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RENK Gears Handle 20,000 RPM
01 Oct 2004
Germany's RENK Aktiengesellschaft has won a contract with America's Pratt & Whitney Power Systems toprovide reduction gears for six Royal Norwegian Navy Skjold class patrol boats. The carbon fibre SES type catamarans are being built at the Umoe Mandal yard in Norway.
A detailed study of various propulsion configurations saw a CODOG arrangement in the 1999 built prototype but the production models will have a COGAG installation in each of the semi-hulls whereby 2,000 kW and 4,000 kW gas turbines will enable a selection of cruise modes and a sprint speed of 60 knots. The power of Pratt & Whitney ST18M and ST40M gas turbines will drive water jets via RENK triple stage BUS 86/75 reduction gears.
The RENK BUS 86/75 gears feature double helical teeth in a low vibration and low noise design.
An aluminium casing structure results in lightness while self-synchronising SSS clutches shift automatically between operational modes. Both gas turbines are flanged one above the other to the gear set, providing compact propulsion modules in combination with the RENK gears. They will be fitted into the narrow semi-hull structures supported by elastic elements for vibration attenuation.
The input speed from the smaller gas turbine rotating at 20,000 rpm, a claimed new record speed for marine gear applications, is being transferred to the gear train with teeth arranged in parallel via a transmission planetary gear of minimum dimensions. This enables the compact design.
The use of double helical teeth throughout the gear configuration avoids axial loads, hence the lightweight casing structure is not subjected to additional forces. All gear stages are of optimised design by tooth corrections to the RENK principle in terms of load capacity and smooth running behaviour.
MJ Information No: 19911
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