In a circular knitting machine including a rotating needle cylinder having vertical grooves in the periphery thereof, a plurality of cylinder needles slidably mounted in the grooves in said cylinder, a sinker cap mounted above and outwardly of said needle cylinder, a plurality of sinkers mounted on said sinker cap and cooperating with said cylinder needle to form knit stitches to produce a single knit fabric, stitch cams for moving said cylinder needles vertically in said grooves, cam holder means for holding said stitch cams in operative position relative to said needle cylinder and said needles, mounting means supporting said cam holder means for vertical adjustment, and yarn feeding means for feeding a plurality of yarns under tension to said cylinder needles, the combination therewith of stitch length adjustment means comprising
- means for detecting the tension in the plurality of yarns and generating a signal indicative of the tension in the yarns being fed to said needles, said detecting means including a circular member mounted for rotation and having a plurality of yarn guides through which the plurality of yarns pass, said circular member rotating in response to variations in the tension in the yarns, and said detecting means further including means for sensing changes in position of said circular member and for generating the signal indicative of the tension in the yarns,
- control means for receiving the signal from the detecting means and comprising a setting means for setting a desired tension for the yarns, comparison means for comparing the signal from said detecting means with the value set by said setting means and generating a comparison result, and converting means for converting the comparison result from said comparison means into a driving signal, and
- adjusting means connected to said cam holder mounting means for vertically adjusting said cam holder means responsive to said driving signal.