Patent ID: 8226522

Claim:
A coupling system comprising: a dynamoelectric device selectively operable as either a generator or an electric motor; a gas turbine engine; a main differential operably connected between the dynamoelectric device and the gas turbine engine, wherein the main differential is a sunless epicyclic gear assembly comprising: a plurality of main differential planet gears arranged to mesh with each other; a first main differential ring gear that meshes with a first of the plurality of main differential planet gears; a second main differential ring gear that meshes with a second of the plurality of main differential planet gears; and a main differential carrier rotatably connected to each of the main differential planet gears; a rotationally powered accessory engaged with the main differential; an epicyclic start differential operatively connected to the main differential; and a brake mechanism configured for selectively braking the epicyclic start differential when the dynamoelectric device operates as an electric motor to direct torque transmission to the gas turbine engine, wherein the brake mechanism is configured to cease braking the epicyclic start differential when the dynamoelectric device operates as a generator such that the main differential transmits torque to power the rotationally powered accessory and to the dynamoelectric device, and wherein the start differential is configured to transmit torque between the first main differential ring gear and the second main differential ring gear when the brake mechanism brakes a start differential carrier.