suction of the dirty cleansing liquid the two suction nozzles 4 are communicating through a piece of horizontal duct 5 passing above the cleaning brush 1 and around the cleansing liquid conveying duct 3 fig6 and 6b show a detailed view of the edges 36 l 36 n of the nozzles 4 each suction nozzle 4 is provided with two lower flexible edges 36 which adhere to the floor p and when the machine moves bend in the direction opposite to its motion the surfaces of both the nozzle 4 edges 36 l which are farthest from the brush 1 are smooth the nozzle edges 36 n which are nearest to the brush 1 have the surface 38 l facing the inside of the nozzle 4 which is smooth while the surface 38 n facing the brush 1 is provided with ribs or protrusions 39 during the use of the floor cleaning machine the smooth edges 36 l of the nozzles 4 adhere to the floor p thus preventing the outflow of the cleansing liquid the ribbed edge 36 n of the nozzle 4 which is positioned before the brush 1 adheres to the floor p with its smooth surface 38 l thus preventing the cleansing liquid from spreading forwards the ribbed edge 36 n of the nozzle 4 which is positioned behind the brush 1 adheres to the floor p with its ribbed surface 38 n thus allowing the cleansing liquid to spread inside the nozzle 4 by which it is sucked the additional suction ducts 40 are positioned inside each nozzle 4 so that its mouth is placed in correspondence with the smooth edge 36 l and in correspondence with the floor p in such a way as to suck the cleansing liquid and.