Question Why do large vehicles use air brakes? Answers Other brake systems squeak too loudly. Air braking systems are very effective. Air brakes are complicated. Air is free. Explanation Air brakes are an effective and safe way of stopping large and heavy vehicles, as long as they are maintained and used properly. Take a FREE Practice Test Now This questions appears in the following tests: Oregon Knowledge Test Class B , Wyoming Double , Massachusetts Air Brakes , New Jersey Air Brakes , North Dakota Air Brakes , South Carolina Air Brakes ,