Abstract: A rotating actuator comprising, eddying causes noise production that is to be avoided flat boundary faces formed at a throttle opening, and a flat boundary face that is formed at an outlet opening. Streamlined transitions with one convex and one concave region each are provided in the inlet connection piece from a frustoconical constriction to the boundary faces, and a streamlined transition with one convex and one concave region to a frustoconical widening of the outlet connection piece is provided in the outlet connection piece. The rotating actuator is used in particular to regulate the idling rpm of internal combustion engines.