Lippstadt: It’s all about testing

No wind energy without slewing bearings

As strange as it may sound, there are no brakes in a wind turbine. The only way to stop these huge systems is to turn the rotary blades out of the wind, which requires bearing solutions. Rothe Erde installs up to five bearings in one wind turbine. They are used for adjusting the blade pitch, turning the nacelle, and as a main bearing. (Carousels, baggage scanners, tunnel boring machines, telescopes, and railway vehicles also all contain slewing bearings.)

To shed some light on this complex technology, these bearings are basically construction elements that connect machine components with one another. They transmit movement or power and contain an outer and inner ring. But that’s enough physics for today.

Ice ice baby

But the really fascinating question is: how to choose the correct bearing for the turbine? The customer first supplies data for his planned system site, for example, the average wind speed. Afterwards, Rothe Erde develops the component and carries out extensive testing. Can the material of the slewing bearings withstand these conditions? How many years of wind, rain, cold, and heat can it take based on the data? The development center uses a range of elaborate technical processes to answer this question and optimize the products as best as possible.

For example, there are salt spray chambers to simulate how the components react to decades of extremely salty coastal winds. There are special refrigerators that transport the bearing to the climate of Siberian polar bears. Alternatively, there are ovens to send the material to the desert for testing.

Huge test benches

But the huge test benches for bearings for wind turbines greater than six megawatts are especially spectacular. These test benches do not actually blow wind through the turbine. Instead, hydraulic power or electricity simulates the wind that affects our slewing bearing. This is at a rate of six megawatts, the amount the largest wind turbines at the top end of the market produce today. This may even increase to 12 megawatts in the future. But I think it’s likely that Rothe Erde will need to expand before then.