Pattern drum control device in a circular knitting machine

A device for controlling the advance movement of a patterning member, like a pattern drum or a number of superposed pattern wheels or disks, in a circular knitting machine having at least one needle cylinder and jack-selecting levers operated by pegs or teeth of said patterning member, comprising a peripheral tooth formation on said patterning member, a pawl for engagement with said tooth formation to cause stepwise advancement thereof about an axis of said patterning member, a support pivotable about said axis of said patterning member and pivotally supporting said pawl, an annular cam rigid with said at least one needle cylinder, a cam follower lever between said annular cam and said support, said cam follower lever being pivotally connected to said support, said cam having a peripheral profile capable of imparting to said cam follower lever and to said support a to-and-fro movement causing said pawl to perform a forward and a return stroke capable of producing a two-tooth advance movement of said peripheral tooth formation at each revolution of said at least one needle cylinder, wherein said profile comprises a first part extending over at least one quarter of a circle, preferably over half a circle, and adapted to cause a one-tooth advance movement of said tooth formation, and a second part having an appreciably greater inclination than said first part and following said first part, said second part being adapted to cause a further one-tooth advance movement of said tooth formation, and wherein said device further comprises means for detaching said pawl from said tooth formation over a half of each of a number of said return strokes, said pegs or teeth being arranged in vertical rows and said patterning member having at least two adjacent equal vertical rows of said pegs or teeth to consecutively act on said jack selecting levers during a two-tooth advance movement of said tooth formation.