SUMMARYPIERBURG has developed a mechanical supercharger working according to the principle of an inner-axle rotary piston machine. The inside rotor has 3 teeth while the outer rotor has 4 teeth, representing the KA ratio of 4:3.In a comparison with other supercharger types the advantages of the PIERBURG rotary piston supercharger (DKL) become evident. The DKL may be used for spark ignition engines with a power range of up to approximately 250 KW and for diesel engines up to approximately 180 kW.The supercharger is designed so that the adaptability to the absorption volume of the engines is achieved only by a length variation. With the exception of the rotors, the housing and the connection pieces, all components are designed in such a way that they may be used as identical parts for all supercharger sizes. The rotors are extruded profiles.With the KA 4:3 a principle has been chosen where the outer rotor functions as a shut-off component, i.e. it is not loaded with torques from compression and pressure differences. Thus during stationary conditions only the low power by bearing friction and ventilation are transmitted in the synchronization gear. The compression work is performed only by the inner rotor. Therefore a grease life lubrification is provided for the bearing and the gear.