RENK Marine Gear Units
16 March 2005 11:19
Vast Variety for Tailor-Made Gear Unit Systems
Commissioned to US Customers After Successful Test Runs
RENK Aktiengesellschaft, a member of the MAN group, is the leading manufacturer of gear unit systems for commercial ships, naval vessels and coastal patrol boats all over the world. Two most impressive examples for the enormously wide range of applications offered by RENK have recently been commissioned after their successful test runs.
The lowest specific weight ever attained worldwide applies to the high-capacity marine propulsion gear with COGAG-arrangement (two gas turbines combined as input to one gear unit). This ultra-compact propulsion system is going to be used om-board the new SES-catamarans of the Royal Norwegian Marine. After a successful completion of the test runs, the first of six marine gear sets has been commissioned to the US-customer Pratt & Whitney Power Systems, Hartford/Connecticut. An entire propulsion module, consisting of two gas turbines and the gear set, is going to be scrutinized under full load conditions by the US-classification authority NAVESEA (Philadelphia, USA) in March 2005.
The RENK gear system, comprising two 3-stage reduction gear units of type BUS 86/75, provides for a most flexible operation at cruising speed and maximum speeds of up to 60 knots on both water-jets. A high-precision double-helical gearing, which avoids axial constraining forces, guarantees extremely low noise and vibrations values.
The COGAG-arrangement, which combines two gas turbines of 2,100kW and 4,200kW power, is integrated in two carbon-fibre semi-hulls. The turbines are arranged vertically and flange-connected to the gear set. The input speed of the smaller gas turbine with 20,0000rpm - a new record for marine gear units - is reduced via an integrated intermediate planetary gear unit of minimum dimensions to 8,000rpm in the parallel offset gear train. Self-synchronising SSS-clutches allow a fully-automatic change-over from one travel mode to the other, thus guaranteeing maximum efficiency over a wide range of ship speeds.
Versatile CODAG Installation for Patrol Boats of the US Coast Guard
With production progressing on schedule and after successful testing, the first CODAG gear unit system (Combined Diesel and Gas) was commissioned to Northrop Grumman Ship Systems almost simultaneously. Other than the gear system described before, this system is a rather heavy-weight (110t) but most modern CODAG-installation combining the RENK gear unit types AS 2/250 and AS 198F.
Based on the excellent experiences with the very first CODAG propulsion system installed worldwide into the new frigate F 124 of the German Navy’s “Sachsenklasse”, the US Coast Guard has adopted this propulsion concept for the new large-size National Security Cutters (NSC). The CODAG system with one central gas turbine and two diesel engines located in between the c.p. propellers and a total of 37,000kW allows a most efficient operation since the propulsion unit may be perfectly adapted to each travel mode.
But the system also excels within the partial load range, i.e. while one diesel engine is acting on both propellers, which covers almost 70% of the operating time. As a consequence, the maintenance intervals of the diesel engines become much longer thus saving maintenance costs and increasing availability.
All gear stages of this system feature double-helical teeth, and, in addition, high-precision grinding technology by RENK. This combination has become common practice at RENK for such sophisticated heavy-duty gears.
These new buildings are another impressive example for the outstanding capacity and versatility of the RENK marine gear units which is reflected in figures: almost 450 propulsion systems aboard destroyers, corvettes and frigates of 30 international marine associations are equipped with RENK gear units.
For more information on this company:
RENK - Marine Gears for Main Propulsion, On-Board Power Generation, Bearings and Couplings
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