The action of braking generates massive amounts of heat. It is known to install brake ducts 9, which channel air from the front of the vehicle to the brake discs 17. The air introduced by the brake ducts 9 is at an ambient temperature, much cooler than the brakes, and the airflow is closer to laminar (rather than turbulent) and continuously moves the hotter air away. This allows the brakes to shed heat at a faster rate and dramatically lowers the average operating temperature. The present invention provides a vortex tube 3 for supplying a stream of air 5 at a temperature substantially different from ambient temperature into brake ducts 9 to improve efficiency of the brake ducts 9.