Tubular-pneumatic action

"Tubular-pneumatic action" refers to an apparatus used in many pipe organs built during the late 19th and early 20th centuries. The term "tubular" refers to the extensive use of lead tubing to connect the organ's console to the valves that control the delivery of "wind" (air under pressure) to the organ's pipes. Many such organs are extant 100 or more years after their construction.

In any organ, each pipe has a valve located at its foot which responds to the organist's commands from the console's keyboard, pedalboard and stop controls. These valves are contained in windchests upon which the organ's pipework is set. Any type of apparatus that connects an organ's console with its windchest is referred to as its "action". An organ that utilizes tubular-pneumatic action is commonly called a "tubular-pneumatic organ".

Until the advent of the tubular-pneumatic action, all organs used a system of levers and wooden rods called trackers to transmit the action of the keys and stops to the valves contained within the windchests. This necessitated a close proximity between the console and the chests. In 1845, Prosper-Antoine Moitessier, an organ-builder of Montpellier, France, patented the tubular-pneumatic system which allowed the console to be at a much greater distance from the organ pipes. Cavaillé-Coll, Henry Willis and Edwin Horsell Pulbrook were pioneers in perfecting and introducing the pneumatic action. The development of the tubular-pneumatic type of organ marked the first departure from the tracker organ style of construction that had been used for hundreds of years.

The operation of a tubular-pneumatic organ is accomplished by a change of air pressure within lead tubes of about ¹⁄₄ in (0.6 cm) inside diameter that connect the organ's console to its windchest. A separate tube is needed for each manual key, pedal key and stop control on the console. A large four manual organ can require over 300 individual tubes.

Two basic types of tubular-pneumatic actions were used: the "pressure" system and the more popular "exhaust" system. Both use three major components for each key and stop: a valve (within the console), a pneumatic (within the windchest), and a lead tube that connects them.

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