The main tasks of this diploma thesis were to acquire knowlegde about the heat flux, the temperature distribution and efficiency of fins in order to give a recommendation on the placing of the fins, either on the inside or the outside of a transfer gearbox. In other words the investigation's aim was to find out how effective heat can be carried off by fins in general. Until now, fins have always been designed on the inside of gearboxes to provide cooling amongst others for esthetical reasons. Throughout this analysis first a look was taken on the theory behind the heat transfer on fins and both, simplified models and gearboxes were used for calculations. This was done by creating a simplified model, which was implemented in Visual Basic for Application (VBA) and compared with results for the same model implemented in the CFD-program Fluent. A simplified gear was then created and the heat flux was investigated for different placing of the fins. The results prove that placing the fins on the outside of the gearbox is better and more effective than placing them on the inside. This knowledge is important for the design of transfer gearboxes. Further on fewer outside-fins are needed due to the better cooling, which implies that the amount of constructive material can be reduced, while at the same time increasing gear efficiency and hence reducing fuel consumption of the entire power train.