Abstract: Studying output shafting in spacecraft mechanism, the analysis and design methods of the reliable operation of space bearing are proposed, which can adapt special environment with alternating temperature and large temperature difference. Based on the relation between thermal deformation of material and displacement coordination, the mathematical model of bearing clearance and preload which change with alternating temperature is established, concerning the material properties of shafting, arrangement style of bearings and preloading. Based on the model, the influence of alternating temperature to the evolution law of bearing used in space between clearance and preload is analyzed. Case with angular contact bearings 71807C, the operation reliability indexes of shafting are proposed, which contain the practical contact angle, radial clearance, preload and the stress between fitting surfaces, and obtained multiple failure modes which the bearing may be faced with in extreme temperatures. To insure of reliable operation of the bearings, the bound of the initial interference fitting and preload are obtained. The methods provide the theoretical reference for space bearing installation, and the graphic results can express the installing regions meeting the conditions of operational reliability.

Key words: alternating temperature, clearance, preload, reliability, space bearing