Paper 7: An Investigation into the Performance of Dynamically Loaded Journal Bearings: Experiment

Abstract

The design of a rig to determine the load and attitude relationships of a hydrodynamically lubricated bearing under steady and dynamic loading is described. The bearing is nominally of 3 in diameter with a diametral clearance of 0·0075 in. Two bearing lands of length-diameter ratio of 0·282 are fed by a central circumferential oil groove. It has been designed on these model conditions to minimize bearing distortion and temperature gradients in order to provide a basis for comparison with the results of the computer program reported in Paper 6. Two perpendicular load components are applied mechanically through spring levers displaced by cams. The load components are measured by strain gauges and the displacement of the bearing is detected by four inductive pick-ups. The arrangement of these permits the relative linear and angular displacements of the journal and bearing axes to be determined. Inlet and outlet oil temperatures are measured for viscosity determination. Both steady and dynamic loads are applied by the loading system. Load diagrams of approximately circular and elliptical form may be obtained directly by adjusting the magnitude and phase of the eccentrics serving as cams, while more complex load patterns may be obtained by special cams. The polar load diagrams recorded are used as data for the computer program of Paper 6. Theoretical and practical results are then compared.