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Journal Bearings for Wind Turbines – JB4WT



Wind energy is a mainstay of electricity generation from renewable sources and plays a central role in the EU Commission's Green Deal. New generations of wind turbines with ever higher power classes and lower electricity generation costs are required in order to realize further expansion and a higher share of renewable energies overall. To further increase the power density of wind turbines, even more compact designs of drive systems are required. Replacing rolling bearings with plain bearings in planetary gearboxes is therefore an obvious solution, as plain bearings require less installation space, thus enabling more planetary gears in smaller gearboxes. Plain bearings for planetary gears in planetary gearboxes of wind turbines are already available on the market.

However, there is currently no standardized approach to wear prediction for planetary gear bearings. In addition, experience regarding the use of plain bearings in WTs over the total lifetime of a WT of up to 30 years has been limited so far. Furthermore, wind turbines increasingly have to reliably generate electricity even under difficult operating conditions, e.g. less steady wind conditions. This means that wind turbines must not be damaged by start-up procedures or by operation at low speeds. However, such operating points are of particular relevance for plain bearings in terms of wear and must therefore be taken into account in the design of the plain bearing. In order to ensure the reliable operation of planetary gears with plain bearings in wind turbines, a calculation method is required which predicts the wear-related service life of the plain bearing over the turbine service life.

In addition, a standardized test procedure is needed to evaluate different plain bearing and lubricant solutions. Finally, a system for condition monitoring of journal bearings is required to detect journal bearing damage at an early stage and avoid early failures of WTs. The calculation method, test procedure, and condition monitoring system collectively form a standardized framework for journal bearing use in WTG planetary gearboxes. The development of this framework represents the overall objective of the project.


Research objectives

The overall objective of JB4WT is to develop a framework for the standardized use of plain bearings as planetary wheel bearings in wind turbines. Sub-objectives of the project are:

  • Development and validation of a simulation-based, multi-scale wear calculation for plain bearings in wind turbine gearboxes. For this purpose, a model chain will be created, wear models will be selected and implemented, and critical conditions for the possible wear and service life of the plain bearings will be determined.
  • Service life calculation under the aspect of wear in the target corridor of up to 30 years turbine service life considering the frequency of start-stop cycles under the general conditions of low wind regions.
  • Development of a benchmark test at machine element level for comparative evaluation of the performance and wear behavior of plain bearing solutions for planetary gearboxes in wind turbines (materials, lubricants, surfaces, geometries)
  • Condition monitoring system adapted to plain bearings for mapping and detection of plain bearing-specific damage mechanisms (esp. wear)
  • Simplified estimation of possible wear amounts without in-depth modeling for the evaluation of concepts
  • Ability to determine requirements on and by the sliding bearing, depending on the location and considering the economic efficiency


01.04.2022 - 31.03.2025


Project partners:

Winergy AG Vestas Wind Systems A/S

Associated project partners:

ZF Friedrichshafen AG KS Gleitlager GmbH

Sponsored by:

Federal ministry for economic and climate affairs

Project promoted by:

Projektträger Jülich Forschungszentrum Jülich GmbH