Anatomy of a WurliTzer Theatre Pipe Organ
SLEIGH BELLS
The magnet/primary pneumatic/valve box is much the same as found in many other actions
in the instrument.
When the magnet is activated air is allowed to exhaust from the primary pneumatic, at the
top, through the hole in the timber above the pneumatic, through the cover plate (not shown)
and through the hole in front of the magnet (bottom right) and out through the magnet cap.
When the primary pneumatic is collaped by the air pressure inside the box it lifts the valves
causing the lower valve to seal against the outside of the box and lifting the top valve to open
a path from inside the box to the channel leading to the secondary pneumatic (with the bells
attached), which is behind this box.
The pressurised air admitted to the secondary pneumatic inflates it causing the bells to sound.
When power is removed from the magnet the primary pneumatic is no longer open to the
outside and is instead connected to the internal pressurised air. This allow the valves to fall
back, closing of the pressurised air to the secondary pneumatic and opening it to the outside air.
The return spring is then able to push out the air inside the secondary pneumatic and collapse it
back to its rest position.
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