The purpose of this research was to determine the conditions for cooperation amongst various components of belt transmission systems in grain harvesters in terms of thermal loads acting on them under operational conditions. A number of field research tests were conducted, using the thermal image measurement method, where selected structural elements of the belt transmission systems were depicted with a thermal imaging technique. The authors focussed on the methodological benefits and problems resulting from the research manner adopted. The authors presented results which could provide a valuable source of information of a utilitarian nature as they could be used for diagnosing the technical condition of kinematic odes in the mechanical transmission systems in question.