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Here I've removed yet another layer of action parts. With
the key frame removed we can see, in the front, a wide board
with a black cloth hinge running across the length of the
section. This is called the "shutter board." It's function is
to control the sound volume from the rear of the organ. By
pulling out the shutter stop we are able to raise the shutter
board, opening the sound area directly in front of the
reeds.
The next item is the "coupler" (it's the board with a series
of metal rods). The coupler, when activated, connects two
octave notes together. In other words, if we were to play A 440
and had the coupler engaged the organ would also play B 440, at
the same time. It's like having an extra pair of hands. When
the coupler stop is pulled, the front of the coupler board is
raised, and the ends of the rods make contact with the bottom
of the keys. (Most organs have two couplers, a bass and a
treble).
Now in the back we can see a line of narrow wooden dowels,
which are called "pittmans." Their function has to do with the
keys and something else called the "valves," which we haven't
talked about yet, but will shortly. In the normal operation of
an organ when a key is pressed down, the key makes contact with
a pittman. The pittman in turn makes contact with a wooden
valve, which is covered in felt and leather. When the valve is
opened by the pittman, a strong airflow is drawn in through the
open valve, which then allows air to be drawn into and through
the reeds (which sit just above the valves).
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