When lever 1 turns clockwise about fixed axis A, plunger 4 prevents rotation of disk 3 which is mounted freely with respect to axis A. As a result, lever 2, carrying segment gear a which meshes with gear segment b on disk 3, turns clockwise about axis B on lever 1 until it runs against screw c. From this moment, levers 1 and 2 turn together to the end of their strokes, forcing back plunger 4. When lever 1 is turned counterclockwise, levers 1 and 2 turn together until disk 3 runs against screw d mounted on the base. At further motion of lever 1, lever 2, meshing with gear segment b, returns to its initial position. Thus, in oscillation of lever 1, rods 5 and 6 have different strokes, but they move synchronously over a portion of their strokes.
$1787$GL,FD$