The Air Compressor Governor controls...

Answer: B — When the air compressor pumps air into the storage tanks

The air compressor governor is a crucial component in a vehicle's air brake system, primarily responsible for regulating air pressure in the storage tanks. Its main function is to control the operation of the air compressor, specifically determining when the compressor should begin and stop pumping air into the storage tanks based on the air pressure levels. When the pressure in the storage tanks falls below a predetermined level, the governor activates the air compressor to fill the tanks back up to an optimal pressure. Conversely, once the pressure reaches a certain threshold, the governor will shut off the compressor to prevent over-pressurization. This automated control helps maintain the necessary pressure for the air brake system to function effectively, allowing for safe and reliable braking performance. Understanding this function is essential for anyone operating vehicles equipped with air brakes, as it ensures that the system remains ready for use, enhancing overall safety.