The Calculated Journal-Bearing Performance of Polymer-Thickened Lubricants

Abstract

The journal-bearing performance of polymer-thickened oils, whose viscosity is a function of the shearing stress, has been calculated using a digital computer. Under isothermal conditions the polymer-thickened oils gave lower friction coefficients and smaller minimum clearances than mineral oils of the same low-shear viscosity. However, even at the highest speeds and loads the influence of the polymer was still felt. The polymer oil did not act like the low-viscosity base oil from which it was formulated. There were also small differences in the shape of the pressure distribution, the attitude angle, oil flow rate and other parameters. When the temperature rise was taken into account, assuming adiabatic conditions, the higher viscosity index of the polymer oils tended to compensate for their “temporary viscosity loss” so that at the highest loads the polymer oils did not give smaller minimum clearances than comparable mineral oils.