Face cam 1 rotates about fixed axis A and has cam slot b of which portion d-d is along a circular arc described from centre A. Slot b meshes with four pins a of pin wheel 2 which rotates about fixed axis B. The axes of pins a are at equal distances from centre B and are located symmetrically. In one revolution of driving face cam 1, pin wheel 2 turns through 90°. Wheel 2 has a dwell during the part of the cycle when circular portion d-d slides along two adjacent pins a,thereby preventing unintentional rotation of pin wheel 2.
$2584$PG,3L$