Ball screw nuts are used together with ball screws in an assembly referred to as a ball screw drive. The ball screw drive converts rotary motion to linear motion with the help of recirculating metal balls.
Ball screw drives work in the same manner as ball bearings, where metal balls move along an inclined inner or outer race to minimise friction. The ball screw nut and screw (a threaded shaft) have matching helical grooves or races where the rolling balls recirculate continuously to minimise friction.
Ball screw nuts are most commonly used in precision machines and industrial machinery. You will find them in robots, precision assembly equipment and machine tools. They're also used in car power steering systems to translate rotary motion to axial motion.
Ball screw nuts are classified by the method of ball circulation into end-cap type, return-pipe type and deflector type. They can also be categorised by preloading method into fixed point preloading types (double-nut method and offset preloading) and constant pressure preloading type.