A Comparison Study Between the Performance Characteristics of Circular and Rectangular Recess Pads of Hydrostatic Bearings

Abstract

As known in mechanical engineering, any rotating shafts must be supported on bearings to reduce friction and wear and so decreasing the power losses and increasing the shaft life. These bearing may be rolling or sliding. Although the rolling bearings have low friction than sliding, but the sliding (journal) bearing can possess high working life than rolling ones if they furnished with good lubrication systems. These lubrication systems are divided into two types. The first type is the hydrodynamic lubrication which generates the oil pressure by the effect of squeeze action. Whereas the other type is the hydrostatic lubrication which generates the oil pressure by the effect of an external pressure source (pump). In the hydrostatic bearing, the oil is pressurized from the external pressure source into a pocket (or pockets) manufactured in the bearing inside the surface between the shaft and the bearing to generate a projected area for carrying the radial applied load. These pockets are generally of circular shape in most applications. In this study, a rectangular recess shape is proposed to be as the pocket instead of the circular one. The bearing characteristic performance parameters as: pressure distribution in the bearing land, the load capacity, the friction torque, the power losses, and the temperature rise are considered. A comparison between the performance of both the circular and rectangular recess pads is given based on unifying the recess shape parameter.