Crank 1 rotates about fixed axis C and is connected by turning pair D to link 4. Link 3 turns about fixed axis A. Link 2 is connected by turning pairs B and E to links 3 and 4, and carries rigidly attached knife b. When crank 1 rotates, knife b rolls along table a. The shape of knife b is chosen so that point B of link 2 describes circular arc x-x with its centre at point A. The distance A͞B on link 3 equals the radius of the arc described by point B. Spring 5 holds knife b against table a.
$1731$LC,FD$