US Patent 7631719 Electrically-driven transfer case with power take-off

A hybrid drive system for a four-wheel drive system arranged to supply motive power to a first output shaft of a transfer case from an internal combustion engine and to a second output shaft from an electric motor/generator. The transfer case includes a reduction gearset driven by the electric motor/generator, a power take-off unit driven by the reduction gearset, and a disconnect clutch operable for selectively coupling the reduction gearset to the second output shaft. This hybrid drive arrangement permits installation of a modified transfer case in place of a conventional transfer case for use in a traditional four-wheel drive driveline arrangement.