Double-arm lever 2 is mounted rigidly on shaft 1 which rotates about axis A-A owing to a constant torque applied to it. Upon reciprocation of pawl 3 in the directions shown by the arrows, shaft 1 rotates intermittently by half-revolutions. The time required for pawl 3 to shift from one position to the other should be slightly less than the time per half-
revolution of shaft 1 .
$132$SL,L$