Pulleys 1 and 2 are of equal diameter. The axis of slot b in slider 3 is parallel to line AB and is perpendicular to the axis of guides p-p. Pulley 1 rotates about fixed axis A and, through flexible link 4, rotates pulley 2 about fixed axis B. Pin a of flexible link 4 slides along slot b of slider 3 which moves in fixed guides p-p. When pulley 1 rotates about axis A, slider 3 reciprocates in guides p-p. When pin a travels along straight portions fg and dh of its path, slider 3 has two dwells: in its upper and lower extreme positions.
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