Lever force F at a point "A" located by the coordinate vector r on the bar. The lever then exerts an output force F at the point "B" located by r. The rotation of the lever about the fulcrum "P" is defined by the rotation angle "θ" in radians. Let the coordinate vector of the point "P" that defines the fulcrum be r, and introduce the lengths which are the distances from the fulcrum to the input point "A" and to the output point "B", respectively. Now introduce the unit vectors e and e from the fulcrum to the point "A"
Lever action the cylinder to the next position and cock the internal hidden hammer. Multiple lever action designs including the Volcanic pistol were designed before the American Civil War, but the first significant lever-action designs were the Spencer repeating rifle and Henry rifle. The Spencer was a magazine-fed lever-operated breech-loading rifle designed by Christopher Spencer in 1860. It was fed from a removable seven-round tube magazine, enabling the rounds to be fired one after another, and which, when emptied, could be exchanged for another. Over 20,000 were made, and it was adopted by the United States and used during the American Civil