Driving member (cam) 1 rotates about fixed axis A and has annular groove c corresponding in width to the diameter of pins b carried by pin wheel 2 which rotates about fixed axis B. Annular groove c is not continuous as there are inclined openings on both sides. When cam 1 rotates clockwise, inclined surface f pushes pin b' to the left, turning wheel 2 clockwise. At the same time, pin b'' enters the opening on the opposite side and is pushed to the central position by inclined surface g. Pin b" remains in groove c until cam 1 makes one revolution, thus locking wheel 2 against unintentional rotation. Then pin b" passes out on the opposite side and another pin b is engaged by surface g and groove c.
$2618$PG,D$