When crank 1 of four-bar linkage BCDE rotates about fixed axis B, link 2 oscillates about fixed axis A. The motion and dwell periods of link 2 can be varied by changing the distance between turning pairs D and E. This is done by moving slider 3 along screw 4. It is necessary, at the same time, to change the angle at which pin a is set with respect to line DE. This is done by shifting screw b in the slot of link 5.
$1756$GL,D$