[turnipsock (OP)]

I'm guessing there is some gizmo that picks up the wind direction and turns the windmills to face the wind but I can't see anything on top of them.

Does anybody know how it's done?

[Madidus_Scientia]

Wouldn't they just naturally swivel that way?

[Don_1]

I would think that a close by wind direction vain governs which way the windmills face. Just a guess.

[elmejor]

Wouldn't they just naturally swivel that way?

even i would like to believe that they swivel naturally coz of air pressure

[Don_1]

Wouldn't they just naturally swivel that way?

even i would like to believe that they swivel naturally coz of air pressure

This might be possible in strong winds, but lighter winds would not be able to turn such a heavy unit. I should think they would be turned by electric motors.

[blakestyger]

Each up-wind turbine unit has a wind vane mounted outside at the back. This measures wind direction and sends a signal to the yaw drive (top of the upright, below the nacelle) to orientate the turbine to head-wind. I've never seen a down-wind type (doesn't need a mechanism) and Norfolk's littered with turbines.

There's a simplified drawing and explanation at:

http://www1.eere.energy.gov/windandhydro/wind_how.html

[erickejah]

so the data gathered from the anemometer is processed and transformed to a signal that feeds the Yaw drive -the yaw drive is used to keep the rotor facing into the wind as the wind direction changes-.

 [] very interesting