CHG Bearing：Bearings for wind turbines

Blade bearings are used to connect blades with hubs in MW wind turbines, and they also can adjust the windward direction of blades to ensure electricity production with power rating and the safe work of wind turbines. Usually, single or double rows four-point contact ball slewing bearings are used as blade bearings, which have preload, special designed seals, anticorrosion surfaces,etc.

Yaw bearings can adjust the windward angle of the cabins and rotors to keep them facing into the wind as the wind direction changes, so wind turbines can produce the maximal amount of electrical energy at all times. Generally, four-point contact ball slewing bearings or crossed cylindrical roller slewing bearings are adopted, whose clearances are close to 0 or preload. In addition, they have special designed seals, and their surfaces are anticorrosion.

There are many kinds of wind turbines. However, the horizontal axis wind turbines are most widely used, and 75%- -80% of which have the structure of inner rings are installed on the rotary main shafts, namely main shaft bearing support structure. 240 or 241 series spherical roller bearings are almost suitable for the fixed and floating ends of main shafts in the structure according to the ratio of radial and axial forces. In other remaining HAWT, bearings' outer rings rotate with hubs, and inner rings are installed on the stationary main shafts, that means hub bearing support structure. This kind of main shaft bearing system commonly includes double-row tapered roller bearings that are preset axial clearance on fixed ends and cylindrical roller bearings on floating ends. Besides, three- -row cylindrical roller combination slewing bearings are also used as main shaft bearings to carry radial loads, axial loads and loads moment.

There are many varieties of gearbox bearings. The main types are NU, NCF and NJ types cylindrical roller bearings and tapered roller bearings. The bearings can be lubricated with gear oil in gearboxes. However, there are many metal particles in that oil, so the bearing life will be shortened. Therefore, good filtration system must be adopted, and bearings should have special heat treatment to form compressive stress on the raceways, reduce the sensitivity of raceways and prolong the life. Furthermore, the surfaces of rollers can be superhard to resist abrasion by coating.

Generator bearings utilize cylindrical roller bearings or deep groove ball bearings, which have the good performance of low noise by improving design structures and processing technics.