Studies in Lubrication IV. The Experimental Variation of the Coefficient of Friction with the Strength of the Lubricant Source for a Complete Journal Bearing

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Abstract
The experimental study of the lubrication of a complete journal bearing has been extended, emphasis being placed upon the role played by the position and strength of the lubricant source upon the coefficient of friction. As predicted theoretically, the friction on the bearing has been found to increase with increasing source strength and to be somewhat higher when the source is at the crown than when at the base (region of highest load) of the bearing. It has also been found that when the source is at the base, where it aids the journal rotation effects in supporting the load, the bearing may be successfully operated at much lower speeds and higher loads than when it is at the crown without encountering the usual thin film phenomena. Moreover, for this case, there exists a critical value of the source strength at which the journal and bearing are concentric and the coefficient of friction is given by the simple Petroff theory. The experimental results confirm qualitatively all the predictions of the hydrodynamic theory previously developed. Quantitatively, experiment and theory also agree for small values of the source strength and high values of the Sommerfeld variable, and especially when the source is at the base of the bearing, the discrepancies becoming marked in regions where the approximations of the theory are inherently inadequate.