Case Studies

The array of bearings within a turbine gearbox are subject to subtle yet critically different operating regimes and installation constraints leading to a diversity of failure modes and many more hypotheses for solutions – none of which have yet provided the full 20 year design life. This project will develop prototypes of a new concept from Ricardo UK Ltd to increase bearing life. Its effectiveness will be tested against standard wind bearings under accelerated test conditions, ahead of series production.

One unavoidable category of installation sees a unidirectional radial load that acts upon the same forty degrees or so of the circumference of the inner race. This situation leads to localised fatigue damage and premature failure of the planet bearings in the epicyclic stages of the gearbox. One pragmatic solution involves rotating the "fixed" inner race every-so-often such that the wear is distributed around the full circumference of the race. This ensures that the fatigue damage never reaches a critical condition during the turbine life. The bearing's name, MultiLife™, will be appropriate if testing proves the 5-fold increase anticipated. A suite of mechanisms to achieve this were devised and the best were patented before presentation by Ricardo at the Offshore Wind Conference in Stockholm in 2009. The challenge came in inventing a solution that was practical for application to relatively standard bearings in both old and new gearboxes - the former being a large market of fault-prone gearboxes in existing turbines that will be re-conditioned.

Detailed estimates have been made for the commercial case for the device and the jobs that would be created in the supply chain. Ricardo has already brokered discussions with the demand chain to create the "pull" for the product and will continue this during the project to ensure seamless transition to the next phases of commercialisation after the end of the NWIP project.

Jonathan C. Wheals
Chief Engineer Innovation/Technology

Ricardo UK
Midlands Technical Centre
Southam Road
Radford Semele
Leamington Spa
Warwickshire
CV31 1FQ, UK

Tel: +44 (0)1926 319331
Email: jonathan.wheals@ricardo.com
Website: www.ricardo.com