The aft supporting structure reduces RPM from the Power Turbine and transfers power forward to the Transmission Shaft. Which component is this describing?

• A. Transmission Shaft
• B. Accessory Gearbox
• C. Gas Generator
• D. Reduction Gearbox

Answer: (D)

In turbine systems, the rotating power from the power turbine is extremely fast, so a reduction gearbox is used to slow that output down while delivering the torque to the next shaft. The reduction gearbox sits in the aft area as the supporting structure and male-fits to the power-turbine output, transferring power forward to the transmission shaft while reducing RPM to a usable speed. The other parts have different roles: the gas generator drives the overall engine core, not the main drive to the transmission; the accessory gearbox powers engine accessories; and the transmission shaft is the output path that carries the reduced-speed power onward, not the device that changes speed itself.