Spring operated actuator

Actuator and electric switching apparatus including a spring to provide movement of the apparatus and a rotary air damper. The damper is arranged to decelerate the spring during at least an end portion of movement. The damper has a toroidal working chamber formed by two circumferential housing parts rotatable relative to each other. Each housing part has internal walls which together define the working chamber. The first housing part has a rotatable displacement wall, sealingly rotatable in the working chamber. The second housing part has a stationary end wall of the working chamber. The second housing part has one recess in its internal walls. The recess is located less than 90° ahead the end wall as seen is the rotational direction of the displacement wall at an actuating movement. The recess has an extension in the circumferential direction that is larger than the effective thickness of the displacement wall. Alternatively the recess is on the first housing part.