Fan Brake Systems 
When selecting brakes for a fan or chipper application the Engineer must strike a balance between the desired stopping time and managing the thermal energy produced by the brake.  Generally, a basic system consists of a pair of air applied disc brakes, a hub mounted ventilated disc and an air control panel.

Reference the brake data sheets to select the appropriate model that will stop the rotating inertia of the fan in the desired time (apply a 125% service factor to your selection).