Increasing requirements to modern vessels concerning performance and ma-
noeuvrability led to very complex drive train designs. Therefore azimuthing thrusters
became very common in the area of offshore supply vessels, tug boats and specialized
research vessels. In order to extend the already huge field of operation and to
better understand dynamic effects in such azimuthing thrusters the research project
"EraNet HyDynPro" was started. The project focuses on the design of a robust drive train which
contains a bevel gear stage. Therefore loads caused by propeller-water-interactions as well as
loads while operating under ice conditions will be analysed. Based on this interdisci- plinary
project a contemporary way of gear calculation will be shown in this paper. For gear calculation
it is necessary to acquire design loads. These can be measured at high costs or be simulated
numerically. In the last few years the Multi-Body-System (MBS) Simulation got more and more
popular to determine static and dynamic properties of large drive trains. This
simulation can contain mathematical models of the propeller behaviour inside the water
and under ice conditions as well as models of the electrical motor. Based on this a
good prediction of gearing loads is possible. By the knowledge of the gearing load
time series a complex tooth contact analysis can be made for every arbitrary point in
time using specialized gearing software. Gear tiltings are considered in order to calculate the
load distribution on the tooth flanks. By this knowledge a local comparison of the
load and load capacity can be carried out. But how to handle the vast variety of load
situations during different load cases and long time series? Therefore an appropriate
classification of the different occurring states of gear deviations and gear loads will be
presented. This way we are able to determine the risk of common gearing failures like pitting
and tooth root breakages in detail for individual drive trains under different operating
conditions. The paper will present the procedure of this contemporary way of designing gears. By
using a simple spur gear set the general idea of simulating the operating conditions of a drive
train and the subsequent complex tooth contact analysis will be explained. On basis of this information a suitable approach to assess the risk of different gearing failures is carried out and the results will be illustrated.
