Abstract: A ball screw and nut actuator assembly comprising an elongate ball screw supported for rotation while restrained from moving axially; a ball nut formed to provide a ball raceway with said screw incorporating load bearing balls therein; partible, normally closed jaw members with opposed curvilinear surfaces for virtually encircling and supporting the screw land interjacent the ends of the ball screw, the jaw members having projecting support legs; a mount system swingably mounting said legs for movement in opposed directions from a first position in which the curvilinear surfaces embrace the land to a removed second spread apart position; and spreaders on each end of the ball nut in position to interact with and spread the jaw members upon axial engagement therewith to permit axial passage of the nut past the jaw members. The methods of constructing and operating the assembly are also disclosed and claimed.