Selectively braked planetary gear carrier for transfer cases and the like

摘要

A two speed transfer case assembly includes a planetary gear speed reduction assembly, a shift sleeve for selecting either reduced speed drive through the planetary gear assembly or direct drive from the transfer case input. The planet carrier of the speed reduction assembly includes a band brake disposed thereabout. A linear actuator selectively, adjustably tightens the band brake to control retardation of the planet carrier thereby controlling the speed of the carrier and thus the output of the planetary gear assembly. This configuration cancels the drag torque typically applied to the input of a transfer case from the associated automatic transmission and minimizes or eliminates the relative rotation between the shifting elements in the transfer case allowing smoother shifts. When fully engaged, the planetary carrier brake can also serve as a wet parking brake.