Question Emergency brakes: Answers Are not required on vehicles with air brakes. Are required only on buses. Are required on all vehicles. Explanation All trucks, truck tractors, and buses must be equipped with emergency brakes and parking brakes. This questions appears in the following tests: Idaho Air Brakes Kentucky Air Brakes Mississippi Class A Knowledge Test Nevada Air Brakes New Mexico Class A Knowledge Test New Mexico Air Brakes Oregon Class A Knowledge Test Vermont Air Brakes Virginia Class A Knowledge Test