See pneumatic stack.

Cylinder music box with the cylinder made in two parts, each of which shifts laterally outward from the center at a different time to provide continuous music during the normal tune-changing process.

See comb base.

The suction- or air-operated series of pouches, valves, and other devices used to sense the paper roll (or music book, paper strip, etc.) and cause an instrument to play automatically. Definition sometimes used to include auxiliary systems as well: pump, blower, reservoir, etc.

A series of air-actuated pouches, valves, and bellows, especially in a piano or orchestrion, built as a coordinated unit and used to play a piano action automatically.