Link 2 has collar b encircling eccentric 1 which rotates about fixed axis A. Link 2 transmits motion to link 3 which is connected to a special device not shown in the drawing. Eccentric 1 oscillates link 2 whose slot a-a slides along stationary roller B. The stroke of link 3 can be changed with screw 4 by adjusting the distance between axis A and the centre of roller B.
$922$LG,3L$