An improvement is made to the design of an epicyclic gearbox that limits the dynamic eccentricities of gearbox components. Gearboxes were manufactured to the new design and tested, showed reduced levels of subsynchronous vibrations at the turbine bearings. The in-situ balancing feature of the gearbox is also found to be very effective in reducing these vibrations further. The improved gearboxes not only assured the service life of the turbine bearings, but also increased the success rate of package testing the first time with substantial cost savings.

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