Do you currently have car insurance? Insurance is mandatory to drive in California Yes I have insurance. But please show me your best quotes. No, please help me find the best insurance. Question What do air brakes use to make the brakes work? Answers Compressed air Outside air Non-compressed air Explanation Many large CMVs are equipped with air brakes. An air braking system uses compressed air to operate. Take a FREE Practice Test Now This questions appears in the following tests: Arizona Knowledge Test Class A , Maine Knowledge Test Class B , Wisconsin Knowledge Test Class B , Louisiana Passenger , Iowa Air Brakes , Michigan Air Brakes , New Mexico Air Brakes , Ohio Air Brakes ,