Slide 26
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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).