Gearbox (noun)

A mechanical device in a vehicle or machine that transmits power from the engine to the wheels or other working parts.

Origin:

A compound of gear + box.

Examples:

1. The mechanic opened up the gearbox and found that one of the gears was damaged.
2. The gearbox allowed the driver to change gears and control the speed of the vehicle.
3. The gearbox was an important component in the design of the machine.
4. The gearbox was lubricated by oil to prevent wear and tear.
5. The gearbox made a grinding noise, indicating a problem with the gears.