a jacquard mechanism mounted in a circular knitting machine for knitting a jacquard fabric , including a fixed selector cam for guiding a knitting needle in a fixed track , a needle selector controlled to raise the knitting needle into a tucking track for a jacquard knitting operation , a movable selector cam moved in a sliding slot in the fixed selector cam to open / close the tucking track , and a driving mechanism controlled to move the movable selector cam in the sliding slot of the fixed selector cam .