In air brake systems, what is used to control the air supply pressure?

Answer: B — The governor

The governor is a key component in air brake systems that plays a crucial role in regulating the air supply pressure. Its primary function is to monitor the pressure within the system and ensure it remains within the optimal operating range. When the air pressure drops below a certain threshold due to brake application or leakage, the governor activates the compressor to replenish the air supply, thus maintaining consistent pressure for effective braking. Conversely, when the pressure reaches a predetermined upper limit, the governor shuts off the compressor to avoid over-pressurization, which could potentially damage the system. In contrast, while the brake compressor is essential for generating airflow to charge the system, it is the governor that directly manages the pressure levels. The air storage tank serves as a reservoir for compressed air but does not actively control pressure. The air filter's role is to clean the incoming air to prevent contaminants from entering the system, which, while important, does not involve pressure control. Understanding the function of the governor is critical for maintaining safe and efficient braking performance in vehicles equipped with air brake systems.