The controlled duocentric oil pump regulates the oil pressure to around 3.5 bar over the entire speed range. A control ring and control spring are responsible for regulating the pressure. Oil pressure less than 3.5 bar: The control spring presses the control ring against the oil pressure, the external rotor is turned and the space between internal and external rotor is enlarged. Oil pumping increases, as does the oil pressure. Oil pressure greater than 3.5 bar: The oil pressure presses the control ring against the control spring. The rotor is turned back and the space between the internal and external rotor is reduced. As the oil quantity drops, so does the oil pressure.