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. This questions appears in the following tests: Arizona Air Brakes Arkansas Air Brakes California Class A Knowledge Test California Air Brakes Hawaii Class B Knowledge Test Idaho Bus Iowa Air Brakes Kentucky Air Brakes Kentucky Air Brakes Louisiana Bus Louisiana Passenger Louisiana Air Brakes Michigan Air Brakes Minnesota Air Brakes Missouri Double Montana Class B Knowledge Test Montana Air Brakes Nebraska Class B Knowledge Test New Hampshire Air Brakes North Carolina Air Brakes Ohio Air Brakes Oregon Air Brakes South Carolina Air Brakes Washington Class B Knowledge Test Wisconsin Class A Knowledge Test Wyoming Air Brakes