Anatomy of a WurliTzer Theatre Pipe Organ
This is the standard arrangement where the magnets and valves are in a
seperate box which attaches to the front of a chest e.g. the Relays, String
Offset Chest, or in idividual units on the 16' Offsets such as the Bourdon.
The Valves sit in the well in the bottom board adjacent to the magnets.
They screw into the primary pneumatics which mount over the small holes in the
At rest the lower valve disk falls onto the valve plate (which screws onto the bottom board)
and air is able to pass from inside the chest, past the top valve disk which is away from its seat,
and through the hole on the side of the bottom board to the secondary pneumatic.
When activated the primary pneumatic pulls the valve upward until the top valve disk seats at the top
of the well. This stops air moving from inside the chest to the secondary pneumatic. Instead air from
the secondary pneumatic is able to flow back past the lower valve disk which is no longer seated on the
valve plate and out through the hole in the valve plate. This allows the air pressure inside the chest to
push the secondary pneumatic closed which, if it is a pipe chest, causes the pallet to open and feed air
to the pipe.