Hydraulic ATB Thrust Block for Noise-Damped Propulsion Systems on Marine Gears
17 July 2006
RENK Aktiengesellschaft manufactures marine gears for naval and merchandise vessels. As well as central components such as toothed gears, radial bearings and casings, RENK also produces auxiliary and lateral outputs, and mostly integrated thrust blocks. The company is a member of the MAN group and excels by meeting all kinds of special requirements regarding the arrangement of input and output, reduction ratio, and weight.
The design of a thrust blocks must be adapted to the design of the vessel, which is 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.
Naval ship design, however, requires 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 the higher weights and the separate oil system required, as well as the need for additional space, this will lead to higher costs.
Recently, RENK has been offering gearboxes which combine the requirements of limited 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,which offers gears combining all power stages. It also offers particular advantages if the propeller thrust can no longer be transmitted through the flexibly supported gear unit, in power values starting with 6,000kW.
Compensation elements in the thrust block enable unlimited effects of the elastic support of the main gear. Under deflection of the flexible support, the slight angular misalignments of the propeller shaft that are transmitted to the thrust collar are counteracted by individual oil pressure cylinders fitted behind the tilting pads. The cylinders are supplied with pressure oil via a common system so that, in the case of different load and displacement conditions, the axial force is identical on all pads. Moreoever, an elastic support is mounted between the thrust block ring and the casing, which acts in axial direction and provides additional noise qualities. The oil required for lubrication is supplied by the gear circuit.
The ATB system offers multiple application possibilities for the highest noise qualities by the compact arrangement of combined thrust block and gear unit. It 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 mega yachts with an input power of up to 35,000kW, RENK once again displays how top technology can be used for marine gears, showing the way to the future.
