longitudinal displacement and a tilting displacement in its guiding slot on the front or outer side of the lift butt 22 2 a second run on surface 22 6 is formed the jack cam race 17 includes lift cam components 36 for engaging the lift butt 22 2 and two circumferentially offset press cam components namely a first press cam component 37 and a second press cam component 38 whose operation will be explained later in connection with fig3 to 8 the two press ca components 37 and 38 are situated before the selecting range a of each selecting magnet 25 when viewed in the direction of circulation of the selecting jacks the selection regions coinciding with the selection points assigned to respective systems of the knitting machine the additional cam components 40 and 41 serve for engaging the head butts 21 2 and for detaining the jacks in the range of their fulcrums 22 3 the cams 40 clear the way for the raising movement of the jacks 22 and guide their head butts downward into the circulation channel 40 1 the needle selection at the needle selection points takes place when the head butts are at the level of the circulation channel 40 1 the cam 41 does not act as a press cam component and a certain play is always present between the cam 41 and the stem of the selecting jack 22 enlarged illustrations in fig3 and 4 show a jack lifting cam 36 together with its lifting edge 36 1 for engaging the lift butt 22 2 whose various positions in the range of the first pressure cam 37 and the second pressure cam 38 are indicated.