onto the surface 11 the brush elements 18 of the tufts 17 on the brushes 3 4 are being moved over the surface to be cleaned 11 and the dirt and other materials are being disconnected from the surface 11 simultaneously the surface is being cleaned by the work fluid by solving and soaking of dirt into said fluid by further moving the cleaning device 1 in the direction as indicated by arrow p 1 the disconnected particles 10 and the cleansing or work fluid on the surface are being moved upwards into the inlet 13 due to the rotational movement of the brushes 3 4 when the brush 3 4 having a diameter of 44 mm is rotated at 8000 revolutions per minute the centripetal acceleration due to the rotational speed and imposed on the tips of the brush elements can be calculated as a 0 5 d brush u03c9 2 0 5 0 044 2 u03c0 8000 60 2 15424 m sec 2 if the brush does not make contact with the floor 11 this may be a good approximation of the actual acceleration of the tips of the brush elements however if the brush tips run into a contact surface the brush elements are deformed near the contact surface and are straightened back again to their original form when the.