<div class="htmlview paragraph">An instrument is described which allows the load bearing capacity of a lubricant to be measured under pressures, shear rates and dynamic loadings typical of those found in automotive crankshaft journal bearings. Using Newtonian lubrication approximations, a theoretical analysis of the Journal Bearing Simulator has been carried out. Good agreement between theory and experiment is found demonstrating that the instrument is a fundamentally sound method for measuring lubricant load bearing capacity.</div>