How do organ bellows supply air to the pipes?

Organ bellows function as a mechanical system to supply pressurized air to the pipes, which is essential for sound production.12

In a traditional setup, bellows consist of a hinged box with flexible sides that expand to draw in air through an inward-opening valve and contract to expel that air through a nozzle. When the boards of the bellows are separated, a partial vacuum pulls air into the chamber; when the boards are brought together, the valve closes, forcing the air out toward the instrument.3

To ensure the pipes receive a steady, consistent flow of air, a reservoir is typically placed between the wind generator (the bellows or a modern rotary blower) and the wind-chest. This reservoir is weighted or spring-loaded to maintain constant wind pressure, and it often includes a safety valve to relieve excess pressure. The air is then directed into the wind-chest, where it waits until the organist presses a key, which opens a valve—or pallet—to allow the pressurized air to enter the corresponding pipe.12