's vintage Steinway LR Duo-Art, following
restoration of all the components.  The piano has both the keybed shift
soft bellows and the hammer rail lift soft bellows.  I want to activate
the keybed bellows only from the Soft/Normal key slip switch.  I want
to activate the hammer rail lift soft bellows just from tracker bar
hole #95.  Here are my 2 sets of operating conditions:

Situation One:  When the key slip switch is actuated three things
happen by tubing from the switch:

- the keybed soft bellows primary is turned on

- a valve in the modulator operates to restrict airflow

- level 2 in the accompaniment accordion bellows is activated.

Under this soft setting I can independently operate the hammer rail
lift soft bellows from the tracker bar for further soft music
shading.  So far no problem.

Situation Two:

With the key slip switch set so the piano is under the normal (louder
than soft level) setting, the keybed bellows and the modulator valve
are not actuated and Accomp level 2 is also not turned on.

- The hammer rail lift soft bellows is operated by the tracker bar hole
#95, as in situation one.

- However to compensate for key movement from the raised hammers I am
told that the accompaniment level 2 accordion should also be turned on.

- If I connect Accomp level 2 to tracker bar #95 and the hammer rail
lift bellows, I will also be connecting the hammer rail bellows primary
to the key slip switch so that the hammer rail bellows will be operated
whenever the key slip switch is turned to the soft position, as opposed
to the hammer rail bellows being operated just from tracker bar #95.

To prevent this I need a one-way check valve in the tube leading from
tracker bar #95 and the hammer rail lift bellows to accompaniment level
2, so operating the key slip switch will operate Accomp level 2 but
won't activate the hammer rail bellows.

Or operating the hammer rail bellows from the tracker bar will operate
Accomp level 2 independent of the key slip switch.

Can I make a one-way valve by using a small sealed wooden block with
two tubes in, one out, and a pouch leather flap over one of the inlet
tubes?  I have no "power" to open or close the pouch leather flap
except the atmosphere level input from opening of the tracker bar hole
or the key slip switch hole.

Your expert advice will be much appreciated.

Pat DeWitt
Fort Wayne, Indiana