What is the primary purpose of the air brake test?

The primary purpose of the air brake test is to ensure that the air brake system is functioning properly. This is critical for the safe operation of any vehicle equipped with air brakes, especially larger commercial vehicles. During the test, the driver assesses various components of the air brake system, including the compressor, air pressure levels, and the functionality of the brake application and release. Conducting this test confirms that the brakes will respond appropriately when engaged, which is essential for vehicle safety on the road. Ensuring proper functionality helps prevent brake failure, which can lead to accidents and poses a severe risk to the driver, passengers, and other road users.

The other options, while related to brake operation, do not encompass the comprehensive approach needed for safety assessment. Checking air pressure levels may be a part of the overall test but does not alone ensure that the entire system is operating properly. Testing brake pads contributes to maintenance but is not a primary focus of the air brake system test. Finally, determining the maximum stopping distance is important but secondary to the immediate concern of confirming that the brakes respond correctly when needed.