Effective Viscosity of Polymer Thickened Oils in Gear Lubrication-Part II

Based on IAE gear OK load tests and Shell four ball wear tests of oils thickened with several polymers, it was concluded that the effective viscosity* in such concentrated contacts is governed by the partial permanent viscosity loss in the limited area of the contact. The fact that sheared oils, which were designed to have a finished permanent viscosity loss as would occur in such concentrated contacts, showed similar OK loads and wear scar diameters also proved the validity of the above mechanism as proposed in the previous paper(1)**.