<Dl> <Dd> r B r A = N B N A . (\ displaystyle (\ frac (r_ (B)) (r_ (A))) = (\ frac (N_ (B)) (N_ (A))).) </Dd> </Dl> <Dd> r B r A = N B N A . (\ displaystyle (\ frac (r_ (B)) (r_ (A))) = (\ frac (N_ (B)) (N_ (A))).) </Dd> <P> The speed ratio of two gears rolling without slipping on their pitch circles is given by, </P> <Dl> <Dd> R = ω A ω B = r B r A, (\ displaystyle R = (\ frac (\ omega _ (A)) (\ omega _ (B))) = (\ frac (r_ (B)) (r_ (A))),) </Dd> </Dl>

Where would a simple gear train be used