The aim of this thesis was to develop a test-based procedure making it possible to estimate the efficiency of gearwheel pairs as well as their friction losses. The thesis is split into three main parts, namely: literature research, a gear shape correction of a FZG-C tooth system and lastly the development of a new testing cell. The first part, literature research, provides a summary of gearwheel tribology. It focuses on the origin of the friction losses and its connection with the gear wheel geometry, the main magnitude of influence, and the improvement potential by technological measures. In the second part the gear tooth shape correction of a FZG-C tooth system is explained. Firstly the elementary circumstances of the sliding movement and the rolling motion between driver and wheel are displayed. Afterwards an efficiency optimization of the gear system was attempted and the resulted optima compared. Lastly, the third part of the thesis describes in detail the development of a new testing cell. It has the aim to examine the exact frictional phenomenon between two discs. The cell was designed to be compatible with the Tribometer TE 77 used at the Department of Mechanical Engineering at the University of Leoben. It reproduces the load- and movement situation of a common tooth contact and measures the traction component of the friction when slip exists. The design of the cell enables also to simulate a slip in transverse direction as it is the case for instance in hypoid gearings. It also offers enough space for all measuring instruments which might be needed.