What does the air compressor governor control?

The air compressor governor primarily regulates the amount of air being pumped into the storage tanks in an air brake system. Its main function is to maintain the correct air pressure level within the system, ensuring that the storage tanks are filled adequately to operate the brakes effectively. When the pressure drops below a certain threshold, the governor activates the compressor to add air to the tanks. Once the pressure reaches the desired level, the governor stops the compressor from working, preventing over-pressurization. This interaction is crucial for maintaining the efficiency and safety of the braking system, ensuring that sufficient air is available for brake application when needed.

While other options touch upon important aspects of vehicle operation, they do not accurately describe the primary role of the governor. For instance, the governor does not directly control brake application time, air pressure release, or the engine's idle speed; those functions involve different components and systems within the vehicle.