As a long term-supplier of rolling bearings for drives found on wind turbines, NSK has now introduced large spherical roller bearings for use on the main rotor. Unveiled at the WindEnergy 2016 exhibition in Hamburg, Germany at the end of September, the first customers have already been secured for this advanced new series of bearings.
With the company’s experience on the demands that are placed on rolling bearings in wind energy applications, NSK engineers have developed a variety of different designs that are optimally matched to the attributes required of main rotor bearings.
For instance, elevated levels of mechanical stress are prevalent as the rotor is exposed to very high wind loads. Although rotational speeds are relatively low at 5-20rpm, the main rotor bearing has to be capable of withstanding both radial and axial loads, including the resulting bending movement of the rotor shaft.
NSKHPS high performance spherical roller bearings featuring a high load factor have been developed specifically for applications of this type, and are manufactured and heat treated in accordance with NSK´s internal Wind Standard U 303.
The breadth of the new range means that selections of different designs are available. For example, a set of two spherical roller bearings is often used in systems up to 3MW, while smaller systems frequently deploy a three-point bearing with a single spherical roller bearing (the attached gear is used as the bearing substitute in this configuration).
NSKHPS high performance spherical roller bearings are proving increasingly popular in wind energy applications. In large systems, some OEMs opt for a combination of double-row tapered roller bearings and cylindrical roller bearings as fixed and floating bearings. This type of rotor assembly can also benefit from NSK rolling bearings manufactured to the company´s Wind Standard U 303, with two tapered roller bearings configured typically in a face-to-face arrangement.
Whichever solution is selected, all of the main rotor bearings developed by NSK are tested rigorously and conform to the highest quality requirements.