Abstract: A foldable wheelchair having opposed main side frames each comprising front and rear members supported on respective front and rear wheels and connected by upper and lower cross members, and a back member mounted for folding movement relative to the rear member wherein the side frames are connected by first and second foldable links for maintaining the side frames spaced apart in the erected condition of the wheelchair in which the back members are aligned with the rear members and support a flexible back panel, and the wheelchair is collapsible to a compact folded condition by folding the links to move the side frames adjacent to each other and by folding the back members to extend downwardly adjacent to the rear members and the associated rear wheels.

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.