Lever Lever A lever ( or ) is a simple machine consisting of a beam or rigid rod pivoted at a fixed hinge, or fulcrum. A lever is a rigid body capable of rotating on a point on itself. On the basis of the location of fulcrum, load and effort, the lever is divided into three types. It is one of the six simple machines identified by Renaissance scientists. A lever amplifies an input force to provide a greater output force, which is said to provide leverage. The ratio of the output force to the input force is the mechanical advantage
Barker lever Barker lever The Barker lever is a pneumatic system which multiplies the force of a finger on the key of a tracker pipe organ. It employs the wind pressure of the organ to inflate small bellows called "pneumatics" to overcome the resistance of the pallets (valves) in the organ's wind-chest . This lever allowed for the development of larger, more powerful organs still responsive to the human hand. These larger organs first flourished in France, e.g., the organ produced by Cavaillé-Coll at St. Sulpice. The first Barker lever was built in the Cavaillé-Coll organ of the Basilica of Saint-Denis. This