JJ Keller Entry Level Driver Training for CDL (Commercial Driver’s License) Practice Test

The correct answer is that the clutch must be in the disengaged position to start the engine or shift gears. This is because disengaging the clutch disengages the engine from the transmission, allowing for a smooth start of the engine without the vehicle moving. It is a crucial step in preventing any engagement of the drivetrain, which could lead to a dangerous situation if the vehicle were to lurch forward or backward when the engine starts.

When shifting gears, the clutch must also be disengaged to allow the driver to change gears smoothly and easily. This process separates the engine's rotational force from the wheels, making it possible to select the desired gear without grind or resistance. When the clutch is in the engaged position, the power from the engine is connected to the transmission, which would not only make it impossible to shift gears but also can cause potential damage to the transmission.

Starting from neutral, while sometimes also considered, does not require the clutch to be engaged, as the engine can also be started in neutral without engaging the clutch. However, the key point is that the clutch must be disengaged when starting the engine or shifting gears, ensuring safe operation of the vehicle.