What is the function of the air compressor in an air brake system?

The correct answer highlights the crucial role of the air compressor within the air brake system. Specifically, its function is to supply compressed air, which is essential for the operation of air brakes. When a driver applies the brakes, the system requires a supply of compressed air to actuate the brake chambers, which in turn engage the brake shoes against the brake drums or discs.

The air compressor is designed to compress the intake air and build up pressure, ensuring that there is a consistent and sufficient supply of compressed air available to operate the brakes effectively. This is critical for the performance and safety of the braking mechanism, allowing for rapid and responsive braking action when needed.

The other functions listed in the question, such as applying brakes, draining air pressure, or maintaining brake fluid levels, do not accurately describe the purpose of the air compressor. In fact, air brake systems typically do not use brake fluid, as they operate solely on compressed air. Therefore, understanding the role of the air compressor is essential for grasping how air brake systems function and ensuring proper maintenance and operation of these systems.