leadscrew

thumb|right|Three types of screw thread used in leadscrews: 3 & 4: [[buttress thread 5: round thread 6: square thread ]] thumb|DVD drive with leadscrew and stepper motor thumb|Floppy disc drive with leadscrew and stepper motor

A leadscrew (or lead screw), pronounced , also known as a power screw or translation screw, is a screw used as a linkage in a machine, to translate turning motion into linear motion. Because of the large area of sliding contact between their male and female members, screw threads have larger frictional energy losses compared to other linkages. They are not typically used to carry high power, but more for intermittent use in low power actuator and positioner mechanisms. Leadscrews are commonly used in linear actuators, machine slides (such as in machine tools), vises, presses, and jacks. The word "lead" – pronounced , from the verb "to lead" – refers to the amount of distance travelled per rotation, not the metal.