Wind mill Hub

In simple designs, the blades are directly bolted to the hub and are unable to pitch, which leads to aerodynamic stall above certain wind speeds. In other more sophisticated designs, they are bolted to the pitch bearing, which adjusts their angle of attack with the help of a pitch system according to the wind speed to control their rotational speed.The pitch bearing is itself bolted to the hub. The hub is fixed to the rotor shaft which drives the generator directly or through a gearbox.