Abstract: A spring-powered actuator especially for operating devices such as fire and/or smoke dampers, doors, hatches, vents, traps, valves and other devices having components which are movable between at least two positions. The spring-powered actuator of the invention comprises a longitudinally-displaceable re-wind screw which is rotatable to recharge the spring of the actuator, and a tilting element on the screw which is mounted for tilting movement with respect to the screw axis to allow longitudinal movement of the re-wind screw so as to permit rapid and reliable release of energy stored in the spring. When used in a combination fire and smoke damper, it thus opens or closes the blades of the latter.