A floor-cleaning device has a cleaning roller for processing a surface to be cleaned. The cleaning roller is designed as a hollow body having an internal liquid space. The hollow body has at least one opening for liquid to exit the liquid space. In order to convey liquid to the surface of the hollow body under certain conditions only, the hollow body opening is associated with a force-actuated automatic valve element which, depending on the amount of centrifugal force acting upon the valve element, can be moved to a closing position in which the hollow body opening is closed and/or to an open position in which the hollow body opening is exposed. The valve element allows liquid to exit the liquid space at a first speed of the cleaning roller and to block liquid from exiting when the rotational speed increases.