Which component is responsible for preventing excessive air pressure in the system?

The correct answer is related to the governor's cut-off pressure, which plays a vital role in regulating the air pressure within the system. The governor is a device that monitors the air pressure level in the air brake system. It is designed to automatically interrupt the operation of the compressor when the air pressure reaches a predetermined level, thereby preventing excessive pressure buildup. This cutting off of air supply is crucial for maintaining the safety and functionality of the braking system, as excessive pressure can lead to component failure or leaks.

Understanding the specific role of the governor helps in recognizing its importance in the overall air brake system, which relies on maintaining optimal air pressure to ensure effective braking performance. An appropriate air pressure level is essential not just for operational efficiency but also for the safety of the vehicle and its occupants.