THOROFARE, N.J.--(BUSINESS WIRE)--The U.S. Army Corps of Engineers (USACE) has approved GGB Bearing Technology’s new HPMB™ filament wound bearings for use in hydropower turbine wicket gates. The approval is based on simulation testing performed by Powertech Labs.
Conducted in April 2015 in accordance with USACE specifications, the testing simulated the operating conditions of a wicket gate in a Francis turbine. Test results showed an extremely low stick-slip effect, indicating smooth operation of the regulating mechanism in a turbine, as well as a low wear rate with no visible bearing damage in wet, dry or edge testing.
According to the test report, “The dynamic and static coefficients of friction were quite close to each other, which indicates a smooth end of stroke direction reversal. The test ran smoothly and quietly and the coefficients of friction remained stable for the duration of the test. Overall the bearing was in excellent condition…the wear rate was exceptionally low.”
In addition, HPMB™ offers high load bearing capacity, plus excellent resistance to shock and misalignment and dimensional stability in water. It is also the best performing bearing material under conditions that include dithering -- the high frequency, small angle oscillations present in turbine operation.
HPMB™ features a machinable liner that provides tight dimensional control and class-leading tribological properties for hydropower applications. Post-installation ID machining allows IT7 diametrical tolerance to be achieved with improved concentricity and cylindricity. Liners can be machined with commercially available inserts.
HPMB™ bearings are available in three configurations: finished by GGB and ready for installation; finished OD and length and ready for end-user ID machining prior to installation; and finished OD and length and ready for end-user ID machining after installation. The last two configurations are valid for refurbishing turbines by OEMs that do not know exact component dimensions and tolerances.