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 .
Highfield lever about 1930. http://www.ybw.com/cb/gloss.html#Highfield https://books.google.com/books?id=Fp63wWByImQC&pg=PA145&lpg=PA145&dq=%22Highfield+lever%22&source=web&ots=dtOvGn79kw&sig=vDH04nBiAXxluXvIdcGcUdh3i_U&hl=en&sa=X&oi=book_result&resnum=3&ct=result Highfield lever A Highfield lever is a lever device which allows tension to be rapidly set up in a wire and equally rapidly released to the required extent. It is frequently used in sailing boats where tension in some part of the rigging needs to be adjusted to a pre-set amount as the wind impinges on one side of the sails or the other. It is typically used in running backstays (runners). To make it work, the backstay is led through a block or fairlead along the deck to a two-legged, second order lever mounted with