Which gearbox changes the angle of drive into the tail gearbox?

• A. Main gearbox/Main Transmission
• B. Tail gearbox
• C. Intermediate gear box
• D. Driveshaft sections

Answer: (C)

Power from the engine goes to the main gearbox, which handles speed reduction and supplies the main rotor. To drive the tail rotor, the drive must be redirected along the tail boom, so a gear box specifically changes the drive angle. That intermediate gearbox takes the main gearbox output and redirects it (typically 90 degrees) into the tail drive shaft, feeding the tail gearbox. The tail gearbox then finalizes the drive to the tail rotor. So the angle change needed to route power to the tail is accomplished by the intermediate gearbox, not by the main gearbox or tail gearbox itself, and not by simple driveshaft sections.