Abstract: A powered linear actuator is provided primarily for releasing stores from aircraft, having dual closed loop servo motor systems driving a screw jack. The dual motors, which have samarium cobalt permanent magnets, drive the screw jack through differential gearing and each has an armature lock which functions automatically if a motor circuit fails thereby enabling the other motor to continue driving the actuator alone. Potentiometer feedback is applied to dual error amplifiers or polarized relays that compare the feedback position signal with the input command signal and drive separate motor energization channels. A replaceable plug-in resistor is provided in series with the potentiometer track so that the actuator stroke can readily be changed by changing one value plug-in resistor for another.