US Patent 10094278 Turbofan engine bearing and gearbox arrangement

A turbofan engine (20) comprises a fan (28). A fan drive gear system (60) is configured to drive the fan. A low spool comprises a low pressure turbine (50) and a low shaft (56) coupling the low pressure turbine to the fan drive gear system. An intermediate spool comprises an intermediate pressure turbine (48), a compressor (42), and an intermediate spool shaft (54) coupling the intermediate pressure turbine to the intermediate spool compressor. A combustor (45) is between a core spool compressor (44) and a high pressure turbine (46). A first (160) main bearing engages a static support (164; 164′) and a forward hub (236) of the intermediate spool. A second (162) main bearing engages the low shaft and the forward hub.