Abstract: A vehicle seat assembly with a linear actuator is disclosed in which the actuator is used to adjust the relative position of two relatively movable components of the seat assembly. The actuator includes a first part attached to one of the seat assembly components in the form of a lead screw with an external helical screw thread. A second part of the actuator, attached to the other seat component, includes a housing containing a spin nut threaded onto the lead screw. The second part further includes means for engaging the spin nut to prevent it from rotating along the lead screw and means for selectively releasing the spin nut to permit rotation about the lead screw and thereby relative movement of the actuator second part relative to the first part. A cam is mounted to the actuator second part to selectively engage and release the spin nut.