A floor detector for a power brush of a vacuum cleaner comprises a lift sensor S1 and a floor sensor S2. The lift sensor S1 has a movable member which yieldably displaces when the power brush is placed on a relatively soft floor while the floor sensor S2 has a movable member which yieldably displaces...http://www.google.se/patents/US4977639?utm_source=gb-gplus-sharePatent US4977639 - Floor detector for vacuum cleaners
