For automation of cam length in weft knitting machine (its characteristics will be describe later) some limitations must be noted which are using the minimum amount of energy, the mechanism must be simple as possible, total number of component must be minimum, no especial mechanical and electrical instrument use, minimum time should be used, minimum expenses should be used, the minimum tensions be applied the cam, easy computer controlling, use of the facilities on the machine,
Flat weft knitting machine made by "UNIVERSAL COMPAUY "in Germany with needle gauge of 12/inch and racking 9 needles and two knitting device was prepared for experimental works.