In small organs the closer the connection between the player's fingers and the pipe valves the better, because the staccato and legato touch can be more easily made to respond exactly to the player's fingers-, he can if he wishes open and close the valves gradualism but with pneumatic actions the pallet is always made to open and close as rapidly as possible. A pneumatic action opens a small bellows instead of the pallet leading to the pipes. The movable part of the bellows is made to work the action, which remains nearly the same as before.

A tubular pneumatic action has a, bellows at each end of a connecting tube; compressing one bellows distends the other, which becomes the motive power to open the pipe pallets. Trackers, squares, rollers, etc., are thus rendered unnecessary. In electric action an electromagnet is generally used to open the valve nearest the finger or to compress the bellows in the tubular pneumatic action. In this case the key has only to make contact and break it. One way in which this is done is by a U-shaped wire staple in the underside of the key, which, when depressed, enters two small cells of mercury into which the ends of the connecting wires are led. This action is not generally used apart from the pneumatic action, because if independent the electromagnets would require to be inside the wind-chest, and this would be inconvenient when adjustment became necessary.