Guam Chauffers Practice Test

The engine governor is the device responsible for controlling the maximum RPM (revolutions per minute) in large vehicles such as tractor-trailers. This mechanism monitors the engine's speed and adjusts the fuel supply to prevent the engine from exceeding a predetermined RPM. By doing so, the engine governor helps maintain optimal engine performance and prevents potential damage caused by over-revving.

This control is particularly important in large vehicles where managing power and efficiency is crucial for safety and operational reliability. The governor ensures that the engine operates within its designed limits, which enhances fuel efficiency and reduces excessive wear and tear on engine components. It also contributes to better handling and stability of the vehicle, especially when loaded.

Other devices mentioned, such as a speed reducer or a transmission control unit, serve different functions related to speed and gear management but do not specifically limit the engine's RPM as effectively as an engine governor does. The throttle position sensor is mainly used for monitoring and reporting the position of the throttle in relation to the accelerator pedal but does not directly control maximum RPM.