US Patent 7452311 Exercise machine with dual fulcrum articulated force lever

An exercise machine includes a dual fulcrum articulated force lever connected to a machine frame. The articulated force lever includes a first force arm and a second force arm. A fixed end of the second force arm is pivotally connected to the frame at a first fulcrum. A movable end of the second force arm is pivotally connected to a first end of the first force arm for pivoting of the first force arm about a second fulcrum. A resistance load is attached intermediately to the first force arm. A handle section is connected to the first end of the first force arm opposite the pivot connection to the second force arm. Movement of the handle section in one direction rotates the first force arm and the second force arm together about the first fulcrum against the load. Movement of the handle section in an opposite direction rotates the first force arm about the second fulcrum against the load.