Question Air brakes use ____ to function. Answers Compressed air Liquid air Nitrogen Explanation Air brakes function through the use of compressed air. This questions appears in the following tests: Arizona Class B Knowledge Test Arizona Air Brakes Idaho Air Brakes Iowa Class B Knowledge Test Missouri Class A Knowledge Test Missouri Double Missouri Air Brakes Missouri Air Brakes Nebraska Class B Knowledge Test New Hampshire Air Brakes Oregon Air Brakes South Dakota Air Brakes Vermont Air Brakes