Abstract
This paper describes the static characteristics of hybrid (water/air lubricated) hydrostatic journal bearings. Aerostatic bearings have often been used for high-speed spindles because of its low friction and high accuracy of motion. However aerostatic bearings have disadvantages such as lower load capacity and bearing stiffness compared with water-lubricated hydrostatic bearings. On the other hand, water-lubricated hydrostatic bearings have higher damping coefficient and larger load capacity though larger power consumption is needed at speeds. In this paper, therefore, we propose a hybrid journal bearing which can be used as both an air-lubricated and a water lubricated hydrostatic bearing. The proposed bearing can achieve both low power consumption and large load capacity by selecting air or water as the operating fluid according to the operating condition of a spindle. In addition, the static characteristics of the proposed bearing are theoretically clarified and the usefulness of the bearing is shown.
