Safety device for restarting windmilling turbojet

A turbojet (1) has a fan (2) and compressor driven respectively by low pressure turbine and high pressure turbine through the coaxial shafts (3,4). The shafts are interconnected, to compensate rotation speed in normal operation of turbojet. A braking system (6) slowdown or blocks a differential (5) having an annular gear (7) rotating about the shafts, when turbojet shuts down.