When knob 1 is turned clockwise about fixed axis B, spiral spring 3 is wound up. At the same time, pin a moves along a helical slot of ratchet wheel 2 and shifts the wheel axially to the right until a tooth of the wheel becomes disengaged from stop b of the base. After this, ratchet wheel 2 has a helical motion, turning through an angle corresponding to one tooth.
$2723$RG,ML$