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. Take a FREE Practice Test Now This questions appears in the following tests: Idaho Knowledge Test Class A , Tennessee Knowledge Test Class B , Alaska Air Brakes , Arkansas Air Brakes , Iowa Air Brakes , Nebraska Air Brakes ,