Question Why do large vehicles use air brakes? Answers Other brake systems squeak too loudly. Air brakes are very effective systems. Other braking systems are hard to come by. Explanation If used and maintained properly, air brakes are a safe and effective way to stop large, heavy vehicles. This questions appears in the following tests: California Class B Knowledge Test Idaho Class B Knowledge Test Idaho Air Brakes Iowa Air Brakes Kentucky Class A Knowledge Test Kentucky Air Brakes Louisiana Double Michigan Class B Knowledge Test Mississippi Bus Ohio Double Oklahoma Air Brakes Oklahoma Air Brakes South Dakota Air Brakes Tennessee Air Brakes Utah Air Brakes Vermont Double Virginia Class A Knowledge Test Virginia Class A Knowledge Test Virginia Air Brakes Virginia Air Brakes Wyoming Air Brakes