A vacuum motor has a piston that linearly oscillates in the internal space of a housing. A gas outlet and a gas inlet (supplying ambient air) located in the housing terminate in the space between the piston and the housing rear side. The piston never covers the outlet or inlet. A valve body closes the inlet. A pestle moves within the housing between the piston and valve body. When the piston moves toward the rear side of the space, the valve body moves against the force of a spring and opens the inlet. The free cross-section of the opened inlet is at least equal in size to the free cross-section of the outlet. A surgical drive system, a medical lavage system, and a medical device for brushing, rasping or sawing of tissue or bone—；all include the vacuum motor. Also disclosed is a method for operating the vacuum motor.
