Pattern drum indexing for circular knitting machines

Claim 1

IN A CIRCULAR KNITTING MACHINE HAVING A ROTARY NEEDLE CYLINDER WITH A DRIVING GEAR THEREFOR, NEEDLES AND JACKS CARRIED BY SAID CYLINDER AND HAVING BUTTS, ACTUATORS IN THE FORM OF CAMS AND SLIDES SELECTIVELY ENGAGING SAID BUTTS FOR DISPLACING SAID NEEDLES, SELECTED ACTUATORS BEING MOUNTED FOR SELECTIVE DISPLACEMENT RADIALLY OF SAID CYLINDER, AND AT LEAST ONE PATTERN DRUM FOR OPERATING SAID SELECTED ACTUATORS; MEANS FOR INDEXING SAID DRUM AT LEAST TWICE FOR A REVOLUTION OF SAID CYLINDER COMPRISING AT LEAST TWO DRUM-ADVANCING DEVICES, EACH DEVICE COMPRISING A RATCHET WHEEL FIXED TO SAID DRUM AND HAVING A TOOTH LENGTH CORRESPONDING TO THE DISTANCE SAID DRUM IS INDEXED FOR EACH REVOLUTION OF THE CYLINDER, AND A SEPARATE PAWL ENGAGEABLE WITH SAID TEETH AND OPERABLE TO ADVANCE THE RATCHET WHEEL AND DRUM A DISTANCE LESS THAN THE DISTANCE OF ONE TOOTH, MEANS TO OPERATE THE PAWLS OF SAID DEVICES IN SEQUENCE SO THAT THE DRUM IS INDEXED THE DISTANCE OF ONE TOOTH IN STEPS, WHEREBY DISENGAGEMENT OF ANY PAWL FROM THE TEETH PREVENTS COMPLETION OF THE INDEXING AND ARRESTS THE INDEXING OF SAID DRUM.