lightning rod 
Metal rod that is attached to the nacelle; it protects the wind turbine from lightning, which it directs toward the ground.
alternator
Rotating machine that is driven by the high-speed shaft; it converts mechanical energy into electric energy and then directs it to the transmission network.
high-speed shaft
Cylindrical piece that transmits the high-speed movement of the rotor to the alternator; it turns at about 1,500 rpm.
speed-increasing gearbox
Part that increases the rotational speed of the rotor to drive the alternator.
low-speed shaft
Cylindrical part that transmits the rotor hub’s movement to the gearbox; the low-speed shaft usually turns at 20 or 30 rpm.
wind vane
Instrument that indicates wind direction using a vane that rotates around a vertical axis.
anemometer
Instrument that measures wind speed using cups that rotate around a mobile shaft at varying speeds.
ball bearing
Part that consists of steel rings with steel balls inserted between them; it reduces friction as the shaft rotates.
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