Ball screws are a type of mechanical linear actuator. The ball screw consists of a screw and nut with matching grooves and ball bearings that move between them. The unique element of ball screws is the ball bearings, which increase the power efficiency by minimizing the friction during the movement of the ball and nut.

​

The unique element of ball screws is the rolling balls in the helical groove which reduces the mechanical contact inside the screw assembly and replaces sliding friction with rolling friction. This mechanism significantly lessens the friction generated, which results in highly efficient power conversion. The efficiency of screws is measured by their capability to transform power utilized in exerting rotational force to the linear distance covered.

​

Ball screws have more complex structures and components and appear to be bulkier than other types of screws. They are more expensive than other screw types, but their benefits and capability outweigh their cost.