Three-ring binder with actuating crank

A ring binder mechanism comprising

• a support plate,
• at least three rings, each comprising a movable segment pivotally attached to said support plate and an immovable segment affixed to said support plate,
• a mechanism for moving said rings between an open position and a closed and locked position, said mechanism comprising
• a crank pivotally supported on said support plate for oscillation about a longitudinal axis, said crank having plural throws offset from said longitudinal axis,
• said movable ring segments being integrally attached to said crank,
• a spring biasing said crank toward a rings-closed position,
• a manually operable lever for moving said crank toward a rings-open position,
• said lever being pivotally mounted on said support plate for oscillating movement,
• said lever having means for engaging a first of said throw so as to move the crank towards its rings-closed position as the lever is depressed toward said support plate,
• an idler arm pivotally supported on said plate adjacent a second of said throws, said idler arm having a pin affixed thereto and a roller retained on said pin, said roller being positioned so as to roll along said second throw, and
• a link connecting the idler arm to the lever, causing the lever and the idler arm move in unison, whereby force manually applied to the lever is distributed to both said crank throws.