The European Parliment stipulated regulations concerning the forestry vehicles operators' health and working conditions. The allowed whole body vibrations were limited, which influenced the design of the vehicles' cabin. Surveys show a strong correlation between operator's comport and their productivity. The object of the research was Rottne AB Comfort Line Cabin, which was designed to increase the comfort for the forwarder operators. The main objective was to determine the cab's inertia properties, position of the centre of gravity and the resonance frequencies of the cab as well as a system consisting of the cab and its suspension. The methods used were an impact test with Mass-Line Analysis for the cab's properties and Operational Modal Analysis for the system. For both tests a Leuven Measurement System was used, but a part of the calculations were made in parallel by use of a MATLAB code written for this thesis. In addition a suspension test was made to estimate the centre of gravity and it was here treated as the reference value. The authors used reference values and the quality of the obtained results to compare the methods used. Further proposals for future research were made together with hints how to use vibration tests more effectively.