What role does the air system play in the functioning of the brakes?

The air system plays a crucial role in providing the necessary pressure to operate the brakes in air brake systems. When the driver engages the brakes, compressed air fills the brake chambers, which then pushes the brake shoes against the brake drum or applies pressure to the brake pads against the rotors, depending on the design of the brake system. This process is essential for efficient braking performance, ensuring that the vehicle can decelerate and stop as needed.

In contrast, the other options reflect misconceptions about the functions of the air system. Lubrication is typically managed through different means, not through the air system. Controlling engine temperature is irrelevant to the function of the brakes; that is managed by the cooling system of the vehicle. Lastly, filtering contaminants is related to brake fluid and does not involve the air system, which is responsible for generating the braking force. Understanding these functions highlights the importance of the air system in vehicle safety and performance.