General laws governing the rate of flow of oil through complete journal bearings are developed in the paper. These laws are based on the assumption that axial flow obeys Poiseuille's Law and is, therefore, a function of the bearing load. Dimensional reasoning indicates that the volumetric efficiency of a bearing considered as a pump is given by an equation of a form in which efficiency equals a function of the viscosity times the rubbing speed divided by the bearing load, the length divided by the clearance and the length divided by the diameter. Experimental evidence is presented which substantiates this point of view.
The general relation of rubbing speed to heat generation and oil-flow is discussed for the purpose of indicating a possible solution of certain high-speed-bearing problems. A plain bearing is, in effect, a pump in which the flow of a viscous lubricant through a passage of varying area develops a pressure sufficient to sustain the imposed load. Oil-flow in the direction of the axis of such a bearing is due to two causes: Oil-film pressure developed to support the bearing load and oil-feed pressure. The oil-flow due to the first of these causes, or the efficiency of the bearing as a pump, is the important factor. The influence of both sources of pressure is considered separately, and the seven conclusions reached are stated.
