Pittsburgh Area Theatre Organ Society, Inc.

WurliTzer chest action

Initially, everything is at the same air pressure (about 10 inches of water or ~1/2 psi).  When the magnet (17) is energized, its armature (13) is lifted off its exhaust hole which lets the primary pneumatic (8) exhaust to the atmosphere through channel (7).  This collapses the primary (8) due to external pressure.  The collapse of the primary pulls up on the valve wire (9) and both attached valves (10 & 11).  This then causes the secondary pneumatic (6) to exhaust via its exhaust channel (7).  Its attached striker (5) presses on the spoon (3) causing the pallet valve (1) to open against spring (2) action permitting air to enter the pipe (not shown) mounted on the top of the chest and it speaks.  When the magnet s de-energized, the armature falls down and permits air pressure in the primary pneumatic to be restored causing it to lower the two valves to the position shown.  Similarly to the primary, the air pressure in the secondary is restored and the pallet then closes and the pipe stops speaking.