<Dl> <Dd> N = (4.76 × 10 6) d r C L 2 (\ displaystyle N = ((4.76 \ times 10 ^ (6)) d_ (r) C \ over L ^ (2))) </Dd> </Dl> <Dd> N = (4.76 × 10 6) d r C L 2 (\ displaystyle N = ((4.76 \ times 10 ^ (6)) d_ (r) C \ over L ^ (2))) </Dd> <Ul> <Li> N = critical speed in RPM </Li> <Li> d = smallest (root) diameter of the leadscrew in inches </Li> <Li> L = length between bearing supports in inches </Li> <Li> C = . 36 for one end fixed, one end free </Li> <Li> C = 1.00 for both ends simple </Li> <Li> C = 1.47 for one end fixed, one end simple </Li> <Li> C = 2.23 for both ends fixed </Li> </Ul> <Li> N = critical speed in RPM </Li>

Screw thread for power transmission in one direction