Which feature helps to prevent the brakes from overheating during heavy use?

The air dryer plays a vital role in the braking system by removing moisture and contaminants from the compressed air before it reaches the air brake components. When brakes are used heavily, especially in conditions that cause excessive heat build-up, the presence of moisture in the system can lead to iced or frozen brake valves, which can impede functionality. By keeping the air supply dry and free of particulates, the air dryer helps maintain optimal performance of the brake system, preventing overheating due to moisture-related issues. This ensures that the brakes operate effectively under high stress, leading to a safer driving experience.

In contrast, while the air compressor, spring brake mechanism, and parking brake system have important functions, they do not specifically address the issue of overheating due to moisture. The air compressor is responsible for generating compressed air, the spring brake mechanism is involved in providing emergency braking, and the parking brake system is primarily for securing the vehicle when it's stationary. None of these components directly contribute to managing the heat generated by heavy braking or preventing moisture-related overheating in the braking system the way the air dryer does.