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

The component that is responsible for preventing excessive pressure in the air brake system is the pressure relief valve. This valve plays a crucial role in maintaining system safety and functionality by ensuring that the pressure within the air brake system does not exceed safe operational limits. When the air pressure rises above a predetermined threshold, the pressure relief valve opens to vent excess air, thereby preventing potential damage to the brake system components, such as hoses, chambers, and tanks, which could occur from over-pressurization.

The pressure relief valve not only protects the system but also enhances reliability in brake performance because consistent pressure levels are essential for effective braking. Maintaining appropriate pressure levels ensures that the air brake system can respond adequately when needed, contributing to the overall safety of the vehicle.

The other components, while essential to the operation of the air brake system, do not directly function to limit pressure. The compressor generates air, the governor regulates when the compressor should operate based on the air pressure levels, and the supply tank stores the compressed air. Each of these components plays a significant role in the system's operation, but the pressure relief valve directly addresses the issue of excessive pressure.