The emergency air line: Do you currently have motorcycle insurance? Insurance is mandatory to drive in Ohio Yes I have insurance. But please show me your best quotes. No, please help me find the best insurance. Question The emergency air line: Answers Is controlled by the foot brake. Is connected to the relay valves. Supplies air to the trailer air tanks. Explanation The emergency air line (also known as the supply line) has two functions. The first is to supply air to the trailer air tanks on a combination vehicle, and the second is to control the emergency brakes.
