Arguments in favor of cyclic servicing, as opposed to random servicing, in connection with machines which stop in a random manner, are not conclusive because hitherto no general formular has been available for calculating the results which may be expected from cyclic servicing. The aim of the following paper is to help in evaluating the cyclic procedure by presenting a formular for calculating the standard efficiency of a group of semi-automatic machines assigned to one operator who will service them on a cyclic pattern