reduction ratio, speed reducing ratio
suurratta ja väikeratta läbimõõtude või hammaste arvude suhe u = z2 / z1 = d2 / d1, seega alati u ≥ 1, capital parameeter of gear pair that is determined by formula u = z2 / z1 ≥ 1, where z2 is a gear wheel number of teeth, while z1 is the pinion number of teeth
