Abstract: An apparatus for extracting sanding dust from rotary sanders includes a suction hood disposed on a suction pipe and enclosing a drive group and a flexible or moveable grinding head which faces the surface to be machined. A sealing profile leads around the entire periphery of the suction hood and at least one secondary air valve disposed in the suction pipe is configured in such a way that an opening in the suction pipe is regulated by the secondary air valve. The suction hood has at least one auxiliary air hole which penetrates the suction hood from the surface to the interior of the suction hood.