To date all bearings and components in the planetary gear set unit that underlie high forces and torque are enhanced for friction reduction. This paper outlines the technical solutions to reduce friction in a planetary gear set. The return part analysis revealed, that even parts with lower load show frictional wear. This is evident for example with the thrust washer which braces the planetary gear. The necessary friction reduction caused by the axial thrust in the planetary gear is the main focus of this paper, supported by validated test results. Surprisingly is the significant share of friction power. A CO_2 saving of approx 1 g/km per automatic transmission with 4 planetary sets can be gained, by substituting the current thrust washers with thrust needle bearings. The challenge consist in the production of a adequate thrust needle bearing for the allocated space.
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