Abstract
Hydrostatic bearings are designed on the assumption of fluid film lubrication. However, during severe operating conditions, for instance, the bearing/seal parts of hydraulic equipment, they are usually operated in the mixed lubrication range. A mixed lubrication model of the parallel film thickness is applied to circular hydrostatic thrust bearings. The characteristics of friction, flow rate and power losses on the fluid and mixed lubrication ranges are calculated and the effects of surface roughness, eccentric loads (moment loads), supply pressure and speed of rotation are clarified numerically. By delivering the concept of the hydrostatic balance ratio, the performances of the hydrostatic bearings on the wide region from the fluid film to the mixed lubrication are expressed effectively. The conclusions are as follows : 1. a larger the roughness, larger the coefficient of friction and power losses; 2. the larger the supply pressure, the larger the coefficient of friction and power losses on the mixed lubrication range; 3. the larger the speed of rotation, the larger the coefficient of friction and power losses, and the effects of roughness become remarkable in the region of the high speed of rotation, and 4. the minimum power losses are given in that the balance ratio is close to unity.
