Lever the power out, and the ratio of output to input force is given by the ratio of the distances from the fulcrum to the points of application of these forces. This is known as the "law of the lever." The mechanical advantage of a lever can be determined by considering the balance of moments or torque, "T", about the fulcrum. where F is the input force to the lever and F is the output force. The distances "a" and "b" are the perpendicular distances between the forces and the fulcrum. Since the moments of torque must be balanced, formula_3 .
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