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Does the automotive industry need a standard engine test to measure journal bearing oil film thickness?
Author(s) -
Spearot James A.
Publication year - 1991
Publication title -
lubrication science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.632
H-Index - 36
eISSN - 1557-6833
pISSN - 0954-0075
DOI - 10.1002/ls.3010030405
Subject(s) - bearing (navigation) , viscometer , viscosity , automotive industry , materials science , measure (data warehouse) , mechanical engineering , shear rate , viscosity index , temperature dependence of liquid viscosity , composite material , computer science , engineering , thermodynamics , relative viscosity , physics , base oil , scanning electron microscope , database , artificial intelligence
Automotive manufacturers are dissatisfied with the high‐temperature portion of the SAE Viscosity Classification, J300. This dissatisfaction occurs because the low‐shear, 100°C conditions at which viscosities are specified are not representative of the conditions to which oils are subjected at operating temperatures in an engine. Recent efforts to modify the high‐temperature viscosity specifications have dealt primarily with developing correlations between oil film thickness measured in the journal bearings of operating engines and viscosity values measured at different high‐temperature, high‐shear rate conditions in laboratory viscometers. However, it has also been suggested that the industry develop a standard engine test for measuring journal bearing oil film thickness, and that oils be ‘classified’ on the basis of film thickness rather than viscosity. This paper reviews the methods which have been developed to measure bearing film thickness, the correlations which have been calculated between film thickness and viscosity, and the conclusions drawn from such efforts. Reasons for relying on high‐temperature, high‐shear viscosity specifications rather than a standard industry bearing film thickness test are offered. In addition, the merits and drawbacks of developing an industry bearing distress test are also discussed.