Theoretical and experimental analyses of swing arm yarn guide motion on warp knitting machines determined the effects of machine speed and inherent frequency on yarn tension. A noncontact displacement transducer measured swing arm motion at machine speeds of 29, 800, 1,200, 1,600, and 2,000 stitches per minute. The main shaft rotational angle across two machine revolutions determined the swing arm curves. The direction of motion determined arm displacement, which was at its highest at a machine speed of 2,000 stitches per minute. Fourier analysis determined an inherent swing arm frequency of 77 hertz up to a machine speed of 530 stitches per minute. The frequency, however, increased at higher speeds, generating a double tension peak, indicating that swing arm motion followed yarn tension more closely at lower machine speeds. 4 refs.