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"
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