Hydraulic ATB Thrust Block for Noise-Damped Propulsion Systems on Marine Gears
17 January 2007
RENK, Augsburg manufactures marine gears for naval and merchandise vessels. Auxiliary and lateral outputs as well as mostly-integrated thrust blocks are part of their manufacturing programme, which also includes central components such as toothed gears, radial bearings and casings.
The company is member of the MAN group and excels by meeting all customers' requirements regarding the arrangement of input and output, reduction ratio, and weight.
The design of thrust blocks must be adapted to the design of the vessel provided by the shipyard. Usually the thrust block is integrated into the gear unit between the propeller shaft and the bull gear. The propeller thrust is transmitted via the rigid connection between the vessel's foundation and the casing. Front-side thrust blocks are applied as well. A short design length is common to both types.
However, naval ship design prescribes more of an elastic support of the gears in order to achieve the lowest structure-borne sound. In this case, the thrust block must be arranged as an individual unit in the shaft system. In view of higher weights and a separate oil system this will lead to higher costs, apart from the additional need of space of course.
RENK offers gearboxes advantageously combining the requirements of little space and elastic support with a thrust block directly attached to the gear unit. The core piece here is the Advanced Thrust Bearing (ATB) system handed in for being patented, which is ideal for combining gears at all power stages. It offers particular advantages for power values starting with 6,000kW if the propeller thrust cannot be transmitted any longer via the flexibly supported gear unit.
Compensation elements in the thrust block enable unlimited effects of the elastic support of the main gear. Under deflection of the flexible support, slight angular misalignments of the propeller shaft transmitted to the thrust collar are compensated by individual oil pressure cylinders fitted backwards of the tilting pads. The cylinders are supplied with pressure oil via a common system so that, in case of different load and displacement conditions, the axial force is identical on all pads. Moreoever, an elastic support is mounted between thrust block ring and casing acting in axial direction, providing additional noise qualities. The oil required for lubrication is supplied by the gear circuit.
The compact arrangement of the combined thrust block and gear unit in the ATB system offers multiple application possibilities for high noise qualities. This represents a development of the proven RENK technology with load compensation on thrust block pads. Suitable for naval vessels equipped with CODAG or CODELAG propulsion systems as well as comfortable mega-yachts with up to 35,000kW of input power, RENK once again provides evidence of how top technology can be applied on marine gears to show the way to the future.
