Abstract: A differential ball screw and nut assembly has an axially and rotatably fixed nut with an internal helical groove having a first lead to cooperate with a tubular ball screw having an external helical groove with a corresponding lead to provide a first raceway for a train of balls. The tubular ball screw also has an internal helical groove of the same hand with a second reduced lead relative to the first lead. A second rotatably fixed, radially inner screw having an external helical groove with a lead corresponding to the second lead cooperates with the internal groove of the tubular screw to provide a second raceway. A second train of load bearing balls transmits load between the tubular screw and second screw to move the screws differentially an axial distance corresponding to the number of rotations of the tubular screw times the lead differential.

Abstract: A ball nut and screw system has a ball screw mounting a coaxial ball nut. A ball train is disposed in the helical trackway defined by the helical grooves of the nut and screw. A ball end return assembly is provided for the nut which has separate end walls carrying generally radially extending return tracks which communicate with the trackway and the nut has an external ball return surface in communication with the tracks. Interengaging parts on the end walls partially envelop the nut and interconnect the end walls.