Temporary Viscosity Loss and Its Relationship to Journal Bearing Performance

To determine the correlation between journal bearing performance and viscosity loss in a capillary, viscosities of eleven base oil-polymer blends were measured in a high-shear, pressurized capillary viscometer (High-Shear Capillary Viscometer, HSCV) at shear rates from 100 to nearly 1 000 000 s^-1. Although low-shear kinematic viscosities do not predict bearing performance differences found by Rosenberg with the same oil blends, HSCV viscosities at shear rates near 500 000 s^-1 correlate well with the bearing performance data. Differences among polymers are strongly related to molecular weight.