US Patent 11193425 Gearbox for boost spool turbine engine

A turbine engine includes a core engine including a first spool and a second spool rotatable about a main engine longitudinal axis, a boost spool powered by a secondary drive system, and an accessory gearbox coupled to the core engine and the boost spool. A differential gear system is coupled between the core engine, the boost spool and the accessory gearbox for distributing power between the boost spool, the core engine and the accessory gearbox.