These are fitted to some WTs to avoid runaway situations when other braking mechanisms have failed. The tips of the blades are separate from the rest of the blade, and mounted on spring-loaded, threaded rods. As the rotor accelerates, centrifugal forces cause the tips to pull away from the body of the blade, and the thread on the rods causes the tip’s sections to rotate, spoiling the aerodynamics of the blade and regulating the speed of the rotor, preventing overspeed.