What device in a manual transmission allows the driver to change gears?

The device in a manual transmission that allows the driver to change gears is the clutch. The clutch facilitates the engagement and disengagement of the engine power from the transmission, enabling smooth transitions between different gears. When a driver presses the clutch pedal, it disengages the engine from the transmission, allowing the driver to shift gears without grinding the gears or causing damage. Once the gear is selected, releasing the clutch pedal reconnects the engine power to the transmission, allowing the vehicle to move in the newly selected gear.

In this context, while the brake is essential for stopping and slowing down the vehicle, it does not play a role in gear changes. The torque converter is found in automatic transmissions and is responsible for transmitting power, but it is not applicable to manual transmissions. The transmission itself is the overall system that includes gears but does not directly enable the gear change without the clutch. Therefore, the clutch is the correct answer as it directly allows for gear shifting by temporarily separating engine power from the transmission.