Abstract: In S.N.Kojefnikof’s “Theory of mechanism and machines” the formula for intermittent involute gears is given. It says that the augle passed every once by the driven δ2 is determined by the contact ratio εs of the pair of gears. This article shows that δ2 is not independent of the value εs and gives a derivation of the formula. According to the derived formula when the pressure angle of involute gears is 20° and the number of teeth of the driven lets between 15 and 100 15