Crank 1 rotates about fixed axis x-x. Link 3 is connected by turning pairs A and B to crank 1 and link 2 which turns about fixed axis y-y. In rotation of crank 1 about axis x-x, link 2 oscillates about axis y-y under the condition that the axes of all the kinematic turning pairs intersect at a single point.
$558$LW,4L$