air 150 also the inlet duct 130 and outlet duct 140 are aerodynamically optimized as depicted in fig2 this for example occurs through ends of the ducts 300 that extend radially into the clutch or the clutch bell housing through a curvature of the ends 300 extending into the clutch through deflection vanes such as guide vanes in the area of the ends of the ducts 300 or in the clutch or a combination of these possibilities also it is advantageous for the ends 300 and the clutch bell housing to terminate in flush fashion the inlet duct 130 and or the outlet duct 140 u2014 especially in the area where they empty into the dutch bell housing u2014 are situated essentially tangentially in the circumferential direction to the dutch be housing or at a preset angle to the tangent line of the clutch bell housing 210 to optimize the aerodynamics the preset angle is chosen to be small for example between 0 and 25 degrees in the event the sensor fails there are in principle two possibilities for solution one is that a second sensor can be provided as a check or as a replacement and the method runs aided by the second sensor another is that if a sensor fails provision can be made to run the fan of the active cooling device 100 continuously but with the conventional clutch temperature model u2014 thus assuming that no active cooling is present u2014 to determine the temperature the.