gearboxes
from the outset with gears supplied by Renk, and the company reported that the US Navy had been impressed with both the up-to-date technology of the products and their reliability. At the beginning of 2011, Renk was successful in achieving a major milestone in its US business with 20 littoral combat ships (LCS) being ordered equipped with Renk marine propulsion gears. The contract covers both LCS classes, and Renk will therefore supply the entire LCS fleet with main propulsion gear units.
The delivery schedule is based on two gear sets per year for each class of vessel, being built in parallel for five years commencing from 2012. Both share the same design principles and technology with purpose-designed gear ratios and mechanical designs
to minimise overall
gearbox weights. Double helical gears are used to ensure reliable torque transmission along with the lowest achievable levels of noise generation, as is required for all modern naval vessels. Work with the US Navy has involved Renk in the establishment of a specific organisational structure to manage its operations and comply with complex government regulations. It has been helped in this by previous experience in the supply of gear units for combined diesel and gas (CODAG) propulsion systems for US Coast Guard applications. Total US naval business for Renk
now represents an order volume of more than €100 million, assuring a basic workload for the German manufacturing plant, where the gear sets will be built, for years to come. In addition to the US order, Renk has experience in the supply of drive train solutions for 35 navies worldwide. The Renk portfolio offers a comprehensive range of marine gear units, and specific experience in military vessels. The product range starts with reversing gears rated at 2,500kW and
A Renk installation on a naval frigate
extends to main gears for naval vessels rated at up to 40MW and more of transmitted power. Planetary and parallel shaft arrangements are available to meet
varying application
requirements and the latter can be arranged for horizontal or vertical offset between input and output shafts. To satisfy more complex drive configurations, twin engine drive gearboxes can be provided, as well as auxiliary drives, and for gas turbine applications, two-stage reduction gearboxes are available. Renk also manufactures marine drive shaft clutches, which begin at a power rating of 6,000kW, rising to an impressive maximum rating of 75MW.
The supply of gears for the luxury motor yachts is a further market for which Renk gearboxes have been selected, one example being the contract awarded for a double combined diesel and diesel (CODAD) gearbox system for the superyacht Predator. Built at the De Vries shipyard in Aalsmer, the Netherlands, it is equipped with four 4,320kW diesel engines,
mounted in pairs and driving two shaft lines through two Renk type BSL 2 x 130/140 gearboxes. Either one or two engines can be operated on each drive train, dependent upon propulsion requirements, and the clutches are integral to the gearbox design. The 72.8m Predator, launched in 2008, is
renowned for its axe-bow design. It is also rated as one of the quietest motor yachts of its type, this being partially due to the double helical gear design which reduces noise generation to a minimum. The gearboxes are also mounted on specialist hard elastic mounts
to reduce
the transmission of structure-borne noise. A multi-disc clutch is incorporated in each input shaft with this ensuring the smooth and safe engagement of drive. A further feature is the specially developed and patented thrust bearing, which has its own separate lubricating oil system and incorporates hydraulically supported thrust pads. All aspects of the gearbox design and manufacture are fully in accordance with Lloyd’s Register requirements. MP
Gear manufacturers develop products at all scales
Supplying gear equipment for both military and commercial marine applications, David Brown, based in Huddersfield, England, has now taken on the heritage of Maag Italia, Alstom Gears (formerly GEC Marine & Industrial Gears) and the gear making facility of the former Vickers Shipbuilding & Engineering
Ltd (VSEL) Group. David
Brown now operates facilities worldwide to provide and support advanced marine gear transmission systems.
Naval applications can be seen across
the world and the company claims that every British naval frigate and destroyer uses David Brown gears. Every British Navy aircraft carrier is also driven by David Brown gear technology and many of the world's nuclear-powered submarines also use the company’s gears for silent primary transmission and for the highly
58 I Marine Propulsion I February/March 2012
specialist application of transmitting power for weapons systems.
Multiple CODAG and similar transmission
configurations are available to suit hybrid engine configurations and the technology used in naval gear systems is shared with the commercial sector. David Brown propulsion systems are available for commercial vessels of all types, including liquid natural gas carriers. All products are optimised to meet specific power requirements, designed to meet any recognised Certification Authority or Class rules and fully quality assured to the latest international standards. All major gear manufacturers are constantly developing their products at all scales, with new equipment being introduced to satisfy new engine or ship design requirements. The engine and machinery division of Hyundai
Heavy Industries Co Ltd (HHI-EMD) started its engine business in 1979 and now claims a global market share of up to 35 per cent. In addition to this, HHI-EMD is now developing its own transmission systems and recently announced a new marine gearbox for its Himsen 6H21/32P engine. Designed
for fixed pitch
applications, the gearbox was fully witness tested against a dynamometer with its diesel engine driver. Rated at 1,200kW the gear was manufactured to meet ISO quality requirements. Despite the high single-stage gear ratio of over six to one, noise and vibration levels were measured at levels below design limits. The first gearbox was installed in a Hanjin Shipping 10,500 dwt coal
carrier in the summer of
2011 and further applications and gearbox developments are expected.
www.mpropulsion.com
propeller
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