The invention relates to a vacuum motor, comprising a housing (1, 2) with acylindricalinternal space (4), a working piston (5) that is arranged in axial directionof the cylinderaxis of the cylindrical internal space (4) such as to be mobile by linearoscillation betweenthe front side and the rear side of the internal space (4)； a first restoringelement (6) that isarranged in the internal space (4)； a gas outlet (7) in the housing (1, 2)； agas inlet (8) inthe housing (1, 2) for supplying ambient air, whereby the gas outlet (7) andthe gas inlet(8) terminate in the internal space (4) between the working piston (5) and therear side ofthe housing (1, 2), and whereby the working piston (5) does not fully or evenpartiallycover the gas outlet (7) and the gas inlet (8) in any of its positions； avalve body (10) thatcan be moved against the gas inlet (8) in order to close the gas inlet (8)； asecondrestoring element (11) that transitions the valve body (10) into the closedposition； at leastone pestle (12) that is arranged such as to be mobile in axial directionwithin the housing(1, 2) between the working piston (5) and the valve body (10), whereby upon amotion ofthe working piston (5) in the direction of the rear side of the internal space(4), the valvebody (10) can be moved against the force of the second restoring element (11)and thusthe gas inlet (8) can be opened, and whereby the free cross-section of theopened gasinlet (8) is at least equal in size to the free cross-section of the gasoutlet (7).The invention also relates to a surgical drive system comprising said vacuummotor, amedical lavage system for the debridement of soft tissue and/or bone tissuecomprisingsaid vacuum motor, and a medical device for brushing, rasping or sawing ofsoft tissueand/or bone tissue comprising said vacuum motor as well as to a method foroperating avacuum motor.
