What is the function of the transmission gear box?

• A. Provide mounting for tail rotor
• B. Reduce speed and change direction
• C. Change main rotor pitch
• D. Produce lift

Answer: (B)

The box primarily converts the engine’s high-speed output into the slower, high-torque rotation needed for the rotor and delivers that drive to the main rotor shaft, effectively changing the direction of rotation as required. This reduction in speed is essential because rotor blades generate lift at much lower RPMs than the engine runs, and the gearbox supplies the appropriate torque to keep the rotor turning smoothly. It does not generate lift itself, and blade pitch is controlled by the rotor control system (cyclic/collective and swashplate), not by the gearbox. While the tail rotor is driven through the overall drive system, the gearbox’s main role is reduction and direction of rotation for the main rotor.