Ball screws are used in aircraft and missiles to move control surfaces, especially for electric fly by wire, and in automobile power steering to translate rotary motion from an electric motor to axial motion of the steering rack. They are also used in machine tools, robots and precision assembly equipment.

Lead is the linear travel the nut makes per one screw revolution and is how ball screws are typically specified. The pitch and lead are equal with single start screws. For multiple start screws the lead is the pitch multiplied by the number of starts.

As the screw or nut rotates, the balls are deflected by the deflector into the ball return system of the nut and they travel through the return system to the opposite end of the ball nut in a continuous path.