Look at a wind turbine on the prairie, and it’s easy to see how the force of blowing air creates rotational movement that can then turn a generator. But here’s the hitch—windmills only move at about 15 rpm, while an off-the-shelf generator needs to spin at 1000+ rpm to output useful 60-cycle AC power.
The solution? Encased within the housing (or “nacelle”) of most wind turbines lies a sophisticated gearbox. In principle, the gearbox simply consists of big gears driving small gears to deliver faster rotational speeds to the generator.