A ram air turbine (RAT) assembly includes a gearbox that supports a gear set with a ring gear that drives a pinion gear. The gear set provides for the transmission of power from the turbine to a generator, pump or other power conversion device. A turbine shaft supports the ring gear and a pinion shaft that rotates about an axis transverse to the turbine shaft supports the pinion gear. A ratio between a face width and a diametrical pitch of the gear set is within a desired ratio that provides sufficient space for supporting bearing assemblies while provide for operation within the physical constraints and desired performance requirements of the RAT.