RENK, a member of the MAN group, is a manufacturer of complex main reduction gears for navies.
Mechanical propulsion systems with combining gears provide the combination of gas turbines and diesel engines. In particular RENK CODAG propulsion gears (COmbined Diesel And Gas turbine) have been implemented on new vessels in the past years, such as the German Sachsen-class frigates or the US Coast Guard National Security Cutters.
Another milestone in this field of RENK gearing applications was the recent factory acceptance trials of the CODAG combining gear set for the Turkish Navy programme Milgem. These consist of two propeller shaft lines each connected to main reduction gears, with the power supply via a cross connecting gear from one 20MW class gas turbine. Two additional diesel engines are arranged inboards for loiter or cruise speed, and sprint speed is achieved together with the gas turbine in CODAG mode. All three sub-gearboxes are positioned on hard elastic foundations of RENK's latest design.
During a one-week trial used to check functionality of mechanical and hydraulic components up to full speed, the 130-tonne gear set provided its full capability in all operational modes. Additionally, low noise signatures were measured with highly sensitive vibration sensor equipment of latest technology. In all ways, records showed best match with expected values.
Additionally, the traditional CODOG arrangement (Combined Diesel or Gas Turbine) as installed in some 40 naval surface combatants for different navies found a further customer. RENK received a contract award for the new Korean FFX frigate propulsion. RENK will provide the design authority and major core components for the two so-called locked train gears for the separate propulsion shaft lines. The prototype gears will be assembled and tested at RENK, with delivery due October 2010.
In the field of propulsion systems for naval vessels larger than 5,000 tonnes, design deals today also with the use of speed-controlled electric motors in place of diesel engines for cruising. A centrally arranged gas turbine additionally supplies power to the two controllable pitch propellers during high-speed operation.
This is called a CODELAG (COmbined Diesel- ELectric And Gas turbine), where all three propelling machines simultaneously generate power for the vessel's maximum speed.
For the first propulsion plant of this kind in Europe, a French-Italian consortium placed an order to the Italian shipyard Fincantieri, Genoa, to design and build the first two frigates for the Italian Navy within the Italian-French bilateral project FREMM (Frégate Europèenne Multi-Mission) and further eight ship sets are to follow, with the decisive participation of RENK as system supplier of the gear units.
Under cooperation with Fincantieri, RENK designed the gear arrangement for the Italian portion of the program, and supplied crucial gear components. The prototype gears underwent successful trials at Fincantieri's facility at Riva Trigoso earlier this year.
Technically derived from well known CODAG versions, the gear unit consists of a cross-connect gear transmitting the power of the 32MW gas turbine to the two propeller shafts. Each of the two main gear units are connected in second stage to the propeller shafts, mechanically linked with the cross connecting gear forming a gear system weighing 140 tonnes at twelve-metre width.
A new RENK patented propeller clutch, type APC, arranged between main gearing outputs and each shaft line, transmits half the gas turbine power. The electric motors arranged directly on the shaft lines supply their power either individually (cruising speed) with disconnected APC clutch or in connection with the gas turbine (CODELAG top speed) when the APC clutches are closed.
All applications as described underline the customer's acceptance of RENK's surpassing technology for naval combatants. Based on the experience with sophisticated gearing solutions aboard vessels in service with over 35 navies, RENK continues to build on this knowledge base to ensure a continued lead as prime supplier over a wide range of naval programme.
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