323 Paper number: 9(2011)2,198, 323 - 330 AGRICULTURAL TRACTOR CAB CHARACTERISTICS RELEVANT FOR MICROCLIMATIC CONDITIONS The basic purposes of an agricultural tractor cab are to provide comfortable environment for an operator and to protect him from vibrations, noise and other adverse inuences. The microclimatic features of middle-sized tractor cabs are the focus of this paper. The microclimatic conditions are related with design features that inuence heat processes between the cab and the environment, including the effects on the operator. One of methods for improvement of the microclimatic conditions and for reducing of air-condition- ing energy consumption is prevention of cab heat gain, achieving this by appropriate heat rejection and insulation. Since the cab material characteristics and cab design play the main role in the heat transfer processes between the cab and the environment, these features are analyzed on existing middle-sized tractor’s cabs. The aim of the paper is to identify and evaluate most important inu- ences, in order to create the basis for microclimatic and energy consumption reduction aspects of a tractor cab design. The results showed that the cab glazing is probably the most inuencing factor, where the selection of the appropriate properties could be the way for cab and operator heat load reduction. Key words: Tractor, Cab, Ergonomics, Microclimate, Glass * Faculty of Technical Sciences, Trg D. Obradovia 6, 21000 Novi Sad; ruzic@uns.ac.rs INTRODUCTION Modern agricultural tractors are complex and highly-efcient systems, whose development is constantly directed towards reduction of nega- tive impact on the environment (higher fuel ef- ciency and lower pollution, less soil compaction, to mention a few), but also towards operator’s space ergonomics. Conditions inside the cab have signicant impact on operator perfor- mance, therefore on total result in the man-trac- tor-environment system too. From the operator’s point of view, cab ergonomic is a key factor in ensuring of his optimum working performance, which could easily become the weakest link in the working process. While, on the one hand, the cab offers the mechanical protection and protection from adverse ambient conditions, on the other hand, even under moderate outside conditions the closed cab act like green house and its closed interior could become unpleasant, unbearable and even dangerous. Mr Dragan Ruži* University of Novi Sad, Faculty of Technical Science Dr Ferenc asnji University of Novi Sad, Faculty of Technical Science This paper covers designing aspects of tractor cab that have direct or indirect effect on ergo- nomics of the thermal environment on operator’s working place. Ergonomics of the thermal envi- ronment is based on the relationship among air temperature, interior surfaces radiant tempera- ture, air velocity and relative humidity, which in combination should obtain the absence of dis- comfort, for given operator’s activity and clothing [6], [15]. Thermal processes in cab system are almost independent from tractor’s working operation, in contrast to noise and vibration, but are de- pending on outside thermal conditions (air tem- perature, air velocity, intensity of solar radiation). Therefore, the cab is here taken as a separate unit. Since decreasing the heat gain of the cab means also reduction of thermal load to the op- erator, relevant design parameters are analyzed in this paper. The aim of the paper is to identify most inuencing factors in order to consider pos-