What function does the governor serve in the air brake system?

The governor in the air brake system plays a crucial role in controlling the air supply to the brake chambers. Its primary function is to maintain the correct pressure within the air system by regulating the compressor operation. It ensures that the appropriate amount of compressed air is delivered to the brake chambers when the brakes are applied and that the air system does not become over-pressurized.

When the air pressure falls below a specific threshold, the governor activates the compressor to increase the pressure. Conversely, when the desired air pressure is reached, the governor prevents the compressor from continually supplying air, thus maintaining a stable operating environment for the brakes. This control is essential for ensuring reliable and effective braking performance.

In contrast, other options do not accurately describe the role of the governor in the context of an air brake system. For example, regulating tire pressure is unrelated to the air brake function, as tire pressure management is handled separately. Similarly, adjusting brake fluid levels is irrelevant because air brake systems operate on compressed air rather than hydraulic fluid. Lastly, preventing engine overheating is outside the purview of the governor's function within the braking system, as it specifically focuses on air pressure regulation for braking efficiency and safety.