Abstract: A ball screw and nut linear actuator has a screw and nut with helical grooves and threads providing a helical raceway between them. The raceway has a ball return portion and provides a track for a train of recirculating load bearing balls. A wiper member carried by the nut has a helical wiper thread which is preloaded to engage an outer side of the helical groove of the screw outboard of the nut. The helical wiper thread has a radially open helical groove for maintaining and distributing a helical ribbon of lubricant on the side of the screw groove upon which it is pressed.

Abstract: A ball nut and screw system has a ball nut with adjacent helical groove turns providing a helical raceway with a screw for load bearing balls received in the raceway. The nut has an opening extending from its exterior to its interior to permit balls to be fed into the raceway. A compressible snap-in crossover, sized for compressed insertion into the opening, provides an axially diagonal, ball return passage in its underface for channeling balls from one portion of one of the adjacent turns over an intervening land surface on the screw to a portion of another turn to recirculate them. The crossover has opposed portions with nut groove entering projections thereon shaped to be snapped into the turns to define unoccupied turn portions on opposite sides of ball-occupied turn portions when the projections clear the opening upon insertion. For some purposes, wedging retainers can be received in the crossover once it is installed.