Barker lever

The Barker lever ( also Barker Machine) is a pneumatic relay, which was used in organ building in order to reduce the forces for actuating a Tonventiles.

In general, all the more forces act on a mechanical action and thus on the button, the bigger the organ. In order to play even large organs yet, various devices have been developed that reduce the exerted by the player on the button pressure. The English organ builder Charles Spackman Barker (1807-1879) developed in 1832 his " pneumatic machine ", later called Barker lever, which was first used in the organs of Cavaillé -Coll.

It is not directly opened by the push of a button the whistle valve, but a valve in an additional wind loading, the so-called game wind loading. Thus, a smaller operating bellows is inflated, which then pulls the actual key action. The advantage of a lower pressure point is, however, characterized bought that the sound responds with a certain delay. Also, is lost, unlike other game aids such as the pilot valve, the direct connection between key and valve.