Link 1, rotating about fixed axis A, is connected by sliding pair C to link 2 which, in turn, is connected by sliding pair D to link 3. Link 3 has circular guiding slot a of radius B͞A and with its centre at point B. Slot a moves along fixed slider b of the upright. When link 1 turns, link 2 slides along it, and link 3 moves along slider b. Thus link 3 oscillates about point B. The angular velocities of all the links are equal.
$959$LG,4L$