Measurement of pressure distribution and hydrodynamic axial forces of wet clutch discs

Within disengaged wet-running multi-plate clutches a certain drag torque is generated as a result of the differential speed between the discs. These losses can be reduced providing uniform clearances within the clutch pack. To this end, reliable and uniform separation of the discs should be achieved, which can be realized using both mechanical components and hydrodynamic pressure of the oil flow. This paper deals with a method for measuring the hydrodynamic axial force generated by wet clutch discs. This system allows the determination of the correlation between the axial force and the operating parameters of the clutch and the groove design. Using the examples of a radial and a complex grooving, the measurements are validated with 3D CFD simulation results.