NKE has developed a modular bearing system for the planetary gears in wind turbine gearboxes.
According to NKE, the system is already in use in the 1.5, two and 2.5MW wind turbine gearboxes of a well-known German gearbox manufacturer.
NKE says most wind turbines use gearboxes to transform the relatively low rotational speed of the main shaft into higher speeds required for power generation. Because the modern wind turbine gearbox has to transmit forces that are forever increasing while itself remaining compact, single- or two-stage planetary gearboxes are commonly used.
The bearings of the planetary gears are among the highest-loaded in this specific application, NKE claims. In modern gearboxes, an integrated planetary bearing arrangement is used, in which cylindrical roller bearings without an outer ring are fitted in the planetary gears, with the bore of the gear forming the outer raceway.
According to NKE, the modular concept is based on single-row cylindrical roller bearings of the RN range, which do not have an outer ring. These bearings are equipped with a one-piece solid brass cage, which is guided by the inner ring (MPB). This cage features inspection grooves for endoscopic inspection of the inner raceways as standard.
NKE supplies ready-to-install matched bearing sets. The tightly toleranced overall height of each individual bearing and their precise matching of these ensures an even distribution of the radial loads.
Each bearing set includes the components required to secure the bearings axially in the planetary gears — such as retaining rings and loose rib rings. If required, the overall width of each bearing set can be adapted to the operating conditions and the available space with spacer rings fitted between the individual bearings.
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