sentences:  A mechanical drum brake or disk brake is used to stop turbine in emergency situation such as extreme gust events or over speed.This brake is a secondary means to hold the turbine at rest for maintenance, with a rotor lock system as primary means.Such brakes are usually applied only after blade furling and electromagnetic braking have reduced the turbine speed as the mechanical brakes can create a fire inside the nacelle if used to stop the turbine from full speed.